TUESDAY, July 19 (HealthDay News) -- The antidepressants most often prescribed to treat depression in dementia patients provide no appreciable relief, and may raise the risk for serious side effects, new British research suggests.

"The two classes of antidepressants most likely to be prescribed for depression in Alzheimer's disease are no more effective than placebo," the study authors said.

The drugs in question are Zoloft (sertraline), and Remeron (mirtazapine).

"In our study, there were more adverse reactions in individuals treated with antidepressants than there were with placebo," the research team added. "Clinicians and investigators need to reframe the way they think about the treatment of people with Alzheimer's disease who are depressed, and reconsider routine prescription of antidepressants."

Led by Sube Banerjee of the Institute of Psychiatry at Kings College London in England, the authors reported their findings online July 19 in The Lancet.

Banerjee and his colleagues focused on 325 patients being treated at any of nine health centers across England for probable or possible Alzheimer's disease. The patients were also subject to bouts of depression lasting at least a month, and all registered above a minimum threshold during dementia-related depression exams.

None had been prescribed antidepressants prior to the study launch, nor were any in a critical stage of depression involving suicidal thoughts.

The patients were divided into three 13-week treatment groups. One group received 150 milligrams (mg) a day of sertraline; a second group received 45 mg a day of mirtazapine; and a third took sugar pills (placebos).

After three months, the authors found no difference in the incidence of depression among the three groups. The lack of an apparent benefit attributable to either sertraline or mirtazapine continued almost 10 months after the study's start, according to a journal news release.

Also, while about a quarter of those given placebos experienced adverse reactions as a result of treatment, that figure rose to between 41 percent and 43 percent in the groups given an antidepressant. Such side effects were also more likely to be serious among the antidepressant recipients than among the placebo group.

Dr. Henry Brodaty, an aging and dementia specialist at the University of New South Wales in Sydney, Australia, and author of an accompanying journal editorial, said the trial "has underscored the need for clinicians to think about creative alternatives to drug treatment for management of depression in people with dementia." It is important to use evidence-based techniques and to work in partnership with family caregivers, he wrote in the news release.

More information

For more on dementia and depression, visit the Alzheimer's Society.