Depression May Raise Dementia Risk

Edit Subject

People who are depressed have a higher risk of dementia in later life, a new study concludes. The research was based on data about 949 older adults from a larger, long-running study. Their average age was 79. Tests showed that 125 had depression. Researchers kept track of them for up to 17 years. In that time, 164 people developed dementia. About 22% of those who were depressed at the start of the study developed dementia. This compares with 17% of those who were not depressed. People who were depressed also had more heart disease and other factors that increase the risk of dementia. Researchers adjusted their data for those differences. After the adjustment, they found that depressed people were about 70% more likely to develop dementia. The reason is unclear. Researchers said being depressed can inflame the brain and increase its output of certain proteins. Depression also can lead to less exercise and social interaction. It's possible that these factors increase dementia risk. The study appears in the journal Neurology July 5.

What Is the Doctor's Reaction?

Headlines about a new study say, "Depression more than doubles your risk for later dementia." This sounds awful. In fact, it is depressing. The study gives a fearsome statistic: 21.6% of people who have depression will later get dementia.

Yes, 21.6% is a huge number. But it is deceptively large.

It is not your lifetime risk for dementia, unless you are looking forward after reaching a ripe old age. It is not a number that applies to young people who get depression. This study refers specifically to your risk for getting dementia if you show signs of depression in your old age. Dementia includes Alzheimer's disease and other types.

The people in this study were a small sub-set from the Framingham Heart Study. They were very old -- an average age of 79 at the beginning of the study. They were in their late 80s, give or take, by the end of the study. This is older than the current life expectancy in the United States. A 21.6% chance of dementia is not surprising in such an aged group.

Without depression, your odds of developing dementia (once you have reached age 79 or so) are about 1 out of 7. With older-age depression, the odds of developing dementia are about 1 out of 4 or 5, this study found.

This study is believable. Depression in the elderly probably does increase the chance for dementia. But why is this so? We don't know, but there are several ways we might explain the connection:

• Staying socially active and exercising your body are important ways to prevent or slow down dementia. Depression can cause people to withdraw from activities. This could increase the risk of dementia.


• Scientists behind the current study think brain chemistry or blood flow patterns could play an important role.


• Depression may be one sign that an elderly person doesn't have much "reserve" in the brain. This could make that person vulnerable to dementia.

What Changes Can I Make Now?

In this study, 13% of elderly people were depressed. What can we do to treat depression in the elderly?

• In this study, people with depression had a higher risk of dementia whether or not it was being treated with medicine. So it is hard to say whether treatment for depression might influence the risk of dementia. But depression is devastating, and it should be treated. Most people who were found to be depressed in this study were not being treated for their symptoms.




• Most people with depression do best if they take antidepressant medicine for 6 to 12 months. One study has suggested that longer treatment might help elderly people with depression.




• Two types of talk therapy are helpful for depression in the elderly. Interpersonal psychotherapy helps you to sort out which people in your life support you and which are unreliable for you. It can help you to resolve stressful disputes and learn to take care of your own needs. Cognitive behavioral therapy teaches you to think positively, to solve problems and to rediscover simple pleasures.




• Correcting vision and hearing loss can help to limit the potential for social withdrawal and depression.

We still don't have foolproof ways to prevent dementia, but you can lower your risk.

A nicely designed study looked at future dementia risk in people ages 39 through 64. Those who exercised at least twice a week in mid-life cut their risk of later dementia in half. Obesity and diabetes also have been linked with increased dementia risk.

Keeping active is the only potential preventive strategy against Alzheimer's disease that doctors can feel completely comfortable recommending. This includes being physically, intellectually and socially active. These life strategies do appear to work.

Other ideas for prevention are not recommended. For example, you should take non-steroidal anti-inflammatory drugs and statin drugs only if you have another reason to use them. Do not take them to prevent dementia. Their protective benefit has not been proven and they have potential harms.

Taking estrogen after menopause has been linked to a higher risk of Alzheimer's. Avoid estrogen after menopause unless it is truly needed to treat symptoms. Stop it after a few years of use.

People with a strong family history of Alzheimer's disease may choose to take vitamin E. The suggested dose is 400 to 800 international units per day. There is some evidence that vitamin E may offer some protection, but its benefit is still unproven.

What Can I Expect Looking to the Future?

The cause of Alzheimer's disease remains a mystery. Scientists will keep working to find which conditions increase dementia risk. This may eventually allow us to understand the biology of dementia, and its triggers.