September 22, 2009
Lifetime blindness prevents schizophrenia?:
Rather mysteriously, no one can find anyone who has been blind from birth and has later been diagnosed with schizophrenia. I found this interesting snippet from a short article from Behavioral and Brain Sciences:
Five independent searches, varying considerably in scope, methods, and population, failed to identify even one well-defined co-occurrence of total blindness and schizophrenia (Abely & Carton 1967; Chevigny & Braverman 1950; Feierman 1982; Horrobin 1979; Riscalla 1980). We dedicated portions of 2000 and 2001 to e-mail and postal mail surveys of relevant professionals; e-mail and telephone discussions with officials of health, mental health, blindness, and schizophrenia organizations and research institutes; and extensive keyword probes of Medline, PsychINFO, and ScienceDirect databases. Some ambiguity was introduced by very low return rates for our surveys, but the consistent result of all these inquiries was that no instance of totally blind/schizophrenic co-occurrence was found.
The authors give a speculative hypothesis that this is because visual experience during development helps to shape brain pathways heavily reliant on the neurotransmitter glutamate and the NMDA receptor.
It is widely accepted that this system plays a role in the development of psychosis but the idea that it is shaped by visual experience to the point where schizophrenia is impossible is just an interesting idea at the present time.
That's not to say no-one with schizophrenia is blind (in fact, there are numerous tragic cases of self-blinding) but it is still the case that no-one has yet produced an example of someone who has been blind from birth who later has become psychotic.
If you do hear of anyone, get in touch, contact your nearest cognitive scientist, or if you are a researcher yourself, write up a case study, as it's an interesting anomaly in the medical literature.
Link to summary of paper on blindness and schizophrenia.
