Alteration of hemoglobin oxygenation in the frontal region in elderly depressed patients as measured by near-infrared spectroscopy.

In an attempt to elucidate the neurobiological basis of hypofrontality in depression, alterations of oxyhemoglobin and deoxyhemoglobin were examined by using near-infrared spectroscopy of the left frontal region in 9 elderly patients with depressive disorders and 10 control subjects. Verbal repetition task, verbal fluency test, hyperventilation, and paper-bag breathing were performed. During the verbal fluency test, oxyhemoglobin significantly increased and deoxyhemoglobin significantly decreased in control subjects, whereas no significant change was observed in patients. During hyperventilation, oxyhemoglobin significantly decreased and deoxyhemoglobin significantly increased in both groups. These findings suggest that functional hypofrontality in elderly depression is not due to altered vasodilator response.