More than half of adults over 60 with clinical depression don’t get better when they are prescribed an antidepressant. A new study has found that adding a second drug — the antipsychotic aripiprazole (brand name Abilify) — relieves depression in a significant number of those patients.

The study also found that the two-drug combination reduced the likelihood of suicidal thoughts in these patients, according to researchers at Washington University School of Medicine in St. Louis.

Previous research has shown that adding a low dose of aripiprazole helped relieve symptoms of depression in younger patients when an antidepressant alone wasn’t effective. The new study is the first to show the same strategy also works in older patients, researchers noted.

“It’s important to remember that older adults may not respond to medications in the same way as younger adults,” said first author Eric J. Lenze, M.D., a Washington University professor of psychiatry.

“There are age-related changes in the brain and body that suggest certain treatments may work differently, in terms of benefits and side effects, in older adults. Even when a strategy works for patients in their 30s, it needs to be tested in patients in their 70s before it can be considered effective in older patients.”

A 2007 study estimated that about seven million of the nation’s 39 million older Americans had clinical depression. Up to 90 percent did not receive necessary care, and 78 percent received no treatment at all.

The consequences are costly, according to scientists. Elderly patients with clinical depression use more health-care services, spending nearly twice as much on medical care as those without the disorder. The suicide rate among people over 75 is higher than in any other age group, they note. Depression also is a risk factor for dementia.

“This is a rare study because it looks at depression specifically in older adults,” said Benoit H. Mulsant, M.D., a co-author of the study and a senior scientist at the Centre for Addiction and Mental Health (CAMH) in Toronto.

“It’s important to treat older adults for depression, especially given that adults with late-life depression are at an increased risk of developing dementia. But this research demonstrates that older adults do respond to depression therapy.”

The new study, conducted at CAMH, Washington University School of Medicine, and the University of Pittsburgh School of Medicine, included 468 people over the age of 60 diagnosed with depression.

Each participant received an extended-release formulation of the antidepressant drug venlafaxine, which is sold under the brand name Effexor XR, for 12 weeks. About half of these patients still were clinically depressed after 12 weeks of treatment, according to the study’s findings.

“We know that in older adults with depression, about half will not respond to medication,” Lenze said. “They may have a minimal response, but they’ll still be depressed. The question we wanted to answer was whether there was anything else we could do for them.”

For the second phase of the study, the patients who did not respond to the venlafaxine continued to receive the drug along with aripiprazole or a placebo.

The two-drug combination led to a remission of depression in 44 percent of the treatment-resistant patients, compared with only 29 percent of those who had received the placebo, the researchers reported.

Some patients who took the two-drug combination experienced restlessness, according to the researchers. Others developed some stiffness, called mild Parkinsonism. But the side effects tended to be mild and short-lived.

“The potential benefits outweighed the side effects,” Lenze said.

He added that the side effects that researchers expected to see, such as weight gain and metabolic problems, never occurred.

“Antipsychotic medications can cause increasing amounts of fat and thereby increase blood sugar, potentially contributing to diabetes,” Lenze said. “But compared with placebo, aripiprazole was no more likely to produce increased fat in these patients and had no effect on blood sugar, insulin or lipids.”

A key remaining question involves predicting which older depressed patients are likely to benefit from the two-drug combination, according to Lenze. Learning the answer is a goal for future research, he noted.

“One of the things we see as critical to our future research will be trying to better understand the factors that make some people respond to specific forms of treatment that may not work for others,” Lenze concluded.

The study, funded by the National Institute of Mental Health and the National Center for Advancing Translational Sciences of the National Institutes of Health (NIH), was published in The Lancet.

Source: Washington University School of Medicine

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