Decreases in dilated pupil size in depressed patients with age may reflect adrenergic changes.

Some studies have suggested that noradrenergic activity may decrease with age in depressed patients. Pupil size is regulated by a balance between norepinephrine and acetylcholine. The present study compares pupil size in 10 unmedicated patients with unipolar depression (296. 3) and in 16 normal controls. Pupil size after dilation with tropicamide, a cholinergic antagonist, was inversely related to age in the patients (r=-0.87), but did not diminish with age in controls. The results suggest that pupil size may provide an index of diminished noradrenergic function with age in patients with major depression.