Linking Dementia and Depression?

Depression linked to cognitive impairment and dementia in seniors

(RxWiki News) Aging is a part of life and it can involve changes in the brain. Most do not develop memory problems or depression, but these two things can develop together in some people.

A recent study found that depression among seniors is linked to cognitive impairment and a higher risk of dementia.

The link is not strong, and it's not clear what the cause of it is. Depression might contribute to cognitive problems. Or cognitive problems might contribute to depression. The same possibilities exist for dementia.

Overall, more research is necessary to understand the relationship between depression, cognitive impairment and dementia.

"Seek treatment for depression."

The study, led by Edo Richard, MD, PhD, of the Department of Neurology at the University of Amsterdam in the Netherlands, looked for links between depression, cognitive impairment and dementia.

A total of 2,160 Medicare recipients, aged 65 and older, were assessed with a standard questionnaire for depression with a scale from 0 to 10. A score of 4 or higher is used to determine that someone is depressed.

At the start of the study, 21 percent (451 total) of the participants had a score of 4 or higher, and 79 percent (1,708 total) had a score under 4.

A panel of neurologists, neuropsychologists and psychiatrists assessed whether a person had dementia or mild cognitive impairment using "all available clinical and neuropsychological information." The researchers adjusted their calculations to account for the participants' age and race/ethnicity.

At the start of the study, 20 percent (429 total) of the participants had mild cognitive impairment. These individuals "were more often depressed than those who were cognitively intact."

However, the link between mild cognitive impairment and depression was only strong for the 222 participants who had amnestic mild cognitive impairment.

The link between depression and the 207 who had non-amnestic mild cognitive impairment could have been due to statistical chance.

Of the 217 participants who were diagnosed with dementia at the start of the study, most (75 percent) had "possible or probable" Alzheimer's disease while the rest had either vascular dementia or other dementia.

Depression occurred among these participants with dementia twice as often as it occurred among the other participants. The strongest link for depression existed with those who had vascular dementia.

However, this link became weaker when the researchers took into account participants' history of diabetes, high blood pressure, smoking, lipoprotein levels and waist to hip ratio. These are all factors that could influence the development of vascular dementia.

After the initial assessments, the researchers followed up with 1,601 of the participants a year and a half to two years later. Among the 304 patients who developed mild cognitive impairment during this time, no link was found with depression.

Among the 207 who developed dementia during the follow-up period, there was a higher rate of depression.

Those who had been depressed at the start of the study and at the follow-up, and those who were only depressed at the follow-up, were almost twice as likely to have developed dementia.

Those who had been depressed at the start of the study but not at follow-up were about 60 percent more likely to have dementia.

Overall, the researchers found links between depression and mild cognitive impairment and depression and dementia. However, the reasons for the link and how they relate to one another are not clear.

For example, depression might be an early symptom of mild cognitive impairment. Or a person could become depressed in response to developing cognitive impairment.

There may also be links between depression and dementia in the parts of the brain dealing with both. Or there might be other physical or mental conditions that happen to influence both depression and cognitive impairment and/or dementia. Additional research is needed to find out more.

The study was published December 31 in the Archives of Neurology. No information was provided regarding funding, but the authors state no conflicts of interest.

Review Date: 
December 28, 2012