Baseline cerebral hypermetabolism associated with carbamazepine response, and hypometabolism with nimodipine response in mood disorders

Background: Positron emission tomography (PET) studies have reported baseli ne (medication free) differences between mood disorder patients and healthy control subjects, but relatively little is known about relationships betwe en baseline PET scans and treatment responses. Carbamazepine (CBZ) and to a more limited extent nimodipine (NIMO) seem useful in mood disorders. We ex plored whether baseline regional cerebral glucose metabolism (rCMRglu) coul d discriminate CBZ and NIMO responders from nonresponders and healthy contr ol subjects. Methods: In refractory mood disorder patients, we examined relationships be tween responses to these drugs, assessed by Clinical Global Impression-Impr ovement scores, and baseline rCMRglu, determined with fluorine-18 deoxygluc ose and PET. Results: CBZ responders had baseline left insular hypermetabolism compared to healthy control subjects and nonresponders, whereas nonresponders had wi despread (including left insular) hypometabolism. Degree of CBZ response co rrelated with baseline paralimbic (including insula) and prefrontal hyperme tabolism, In responders but not nonresponders, CBZ decreased widespread met abolism, with the degree of decrease in left insula correlating with respon se. In contrast, NIMO responders but not nonresponders had baseline widespr ead (including left insular) hypometabolism, Left prefrontal and left insul ar baseline hypometabolism but not metabolic changes with treatment correla ted with degree of NIMO response. Conclusions: These data suggest that baseline anterior paralimbic and prefr ontal hypermetabolism may be associated with CBZ response, and hypometaboli sm with NIMO response. Based an these preliminary data, further exploration of relationships between baseline PET scans and treatment responses is ind icated.