Changes in brain function during administration of venlafaxine or placebo to normal subjects

Previous research has demonstrated neurophysiologic effects of antidepressants in depressed subjects. We evaluated neurophysiologic effects of venlafaxine in normal subjects. Healthy adults (n=32) received a 1-week placebo lead-in followed by 4 weeks randomized double-blind treatment with venlafaxine IR 150 mg. (n = 17) or placebo (n = 15). Brain function was examined using quantitative electroencephalographic (QEEG) power and theta cordance. Normal subjects receiving venlafaxine showed a decrease in theta-band cordance in the midline-and-right-frontal (MRF) region at 48 hours and at 1 week after randomization. Decreases in relative power also were seen in the MRF region; there were no significant changes in absolute power. These changes were significantly different from those in subjects receiving placebo. Changes in MRF cordance accurately identified treatment condition at 48 hours in 81.3% of subjects, and relative power from this region identified 60.7% of subjects. In conclusion, cordance may detect the pharmacological effects of antidepressant medication in normal subjects. Future studies should examine other classes of medication, as well as antidepressants with other mechanisms of action, to determine if cordance detects antidepressant medication effects in general in normal subjects.