Autism Vox

VENs, frontotemporal dementia, and autism

by Kristina Chew, PhD on December 22nd, 2006

Von Economo neurons (VENs) are unusually shaped cells—”large, cigar-shaped and tapered at each end, with only a few dendritic processes extending away from them,” and located in the two frontal lobes of the brain. Scientists at the University of California at San Francisco have identified VENs as the “primary target of the degenerative brain disease known as frontotemporal dementia” (FTD), as reported in today’s Eurekalart. For those who develop dementia before the age of 65, FTD is as common as Alzheimer’s disease. VENs arise in two areas of the brain (the anterior cingulate and frontoinsular cortex) which are “key targets” of FTD; among primates, VENs are seen only in humans and great apes and

Because the cells arose only recently in evolutionary history — in a common ancestor of great apes and humans– and are particularly abundant in humans, and the finding supports the concept that evolution has rendered the human brain vulnerable to disease, including frontotemporal dementia, and, possibly, disorders such as autism and schizophrenia, the researchers say.

These findings are reported in the December 22nd issue of Annals of Neurology. Researchers at the California Institute of Technology have also studied the role of VENs in the “fast intuitive assessment of cognitive situations” in Intuition and autism: a possible role for Von Economo neurons (published in Trends in Cognitive Science, Vol.9 No.8 August 2005). They note that VENs “emerge mainly after birth and increase in number until age 4 yrs,” and hypothesize that they do not develop normally in autistic children. Regarding the relatively recent emergence of VENs in evolutionary history, the CalTech researchers write

Because of this late emergence in phylogeny, natural selection has had only a relatively short time to shape VEN functioning and integration with other cell populations. Consequently the VENs might be particularly vulnerable to dysfunction in a manner analogous to the propensity of humans to suffer lower back, hip and knee disorders as a consequence of the recent evolution of bipedal posture.

Regarding VENs and autism specifically, the CalTech researchers posit:

Our theory predicts that autistic subjects will be abnormal in making intuitive decisions under conditions involving a high degree of uncertainty. We further predict that these deficiencies will be most clearly manifested in social situations, but will be observable in non-social tasks, such as those involving gambling or ambiguity. For example, these abnormalities might involve delayed responses, poor adaptation to rapidly changing circumstances, or abnormal physiological responses.

It is the case that situations “involving a high degree of uncertainty” seem to lead to a great deal of anxiety in my son Charlie, who seems to learn best and to be at his most “peaceful easy feeling” when what he has to do is clearly structured and presented to him as such. I would posit that Charlie’s ritualistic behaviors—such as always expecting to get sushi when we go to the grocery store—are a way that he tries to avoid finding himself having to be in situations “involving a high degree of uncertainty”; uncertainty in Charlie often leads straight to anxiety.

Besides FTD, the CalTech researchers also posit that VENs might play a role in “bipolar and obsessive-compulsive disorder, anorexia, and psychopathy.”

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POSTED IN: Anorexia, Genetics, Health, History, Neuroscience, Psychiatry, Psychology, Science