Light therapy promising for treating major depression

The trial was run by a team led by Dr. Ritsaert Lieverse of GGZ inGeest and the VU University Medical Center in Amsterdam, and studied 89 adults aged 60 or over who had been diagnosed with clinical depression (also called Major Depression Disorder or MDD), around half of whom were randomly assigned to bright light therapy for three weeks.

The therapy involved spending an hour each morning with the same kind of light-therapy box as that used for treating seasonal affective disorder, which is a type of depression related to seasons such as winter, when the days are shorter and people are exposed to less natural light. The control group used a light box that emitted a dim red light (50 lux) rather than the bright pale blue light (7500 lux) of the light-therapy box. Dim red light has no known benefits or detrimental effects on humans.

The results of the trial showed those given bright light therapy made improvements over the controls, and the improvements were comparable to the use of antidepressant drugs. Improvements were measured using the standard Hamilton Scale for Depression. The light-therapy group also showed an increased level in the evening of the sleep-promoting hormone, melatonin, and a decrease in levels of cortisol, the stress hormone.

The light-therapy group continued to improve for the three weeks after the treatment, with 54 percent experiencing improvement of their symptoms compared to 33 percent of the control group.

Other research has shown that bright light affects the levels of some chemicals in the brain, such as serotonin, which is implicated in some forms of depression. Light also appears to affect the same areas of the brain as those targeted by antidepressant drugs.

Dr. Lieverse said the findings offer hope for the many older people who do not receive or who refuse treatment with antidepressant drugs, and for those who experience serious side effects. He said older people were more prone to side effects than younger patients. Light therapy may also useful as an add-on therapy for those for whom the drugs are ineffective.

Dr. Lieverse warned that because major depression is a serious disorder, people with symptoms should not self-treat, even though light boxes are available without prescription. Light therapy may not be appropriate for people with eye conditions such as diabetic retinopathy, and they can cause side effects such as nausea, headache, irritability and eye strain in some individuals.

The paper is published in the Archives of General Psychiatry.

More information: Arch Gen Psychiatry. 2011;68(1):61-70. doi:10.1001/archgenpsychiatry.2010.183

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