Outcome of cognitive-behavioral therapy for depression: relation to hemispheric dominance for verbal processing.

Unmedicated depressed outpatients were tested on dichotic syllable and complex tone tests prior to receiving 16 weekly sessions of cognitive therapy (n = 31) or 6-12 weeks of placebo treatment (n = 45). Cognitive-therapy responders had twice the right-ear (left hemisphere) advantage for syllables when compared with nonresponders but did not differ from nonresponders on the nonverbal task. The larger right-ear advantage in cognitive-therapy responders was due to better right-ear accuracy; they did not differ from nonresponders in left-ear accuracy. No differences in perceptual asymmetry or accuracy were found between placebo responders and nonresponders. Right-ear accuracy for syllables was the best predictor of response to cognitive therapy in a logistic regression analysis. The findings suggest that greater left-hemisphere advantage for verbal processing is associated with more favorable outcome of cognitive therapy for depression.