Subjects Who Were Depressed in Middle Age Had an Elevated Risk of Dementia in Old Age, Analysis Finds

By JENNIFER CORBETT DOOREN – (Wall Street Journal)

People who suffer from chronic depression throughout their lives are more likely to develop dementia compared with people who aren’t depressed, according to a study released Monday.

The study, by California researchers, sheds light on whether depression might cause dementia and Alzheimer’s disease, or if it is merely an early sign of memory loss and other problems associated with dementia. Alzheimer’s disease is the leading cause of dementia; the second-leading cause is impaired blood supply to the brain, resulting in what is known as vascular dementia.

“It’s quite clear depression late in life can be an early sign of Alzheimer’s,” explained Rachel Whitmer, a study researcher and an investigator at the Kaiser Permanente Northern California Division of Research. “There’s a lot of debate whether [depression] is really a risk factor for dementia, or if it just shows up.”

The findings, published in the May issue of Archives of General Psychiatry, add to the evidence that late-in-life depression is a likely early sign of Alzheimer’s disease and suggest that chronic depression appears to increase the risk of developing vascular dementia. Adequate treatment for depression in midlife could cut the risk of developing dementia. The study is the first to examine whether midlife or late-life depression is more likely to lead to either Alzheimer’s disease or vascular dementia over the long term.

To look at links between depression and dementia, Dr. Whitmer and other researchers looked at 13,535 long-term Kaiser Permanente members who had enrolled in a larger study in the period from 1964 to 1973 at ages ranging from 40 to 55 years old. Health information, including a survey that asked about depression, was collected at the time.

Researchers looked at whether the same people were depressed late in life, in the period from 1994 to 2000, and then looked at whether they were diagnosed with dementia or Alzheimer’s disease in 2003. The participants’ average age in 2003 was 81 and 57.9% were women. The study found depression present in 14.1% of subjects in midlife only, in 9.2% in late life only and in 4.2% in both.

Looking at those who later developed dementia, the study found 20.7% of study participants without depression developed dementia, compared with 23.5% of people who reported depression in midlife only and 31.4% of those who were depressed later in life. Among those who were depressed at both mid- and late-life, 31.5% developed dementia.

Researchers then did more analysis to tease out Alzheimer’s diagnoses from the broader dementia category. They found people who were depressed in midlife but not late in life had no increased risk of developing Alzheimer’s disease or vascular dementia. People who were depressed late in life were more likely to develop Alzheimer’s while those depressed at both mid- and late life were three times as likely to develop vascular dementia.

Dr. Whitmer’s research focused on people’s health and how it affects brain aging. Previous studies she has conducted using Kaiser’s database of long-term members, have shown that factors such as smoking, diabetes, high cholesterol and belly fat increase the risk of developing Alzheimer’s and other brain diseases. A 2008 study looking at belly fat showed people who had more belly fat during middle age had higher rates of dementia when they reached old age. The finding held true even for people whose overall body weight was considered normal.

Kaiser Permanente Northern California is a large, nonprofit health maintenance organization that provides health services to more than one-quarter of the population in the San Francisco and Oakland, Calif., areas.

Dr. Whitmer’s most recent study, conducted with researchers from the University of California in San Francisco, was funded by Kaiser Permanente, the National Institutes of Health and the Brain and Behavior Research Foundation.

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