Cerebral blood flow in major depression and dysthymia.

Using single photon emission computerized tomography (SPECT) with a 99mTc-HMPAO perfusion technique, we studied the regional cerebral blood flow (rCBF) of 42 drug-free inpatients suffering from Major Depression' (n = 21) or dysthymia with the super-imposed diagnosis of a major depressive episode (n = 21). The patients with Major Depression had a significantly lower frontal and posterior rCBF ratio than those with Double Depression. Left frontal region indices showed a slight overlap between the two groups. There was no correlation between the severity of the illness and the rCBF indices. Different qualitative cerebral dysfunctions may be implicated in these two affective disorder sub-types.