Studied 11 younger (mean age= 25 yrs) and 9 older (mean age= 61 yrs) chronic schizophrenic inpatients. The younger patients were well preserved intellectually. All the older ones showed advanced deterioration with autism, bizarre behavior, symptoms of catatonia, and ongoing hallucinations. Regional cerebral blood flow (rCBF) was measured in the dominant hemisphere at rest and during attempts at mental activation. Both groups showed normal mean rCBF variables. In the older group, significant correlations were established between the mean hemisphere flow level and the degree of psychosis. The regional rCBF distribution was normal in the younger group, with a predominance of high flows in frontal regions. In the older patients, a hypofrontal pattern was found with relatively low flows frontally, and, in many cases, relatively high flows occipito-temporally. Psychological testing with Raven's Progressive Matrices in the younger group gave normal flow augmentations within expected hemisphere regions. In the most autistic older patients, only very slight flow changes were recorded postcentrally in connection with a simple picture test. The hypofrontal rCBF distribution pattern found in older deteriorated schizophrenics indicates that an abnormally low level of activity may prevail within the frontal lobe in such patients. Similarities between the emotional defects, speech, and motor abnormalities seen in chronic schizophrenia, and symptoms found in patients with frontal lobe lesions are pointed out.(71 ref)(PsycINFO Database Record (c) 2016 APA, all rights reserved)