June 1988

Effect of Neuroleptics on Altered Cerebral Glucose Metabolism in Schizophrenia

Author Affiliations

From the Departments of Neurosciences (Drs Szechtman and Brown) and Psychiatry (Drs Szechtman, Brown, Kaplan, and Cleghorn), McMaster University, and the Department of Nuclear Medicine, Chedoke-McMaster Hospitals (Drs Nahmias, Garnett, and Firnau), Hamilton, Ontario.

Arch Gen Psychiatry. 1988;45(6):523-532. doi:10.1001/archpsyc.1988.01800300019002

• This study examines whether the duration of treatment with antipsychotic drugs influences the regional distribution of cerebral [18F]2-fluoro-2-deoxy-D-glucose utilization as measured by positron emission tomography. Two groups of schizophrenic patients are compared with normal volunteers (n =10). One group (n = 5) consisted of patients treated for one year, and the second (n=12) of patients medicated for four to 14 years (mean ± SD duration, 7.4±3.4 years). The first group was also examined before patients received their first dose ever of antipsychotic medication. One year of medication was not sufficient to alter the schizophrenic profile of cerebral cortical glucose activity but did elevate activity of the corpus striatum. Medication for 7.4 years also did not alter the schizophrenic pattern of frontal hyperactivity and posterior hypoactivity, although deviations from control values appeared less marked than after one year. On the other hand, in patients medicated for 7.4 years, there was perhaps an even greater increase in the activity of the corpus striatum and of the thalamus. Thus, duration of exposure to antipsychotic medication may affect the pattern of cerebral glucose activity; possibly, even longer exposure may contribute to the hypofrontality noted by others, although this can be confounded with the duration of illness as a factor. In considering the biological significance of the observed profile of cortical glucose activity, we introduce the concept of cerebral metabolic tone. We suggest that a disturbance of this tonus may account for some symptoms of schizophrenia and could be consistent with the hypothesis of abnormal developmental changes in the brains of schizophrenics.