Context: Major depressive disorder (MDD) in elderly individuals is prevalent and debilitating. It is accompanied by circadian rhythm disturbances associated with impaired functioning of the suprachiasmatic nucleus, the biological clock of the brain. Circadian rhythm disturbances are common in the elderly. Suprachiasmatic nucleus stimulation using bright light treatment (BLT) may, therefore, improve mood, sleep, and hormonal rhythms in elderly patients with MDD.
Objective: To determine the efficacy of BLT in elderly patients with MDD.
Design: Double-blind, placebo-controlled randomized clinical trial.
Setting: Home-based treatment in patients recruited from outpatient clinics and from case-finding using general practitioners' offices in the Amsterdam region.
Participants: Eighty-nine outpatients 60 years or older who had MDD underwent assessment at baseline (T0), after 3 weeks of treatment (T1), and 3 weeks after the end of treatment (T2). Intervention Three weeks of 1-hour early-morning BLT (pale blue, approximately 7500 lux) vs placebo (dim red light, approximately 50 lux).
Main outcome measures: Mean improvement in Hamilton Scale for Depression scores at T1 and T2 using parameters of sleep and cortisol and melatonin levels.
Results: Intention-to-treat analysis showed Hamilton Scale for Depression scores to improve with BLT more than placebo from T0 to T1 (7%; 95% confidence interval, 4%-23%; P = .03) and from T0 to T2 (21%; 7%-31%; P = .001). At T1 relative to T0, get-up time after final awakening in the BLT group advanced by 7% (P < .001), sleep efficiency increased by 2% (P = .01), and the steepness of the rise in evening melatonin levels increased by 81% (P = .03) compared with the placebo group. At T2 relative to T0, get-up time was still advanced by 3% (P = .001) and the 24-hour urinary free cortisol level was 37% lower (P = .003) compared with the placebo group. The evening salivary cortisol level had decreased by 34% in the BLT group compared with an increase of 7% in the placebo group (P = .02).
Conclusions: In elderly patients with MDD, BLT improved mood, enhanced sleep efficiency, and increased the upslope melatonin level gradient. In addition, BLT produced continuing improvement in mood and an attenuation of cortisol hyperexcretion after discontinuation of treatment.
Trial registration: clinicaltrials.gov Identifier NCT00332670.