REGIONAL CEREBRAL BLOOD-FLOW ABNORMALITIES IN LATE-LIFE DEPRESSION - RELATION TO REFRACTORINESS AND CHRONIFICATION

We examined patterns of regional cerebral blood flow (rCBF) abnormalit ies in 18 patients with major depressive disorder in late life using s ingle photon emission computed tomography (SPECT) and Tc-99m-hexamethy lpropylenamine oxime (Tc-99m-HMPAO). Compared with 13 age-matched cont rols, relative rCBF was significantly decreased bilaterally in the ant erior cingulate virus, the prefrontal cortex, the temporal cortex, the parietal cortex, the hippocampus and the caudate nucleus. However, it was not correlated with the severity of depression or global cognitiv e dysfunction. In 10 patients with a prolonged depressive episode or p rolonged residual symptoms (the refractory subgroup), robust and exten sive decreases in rCBF were found compared with controls and the rCBF decreased significantly in the anterior cingulate virus and the prefro ntal cortex compared with that in the non-refractory subgroup. In the non-refractory subgroup, rCBF decreased significantly in the caudate n ucleus and tended to decrease in the anterior cingulate gyrus compared with controls. These findings indicate that dysfunction of the limbic system, the cerebral association cortex and the caudate nucleus may b e implicated in late-life depression and that robust and extensive hyp operfusion, especially in the anterior cingulate and the prefrontal re gions, may relate to refractoriness or chronification of depression.