Neo-striatal rCBF correlates of psychomotor slowing in patients with majordepression

Psychomotor slowing is a fundamental clinical feature of severe depression and is thought to reflect dysfunction within prefrontal-subcortical circuit s. This study utilised a split-dose single photon emission computerised tom ography (SPECT) scanning technique in association with a two-stage test of psychomotor speed. Twenty-five patients with primary depressive disorders w ere injected with technetium-99m hexamethylpropylene amine oxime (Tc-99m-HM PAO) whilst performing each component of a two-stage psychomotor task. The first stage, 'simple reaction time' (RT) and the second stage, 'choice reac tion time' (CRT), were each followed by 30-min SPECT scans. Regions of inte rest (ROIs) corresponding to the left and right neo-striatum (caudate-putam en) were drawn, and regional cerebral blood flow (rCBF) values were calcula ted. Importantly, the change in rCBF measure in the left neo-striatum was i nversely correlated with RT (r = -0.48, P < 0.05). That is, the patients wi th the greatest psychomotor slowing initially showed the least increase in rCBF during the CRT condition. This effect was independent of age. The stud y demonstrates that a simple two-stage motor paradigm can be used to elicit rCBF correlates of psychomotor slowing in patients with primary depression . Such rCBF findings may implicate the neo-striatum in the neurobiology of major depression. (C) 1999 Elsevier Science Ireland Ltd. All rights reserve d.