New Evidence For Progressive Theory Of Schizophrenia

Since the naming of schizophrenia, experts have argued about its course: Is it a structurally progressively disease or are its symptoms the result of existing lesional damage to the brain, perhaps present from birth? While the dominant theories support the latter idea, progressive and substantial losses of gray matter have been repeatedly noted, suggesting the former. A huge boost to the argument would be linking these losses were associated with worsening cortical function. Studying 35 schizophrenic patients recruited during their first hospitalization, a study published in this month's Archives of General Psychiatry has done just that.

Researchers used electroencephalogram recordings to monitor mismatched negativity (MMN), a measure of the automatic processes involved in sensory memory found to be reduced in schizophrenics, and MRI scans to chart the loss of gray matter volume in the left hemisphere Heschl gyrus in 20 schizophrenic patients. These results were compared with a control group of 32 psychiatrically well individuals and 21 patients with bipolar disorder and psychosis both at the at the beginning of the study and 1.5 years later.

At the initial assessment, researchers found that subjects with schizophrenia already showed reduced cortical volume compared to healthy patients. Mean MMN amplitudes of schizophrenics fell largely within the normal range, but an abnormal relationship between MMN and underlying left hemisphere primary auditory cortex volumes, was noted in some subjects, suggesting that prehospitalization cortical volume reductions had taken place. At the second assessment, mean MMN amplitudes had fallen significantly in schizophrenic patients, while the control and bipolar group generally saw no change. These changes were found to be "highly correlated" to reductions in left Heschl gyrus gray matter volume during this time.

This strong correlation suggests that MMN amplitudes may serve as an index of the course of brain reduction both pre-hospitalization and subsequently. The study further makes a strong case for the idea that schizophrenia is caused by "a late progressive lesion."

FULL TEXT: Progressive and Interrelated Functional and Structural Evidence of Post-Onset Brain Reduction in Schizophrenia