THE EPIDEMIOLOGY OF SEVERE PSYCHIATRIC DISORDERS

THE EPIDEMIOLOGY OF SEVERE PSYCHIATRIC DISORDERS: IS IT TIME TO PUT THE

CAT OUT?

It is known that some infectious agents can cause brain diseases

indistinguishable from schizophrenia and manic-depressive illness. 

Epidemiological aspects, including winter-spring birth, urban birth, and

migration as risk factors, are also compatible with an infectious cause. 

Pet cats are known to carry many infectious agents that can be transmitted to

humans; two studies have demonstrated that individuals with schizophrenia and

manic-depressive illness as compared to well controls have had greater exposure

to cats in childhood.  Toxoplasmosis is especially interesting because it

has been reported to affect personality traits and to occasionally cause

schizophrenia-like symptoms.  Toxoplasmosis has also been found to affect

neurotransmitters in animal studies.  Furthermore, antipsychotic drugs are

known to “have lethal effects on protozoa.”  Most importantly,

increased antibodies to toxoplasmosis have been found in the sera of individuals

with schizophrenia and manic-depressive illness.  The critical variables

whether toxoplasmosis causes these illnesses may be the timing of the primary

infection

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