Protective effect of blindness on Schizophrenia
In a study by Steven M. Silverstein1, Yushi Wang and Brian P. Keane University of Medicine and Dentistry of New Jersey, Piscataway, NJ, USA published as Cognitive and neuroplasticity mechanisms by which congenital or early blindness may confer a protective effect against schizophrenia, the researchers noted that "Several authors have noted that there are no reported cases of people with schizophrenia who were born blind or who developed blindness shortly after birth, suggesting that congenital or early (C/E) blindness may serve as a protective factor against schizophrenia"
Research concluded that:
(1) schizophrenia is primarily a cognitive disorder
(2) many of the cognitive functions that are impaired in schizophrenia are enhanced among the C/E blind
(3) C/E blindness involves reduced flexibility in language and in dynamic representation of the body, and these reductions may protect against thought disorder and alterations in experience of the self, respectively
(4) the mechanisms noted in 2 and 3 above are significantly less affected if the onset of blindness is after the first few months of life
(5) other forms of C/E sensory loss do not protect against schizophrenia
(6) C/E blindness does not protect against other disorders, suggesting that there is a special link between schizophrenia and visual processing.