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Disorders Usually First Evident in Infancy,
Childhood, or Adolescence
The disorders described in this chapter are those that usually appear and are first
evident in infancy, childhood, or adolescence. There is no arbitrary age limit here
that defines childhood and adolescence, and this section includes some
disorders characteristic of older adolescents, such as Bulimia Nervosa, which
may first appear in early adulthood.
In diagnosing an infant, child, or adolescent, the clinician could first consider
the diagnoses included in this section.
Because the essential features of Mood Disorders and Schizophrenia are the
same in children and adults, there are no special categories corresponding to
these disorders in this section of the classification. Therefore, if, for example, a
child or adolescent has an illness that meets the criteria for Major Depression,
Dysthymia, or Schizophrenia, these diagnoses should be given, regardless of the
person's age. (In some instances, age-specific associated features that apply to
infants, children, or adolescents are included in the text.)
Other diagnostic categories that are often appropriate for children and
adolescents are the following
Organic Mental Disorders Psychoactive Substance Use Disorders
Schizophrenia
Mood Disorders
Schizophreniform Disorder
Somatoform Disorders
Sexual Disorders
Adjustment Disorder
Psychological Factors Affecting Physical Condition
Personality Disorders
Adults should be given diagnoses from this section if, as infants, children, or
adolescents, they had symptoms of any of these disorders and the condition has
persisted. Examples include the residual phase of Attention-deficit Hyperactivity
Disorder and some cases of Conduct Disorder. Finally, some people may
develop in adulthood a disorder, such as Anorexia Nervosa, that is included in
this section because the disorder usually first develops in children or
adolescents.
Many children who come to clinical attention have problems that do not
warrant a diagnosis of a mental disorder, such as Parent-Child Problem,
Childhood or Adolescent Antisocial Behavior, or Other Specified Family
Circumstances.
Children who are psychologically, physically, or sexually abused may react in
a variety of ways. If the reaction constitutes a mental disorder, the following
categories should be considered: Reactive Attachment Disorder of Infancy or
Early Childhood, Post-traumatic Stress Disorder (generally for the older child),
and Adjustment Disorder.
DEVELOPMENTAL DISORDERS
The essential feature of this group of disorders is that the predominant
disturbance is in the acquisition of cognitive, language, motor, or social skills.
The disturbance may involve a general delay, as in Mental Retardation, or a
delay or failure to progress in a specific area of skill acquisition, as in Specific
Developmental Disorders, or multiple areas in which there are qualitative
distortions of normal development, as in the Pervasive Developmental
Disorders.
The course of the Developmental Disorders tends to be chronic, with some
signs of the disorder persisting in a stable form (without periods of remission or
exacerbation) into adult life. However, in many mild cases, adaptation or full
recovery may occur.
MENTAL RETARDATION
The essential features of this disorder are: (1) significantly subaverage
general intellectual functioning, accompanied by (2) significant deficits or
impairments in adaptive functioning, with (3) onset before the age of 18. The
diagnosis is made regardless of whether or not there is a coexisting physical or
other mental disorder.
General intellectual functioning.
General intellectual functioning is defined as an intelligence quotient (IQ or
IQ equivalent) obtained by assessment with one or more of the individually
administered general intelligence tests (e.g., Wechsler Intelligence Scale for
Children-Revised, Stanford Binet, Kaufman Assessment Battery for Children).
Significantly subaverage intellectual functioning is defined as an IQ of 70 or
below on an individually administered lQ test. Since any measurement is fallible,
an IQ score is generally thought to involve an error of measurement of
approximately five points; hence, an IQ of 70 is considered to represent a band
or zone of 65 to 75.
Treating the IQ with some flexibility permits inclusion in the Mental
Retardation category of people with IQs somewhat higher than 70 who exhibit
significant deficits in adaptive behavior. It also permits exclusion from the
diagnosis of those with lQs somewhat lower than 70 if the clinical judgment is
that there are no significant deficit or impairments in adaptive functioning. An IQ
level of 70 was chosen because most people with IQs below 70 require special
services and care, particularly during the school-age years.
The arbitrary IQ ceiling values are based on data indicating a positive
association between intelligence (as measured by IQ score) and adaptive
behavior at lower IQ levels. This association declines at the mild and moderate
levels of Mental Retardation.
Adaptive functioning. Adaptive functioning refers to the person's effectiveness
in areas such as social skills, communication, and daily living skills, and how well
the person meets the standards of personal independence and social
responsibility expected of his or her age by his or her cultural group. Adaptive
functioning in people with Mental Retardation (and in people without Mental
Retardation) is influenced by personality characteristics, motivation, education,
and social and vocational opportunities. Adaptive behavior is more likely to
improve with remedial efforts than is IQ, which tends to remain more stable.
Useful scales have been designed to quantify adaptive functioning or
behavior (e.g., the Vineland Adaptive Behavior Scales, American Association of
Mental Deficiency Adaptive Behavior Scale). Ideally, these scales should be
used in conjunction with a clinical judgment of general adaptation. If these scales
are not available, clinical judgment of general adaptation alone, the person's age
and cultural background being taken into consideration, may suffice.
Associated features. When a specific physical disorder is associated with
Mental Retardation, the features of the physical disorder will, of course, also be
present. For example, in cases of Mental Retardation associated with Down
syndrome, the physical features of Down syndrome will be present. The more
severe the Mental Retardation (especially if it is severe or profound), the greater
the likelihood of associated abnormalities in one or more systems, such as the
neurologic (e.g., seizures), Neuromuscular, visual, auditory, and cardiovascular
systems. These abnormalities may further impair the person's adaptive
functioning. It should be noted, however, that in Mental Retardation associated
with Down syndrome,, social skills are likely to be higher than would he expected
by the level of Mental Retardation.
Behavioral symptoms commonly seen in Mental Retardation include
passivity, dependency, low self-esteem, low frustration tolerance,
aggressiveness, poor impulse control, and stereotyped self-stimulating and
self-injurious behavior. In some cases, these behaviors may be learned and
conditioned by environmental factors; in other cases, they may be linked to an
underlying physical disorder, such as self-injurious behavior associated with
Lesch-Nyhan syndrome. At the present time there is no satisfactory
subclassification of behavioral symptoms associated with Mental Retarda�
tion.
The prevalence of other mental disorders is at least three or four times
greater among people with Mental Retardation than in the general population.
Particularly common as associated diagnoses are Pervasive Developmental
Disorders, Attention-deficit Hyperactivity Disorder, and Stereotypy/Habit
Disorder.
Age at onset. By definition, Mental Retardation requires that onset be before
age 18. When a similar clinical picture develops for the first time after the age of
18, the syndrome is a Dementia, not Mental Retardation. An example would be
a 19-year-old with previously normal intelligence who developed the clinical
picture of Mental Retardation after sustaining brain damage in an automobile
accident. However, a Dementia can be superimposed on previously existing
Mental Retardation. An example would be a child with mild Mental Retardation
whose functioning deteriorates after sustaining brain damage in an automobile
accident. When the clinical picture develops before the age of 18 in a person
who previously had normal intelligence, Mental Retardation and Dementia should
both be diagnosed.
Course. The course of Mental Retardation is a function of both biologic factors,
such as an underlying etiologic physical disorder, and environmental factors,
such as educational and other opportunities, environmental stimulation, and
appropriateness of management. If the underlying physical abnormality is static
(as in fragile X syndrome), the course of the Mental Retardation is variable: with
good environmental influences, functioning may improve; with poor
environmental influences, it may deteriorate. If the underlying physical
abnormality is progressive (as in a lipid storage disorder), functioning will tend to
deteriorate, although with good environmental influences, the deterioration may
proceed more slowly.
As a rule, children with Mental Retardation are no longer admitted to
custodial-type institutions, and adults with Mental Retardation are only rarely thus
institutionalized. As a result, the prognosis for Mental Retardation has improved
dramatically in recent years. The majority of people with Mental Retardation now
adapt well to life in the community, within the limits of their handicap.
Some people with mild Mental Retardation develop good adaptive skills and
maintain jobs in competitive employment. For such people the diagnosis of
Mental Retardation may no longer be justified, even if it was appropriate when
they were of school age and their intellectual deficits limited their academic
functioning.
Impairment. By definition, there is always impairment in adaptive
functioning. The degree of impairment is correlated with the level of general
intellectual functioning, the presence of associated features and complications,
and educational and other environmental opportunities.
Complications. Other mental disorders, such as Depressive Disorders,
psychotic disorders, and Personality Disorders, may be complications. The
diagnosis of other mental disorders may be difficult because of cognitive and
language deficits that may mask the clinical manifestations of the other disorders.
For example, a person with Mental Retardation may have difficulty verbalizing
depressive thoughts and feelings. For nonverbal people with Mental Retardation,
the nonspecific diagnostic categories (e.g., Depressive Disorder Not Otherwise
Specified), rather than the specific ones, may have to be employed.
People with Mental Retardation are particularly vulnerable to exploitation by
others, such as being physically and sexually abused or being denied rights and
opportunities.
Etiologic factors and familial pattern. Etiologic factors may be primarily
biologic, psychosocial, or a combination of both. In approximately 30%-40% of
the cases seen in clinical settings, no clear etiology can be determined despite
extensive evaluation efforts. The following are the major causative factors in the
remaining cases:
(1) hereditary factors (in approximately 5% of cases), such as inborn
errors of metabolism (e.g., Tay-Sachs disease), other single-gene abnormalities
(e.g., tuberous sclerosis), and chromosomal aberrations (e.g., translocation
Down syndrome);
(2) early alterations of embryonic development (in approximately 30%),
such as chromosomal changes (e.g., trisomy 21 syndrome), prenatal damage
due to toxins (e.g., maternal alcohol consumption, infections) or unknown
causes;
(3) pregnancy and per natal problems (in approximately 10%), such as
fetal malnutrition, prematurely, hypoxia, trauma;
(4) physical disorders acquired in childhood (in approximately 5%),
such as infections, traumas, and lead poisoning;
(5) environmental influences and mental disorders (in approximately
15%-20%), such as deprivation of nurturance and of social, linguistic, and other
stimulation, and complications of severe mental disorders (e.g., a drop in
adaptive functioning in a person with a borderline level IQ following early-onset
Schizophrenia).
The prevalence of Mental Retardation due to known biologic factors is similar
among children of upper and lower socioeconomic classes, except that certain
etiologic logic factors are linked to lower socioeconomic status, such as lead
poisoning and premature births. In cases in which no specific biologic causation
can be identified, lower socioeconomic classes are overrepresented, and the
Mental Retardation is usually milder (but all degrees of severity are
represented).
The age at which a diagnosis of Mental Retardation is first made in a person
depends on the degree of its severity and whether a physical disorder with
characteristic phenotypic features is present. thus, children with Severe Mental
Retardation and children with Down syndrome are diagnosed earlier than
children with mild retardation of unknown cause.
Prevalence. Recent studies suggest that at any one point in time, the
prevalence rate of Mental Retardation is approximately 1%.
Sex ratio. Mental Retardation is more common among males, with a
male:female ratio of approximately 1.5:1.
Differential diagnosis. The diagnosis of Mental Retardation should be
made when the criteria are met, regardless of the presence of another diagnosis.
In Specific Developmental Disorders (unassociated with Mental Retardation)
there is a delay or failure of development in a specific area, such as reading or
language, but in other areas of development the child is developing normally. in
contrast, a child with Mental Retardation always has general delays in
development in many areas.
In Pervasive Developmental Disorders there is qualitative impairment in
the development of rec iprocal social interaction, in the development of verbal and
nonverbal communication skills, and in the development of imaginative activity.
These abnormalities are not normal for any stage of development, whereas in
Mental Retardation (unassociated with ano ther disord er) there are generalized
delays in development, but the person behaves as if he or she were passing
through an earlier normal developmental stage.
Mental Retardation may, however, coexist with Specific Developmental
Disorders (e.g., a severe language deficit out of proportion to other areas of
development in an person with Mild Mental Retardation). People with a
Pervasive Developmental Disorder also frequently have Mental Retardation.
The V code Borderline intellectual Functioning is given when there is
borderline intellectual functioning, which generally is in the IQ range of 71 to 84,
and the diagnosis of Mental Retardation is not warranted. Differentiating Mild
Mental Retardation from Borderline Intellectual Functioning requires careful
consideration of all available information, including psychological test
scores.
Diagnostic criteria for Mental Retardation
A. Significantly subaverage general intellectual functioning: an IQ of 70 or
below on an individually administered IQ test (for inf ants, a c linical judg ment
of significantly subaverage intellectual functioning, since available
intelligence tests do not yield numerical lQ values)
B. Concurrent deficits or impairments in adaptive functioning, i.e., the person's
effectiveness in meeting the standards expected for his or her age by his or
her cultural group in areas such as social skills and responsibility,
communication, daily living skills, personal independence, and
self-sufficiency.
C. Onset before the age of 18.
Degrees of severity. There are four degrees of severity, reflecting the
degree of intellectual impairment: Mild, Moderate, Severe, and Profound. IQ
levels to be used as guides in distinguishing the four degrees of severity are:
Degree of severity
Mild
Moderate
Severe
Profound
IQ
50-55 to approx. 70
35-40 to 50-55
20-25 to 35-40
Below 20 or 25
Mild Mental Retardation
Mild Mental Retardation is roughly equivalent to what used to be refereed to
as the educational category of "educable." This group constitutes the largest
segment of those with the disorder about 85%. People with this level of Mental
Retardation typically develop social and communication skills during the
preschool years (ages 0-5), have minimal impairment in sensorimotor areas, and
often are not distinguishable from normal children until a later age. By their late
teens they can acquire academic skills up to approximately sixth-grade level;
during their adult years, they usually achieve social and vocational skills
adequate for minimum self-support, but may need guidance and assistance
when under unusual social or economic stress. At the present time, virtually all
people with Mild Mental Retardation can live successfully in the community,
independently or in supervised apartments or group homes (unless there is an
associated disorder that makes this impossible).
Moderate Mental Retardation
Moderate Mental Retardation is roughly equivalent to what used to be referred to
as the educational category of "trainable." This former term should not be used
since it wrongly implies that people with Moderate Mental Retardation cannot
benefit from educational programs. This group constitutes 10% of the entire
population of people with Mental Retardation.
Those with this level of Mental Retardation can talk or learn to communicate
during the preschool years. They may profit from vocational training and, with
moderate supervision, can take care of themselves. They can profit from training
in social and occupational skills, but are unlikely to progress beyond the second
grade level in academic subjects. They may learn to travel independently in
familiar places. During adolescence, their difficulties in recognizing social
conventions may interfere with peer relationships. In their adult years, they may
be able to contribute to their own support by performing unskilled or semiskilled
work under close supervision in sheltered workshops or in the competitive job
market. They need supervision and guidance when under stress. They adapt well
to life in the community, but usually in supervised group homes.
Severe Mental Retardation
This group constitutes 3%-4% of people with Mental Retardation. During the pre�
school period, they display poor motor development, and they acquire little or no
communicative speech. During the school-age period, they may learn to talk, and
can be trained in elementary hygiene skills. They profit to only a limited extent
from instruction in pre-academic subjects, such as familiarity with the alphabet
and simple counting, but can master skills such as learning sight-reading of
some "survival" words, such as "men" and "women" and "stop." In their adult
years, they may be able to perform simple tasks under close supervision. Most
adapt well to life in the community, in group homes or with their families, unless
they have an associated handicap that requires specialized nursing or other
care.
Profound Mental Retardation
This group constitutes approximately 1 %-2% of people with Mental Retardation.
During the early years, these children display minimal capacity for sensorimotor
functioning. A highly structured environment, with constant aid and supervision,
and an individualized relationship with a caregiver are required for optimal
development. Motor development and self-care and communication skills may
improve if appropriate training is provided. Currently, many of these people live in
the community, in group homes, intermediate care facilities, or with their families.
Most attend day programs, and some can perform simple tasks under close
supervision in a sheltered workshop.
Unspecified Mental Retardation
This category should be used when there is a strong presumption of Mental
Retardation but the person is untestable by standard intelligence tests. This may
be the case when children, adolescents, or adults are too impaired or
uncooperative to be tested. It may also be the case with infants when there is a
clinical judgment of significantly subaverage intellectual functioning, but the
available tests, such as the Bayley, Cattle, and others, do not yield IQ values. In
general, the younger the age, the more difficult it is to make a diagnosis of
Mental Retardation, except for those with profound impairment.
This category should not be used when the intellectual level is presumed to
be above 70
PERVASIVE DEVELOPMENTAL DISORDERS
The disorders in this subclass are characterized by qualitative impairment in the
development of reciprocal social interaction, in the development of verbal and
nonverbal communication skills, and in imaginative activity. often there is a
markedly restricted repertoire of activities and interests, which frequently are
stereotyped and repetitive. The severity and expression of these impairments
vary greatly from child to child.
These disorders frequently are associated with a variety of other conditions.
Distortions or delays in development are common in the following areas;
intellectual skills, as measured by standardized intelligence tests (in most cases
there is an associated diagnosis of Mental Retardation); comprehension of
meaning in language and the production of speech (in addition to problems in the
social use of speech for reciprocal communication); posture and movements;
patterns of eating, drinking, or sleeping; and responses to sensory input
Various diagnostic terms, including Atypical Development, Symbiotic Psychosis,
Childhood Psychosis, Childhood Schizophrenia, and others, have been used to
describe these disorders in the past. However, clinical descriptions have typically
over-lapped; and apart from Autistic Disorder, no generally recognized subtypes
have yet emerged. Though some early investigators suggested that these
disorders were continuous with adult psychoses (e.g., Schizophrenia),
substantial research suggests that they are unrelated to the adult psychoses. For
that reason, and the difficulties of assessing psychosis in childhood, the term
psychosis has not been used here to label this group of disorders: Pervasive
Developmental Disorders is used because it describes most accurately the core
clinical disturbance in which many basic areas of psychological development are
affected at the same time and to a even degree
This classification recognizes only one subgroup of the general category
Pervasive Developmental Disorders: Autistic Disorder, also known as Infatile
Autism and Kanner's syndrome. The evidence suggests, however, that this
disorder is merely the most severe and prototypical form of the general category
Pervasive Developmental Disorders. Cases that meet the general description of
a Pervasive Developmental Disorder but not the specific criteria for Autistic
Disorder are diagnosed as Pervasive Developmental Disorder Not Otherwise
Specified (PDDNOS). Whereas in clinical settings Autistic Disorder is more
commonly seen than PDDNOS, studies in England and the United States, using
criteria similar to those in this manual, suggest that PDDNOS is more common
than Autistic Disorder in the general population.
Qualitative impairment in reciprocal social interaction.
This impairment is characterized by failure to develop interpersonal
relationships and by lack of responsiveness to, or interest in, people. In infancy
these deficiencies may be manifested by a failure to cuddle, by lack of eye
contact and facial responsiveness, and by indifference or aversion to affection
and physical contact. As a result, parents often suspect that the child is deaf (not
realizing that deafness, by itself, is rarely associated with extreme social
indifference). Adults may be treated as interchangeable, or the child may cling
mechanically to a specific person. The attachment of some toddlers to their
parent(s) may be bizarre, e.g., a child may seem to recognize his mother
primarily on the basis of smell.
In some cases the disorder apparently follows a period of normal, or
relatively normal, social development in the first years of life; but even in early
childhood, there is invariably failure to develop cooperative play, imaginative
play, and friendships. As the child grows older, however, greater awareness of,
and social interest in, others may develop. Some of the least handicapped may
eventually reach a stage in which they can become passively involved in other
children's games or physical play, or include other children as "mechanical aids"
in their own stereotyped activities.
Impairment in communication and imaginative activity.
Impairment in communication includes both verbal and nonverbal skills.
Language may be totally absent. When it develops, it is often characterized by:
immature but essentially normal grammatical structure; delayed or immediate
echolalia; pronoun reversals (e.g., use of "you" when -i- is intended); inability to
name objects; inability to use abstract terms; idiosyncratic utterances whose
meaning is clear only to those who are familiar with the child's past experiences
(termed metaphorical language by Kanner); and abnormal speech melody, such
as questionlike rises at ends of statements or monotonous tone of voice.
Nonverbal communication, e.g., facial expression and gesture, is absent or
minimal or, if present, is socially inappropriate in form.
Even when there are no gross abnormalities in language skills,
communication is often impaired by circumstantially and irrelevancies. A
disturbance in the comprehension of language may be evidenced by an inability
to understand jokes, puns, and sarcasm.
Impairment in imaginative activity may include absence symbolic or fantasy
play with toys or absence of playacting of adult roles, or imaginative activity may
be restricted in content and repetitive and stereotyped in form. This is in marked
contrast to the varied content of normal "pretend" play. For example, a child with
the disorder may insist on lining up an exact number of playthings in the same
manner over and over again, or repetitively mimic the actions of a television
character.
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In diagnosing an infant, child, or adolescent, the clinician could first consider the diagnoses included in this section.
Because the essential features of Mood Disorders and Schizophrenia are the same in children and adults, there are no special categories corresponding to these disorders in this section of the classification. Therefore, if, for example, a child or adolescent has an illness that meets the criteria for Major Depression, Dysthymia, or Schizophrenia, these diagnoses should be given, regardless of the person's age. (In some instances, age-specific associated features that apply to infants, children, or adolescents are included in the text.)
Other diagnostic categories that are often appropriate for children and adolescents are the following
Organic Mental Disorders Psychoactive Substance Use Disorders
Schizophrenia
Mood Disorders
Schizophreniform Disorder
Somatoform Disorders
Sexual Disorders
Adjustment Disorder
Psychological Factors Affecting Physical Condition
Personality Disorders
Adults should be given diagnoses from this section if, as infants, children, or adolescents, they had symptoms of any of these disorders and the condition has persisted. Examples include the residual phase of Attention-deficit Hyperactivity Disorder and some cases of Conduct Disorder. Finally, some people may develop in adulthood a disorder, such as Anorexia Nervosa, that is included in this section because the disorder usually first develops in children or adolescents.
Many children who come to clinical attention have problems that do not warrant a diagnosis of a mental disorder, such as Parent-Child Problem, Childhood or Adolescent Antisocial Behavior, or Other Specified Family Circumstances.
Children who are psychologically, physically, or sexually abused may react in a variety of ways. If the reaction constitutes a mental disorder, the following categories should be considered: Reactive Attachment Disorder of Infancy or Early Childhood, Post-traumatic Stress Disorder (generally for the older child), and Adjustment Disorder.
DEVELOPMENTAL DISORDERS
The essential feature of this group of disorders is that the predominant disturbance is in the acquisition of cognitive, language, motor, or social skills. The disturbance may involve a general delay, as in Mental Retardation, or a delay or failure to progress in a specific area of skill acquisition, as in Specific Developmental Disorders, or multiple areas in which there are qualitative distortions of normal development, as in the Pervasive Developmental Disorders.
The course of the Developmental Disorders tends to be chronic, with some signs of the disorder persisting in a stable form (without periods of remission or exacerbation) into adult life. However, in many mild cases, adaptation or full recovery may occur.
MENTAL RETARDATION
The essential features of this disorder are: (1) significantly subaverage general intellectual functioning, accompanied by (2) significant deficits or impairments in adaptive functioning, with (3) onset before the age of 18. The diagnosis is made regardless of whether or not there is a coexisting physical or other mental disorder.
General intellectual functioning.
General intellectual functioning is defined as an intelligence quotient (IQ or IQ equivalent) obtained by assessment with one or more of the individually administered general intelligence tests (e.g., Wechsler Intelligence Scale for Children-Revised, Stanford Binet, Kaufman Assessment Battery for Children). Significantly subaverage intellectual functioning is defined as an IQ of 70 or below on an individually administered lQ test. Since any measurement is fallible, an IQ score is generally thought to involve an error of measurement of approximately five points; hence, an IQ of 70 is considered to represent a band or zone of 65 to 75.
Treating the IQ with some flexibility permits inclusion in the Mental Retardation category of people with IQs somewhat higher than 70 who exhibit significant deficits in adaptive behavior. It also permits exclusion from the diagnosis of those with lQs somewhat lower than 70 if the clinical judgment is that there are no significant deficit or impairments in adaptive functioning. An IQ level of 70 was chosen because most people with IQs below 70 require special services and care, particularly during the school-age years.
The arbitrary IQ ceiling values are based on data indicating a positive association between intelligence (as measured by IQ score) and adaptive behavior at lower IQ levels. This association declines at the mild and moderate levels of Mental Retardation.
Adaptive functioning. Adaptive functioning refers to the person's effectiveness in areas such as social skills, communication, and daily living skills, and how well the person meets the standards of personal independence and social responsibility expected of his or her age by his or her cultural group. Adaptive functioning in people with Mental Retardation (and in people without Mental Retardation) is influenced by personality characteristics, motivation, education, and social and vocational opportunities. Adaptive behavior is more likely to improve with remedial efforts than is IQ, which tends to remain more stable.
Useful scales have been designed to quantify adaptive functioning or behavior (e.g., the Vineland Adaptive Behavior Scales, American Association of Mental Deficiency Adaptive Behavior Scale). Ideally, these scales should be used in conjunction with a clinical judgment of general adaptation. If these scales are not available, clinical judgment of general adaptation alone, the person's age and cultural background being taken into consideration, may suffice.
Associated features. When a specific physical disorder is associated with Mental Retardation, the features of the physical disorder will, of course, also be present. For example, in cases of Mental Retardation associated with Down syndrome, the physical features of Down syndrome will be present. The more severe the Mental Retardation (especially if it is severe or profound), the greater the likelihood of associated abnormalities in one or more systems, such as the neurologic (e.g., seizures), Neuromuscular, visual, auditory, and cardiovascular systems. These abnormalities may further impair the person's adaptive functioning. It should be noted, however, that in Mental Retardation associated with Down syndrome,, social skills are likely to be higher than would he expected by the level of Mental Retardation.
Behavioral symptoms commonly seen in Mental Retardation include passivity, dependency, low self-esteem, low frustration tolerance, aggressiveness, poor impulse control, and stereotyped self-stimulating and self-injurious behavior. In some cases, these behaviors may be learned and conditioned by environmental factors; in other cases, they may be linked to an underlying physical disorder, such as self-injurious behavior associated with Lesch-Nyhan syndrome. At the present time there is no satisfactory subclassification of behavioral symptoms associated with Mental Retarda� tion.
The prevalence of other mental disorders is at least three or four times greater among people with Mental Retardation than in the general population. Particularly common as associated diagnoses are Pervasive Developmental Disorders, Attention-deficit Hyperactivity Disorder, and Stereotypy/Habit Disorder.
Age at onset. By definition, Mental Retardation requires that onset be before age 18. When a similar clinical picture develops for the first time after the age of 18, the syndrome is a Dementia, not Mental Retardation. An example would be a 19-year-old with previously normal intelligence who developed the clinical picture of Mental Retardation after sustaining brain damage in an automobile accident. However, a Dementia can be superimposed on previously existing Mental Retardation. An example would be a child with mild Mental Retardation whose functioning deteriorates after sustaining brain damage in an automobile accident. When the clinical picture develops before the age of 18 in a person who previously had normal intelligence, Mental Retardation and Dementia should both be diagnosed.
Course. The course of Mental Retardation is a function of both biologic factors, such as an underlying etiologic physical disorder, and environmental factors, such as educational and other opportunities, environmental stimulation, and appropriateness of management. If the underlying physical abnormality is static (as in fragile X syndrome), the course of the Mental Retardation is variable: with good environmental influences, functioning may improve; with poor environmental influences, it may deteriorate. If the underlying physical abnormality is progressive (as in a lipid storage disorder), functioning will tend to deteriorate, although with good environmental influences, the deterioration may proceed more slowly.
As a rule, children with Mental Retardation are no longer admitted to custodial-type institutions, and adults with Mental Retardation are only rarely thus institutionalized. As a result, the prognosis for Mental Retardation has improved dramatically in recent years. The majority of people with Mental Retardation now adapt well to life in the community, within the limits of their handicap.
Some people with mild Mental Retardation develop good adaptive skills and maintain jobs in competitive employment. For such people the diagnosis of Mental Retardation may no longer be justified, even if it was appropriate when they were of school age and their intellectual deficits limited their academic functioning.
Impairment. By definition, there is always impairment in adaptive functioning. The degree of impairment is correlated with the level of general intellectual functioning, the presence of associated features and complications, and educational and other environmental opportunities.
Complications. Other mental disorders, such as Depressive Disorders, psychotic disorders, and Personality Disorders, may be complications. The diagnosis of other mental disorders may be difficult because of cognitive and language deficits that may mask the clinical manifestations of the other disorders. For example, a person with Mental Retardation may have difficulty verbalizing depressive thoughts and feelings. For nonverbal people with Mental Retardation, the nonspecific diagnostic categories (e.g., Depressive Disorder Not Otherwise Specified), rather than the specific ones, may have to be employed.
People with Mental Retardation are particularly vulnerable to exploitation by others, such as being physically and sexually abused or being denied rights and opportunities.
Etiologic factors and familial pattern. Etiologic factors may be primarily biologic, psychosocial, or a combination of both. In approximately 30%-40% of the cases seen in clinical settings, no clear etiology can be determined despite extensive evaluation efforts. The following are the major causative factors in the remaining cases:
(1) hereditary factors (in approximately 5% of cases), such as inborn errors of metabolism (e.g., Tay-Sachs disease), other single-gene abnormalities (e.g., tuberous sclerosis), and chromosomal aberrations (e.g., translocation Down syndrome);
(2) early alterations of embryonic development (in approximately 30%), such as chromosomal changes (e.g., trisomy 21 syndrome), prenatal damage due to toxins (e.g., maternal alcohol consumption, infections) or unknown causes;
(3) pregnancy and per natal problems (in approximately 10%), such as fetal malnutrition, prematurely, hypoxia, trauma;
(4) physical disorders acquired in childhood (in approximately 5%), such as infections, traumas, and lead poisoning;
(5) environmental influences and mental disorders (in approximately 15%-20%), such as deprivation of nurturance and of social, linguistic, and other stimulation, and complications of severe mental disorders (e.g., a drop in adaptive functioning in a person with a borderline level IQ following early-onset Schizophrenia).
The prevalence of Mental Retardation due to known biologic factors is similar among children of upper and lower socioeconomic classes, except that certain etiologic logic factors are linked to lower socioeconomic status, such as lead poisoning and premature births. In cases in which no specific biologic causation can be identified, lower socioeconomic classes are overrepresented, and the Mental Retardation is usually milder (but all degrees of severity are represented).
The age at which a diagnosis of Mental Retardation is first made in a person depends on the degree of its severity and whether a physical disorder with characteristic phenotypic features is present. thus, children with Severe Mental Retardation and children with Down syndrome are diagnosed earlier than children with mild retardation of unknown cause.
Prevalence. Recent studies suggest that at any one point in time, the prevalence rate of Mental Retardation is approximately 1%.
Sex ratio. Mental Retardation is more common among males, with a male:female ratio of approximately 1.5:1.
Differential diagnosis. The diagnosis of Mental Retardation should be made when the criteria are met, regardless of the presence of another diagnosis. In Specific Developmental Disorders (unassociated with Mental Retardation) there is a delay or failure of development in a specific area, such as reading or language, but in other areas of development the child is developing normally. in contrast, a child with Mental Retardation always has general delays in development in many areas.
In Pervasive Developmental Disorders there is qualitative impairment in the development of rec iprocal social interaction, in the development of verbal and nonverbal communication skills, and in the development of imaginative activity. These abnormalities are not normal for any stage of development, whereas in Mental Retardation (unassociated with ano ther disord er) there are generalized delays in development, but the person behaves as if he or she were passing through an earlier normal developmental stage.
Mental Retardation may, however, coexist with Specific Developmental Disorders (e.g., a severe language deficit out of proportion to other areas of development in an person with Mild Mental Retardation). People with a Pervasive Developmental Disorder also frequently have Mental Retardation.
The V code Borderline intellectual Functioning is given when there is borderline intellectual functioning, which generally is in the IQ range of 71 to 84, and the diagnosis of Mental Retardation is not warranted. Differentiating Mild Mental Retardation from Borderline Intellectual Functioning requires careful consideration of all available information, including psychological test scores.
Diagnostic criteria for Mental Retardation
A. Significantly subaverage general intellectual functioning: an IQ of 70 or below on an individually administered IQ test (for inf ants, a c linical judg ment of significantly subaverage intellectual functioning, since available intelligence tests do not yield numerical lQ values)
B. Concurrent deficits or impairments in adaptive functioning, i.e., the person's effectiveness in meeting the standards expected for his or her age by his or her cultural group in areas such as social skills and responsibility, communication, daily living skills, personal independence, and self-sufficiency.
C. Onset before the age of 18.
Degrees of severity. There are four degrees of severity, reflecting the degree of intellectual impairment: Mild, Moderate, Severe, and Profound. IQ levels to be used as guides in distinguishing the four degrees of severity are:
Degree of severity
Mild
Moderate
Severe
Profound
IQ
50-55 to approx. 70
35-40 to 50-55
20-25 to 35-40
Below 20 or 25
Mild Mental Retardation
Mild Mental Retardation is roughly equivalent to what used to be refereed to as the educational category of "educable." This group constitutes the largest segment of those with the disorder about 85%. People with this level of Mental Retardation typically develop social and communication skills during the preschool years (ages 0-5), have minimal impairment in sensorimotor areas, and often are not distinguishable from normal children until a later age. By their late teens they can acquire academic skills up to approximately sixth-grade level; during their adult years, they usually achieve social and vocational skills adequate for minimum self-support, but may need guidance and assistance when under unusual social or economic stress. At the present time, virtually all people with Mild Mental Retardation can live successfully in the community, independently or in supervised apartments or group homes (unless there is an associated disorder that makes this impossible).
Moderate Mental Retardation
Moderate Mental Retardation is roughly equivalent to what used to be referred to as the educational category of "trainable." This former term should not be used since it wrongly implies that people with Moderate Mental Retardation cannot benefit from educational programs. This group constitutes 10% of the entire population of people with Mental Retardation.
Those with this level of Mental Retardation can talk or learn to communicate during the preschool years. They may profit from vocational training and, with moderate supervision, can take care of themselves. They can profit from training in social and occupational skills, but are unlikely to progress beyond the second grade level in academic subjects. They may learn to travel independently in familiar places. During adolescence, their difficulties in recognizing social conventions may interfere with peer relationships. In their adult years, they may be able to contribute to their own support by performing unskilled or semiskilled work under close supervision in sheltered workshops or in the competitive job market. They need supervision and guidance when under stress. They adapt well to life in the community, but usually in supervised group homes.
Severe Mental Retardation
This group constitutes 3%-4% of people with Mental Retardation. During the pre� school period, they display poor motor development, and they acquire little or no communicative speech. During the school-age period, they may learn to talk, and can be trained in elementary hygiene skills. They profit to only a limited extent from instruction in pre-academic subjects, such as familiarity with the alphabet and simple counting, but can master skills such as learning sight-reading of some "survival" words, such as "men" and "women" and "stop." In their adult years, they may be able to perform simple tasks under close supervision. Most adapt well to life in the community, in group homes or with their families, unless they have an associated handicap that requires specialized nursing or other care.
Profound Mental Retardation
This group constitutes approximately 1 %-2% of people with Mental Retardation. During the early years, these children display minimal capacity for sensorimotor functioning. A highly structured environment, with constant aid and supervision, and an individualized relationship with a caregiver are required for optimal development. Motor development and self-care and communication skills may improve if appropriate training is provided. Currently, many of these people live in the community, in group homes, intermediate care facilities, or with their families. Most attend day programs, and some can perform simple tasks under close supervision in a sheltered workshop.
Unspecified Mental Retardation
This category should be used when there is a strong presumption of Mental Retardation but the person is untestable by standard intelligence tests. This may be the case when children, adolescents, or adults are too impaired or uncooperative to be tested. It may also be the case with infants when there is a clinical judgment of significantly subaverage intellectual functioning, but the available tests, such as the Bayley, Cattle, and others, do not yield IQ values. In general, the younger the age, the more difficult it is to make a diagnosis of Mental Retardation, except for those with profound impairment.
This category should not be used when the intellectual level is presumed to be above 70
PERVASIVE DEVELOPMENTAL DISORDERS
The disorders in this subclass are characterized by qualitative impairment in the development of reciprocal social interaction, in the development of verbal and nonverbal communication skills, and in imaginative activity. often there is a markedly restricted repertoire of activities and interests, which frequently are stereotyped and repetitive. The severity and expression of these impairments vary greatly from child to child.
These disorders frequently are associated with a variety of other conditions. Distortions or delays in development are common in the following areas; intellectual skills, as measured by standardized intelligence tests (in most cases there is an associated diagnosis of Mental Retardation); comprehension of meaning in language and the production of speech (in addition to problems in the social use of speech for reciprocal communication); posture and movements; patterns of eating, drinking, or sleeping; and responses to sensory input
Various diagnostic terms, including Atypical Development, Symbiotic Psychosis, Childhood Psychosis, Childhood Schizophrenia, and others, have been used to describe these disorders in the past. However, clinical descriptions have typically over-lapped; and apart from Autistic Disorder, no generally recognized subtypes have yet emerged. Though some early investigators suggested that these disorders were continuous with adult psychoses (e.g., Schizophrenia), substantial research suggests that they are unrelated to the adult psychoses. For that reason, and the difficulties of assessing psychosis in childhood, the term psychosis has not been used here to label this group of disorders: Pervasive Developmental Disorders is used because it describes most accurately the core clinical disturbance in which many basic areas of psychological development are affected at the same time and to a even degree
This classification recognizes only one subgroup of the general category Pervasive Developmental Disorders: Autistic Disorder, also known as Infatile Autism and Kanner's syndrome. The evidence suggests, however, that this disorder is merely the most severe and prototypical form of the general category Pervasive Developmental Disorders. Cases that meet the general description of a Pervasive Developmental Disorder but not the specific criteria for Autistic Disorder are diagnosed as Pervasive Developmental Disorder Not Otherwise Specified (PDDNOS). Whereas in clinical settings Autistic Disorder is more commonly seen than PDDNOS, studies in England and the United States, using criteria similar to those in this manual, suggest that PDDNOS is more common than Autistic Disorder in the general population.
Qualitative impairment in reciprocal social interaction.
This impairment is characterized by failure to develop interpersonal relationships and by lack of responsiveness to, or interest in, people. In infancy these deficiencies may be manifested by a failure to cuddle, by lack of eye contact and facial responsiveness, and by indifference or aversion to affection and physical contact. As a result, parents often suspect that the child is deaf (not realizing that deafness, by itself, is rarely associated with extreme social indifference). Adults may be treated as interchangeable, or the child may cling mechanically to a specific person. The attachment of some toddlers to their parent(s) may be bizarre, e.g., a child may seem to recognize his mother primarily on the basis of smell.
In some cases the disorder apparently follows a period of normal, or relatively normal, social development in the first years of life; but even in early childhood, there is invariably failure to develop cooperative play, imaginative play, and friendships. As the child grows older, however, greater awareness of, and social interest in, others may develop. Some of the least handicapped may eventually reach a stage in which they can become passively involved in other children's games or physical play, or include other children as "mechanical aids" in their own stereotyped activities.
Impairment in communication and imaginative activity.
Impairment in communication includes both verbal and nonverbal skills. Language may be totally absent. When it develops, it is often characterized by: immature but essentially normal grammatical structure; delayed or immediate echolalia; pronoun reversals (e.g., use of "you" when -i- is intended); inability to name objects; inability to use abstract terms; idiosyncratic utterances whose meaning is clear only to those who are familiar with the child's past experiences (termed metaphorical language by Kanner); and abnormal speech melody, such as questionlike rises at ends of statements or monotonous tone of voice. Nonverbal communication, e.g., facial expression and gesture, is absent or minimal or, if present, is socially inappropriate in form.
Even when there are no gross abnormalities in language skills, communication is often impaired by circumstantially and irrelevancies. A disturbance in the comprehension of language may be evidenced by an inability to understand jokes, puns, and sarcasm.
Impairment in imaginative activity may include absence symbolic or fantasy play with toys or absence of playacting of adult roles, or imaginative activity may be restricted in content and repetitive and stereotyped in form. This is in marked contrast to the varied content of normal "pretend" play. For example, a child with the disorder may insist on lining up an exact number of playthings in the same manner over and over again, or repetitively mimic the actions of a television character.
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