It's complete b*ll*cks. The hand you write with and your dominant brain hemisphere have absolutely nothing to do with schizophrenia, depression or anything else for that matter.
The most solid evidence for the development of disoders like schizophrenia, depression, OCD etc comes from a dormant gene which is triggered by stressful and traumatic experiences. Chemical imbalances is another one the professionals are fond of. But nowhere is there the slightest mention of dominant brain hemispheres.
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