High Cortisol Levels as a Risk Factor for Depression in the Elderly and the Effect of Bright Light Treatment on Mood, Sleep-Wake Pattern and Self-Sufficiency

Background: Depression frequently occurs in the elderly. In normal aging, and in depression, the functioning of the suprachiasmatic nucleus (SCN) is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, e.g. sleeping disorders. Also, the normal inhibition of SCN neurons on corticotrophin-releasing hormone (CRH) producing cells is decreased, which could be responsible for the hyperactive hypothalamus-pituitary adrenocortical axis (HPA-axis). This raises the question whether elderly patients with depression have more impaired SCN activity and whether HPA-activity is enhanced. Using bright light therapy (BLT) the SCN can be stimulated. And, the beneficial effects of BLT on seasonal depressive disorders are well accepted. Nevertheless, the effects of BLT in aged depressed patients have never been studied, as yet.

Aims: The aim of this study is to test the hypothesis that BLT improves sleep, mood, concentration and self-efficacy of older people with depression and this improvement is accompanied by a normalization of HPA-indices.

Methods: Randomised double blind placebo controlled trial in 120 subjects of 60 years and older with a diagnosis of major depressive disorder (DSM-IV/SCID-I). Subjects are recruited through referrals of psychiatric outpatient clinics and from case-finding from databases of general practitioners and old-people homes in the Amsterdam region. After inclusion subjects are randomly allocated to bright blue light vs. dim red light groups using two Philips Bright Light Energy boxes type HF 3304 per subject from which the light bulbs have been covered with bright blue or dim red light permitting filters. Criteria for stratification are the use of SSRIs. Prior to treatment a 1-week run-in period without treatment will be used as a baseline condition. At three time points several endocrinological, psychophysiological, psychometrically, neuropsychological, and neuroimaging measures are performed: just before start of light therapy (T0), after completion of the three week light therapy period (T1), and three weeks thereafter (T2).

Relevance: This study is designed to show whether light therapy can reduce depressive symptoms of elderly patients with a major depressive disorder. If this is the case, then additional lightning may easily be installed in the homes of patients to serve as a maintenance treatment. Also, if our data support the role of a dysfunctional biological clock in depressed elderly subjects, such a finding may guide the further development of drugs that inhibit the HPA axis.