Tuesday, 20 May 2008

Intelligence and mental illness

In my last post, I suggested that intelligence, or more precisely neural plasticity, was originally an infant trait in ancestral humans. In modern humans, it seems to have progressively been extended into older age groups.

This isn’t a novel idea. It has been put forward by such people as Ashley Montagu (1989), Stephen J. Gould (1977), and Konrad Lorenz (1971). Interestingly, one author has argued that this persistent brain plasticity has made the human mind more susceptible to certain neuroses and other personality disorders.

Therefore, psychotic disorders may be the ‘price’ for the delay of maturation and for the rapid increase of brain size during the past 150,000 years. For example, normal development of the human nervous system is particularly dependent on sensory input. Social deprivation leads to stereotyped and self-injurious behaviour, resulting from an alteration of dopamine receptor sensitivity. The assumption of an enhanced susceptibility to psychotic disorders by delayed maturation may be underlined by the fact that most psychiatric disorders originate in early childhood, when the growth rate of the brain and acquisition of learned material is particularly high. (Brüne, 2000)

This point is interesting because it links up with Dr. Kawecki’s suggestion that “some diseases are a byproduct of intelligence” (see previous post).

References

Brüne, M. (2000). Neoteny, psychiatric disorders and the social brain: hypotheses on heterochrony and the modularity of the mind. Anthropology & Medicine, 7(3), 301-318.

Gould, S.J. (1977). Ontogeny and Phylogeny. Cambridge: Harvard University Press.

Lorenz, K. (1971). Studies in Animal and Human Behaviour, Vol 2. London: Methuen & Co.

Montagu, M.F.A. (1989). Growing Young. 2nd ed. New York: Bergin & Garvey.

3 comments:

Anonymous said...

I remember Gould talking about the increased neoteny of humans compared with other primates ...

He was also on about differential selection pressures ... however, what he seemed unable to understand is that there might have been different selection pressures on different groups and thus different outcomes.

Tod said...

"Social deprivation leads to... self- injurious behavior"
Is this an idea referring back to the Harry Harlow monkeys put into solitary confinment from birth,and unsurprisingly, exibiting behavioral pathology.

For a human being what is meant by "social deprivation"?
Surely not cold disconfirming or "schizogenic" mothers - such theories are long abandoned for autism and schizophrenia - self harm disorders.

You are much less likely to develop schizophrenia if you are in the countryside, when BORN, that is early chidhood I admit.

If your delay of maturation theory is correct -
susceptibility to psychotic disorders might tend to run in families with a lot of neural plasticity.

I believe Aspergers Syndrome is more common in intellectualy gifted families, and it is sometimes confused with schizotypal personality disorder.

Yes it holds good for Aspergers Syndrome ,I am not sure about schizophrenia .

Tod said...

Absolute Pitch In Williams Syndrome

Investigates "near ceiling levels of absolute pitch" in those tested. (General intelligence is said to correlate moderately with pitch discrimination)

also discusses the possibility that "the normal early childhood critical period of absolute pitch acquistition may be extended in individuals with Williams syndrome".