Bilaterally reduced frontal activation during a verbal fluency task in depressed patients as measured by near-infrared spectroscopy.

The present study investigated functional changes of brain oxygenation in prefrontal brain areas of nine depressed patients and nine age- and sex-matched healthy comparison subjects by using near-infrared spectroscopy. During a verbal fluency task, the healthy subjects exhibited the typical activation pattern, with a significant increase in oxyhemoglobin and a decrease in deoxyhemoglobin, as compared to a resting baseline condition. Patients had significantly lower activation bilaterally during the cognitive task, with no significant differences in behavioral performance. The results underscore the hypothesis of a functional deficit in prefrontal cortex in depression and confirm the feasibility of near-infrared spectroscopy in measuring functional brain activation.