Contributing factors to changes of cerebral blood flow in major depressive disorder.

Background: Results of single photon emission computed tomography (SPECT) regarding mood disorders have been inconsistent. The aim of the study was to elucidate factors contributing to changes in cerebral blood flow in patients with major depressive disorder.

Methods: A total of 89 consecutive patients diagnosed with major depressive disorder using DSM-IV semistructured interviews were evaluated using single photon emission computed tomography, the 17-item Hamilton Rating Scale for Depression (HRSD), and the Global Assessment of Function (GAF) scale. Nineteen of these patients also underwent the same tests during remission.

Results: Global cerebral blood flow (gCBF) was significantly higher during remission than at the time of enrollment. Significant correlations were seen between gCBF and age, duration of previous episode of depression, and hypochondriasis. However, no correlation was seen between gCBF and HRSD, GAF, severity and duration of depressive episode, or melancholia-type depression. Correlations between gCBF and age were seen only at enrollment and disappeared during remission. No differences in regional cerebral blood flow at any site were seen between time of enrollment and remission for the same patient.

Limitation: Analysis that adequately accounts for these factors to changes of cerebral blood flow in major depressive disorder will require a large subject population.

Conclusions: These results suggest that although there is a decrease in gCBF in major depressive disorder, the level of the decrease is determined by conditions present before episode onset, rather than by the characteristics of the episode itself. The findings also suggest that the correlation between gCBF and age is state-dependent.