Contribution of alcohol abuse to cerebellar volume deficits in men with schizophrenia

Background: It is controversial whether cerebellar tissue volume deficits o ccur in schizophrenia and, if so, what regions and tissue types are affecte d. Complicating such investigations is the high incidence of alcoholism com orbidity in patients with schizophrenia that itself can contribute to cereb ellar abnormalities. Method: We studied 61 healthy men (control subjects), 25 men with alcoholis m, 27 men with schizophrenia, and 19 men comorbid for schizophrenia and alc oholism with the use of magnetic resonance imaging. Cerebellar structures w ere outlined manually, tissue classification was determined statistically, and regional volumes were corrected for normal variation in head size and a ge. Results: Patients with schizophrenia alone had enlarged fourth ventricles ( 1.5 SD relative to controls) but showed no cerebellar tissue volume deficit s. The alcoholic group had gray and white matter vermian deficits (-0.5 SD) , most prominent in anterior superior lobules, and gray matter hemisphere d eficits (-0.8 SD), but not fourth ventricle enlargement. The comorbid group had cerebellar hemisphere (-1.3 SD) and vermian gray matter volume deficit s (-0.7 SD) and fourth ventricular enlargement (1.6 SD); these abnormalitie s were greater than in either single-diagnosis group, despite significantly lower levels of alcohol consumption compared with the alcoholic group. Gra y matter volume in the anterior superior vermis correlated with lifetime al cohol consumption in the schizophrenic and comorbid groups when combined. Conclusions: Cerebellar tissue volume deficits were detected in schizophren ia only when accompanied by alcoholism. By contrast, fourth ventricular enl argement occurred in schizophrenia even without alcoholism, although it was exacerbated by alcoholism. These findings support a model of cerebellar su persensitivity to alcohol-related tissue volume deficits in schizophrenia.