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For more than 200 years, scientists have found various structural abnormalities in the brains of many dead schizophrenics. These abnormalities are clues which offer researchers hints in understanding the disorder. Nowadays, new devices such as computerized axial tomography (the CAT scan) and magnetic resonance imaging have enabled researchers to study the brains of living schizophrenics. These also revealed a number of abnormalities. Yet their roles in the disorder, if any, still remain as merely a conjecture. The genetic determination of such abnormalities has not been proved.

Structural Difference
between the Left and Right Hemispheres

Both autopsy and living-brain examinations have detected structural differences between the left and right hemispheres in schizophrenics, which were not found in normal individuals.

The brains of schizophrenics are lighter than those of normal people. Certain parts, such as the two key centers of the emotions-hippocampus and the amygdala, are smaller in schizophrenics.

Enlarged Ventricles in the Brain

The ventricles are composed of a chain of connected cavities that the cerebrospinal fluid flows through. This liquid helps to cushion the brain and the spinal cord against injury. Enlarged ventricles indicate some contraction of adjacent brain tissue, usually leading to deterioration of that tissue. However, this difference does not convince everyone because some experts found no significant difference in ventricle size between individuals with the disorder and those without it.

A higher dopamine level in the left hemisphere but a normal dopamine level in the right hemisphere. Dopamine is one of the neurotransmitters that nerve cells use to communicate and transfer messages. Dopamine is considered to play an important role in schizophrenia. A number of differences in the physical structure as well as in the chemical activities of the two hemispheres have been reported in the brains of schizophrenics.

A number of biological theories have been established to explain schizophrenia.

• The neurotransmitter dopamine. Evidences: first, high dose of amphetamines can cause severe schizophrenia-like symptoms, and amphetamines increase the dopamine levels in the brain. Second, when the drug L-dopa, which increases the brain's output of dopamine, is given to schizophrenics, their condition gets worse.
• Another popular theory blames nutritional deficiencies. Supporters of this theory advocate treatment with large doses of vitamins as well as such minerals as zinc and manganese.

The brains of many schizophrenics contain abnormal structures or anomalous chemical activities. If brain abnormalities are always present, then why is schizophrenia often an episodic disease? These questions remain unanswered.