▪ Autism and Related Disorders

BACKGROUND

Autism and the related disorders, also referred to as pervasive developmental disorders (PDDs) or autism spectrum disorders (ASDs), are a group of conditions characterized by significant social difficulties associated to varying degrees with communicative and behavioral problems. These conditions and their similarities and differences are listed in Table 4.1. Of these conditions, childhood autism (autistic disorder) has been the most extensively studied.

AUTISTIC DISORDER

Definition and Clinical Features

For a diagnosis of autism, characteristic problems in social interaction (autism) are required along with problems in communication and play as well as unusual restricted and repetitive interests. By definition, autism has its onset before age 3 years. Social problems are the central defining feature of autism and are weighted more heavily than other factors. International Classification of Diseases (ICD-10) criteria for the disorder are listed in Table 4.2. The condition was first described by Leo Kanner in 1943. Kanner noted that the children exhibited an apparently congenital inability to relate to others (autism) and were overly concerned with changes in the nonsocial environment. Hand flapping and other purposeless repetitive movements were common as were unusual aspects of language (when language developed at all). For example, Kanner mentioned that children with autism often repeated words or phrases, had trouble in pronoun use (referring to themselves in the third person), or had highly idiosyncratic language. For some years after his description, there was confusion about whether autism might represent the earliest form of childhood schizophrenia, but by the 1970s, it was clear that autism was a distinct condition. Similarly, there was speculation, particularly in the 1950s that parents might “cause” autism, such as through deviant parenting, but longitudinal data made it clear that autism was a strongly genetic, brain-based disorder.

Autism is an early-onset disorder. Most parents report concerns in the first year of the child’s life, and about 90% are worried by age 2 years. Common concerns include language delay, social deviance, or odd interests in the nonsocial environment (Table 4.3). Although
Kanner originally believed autism to be congenital but in a minority of cases (∽20%), it appears that the child develops normally or near normally for some months before development slows or actually regresses. This phenomenon has been difficult to study given the reliance on retrospective report, but prospective studies of at-risk populations (e.g., siblings) should help to clarify aspects of this issue.

TABLE 4.1 DIFFERENTIAL DIAGNOSTIC FEATURES OF AUTISM AND NONAUTISTIC PERVASIVE DEVELOPMENTAL DISORDERS

Feature	Autistic Disorder	Asperger Disorder	Rett’s Disorder	Childhood Disintegrative Disorder	Pervasive Developmental Disorder Not Otherwise Specified
Age at recognition (months)	0-36	Usually >36	5-30	>24	Variable
Sex ratio	M >F	M> F	F (?M)	M >F	M> F
Loss of skills	Variable	Usually not	Marked	Marked	Usually not
Social skills	Very poor	Poor	Varies with age	Very poor	Variable
Communication skills	Usually poor	Fair	Very poor	Very poor	Fair to good
Circumscribed Interests	Variable (Mechanical)	Marked (facts)	NA	NA	Variable
Family history of similar problems	Sometimes	Frequent	Not usually	No	Sometimes
Seizure disorder	Common	Uncommon	Frequent	Common	Uncommon
Head growth decelerates	No	No	Yes	No	No
IQ range	Severe MR to normal	Mild MR to normal	Severe MR	Severe MR	Severe MR to normal
Outcome	Poor to good	Fair to good	Very poor	Very poor	Fair to good
MR, mental retardation.
Adapted with permission from Volkmar, F. R., & Cohen, D. Nonautistic pervasive developmental disorders. In R. Michaels & J. Cavenar (Eds.), Psychiatry, p. 4. Lippincott-Raven Publishers.

The social disturbance in autism is very distinctive and is an essential diagnostic feature. It cannot be accounted for simply by associated cognitive problems or intellectual deficiency (see Chapter 5). Normally developing infants are profoundly social from the first months of life, but those with autism appear to have little interest in the human face or social interaction. Early social problems can include lack of engagement as expressed in a failure to respond to name, failure to engage in joint attention, and reduced babble or vocal play; these problems are the basis for many early screening procedures (Coonrod & Stone, 2005; Volkmar & Wiesner, 2009).

Delays in speech are a common presenting problem, and communication problems are a major defining feature of the condition. In the past, about half of individuals with autism had little or no expressive speech; with earlier diagnosis and treatment, that number has decreased. Children who do talk have speech remarkable for echolalia (immediate or delayed repetition of words or phrases), problems with a monotonic voice, idiosyncratic language, pronoun reversal, and major difficulties with the social use of language (pragmatics). These problems are very specific to autism (i.e., they are not like those of children with other kinds of language delay).

Behavioral problems are often striking with a marked contrast between the child’s lack of engagement with the social work (autism) and an overfocusing on aspects of the nonsocial environment (problems with change or preoccupations with sensory experiences). Often, the child is very sensitive to nonspeech sounds but much less responsive to speech. Stereotyped (purposeless and repetitive) movements are common and include hand flapping, toe walking, and so forth, and they may consume much of the child’s time. Unusual affective responses are also common, and play skills are often delayed.

TABLE 4.2 INTERNATIONAL CLASSIFICATION OF DISEASES (ICD-10) CRITERIA FOR CHILDHOOD AUTISM (F84.0)

Abnormal or impaired development is evident before the age of 3 years in at least one of the following areas:
1. Receptive or expressive language as used in social communication
2. The development of selective social attachments or of reciprocal social interaction; functional or symbolic play
A total of at least six symptoms from (1), (2), and (3) must be present, with at least two from (1) and at least one from each of (2) and (3).
1. Qualitative impairments in social interaction are manifest in at least two of the following areas:
  1. Failure adequately to use eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction
  2. Failure to develop (in a manner appropriate to mental age and despite ample opportunities) peer relationships that involve a mutual sharing of interests, activities, and emotions
  3. Lack of socioemotional reciprocity as shown by an impaired or deviant response to other people’s emotions; lack of modulation of behavior according to social context; or a weak integration of social, emotional, and communicative behaviors
  4. Lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g., a lack of showing, bringing, or pointing out to other people objects of interest to the individual)
2. Qualitative abnormalities communication as manifest in at least one of the following areas
  1. Delay in, or total lack of, development of spoken language that is not accompanied by an attempt to compensate through the use of gestures or mime as an alternative mode of communication (often preceded by a lack of communicative babbling)
  2. Relative failure to initiate or sustain conversational interchange (at whatever level of language skill is present) in which there is reciprocal responsiveness to the communications of the other person
  3. Stereotyped and repetitive use of language or idiosyncratic use of words or phrases
  4. Lack of varied spontaneous make-believe play or (when young) social imitative play
3. Restricted, repetitive, and stereotyped patterns of behavior, interests, and activities are manifested in at least one of the following:
  1. An encompassing preoccupation with one or more stereotyped and restricted patterns of interest that are abnormal in content or focus or one or more interests that are abnormal in their intensity and circumscribed nature, although not in their content or focus
  2. Apparently compulsive adherence to specific, nonfunctional routines or rituals
  3. Stereotyped and repetitive motor mannerisms that involve either hand or finger tapping or twisting or complex whole-body movements
  4. Preoccupations with part objects or nonfunctional elements of play materials (e.g., their odor, the feel of their surface, or the noise or vibration they generate)
The clinical picture is not attributable to the other varieties of pervasive developmental disorders; specific development disorder of receptive language (F80.2) with secondary socioemotional problems, reactive attachment disorder (F94.1), or disinhibited attachment disorder (F94.2); mental retardation (F70-F72) with some associated emotional or behavioral disorders; schizophrenia (F20) of unusually early onset; and Rett’s syndrome (F84.12)

Reprinted with permission from: World Health Organization. (1993) . Mental and Behavioural Disorders (including disorders of psychological development): Diagnostic Criteria for Research. ICD-10, pp. 147-149 (F84.0-F84.1). Geneva: WHO.

Kanner initially believed children with autism probably had normal cognitive potential because the children often did well with nonverbal tasks (puzzles). The trouble they had with verbal activities was initially “written off” to negativism, but over time, it became clear that children with autism often have areas of cognitive strength and areas of great weakness and that poor performance should not simply be ascribed to lack of motivation. By around age 5 years, IQ scores (even when scattered) become more stable and begin to predict outcome. As with language development, earlier detection and intervention may well be leading to improved cognitive outcomes, presumably by way of minimizing the negative effects of autism on learning. Occasionally, unusual islets of marked ability (e.g., rote memory or block design) may be present. A few persons with “autistic savant skills” exhibit remarkable abilities in drawing, musical ability, or calendar calculation, but these abilities are usually accompanied by major deficits in other areas (see Hermelin, 2001). Typically, nonverbal skills are stronger than verbal skills. It is fairly common for autism to be associated with overall cognitive skills in the intellectual deficient range, although it appears that with early intervention, this number is decreasing.

Epidemiology and Demography

Many different studies of epidemiology have been conducted. The median rate of autism (strictly defined) is about one per 800 to 1000 people. Rates of autism appear to have increased in recent years, although this change also parallels greater recognition of cases, particularly in more able children as well as changes in diagnostic criteria; the latter were, in part, intended to improve detection in more cognitively able individuals.

There is a male predominance (three to five times more common), although in lower IQ groups, this is much less pronounced, and in high IQ cases much more pronounced. Among individuals with normal cognitive levels, the male predominance may be 25 or more to 1. Although cultural and ethnic issues may impact treatment and, to some extent, case detection, autism generally is remarkably similar around the world. The early impression that autism was more likely in children of parents with more education and higher occupational status proved to be incorrect and probably reflected bias in referral source.

Etiology

A host of findings support the importance of neurobiology in autism (Table 4.4 and Figure 4.1). Individuals with autism exhibit an increased frequency of physical anomalies, persistent primitive reflexes, and various neurologic soft signs, as well as increased abnormalities on electroencephalograms (EEGs). Neurobiological theories have focused on different brain regions related to social information processing. Given that some aspects of functioning are spared, it does it seems likely that some areas must be less affected (e.g., occasionally, a person severely impaired with autism may have unusual musical or drawing ability or remarkable memory skills). Increasingly, sophisticated neuroimaging methods have suggested a possible role for the amygdala (e.g., in social perception and social thinking) as well as in portions of the frontal lobe and areas of the brain involved in social information processing. Overall brain size in autism becomes increased in those with autism in the first years of life, possibly suggesting abnormalities in neural connectivity. Studies using functional magnetic resonance imaging (fMRI) have shown underactivation of the fusiform gyrus during facial recognition tasks, an observation consistent with a large literature suggesting important differences in processing of faces and face-like stimuli (Figure 4.2). Difficulties with social information processing are also suggested by studies of eye tracking in individuals with autism showing that individuals with autism are more preoccupied with less socially salient aspects of scenes and may overfixate on less relevant details. Available postmortem studies have revealed some abnormalities in the limbic system and other areas involved in social cognition. Some animal models (e.g., based on lesion work) have been proposed.

TABLE 4.3 SIGNS OF AUTISM IN THE FIRST THREE YEARS OF LIFE

	Age 0-12 Months	Age 12-36 Months
Social	Limited ability to anticipate being picked up Low frequency of looking at people Limited interest in interactional games Limited affection toward familiar people Content to be left alone	Abnormal eye contact Limited social referencing Limited interest in other children Limited social smile Low frequency of looking at people Limited range of facial expression Limited sharing of affect or enjoyment
Play	Little interest in interactive games	Limited functional play No pretend play Limited motor imitation
Communication	Poor response to name (does not respond when called) Does not frequently look at objects held by others	Low frequency of verbal or nonverbal communication Failure to share interests (e.g., through pointing, sharing, giving, or showing) Poor response to name Failure to respond to communicative gestures (pointing, giving, showing) Use of other’s body as a tool (pulls hand to desired object without making eye contact, as if hand rather than person obtains object)
Restricted interests or behaviors	Mouths objects excessively Does not like to be touched	Unusual sensory behaviors Hyper- or hyposensitivity to sounds, texture, tastes, visual stimuli Inappropriate use of objects Repetitive interest or play

TABLE 4.4 NEUROBIOLOGICAL FINDINGS IN AUTISM

Increased (peripheral) serotonin levels

Persistent “primitive” reflexes

Increased head size (macrocephaly) in younger children

Changes in brain morphology or cytoarchitecture

Failure to activate fusiform face region

High rates of EEG abnormality or seizure disorder

EEG, electroencephalogram.

Reprinted from Volkmar, F. R., Lord, C., Klin, A., et al. (2007). Autism and the pervasive developmental disorders. In A. Martin & F. Volkmar (Eds.), Lewis’s Child and Adolescent Psychiatry: A Comprehensive Textbook, p. 386. Philadelphia: Lippincott, Williams & Wilkins.

FIGURE 4.1. Functional magnetic resonance imaging (MRI) abnormalities observed in autism spectrum disorder (ASD). A. These coronal MRI images show the cerebral hemispheres above, the cerebellum below, and a circle over the fusiform gyrus of the temporal lobe. The examples illustrate the frequent finding of hypoactivation of the fusiform gyrus to faces in an adolescent boy with ASD (right) compared with an age- and IQ-matched healthy control subject (left). Note the lack of face activation in the boy with ASD but average levels of nonface object activation. B. Schematic diagrams of the brain from lateral and medial orientations illustrating the broader array of brain areas found to be hypoactive in ASD during a variety of cognitive and perceptual tasks that are explicitly social in nature. Some evidence suggests that these areas are linked to form a “social brain” network. A = amygdale (hypoactive during a variety of social tasks); FG = fusiform gyrus, also known as the fusiform face area (hypoactive during perception of personal identity); IFG = inferior frontal gyrus (hypoactive during facial expression imitation); pSTS = posterior superior temporal sulcus (hypoactive during perception of facial expressions and eye gaze tasks); SFG = superior frontal gyrus (hypoactive during theory of mind tasks, i.e., when taking another person’s perspective). Reprinted from Volkmar, F., Lord, C., Klin, A., Schultz, R., Cook E. (2007). Autism and the Pervasive Developmental Disorders. In A. Martin & F. Volkmar (Eds.), Lewis’ Child and Adolescent Psychiatry, p. 387. Philadelphia: Lippincott Williams & Wilkins.

FIGURE 4.2. Successive visual focus of a typically developing individual (top left) and a person with autism (top right) shown a film clip of a young couple observing a frightening event. Whereas the individual who is typically developing focuses on the upper half of the face while the individual with autism is drawn to the mouth region. (Adapted and reprinted with permission from Klin, A., Jones, W., Schultz, R., Volkmar, F., & Cohen, D. (2002). Defining and quantifying the social phenotype in autism. American Journal of Psychiatry, 159:895-908.)

Only gold members can continue reading. Log In or Register to continue