EXPOSURE to bright light may be just as effective for depressed elderly people as taking antidepressant medication, scientists have found, and the benefits seem to last even after the treatment is discontinued.
In the Dutch study, 89 people aged 60 or older with a diagnosis of major depression were given a light box to take home and instructed to sit beside it for an hour each morning over three weeks.
For half the group, the light it emitted was bright and blue, while others were subjected to a dim red light.
Advertisement: Story continues below After three weeks, more of those exposed to the bright light experienced a lifting in their mood, measured using a standard psychiatric questionnaire.
But after another three weeks, during which the men and women no longer used the light box, the difference between the two groups was even more pronounced.
The bright light treatment group also displayed lower levels of the stress hormone cortisol, and got out of bed earlier than the patients who received dim light, says the study by psychiatrists and neuroscientists from several Netherlands universities. It is the first in the world to include enough patients to draw statistically reliable conclusions.
Bright light, which had proven successful for some people who suffered from the winter depression known as seasonal affective disorder, might be important for depressed elderly people, said the study leader, Ritsaert Lieverse.
”Elderly people expose themselves less frequently to bright environmental light,” Dr Lieverse wrote in the journal Archives of General Psychiatry, and might also absorb less light through their retinas. They were also more prone to medication side-effects.
The beneficial effects might in part be due to the resetting of the body clock, said Dr Lieverse, who also observed a bigger evening rise in the circadian hormone melatonin among those who received the bright light therapy.
David Ames, the director of the National Ageing Research Institute in Melbourne, said about one in 100 elderly people were depressed enough to need treatment from a psychiatrist, while 15 per cent had milder forms of the illness.
”Some forms of depression do have some characteristics of circadian disturbance,” Professor Ames said.
Elderly people who were more vulnerable to depression, because of physical illness or isolation, were also those whose body clocks were likely to be adversely affected by receiving less daylight, he said.
Further research should compare light therapy with antidepressants, Professor Ames said. If it proved effective, bright light would be ”reasonably non-toxic” and inexpensive.
Julie Robotham
The Sydney Morning Herald