Limbic Hyperactivity Research Articles

Increased vulnerability to tardive dyskinesia development inschizophrenics with cortical metabolic dysfunction

Cortical metabolic dysfunction may affect subcortical dopamine activity. To examine this theory, a group of schizophrenics underwent PET FDG and MRI scanning to determine if limbic hyperactivity or frontal hypoactivity was associated with a greater degree of tardive dyskinesia (TD) development. Forty-two DSM-III-R schizophrenic patients without TD underwent PET FDG and MRi studies following a drug washout. Eight patients (88% male) developed TD during a 3-year follow-up period. These eight subjects were matched by age, sex, stage of illness, and duration of washout to eight patients without TD. Absolute metabolic rates and region/whole brain ratios were obtained based ~m the count rates of 42 regions of interest (ROl)/hemisphere using a MRI-based ROI eoregistration system transposed onto the PET images. Whole brain metabolism did not differ significantly between the two groups; however, hypermetabolic limbic, basal ganglia, midbrain, and cerebellar regions relative to whole brain and hypometabolic frontal areas relative to temporal lobe were found in the patients who developed TD in contrast to those who did not. The data indicates that limbic hyperactivity and relative frontal hypoactivity may increase the vulnerability to TD development.