Natural History, Prognostic Factors, Outcomes
Neuropsychology and Psychology of Autistic Disorder
References and Readings
Autistic disorder is a neurodevelopmental condition characterized by marked problems in social interaction, communication/play, and a set of unusual behaviors related to difficulties in tolerating change in the environment. The condition is of early onset. In most cases, it appears to be congenital, but perhaps in 20% of cases, a period of normal development is observed. The condition always appears before 3 years of age.
Autism was first described by Leo Kanner in 1943 (Kanner, 1943). Early controversy centered around the idea that autism might be a form of schizophrenia, but several lines of evidence suggest this is not the case. Changes in approaches to the definition of autism have occurred over time. Currently, both the American Psychiatric Association (DSM-IV-TR) (World Health Organization, 2000) and International (ICD-10) (World Health Organization, 1994) categorization systems define autistic disorder in essentially the same way. Autistic disorder is one or a group of conditions referred to as the pervasive developmental disorders (PDD). Other conditions in that class include Aspeger's disorder (in which marked social deficits are observed but some aspects of language are relatively preserved); Rett's disorder (a condition largely confined to girls and characterized by marked deterioration in motor, cognitive, and communicative skills); childhood disintegrative disorder (a rare condition where at least 2 years of normal development precedes the emergence of an 'autistic like' illness); and PDD-NOS (not otherwise specified) - a term reserved for cases exhibiting some features of autism but not the full syndrome.
A number of epidemiological studies have been undertaken around the world. Their interpretation is complicated by methodological differences including case finding and definitions used. The earliest studies reported rates on the order of 1 in 2,000 children, but more recent work suggests that a figure of 1 in 800-1,000 children is probably more accurate; the broader PDD spectrum is much more ambiguously defined and probably affects as many as 1 in 150 children (Fombonne, 2005). Much debate has centered on whether autism is increasing in frequency, but this issue remains unclear despite better methods of case detection and greater public awareness (Fombonne, 2005).
Rates of autistic disorder are typically three to four times higher in boys than in girls. The nature of this gender difference remains unclear, but speculation has centered on lower thresholds for expression of the condition in boys. An early impression of increased rates in better educated families appears to have been due to referral bias and has not been supported by later work.
Natural History, Prognostic Factors, Outcomes
Issues of diagnosis can be complex in infants as not all required features may be exhibited until around age 3 (Lord & Venter, 1992). After that time, diagnostic agreement increases substantially. By school age, autistic children become more sociable and may make significant academic gains although behavioral difficulties are prominent. During adolescence, some children make substantial gains and others lose skills. There is increased risk for development of epilepsy throughout the developmental period, with peak frequencies of new onset of epilepsy in early childhood and adolescence (Volkmar & Nelson, 1990).
The first studies of long-term outcome in children with autism were relatively pessimistic with only 2-3% of cases being able to achieve adult independence and self-sufficiency. Several factors appear to significantly improve prognosis: cases are now detected at early ages (when intervention may be more effective (National Research Council, 2001), and in many countries, educational services are now mandated). It appears that at least 20% or more of children with autism are capable of self-sufficiency in adulthood with at least another 15-20% able to be largely independent (Howlin, 2005). Major predictors of long-term outcome include nonverbal cognitive ability and the capacity to use language to communicate only around age 5. Adaptive abilities (the ability to cope with real world situations) are also important particularly as the person becomes older.
Neuropsychology and Psychology of Autistic Disorder
The first attempts to develop psychological models of autism centered around the notion that experiential factors might be involved. As evidence of brain involvement accumulated, theories shifted to focus on neurocognitvie and brain-based mechanisms.
Autistic Disorder. Figure 1 Visual focus of an autistic man and a normal comparison subject showing a film clip of a conversation. Typically developing person (top line) goes back and forth between the eyes in viewing a social scene, a high functioning person with autism goes back and forth between the mouths of the speakers. Reprinted with permission from Klin, Jones, Schultz, Volkmar, and Cohen (2002)
A focus on specific brain mechanisms was suggested by high rates of epilepsy and various neurological signs and symptoms (e.g., persistence of 'primitive' reflexes, delayed development of hand dominance, etc.). A range of abnormalities has been found in post-mortem studies. Lesion studies, e.g., of the amygdala or hippocampus, have produced some behaviors in monkeys similar to some of those seen in autism (Bachevalier, 1996). Other studies have focused on abnormalities in the cerebellum and overall brain size which appears to be increased in autism (Courchesne et al., 2004).
Other approaches have focused on specific neuropsychological processes. For example, Scultz and colleagues (Schultz et al., 2000) used fMRI techniques to demonstrate that more cognitively able individuals with autism process faces differently than typical controls; essentially they fail to activate the fusiform 'face area'. This observation is of interest given a large body of experimental work on differences in face processing in autism. Another work, e.g., using eye tracking technology, has revealed marked differences in scanning of the environment during social situations with more able individuals with autism tending to focus on the lower half of the face or objects, thus losing a considerable amount of social-affective information (Klin, Jones et al., 2002).
Beginning with the first twin studies of autism in the late 1970s a considerable body of work has strongly implicated genetic factors in the pathogenesis of autism. There are significantly increased rates of autism in identical twins and a higher risk in siblings both of autism and a range of other developmental problems. It appears that multiple genes are involved and several candidate genes are now being studied (Rutter, 2005).
Evaluation of the child with autism typically involves the efforts of members of several different disciplines - psychology, speech-language pathology, medicine, occupational and physical therapy, and special education. Goals for evaluation include clarification of the diagnosis and establishment of patterns of strengths/weakness that have implications for programming. Medical evaluations are indicated to look for conditions like Fragile X syndrome and seizures sometimes associated with autism (Volkmar et al., 1999).
Over the past decade a considerable body of work on intervention has become available. In its influential 2001 review a panel from the US National Research Council systematically evaluated ten treatment programs for younger children with autism. Although differing in some respects these programs shared many similarities including intensive individualized programs and structured teaching. Many, although not all, of these programs make extensive use of applied behavior analytic principles to teach basic skills which can then be expanded. Increasing social and communication abilities are important goals. Psychotherapy is not a mainstay of treatment but is sometimes used in older and more able individuals but is to be problem-focused in nature.
Drug treatments can be helpful relative to certain symptoms (e.g., agitation, stereotyped mannerisms) but do not address the core social deficit (Scahill & Martin, 2005).
References and Readings
- American Psychiatric Association. (2000). Diagnostic and statistical manual (4th ed., Text Rev.). Washington, DC: APA Press.
- Bachevalier, J. (1996). Brief report: Medial temporal lobe and autism: A putative animal model in primates. Journal of Autism and Developmental Disorders, 26(2), 217-220.
- Baron-Cohen, S. (1989). The theory of mind hypothesis of autism: A reply to Boucher [comment]. The British Journal of Disorders of Communication, 24(2), 199-200.
- Courchesne, E., Redcay, E., Kennedy, D. P. (2004). The autistic brain: Birth through adulthood. Current Opinion in Neurology, 17(4), 489-496.
- Fombonne, E. (2005). Epidemiological studies of pervasive developmental disorders. In F. R. Volkmar, A. Klin, R. Paul, & D. J. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (Vol. 1, pp. 42-69). Hoboken, NJ: Wiley.
- Happe, F. (2005). The weak central coherence account of autism. In F. R. Volkmar, A. Klin, R. Paul, & D. J. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (Vol. 1, pp. 640-649). Hoboken, NJ: Wiley.
- Howlin, P. (2005). Outcomes in autism spectrum disorders. In F. R. Volkmar, A. Klin, R. Paul, & D. J. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (Vol. 2, pp. 201-222). Hoboken, NJ: Wiley.
- Kanner, L. (1943). Autistic disturbances of affective contact. Nervous Child, 2, 217-250.
- Klin, A., Jones, W., Schultz, R., Volkmar, R., & Cohen, D. (2002). Visual fixation patterns during viewing of naturalistic social situations as predictors of social competence in individuals with autism. Archives of General Psychiatry, 59(9), 809-816.
- Klin, A., Jones, W., Schultz, R., & Volkmar, F. (2003). The enactive mind, or from actions to cognition: Lessons from autism. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 358(1430), 345-360.
- 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.
- Lord, C., & Venter, A. (1992). Outcome and follow-up studies of high-functioning autistic individuals. In E. Schopler & G. B. Mesibov (Eds.), High-functioning individuals with autism current issues in autism (Vol. xviii, pp. 187-199; 316). Plenum: NY.
- National Research Council. (2001). Educating young children with autism. Washington, DC: National Academy Press.
- Ozonoff, S., South, M., & Provencal, S. (2005). Executive functions. In F. R. Volkmar, A. Klin, R. Paul, & D. J. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (3rd edn, pp. 606-27). New York: Wiley.
- Rutter, M. (2005). Genetic influences and autism. In F. R. Volkmar, A. Klin, R. Paul, & D. J. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (Vol. 1, pp. 425-452). Hoboken, NJ: Wiley.
- Scahill, L., & Martin, A. (2005). Psychopharmacology. In F. R. Volkmar, A. Klin, R. Paul, & D. J. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (Vol. 2, pp. 1102-1122). Hoboken, NJ: Wiley.
- Schultz, R. T., Gauthier, I., Klin, A., Fulbright, R. K., Anderson, A. W., Volkmar, F. (2000). Abnormal ventral temporal cortical activity during face discrimination among individuals with autism and Asperger syndrome. Archives of General Psychiatry, 57(4), 331-340.
- Volkmar, F., Cook, E. Jr., Pomeroy, J., Realmuto, G., Tanguay, P. (1999). Summary of the practice parameters for the assessment and treatment of children, adolescents, and adults with autism and other pervasive developmental disorders. Journal of the American Academy of Child and Adolescent Psychiatry, 38(12), 1611-1616.
- Volkmar, F. R., & Nelson, D. S. (1990). Seizure disorders in autism. Journal of the American Academy of Child and Adolescent Psychiatry, 29(1), 127-129.
- World Health Organization. (1994). Diagnostic criteria for research. Geneva: World Health Organization.