Late-life depression may signal memory loss or dementia ahead

Depression can strike at any age. Children can develop it, as can octogenarians. No matter when it starts, depression can drain the joy and pleasure from life. The first appearance of depression later in life may also be a signal of memory loss or dementia down the road.

According to a study in the Archives of General Psychiatry, dementia is more common among people who become depressed in middle age or later in life than among those who aren’t depressed. In that study, age of onset was also linked to the type of dementia—individuals with late-life depression had about double the risk for Alzheimer’s disease, while those whose depression began in midlife faced three times the risk for vascular dementia (which is caused by poor blood flow in the brain).

Depression is often overlooked in older adults. “I think older individuals are more in denial about having depressive illness,” says Dr. M. Cornelia Cremens, assistant professor of psychiatry at Harvard Medical School and a geriatric psychiatrist in the senior health practice at Massachusetts General Hospital. “They’ll say, ‘Well, I’m 83 years old—who wouldn’t be depressed?‘” Ignoring sadness or dismissing it as a normal side effect of aging could allow potentially treatable memory issues to progress unchecked.

As I write in the October 2012 Harvard Women’s Health Watch, researchers have long known that depression and dementia often go hand in hand. The two conditions may simply share common causes. And the Archives study suggests that depression late in life may be a sign of brain changes that can make an individual more prone to developing dementia.

Recognizing depression

The signs of depression are slightly different in older adults—and many of them can mimic memory loss and illness. If you are experiencing these symptoms, or see them in a loved one, a visit to a primary care physician or psychiatrist for an evaluation is appropriate:

• feelings of helplessness, hopelessness, or worthlessness
• lack of energy; fatigue
• irritability, pessimism
• loss of interest in activities
• difficulty concentrating or remembering
• confusion
• trouble sleeping
• appetite loss or overeating
• aches and pains that don’t go away

“If somebody appears to have the beginning of dementia and they are depressed, it’s very important to treat their depression, and to treat it as aggressively as possible,” Dr. Cremens says. Older individuals who are depressed should also be evaluated for dementia, she adds. Screening tests such as the Mini-Mental State Exam and the Montreal Cognitive Assessment are short questionnaires that doctors use to identify cognitive impairment.