DOMINANCE OF THE NONDOMINANT HEMISPHERE IN DEPRESSION

We examined 36 patients with major depression diagnosed by DSM-III-R t o find and qualify disturbances in brain oxygenation and hemodynamics during a psychological task. A group of 36 age- and sex-matched health y volunteers were monitored as controls. Multichannel near-IR spectrop hotometry (NIRS) was used to observe real-time alterations in the oxyg enation in corresponding areas of the hemispheres at the forehead duri ng the mirror drawing task (MDT). Nearly half of the patients (12 of 2 4 males and 4 of 12 females) showed a 'nondominant hemisphere response pattern', which was never observed in normal volunteers during the MD T. The other half of the patients showed a 'bilateral response pattern ', There was no 'dominant hemisphere response pattern', the pattern ob served in most normal males. When re-examined after recovery from depr ession, the response pattern of the two patients who had shown the 'no ndominant hemisphere response pattern' during the course of the illnes s had changed to the 'bilateral response pattern'. The response patter n of the three patients with refractory depression who first showed th e 'bilateral response pattern' changed to the 'nondominant response pa ttern' after several months. The nominally 'nondominant' hemisphere ma y become dominant during the course of depression.