November 11, 2008
Parental gene fight theory of mental illness:
The New York Times discusses a new theory on the link between schizophrenia and autism that suggests that each may depend on the outcome of a battle between the genetic information we inherit from each parent. According to the theory - more genes from the father increases the chance of autistic traits, while more from the mother increases the tendency to experience psychotic experiences.
The theory is proposed by sociologist Christopher Badcock and biologist Bernard Crespi who recently wrote an opinion piece in Nature outlining their idea a few months ago (we discussed it here).
There idea is based on a known effect called genomic imprinting, where the same genes inherited from one parent can have a different effect when compared to when they're inherited from the other parent.
However, they're not the first to suggest that autism and schizophrenia may be different sides of the same coin.
Neuropsychologist Chris Frith wrote an influential 1992 book with the snappy title of The Cognitive Neuropsychology of Schizophrenia where he suggested that the core problem in both schizophrenia and autism was an impairment in 'metarepresentation' - that is, the ability of the mind to monitor and represent mental states in both ourselves and other people.
Frith argued that schizophrenia is where a working metarepresentation system goes wrong, so affected people lose a sense of ownership of their own thoughts and make impaired inferences about the intentions of others. He further suggested that autism is where the metarepresentation never develops properly, so affected people barely develop the ability to understand the perspective of other people.
Interestingly, the word 'autism' itself was first used to describe an aspect of schizophrenia. Eugen Bleuler coined it to capture the introverted withdrawn behaviour seen in some people diagnosed with schizophrenia, and it was later adopted by Hans Asperger to describe the withdrawn introverted behaviour of a group of children he was studying who would now likely be diagnosed with autism of Asperger syndrome.
Link to NYT article on Crespi and Baddock theory.
