The early history of research in autism is marked by a paucity of neuropathological studies. In agreement with Descartes dualist theory mental disorders were attributed to the mind and thus were thought to lack a structural substrate in the brain. Even as late as the 1960’s and 70’s few psychiatric institutions promoted autopsying their patients. Still, those who died within a psychiatric institution were examined by a medical examiner (coroner) whose mandate was to establish cause of death, nothing more. Seldom was an autopsy done by a specialist (neuropathologist) or pursued by microsocopic examination.
There were few exceptions to the distancing of psychiatry and neuropathology. Wilhelm Griesinger (1817-1868) who headed an institution for the mentally handicapped in Germany was a firm believer that mental conditions were brain conditions. His famous quote was: “Psychiatry and neuropathology are not merely two closely related fields; they are but one field in which only one language is spoken and the same laws rule”. However, despite these exceptions, the whole of psychiatry distanced itself from neurobiological investigations thus leaving the field open to psychoanalytical ruminations. It did not help that throughout the early years of research people who had an interest in the condition had to wrestle their way through confusing terminology. Before and even after Kanner’s description published articles variously referred to autism as childhood psychosis, dementia praecoccisima, dementia infantilis, or childhood schizophrenia. Many early descriptions of autism thus lay hidden under the diagnosis of mental retardation or epilepsy.
Two decades after Kanner made his initial description of autism, Bernard Rimland reviewed the medical literature to find only one autopsied case with some scant information. By 1997 Isabel Rapin indicated that there were less than 30 brains with detailed postmortem examination (Rapin, 1999). The numbers rose slightly over the next decade. In a review by Palmen the total number of reported cases was 40 (Palmen et al., 2004).
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The most comprehensive review of the early neuropathological literature of autism was performed by John Darby during his tenure as Director for Research and Education at the Scott and White Hospital and Clinic in Texas. Darby reviewed the available literature (an annotated bibliography of over 1,700 references) and held correspondence with many higher academic institutions. The result of his perusal gave rise to a series of 33 cases, 29 of which had been previously reported in the literature (Darby, 1976).
The cases in Darby’s series varied tremendously in regards to clinical presentation and tissue availability. Gross examination of the brains was unremarkable. Under the microscope the most common reported finding was that of “cerebral lipidosis”. The term made reference to the accumulation of the pigment lipofuscin, also known as the “wear and tear” pigment of the brain. (Note: A recent report by Lopez-Hurtado and Prieto in 2008 revealed a significantly increased number of pigmented neurons in autistic patients. The authors believed their findings were consistent with accelerated neuronal death or increased oxidative metabolism).
The arrow indicates the accumulation of a golden brown pigment (lipofuscin) in a neuron.
Darby (1976) concluded that the variability he observed in clinical presentation suggested that autism was the expression of a number of disorders. Many years after the fact he published a letter to the editor of the American Journal of Psychiatry entitled: “Autism Syndrome as a Final Common Pathway of Behavioral Expression for Many Organic Disorders” (Darby and Clark, 1992). The espoused concept reminds us of a similar proposal by Bellak (1958) who claimed a “final common pathway” to the nature of schizophrenia wherein a variety of insults were somehow funneled to provide a similar set of manifestations.
A few other authors contributed isolated efforts, primarily as case reports in the 1970’s and 1980’s. The new era was to be ushered by the neuropathological studies of Margaret Bauman and Tom Kemper in the mid 1980’s. However, the lessons from Darby and other early investigators were valuable and can be summarized as:
1) There is an inherited tendency to autism as shown by pairs of siblings within case reports.
2) Idiopathic autism comprises the majority of reported cases, but so-called secondary autism is common. Genetic conditions, especially tuberous sclerosis, have always been recognized as a common cause of secondary autism.
3) Gross examination of the brain is almost always normal.
4) Early investigators questioned some pathological findings as artifacts, e.g. prolonged postmortem intervals.
Jon Darby received his medical degree from the University of Texas-Southwestern in 1967. In the same year, he received a National Foundation Merit Award to study Congenital Birth Defects. From 1990 till present he has been a Consultant in Neuropsychiatry for Agnes State Hospital in San Jose, California. According to PubMed Dr. Darby’s contribution to autism in 1976 was his first effort at a publication. The same is considered a classic within the field of autism research.
References
Bellak, L. (1958). Schizophrenia: a review of the syndrome. New York: Logos Press.
Darby, J. K.. Neuropathologic aspects of psychosis in children. Journal of Autism and Childhood Schizophrenia, 6, 339¬¬–352, 1976.
Darby, J.K., Clark, L. Autism syndrome as a final common pathway of behavioral expression for many organic disorders. AJP 149(1):146, 1992.
López-Hurtado, E., Prieto, J. J. A microscopic study of language-related cortex in autism. American Journal of Biochemistry and Biotechnology, 4, 130–145, 2008.
Palmen, S. J., Van Engeland, H., Hof, P. R., Schmitz, C. Neuropathological findings in autism. Brain, 127, 2572–2584, 2004.
Rapin, I. Autism in search of a home in the brain. Neurology, 52, 902–904, 1999.