Dementia Causes: Can Depression Play a Role?

Studies continue to shed light on dementia causes, even as debates continue. Here's what research is revealing about depression as a dementia risk factor.

dementia causes

suggested that major and worsening depression in seniors may significantly raise the risk for dementia.

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Dementia causes can be a mystery, but there’s no doubt the condition is too prevalent. About 5.4 million Americans are thought to have some degree of dementia, and its destructive effects on our cognitive abilities come at huge cost to our overall wellbeing—and that of our loved ones.

“The decline in reasoning and memory that accompanies dementia impairs our ability to carry out everyday tasks, and [can have an] impact on spousal and familial relationships,” says Judith Neugroschl, MD, assistant professor of psychiatry at Mount Sinai. “Many people with dementia eventually become totally dependent on others for their care—it is the leading reason for placement of older adults in nursing homes.”

What causes dementia remains unclear, although research points to a number of underlying conditions that may raise your risk, including diabetes, stroke, heart disease, high blood pressure and cholesterol, and obesity. Another significant factor is depression.

Dementia Causes: Late-Life Depression Can Come Into Play

Several large studies have pointed to a link between late-life depression and a greater risk for all-cause dementia and Alzheimer’s disease (the most common form of dementia in the elderly).

Late-life depression is common in American seniors, affecting about 15 percent of those age 65 and older. In some instances, it may be a relapse of earlier depression, but older adults also are susceptible to new-onset depression, particularly if they’re grieving after loss, have a chronic illness, take certain drugs, or have been hospitalized.

A 2016 study (JAMA Psychiatry, May 1) suggested that major and worsening depression in seniors may significantly raise the risk for dementia. The disease developed in about 21 percent of study participants who had serious, escalating depressive symptoms, compared to about 12 percent of participants with consistently minimal depressive symptoms. Another 2016 study (Lancet Psychiatry, April 29) also suggested that participants whose symptoms of depression increased over time were at an increased risk for dementia.

Depression and Dementia: How Are They Linked?

Several theories have been advanced for how depression might be linked to dementia. One holds that cortisol—a stress hormone that’s elevated in depressed people—may damage the brain. Another theory posits that depression might result in reduced brain volume, which is associated with a greater risk for dementia.

Depression also may deplete a senior’s cognitive reserve, which experts define as the brain’s ability to withstand neurological damage due to aging and other factors.

Dr. Neugroschl points out that there also could be an underlying causative factor for both depression and dementia. “People who are depressed are more likely to be socially isolated, eat a poor diet, drink too much, smoke, and avoid exercise—behavioral and lifestyle factors that also have been shown to increase the risk for dementia,” she notes.

Further research may ascertain whether depressive symptoms could be used to identify older adults at increased risk for dementia, but if you suffer from depression, don’t panic—not every senior with depression goes on to develop dementia.

Getting Help for Depression Is Vital

Depression isn’t inevitable as we age, and effective treatments—including cognitive behavioral (or “talk”) therapy, and medications—are available.

“As well as improving your mood and outlook on life, treating depression may reduce other health risks,” Dr. Neugroschl adds. “For example, depression is associated with a greater risk for cardiovascular diseases, obesity, chronic pain, falls, and social isolation.”

No studies have indicated that treating the symptoms of depression helps stave off dementia. But Dr. Neugroschl points out that getting help for depression can help improve quality of life for people in the early stages of dementia, as well as keep them independent for longer.

“For people with dementia, support groups can be helpful when it comes to dealing with depression alongside cognitive issues,” she says, adding that if you are the main caregiver for a spouse or relative with dementia, you should be vigilant for signs that might indicate depression in your loved one (see sidebar box below).

And take care to protect your own mental wellbeing. According to the Alzheimer’s Association, 30 to 40 percent of family caregivers of people with dementia suffer from depression, compared with 5 to 17 percent of non-caregivers of similar ages.

WHAT YOU SHOULD KNOW

DIAGNOSING DEPRESSION IN PEOPLE WITH DEMENTIA

It can be challenging to diagnose depression in people with dementia, due to the overlap of symptoms. Dementia sufferers also may be less able to articulate their symptoms. The National Institute of Mental Health (NIMH) suggests that demented patients with a depressed mood or decreased pleasure in activities be evaluated by their doctors for two or more of the following, which could suggest
a diagnosis of depression:

  • Feelings of worthlessness or hopelessness, or inappropriate or excessive guilt.
  • Social isolation or withdrawal.
  • Appetite changes that are not related to another medical condition.
  • Poor sleep.
  • Agitation or slowed behavior.
  • Irritability.
  • Fatigue or loss of energy.
  • Recurrent thoughts of death, or a suicide attempt.
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