Hypofrontal vs. hypo-sylvian blood flow in schizophrenia

Hypofrontality in schizophrenia has been a frequent but not consistent finding in regional cerebral blood flow studies. However, the con-tributions of subject and state variables such as age, education, task activation, and anxiety, some of which are known to influence blood flow profiles, have not been thoroughly examined in this popu-lation. Here, in a sample including 24 normal, 18 schizophrenic, 22 bipolar, and 13 unipolar depressive subjects, narrative prose memory deficit was found to distinguish both schizophrenic and bipolar subjects from normal controls. Fur-ther, when these subjects were engaged in repeated trials of a ver-bal recognition memory task, left hemisphere hypofrontal blood flow in the early stage of learning was related to narrative memory, in-dependent of diagnostic group. In the late stage of learning, state anxiety was significantly associated with left hypofrontality, while right hypofrontality was significantly related to narrative memory—both findings again independent of diagnostic group. A focal suppres-sion of left hemispheric peri-Sylvian activation (in Broca's and Wemicke's areas) uniquely characterized schizophrenia after taking into account variance due to age, education, gender, state anxiety, and verbal memory. It is concluded that a failure of left peri-Sylvian activation during memory task performance reflects a unique language-related focal deficit in schizophrenia. Since it was first reported by Ingvar and Franzen (1971), hypofrontal blood flow in schizophrenia has been the stimulus for a lengthy and wide-ranging debate. There does appear to be a strong empirical tendency for schizophrenic patients to have lower frontal activation (as indexed by blood flow or metabo-lism) than normal subjects hav