Pathophysiology of secondary depressions in the elderly

Although the pathophysiology of depression is not fully understood in; eith er primary depression (i.e., no known neuropathology related to depression) or secondary depression (i.e., neuropathologic disorder that leads to depr ession), a number of studies have begun to identify aspects of the pathophy siology of both primary and secondary depression. This article reviews the findings of studies examining the pathophysiology of depression following s troke, Parkinson's disease, or Huntington's disease and compares them to fi ndings: in primary depression.-Studies examining glucose metabolic rates or blood flow changes in regional brain areas found that stroke! Parkinson's disease, and Huntington's disease; as well as primary depression, were all associated with decreased activity or brain lesions in the orbital frontal cortex and basal ganglia. There were also abnormalities noted in the basal temporal lobes, cingulate cortex, and thalamus in some but not all disorder s. Studies in stroke have also noted depletions of serotonin receptors in l eft temporal cortex associated with depression.;These findings are consiste nt with the hypothesis that the pathophysiology of secondary and primary de pression involves the dysfunction of one or more of the cortical-basal gang lia-thalamic neuronal loops, This dysfunction may be mediated by decreased serotonin release. These studies may ultimately lead to more focused and sp ecific treatments.