Philosophical Society of Washington

Minutes of the 2128th Meeting


Speaker: Kenneth Towbin and Ann Wagner, National Institute of Mental Health, NIH
Topic: “Autistic Spectrum Disorders”

President McDiarmid called the 2138th meeting to order at 8:17 p.m. on, December 14, 2001. The Recording Secretary read the minutes of the 2137th meeting and they were approved.

The speakers for the evening were Kenneth Towbin and Ann Wagner, National Institute of Mental Health, NIH. The title of their presentation was “Autistic Spectrum Disorders”.


Mr. Towbin began with the original clinical description of autism. In 1943, Leo Kanner described children with certain characteristic deviations from typical child development he termed “autistic disturbances of affective contact”, or autism. Today, these symptoms fall within a class of disabilities referred to as “autistic spectrum disorders”, including Asperger syndrome, pervasive developmental disorder, Rett syndrome, and childhood disintegrative disorder.

Autism is a biological disorder of social learning and reciprocity that is usually evidenced by an onset of symptoms before age 3. There is an impairment of reciprocity behavior, or understanding of motivation of others. There are deficits in non-verbal communication and in processing personal relationships. There are limitations in empathy, or reading emotional context, in showing, sharing and emotional sharing. There are impairments of language skills and delays in language acquisition, deficits in the ability to sustain conversation, and repetitive or idiosyncratic language. There are deficits in socially imitative or imaginary play, dedication to non-functional routines, restricted or narrow interests, repetitive behaviors or stereotypies, and preoccupations with parts of objects.

Epidemiological studies of autism estimated in 1960 there were 4 affected individuals per 10,000, in 1966-1988 4.3 per 10,000, and in 1988-1998 7.2 per 10,000. These numbers led to discussions of a “rising epidemic” of autism in the 90's. However, these numbers may be an abuse of statistics, and reflect more changes in diagnostic criteria that changes in prevalence. Before 1982, investigators created their own criteria based on Kanner's definitions. Since 1990 investigators have employed standard tests, improved diagnostic methods, improved record keeping, structured interviews and structured observations. There does seem to have been an inverse relationship between estimates of prevalence and the size of the sample. There have been some investigations of sporadic, apparent “outbreaks” of autism.

Twin and family studies indicate a concordance of 70-82%, depending on the definition standard. The recurrence risk in siblings is 2-6% rather than 0.05%. Genetic analysis indicates no single gene is responsible, but rather there are 2-10 independent, or 2-6 epistatic (interacting) loci, with an affected individual inheriting 2-5 predisposing genes. Suspect genes have been placed on all but six chromosomes. Especially implicated are 2q and 7q, particularly the 7q22-31 region associated with language disorders, 15q11-13 the Angleman region, and 16p13 the NMDA receptor and TSC2 genes. There is a high incidence of ASD associated with tuberous sclerosis.

The typical neuropathologies of autism are a large head circumference, with no evidence of atrophy by MRI. Increased brain volume suggests dysgenic rather than degenerative processes. The presence in the hippocampal region of tightly packed cells with stunted dendrites suggests miswired cells. There is increased white matter in cerebellar neocortical gray matter, and slowed cerebellar growth.

Ms. Wagner described the neuropsychology in pervasive developmental disorder (PDD). Typically there is a split in the verbal and performance IQ's; verbal is less than the spatial in classic autism, and the spatial is less than the verbal in Asperger's. Developmental patterns that are clear at age 2 to 3 are changed and not so clear at age 9 to 10. In older, normal IQ patients there is less of a split in verbal and performance IQ.

The psychological “theory of mind” is the ability to appreciate others' thoughts and feelings and predict their behavior. PDD patients have relatively defective “theory of mind” as evidenced by “false belief” tasks, inability to produce pretend play, difficulty in assessing causes of emotion, what is accidental or intended, and difficulty in understanding or engaging in deception or non-literal statements. This defective “theory of mind” is presumed to be neurological and is considered a developmental delay, rather than a complete absence of the skill. Early symptoms are problems with “joint attention”, such as “oh, look” requests, problems with sustaining and shifting attention, and poor “executive” functions. These attention difficulties are different from “attention deficit disorder”. The problem with joint or social attention is consistently recognized by parents and teachers, and it affects daily living skills as well as academics

Children with PDD have an advantage in tasks where the context is a distractor, such as embedded figures, but they are less likely to be helped by contextual clues. They have a tendency to fail to use context in reading ambiguous words. There is a correlation between central coherence ability and “theory of mind” proficiency

There have been few population based follow-up studies on the course of the disorder. 10-15% make exceptionally good progress and can obtain college degrees. Challenges include pubertal changes associated with increased social complexity and discontinuity of services, risk of depression or anxiety, especially in Asperger's, and 40% institutionalization. Although there is no cure for autism spectrum disorders, there are interventions that can reduce symptoms and promote adaptive functioning. These helpful interventions include pivotal response therapy, family support and training in behavioral controls. There is substantial private and public funding for research on these disorders. At the NIH, for example, several institutes contribute to autism research including the NIMH, NICHD (Child Health and Human Development), NIDCD (Deafness and Commuication Disorders) and NINDS (Neurological Diseases and Stroke). The total funding from all NIH institutes is over $60 million.



Mr. Towbin and Ms. Wagner kindly answered questions from the floor. President McDiarmid thanked them for the society, and welcomed them to its membership. The President made the announcements about the next meeting, parking, and refreshments, and adjourned the 2138th meeting to the 181st Annual Business Meeting of the Society at 9:28 p.m.

Attendance: 39
Temperature: 17.8°C
Weather: partly cloudy

Respectfully submitted,
 
John S. Garavelli
Recording Secretary

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