A reader asks:

 What is the evidence to support the use of light therapy to treat behavioral problems in the demented elderly? (I would like to read the research studies.) How does is it thought to work?


Quoting from Dr. Terman’s 2005 CNS Spectrums review (downloadable at www.cet.org): “Light therapy for elderly patients deserves separate mention. Although its use to alleviate disruptive and cognitive symptoms of senile dementia has been extensively investigated, a review of the effect on sleep and behavior found the results inconclusive, with further confirmation in another Cochrane review that also considered effects on mood. Few light therapy studies have focused on geriatric depression, per se. A small crossover study (N=10) in institutionalized patients without MDD but with moderate-to-high Geriatric Depression Scale scores tested morning bright versus dim light (10,000 lux versus 300 lux, 30 minutes, 5 days), and obtained significant mood improvement under the active condition. In Taiwan, a trial of hospitalized patients with MDD (N=30) found alleviation of depressive symptoms after 5 days of morning light treatment (5000 lux, 50 minutes) in comparison with an untreated control group. However, the largest such trial (N=80, 5 weeks) found no significant benefit of bright light (10,000 lux, 1 hour; morning, midday, or evening) over a 10-lux dim red control. This raises doubt about the general utility of bright light therapy for geriatric depression, even though there was a trend toward greater improvement with morning exposure.” See the references in the paper, and you will have a route into the literature.