Schizophrenia and IQ

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Low IQ is a risk factor for developing schizophrenia, though the mechanism behind this association is somewhat unclear. A new study sheds a little light on this subject, and suggests the link might be genetic. The gene in questions is neuregulin 1, about which little is known. They find, first, that a regulatory SNP is associated with the development of psychotic symptoms in a particularly at-risk population (see part a above– each bar is the percentage of subjects developing symptoms for a given genotype). They also find lower levels of activity in certain part of the brain in the patients with the TT genotype (see parts b and c above).

Further, here are the means and standard deviations of the IQ distributions of the different genotypes:

CC: 101.9 (8.4)
CT: 100.4 (9.4)
TT: 94.3 (6.9)

So this regulatory polymorphism could explain some of the natural variation in IQ.

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9 Comments

  1. There may be some connection to working memory deficits which are seen in both schizophrenics and their relatives.

  2. I always thought they were positively correlated (e.g. Nash). Could it be that it’s correlated with both ends of the spectrum?

  3. I’ve known at least 3 schizophrenics who were very bright and talented.

  4. I haven’t seen any study correlating high IQ with schizophrenia.

  5. There’s just a lot of anecdotal stuff about very bright mentally ill. Nash was only one of a large number of logician types who had mental problems. Goedel was another, and I think that Zermelo was another, but there are a half-dozen major figures. Not all were specifically schizophrenic, though. (Turing’s problem’s were probably not psychological, though I don’t know).

  6. There’s just a lot of anecdotal stuff about very bright mentally ill. … Not all were specifically schizophrenic, though.  
     
    You might need to make a distinction between schizophrenia and autism/Asperger’s Syndrome. 
     
    For mathematicians with Asperger’s Syndrome, see the work of Simon Baron-Cohen, e.g. 
     
    S. Baron-Cohen, S. Wheelwright, R. Skinner, J. Martin and E. Clubley, (2001) 
    The Autism Spectrum Quotient (AQ) : Evidence from Asperger Syndrome/High Functioning Autism, Males and Females, Scientists and Mathematicians 
     
    The diagnostic boundary between autism and schizophrenia hasn’t always been clear-cut, so (for example) some older work uses the term “childhood schizophrenia” where we might now use “autism”. So, if you want to test for a statistically significant difference in schizophrenia rates between mathematicians and non-mathematicians, you’ld need to be very careful how you’re measuring schizophrenia to avoid the result being confounded by the already-known difference in rates of AS. (there are symptoms you can use for differential diagnosis).

  7. Biology is not normative: it’s descriptive science. Darwinism is completely amoral with no normative concept at all. What seems unhealthy in one environment can mean survival in another. What seems healthy one place/time can be death in another. “Fittest” doesn’t imply “the good, the strong, the beautiful” (to use the Ionian phrase): it means whatever can produce the most viable offspring.  
     
    Then: Biology is adopted for normative purposes as medicine. “Health” as some kind of socially desirable state.  
     
    Then: Medicine is then adopted for normative purposes as psychology. “Mental Health” as some kind of socially desirable behavior.  
     
    What the difference between “autism” and “Asperger’s Syndrome”? Kind of like the difference between “terrorist” and “freedom fighter.”  
     
    Medicine and Psychiatry are technology, not science.

  8. I have read a book (“Discovering my Autism” by Schneider) by an Aspergers who (only 20-30 years ago or so) was diagnosed and treated as schizophrenic for several years. So some of those I’ve seen described as schizophrenic probably weren’t. 
     
    There’s a real difference between Aspergers and autism though. Aspergers people can be fully functional and even brilliantly successful, with specific serious difficulties in personal relationships, whereas the autistic often are not able to do much of anything at all.

  9. What the difference between “autism” and “Asperger’s Syndrome”? Kind of like the difference between “terrorist” and “freedom fighter.”  
     
    that is utter bullshit.

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