Abnormal resting state corticolimbic blood flow in depressed unmedicated patients with major depression: a (15)O-H(2)O PET study.
OBJECTIVE To show that PET investigations of brain function in patients with major depression can contribute with valuable pathophysiological knowledge about brain function of these states. METHODS PET studies of cerebral blood flow or glucose metabolism in patients with unipolar or bipolar depression were reviewed. RESULTS The studies have great discrepancies related to sample size, subject selection, imaging protocol and image analysis. In spite of this shortcoming, there is evidence that patients with major depression have reduced blood flow and metabolism in the prefrontal cortex, particularly when they exhibit psychomotor retardation. Abnormalities are also found in the anterior cingulate gyrus and the basal ganglia. A few studies point to the possibility that response to antidepressant treatment can be predicted from PET scans. CONCLUSION This evidence is consistent with the hypothesis that depressive symptoms are caused by dysfunction of regions of the limbic system and the frontal lobes in close connection with the basal ganglia.