Is Depression a Risk Factor for Alzheimer's Disease?

Related topics: Alzheimer's Disease

Depression is one of the most common conditions affecting older adults. According to the University of Pittsburgh School of Medicine, an estimated 15 percent of people older than 65 are dealing with depression, which affects the whole person: mind, body and emotions. Symptoms include a persistent feeling of sadness, lack of energy, changes in normal eating and sleeping, memory disturbances and impaired concentration, loss of interest in usual activities, and trouble keeping up with normal activities at home and work.

If you compare these symptoms to those of Alzheimer's disease and related conditions, you will notice some striking similarities. Many of the symptoms of depression are known to mimic dementia, so closely that families and even healthcare providers may at first mistakenly suspect that a person with depression has Alzheimer's disease. Ruling out depression is an important first step in diagnosing dementia.

Further complicating things, depression itself may be one early sign of dementia. But if depression is a symptom of Alzheimer's disease, could it also be a risk factor?  For years, researchers have speculated that people with depression are more likely to later develop dementia. What is the connection? How could a history of depression make it more likely that a person will suffer cognitive losses later in life?

The American Academy of Neurology states that depression may nearly double a person's risk of developing dementia. Researcher Jane Saczynzki, Ph.D., of the University of Massachusetts Medical School says, "While it's unclear if depression causes dementia, there are a number of ways depression might impact the risk of dementia. Inflammation of the brain tissue that occurs when a person is depressed might impact the risk of dementia. Certain proteins found in the brain that increase with depression may also increase the risk of developing dementia." Researchers from the University of Edinburgh also looked at brain shrinkage caused by high levels of certain stress hormones.

It could also be that a particular factor—perhaps not yet known—underlies both depression and dementia. Research is underway to determine the precise nature of the connection between the two conditions. 

Treating depression supports brain health

One thing researchers agree upon: Depression makes it much less likely that we will follow a healthy lifestyle that protects our memory health. It saps our will and motivation and our desire to be active. Says Saczynski, "Several lifestyle factors related to long-term depression, such as diet and the amount of exercise and social time a person engages in, could also affect whether they develop dementia."

This is yet another reason to seek professional help if you or a loved one is showing signs of depression. Depression can become disabling if not properly treated. All too often, people are resistant to the idea that they might have a true depression, feeling that somehow they will "just snap out of it." But depression is an illness that results from a chemical imbalance in the brain, and it can respond successfully to treatment.

The first step in reversing depression is to have it diagnosed by a physician or other qualified professional. After a thorough exam, the healthcare provider will first try to identify the cause of the depression, which might stem from:

  • Distressing life events such as the death of a spouse, financial worries or illness
  • Chronic pain
  • Nutritional deficiencies such as lack of vitamin B-12 or folic acid, or poor nutrition in general
  • Underlying medical conditions such as low thyroid or other hormone changes, diabetes, heart disease or Parkinson's disease
  • Side effects of specific medications, overmedication, or effects of polypharmacy—taking many drugs which might have a negative interaction.

Treatment for depression may include…

Lifestyle changes—Patients are advised to focus on better nutrition, spending more time with others, increasing physical activity, making more time for enjoyable activities, managing other health conditions, and confronting and dealing with negative thoughts.

Counseling—It's not always possible for a person with depression to work through troubling thoughts on their own. Talking with a mental health professional may help identify the stressors that have led to depression, aid in developing strategies to lessen those stressors, and change negative thoughts as patients learn to take better care of themselves.

Medication—Antidepressant medications work by helping the brain make its normal chemicals again. These medications can help with sleep, improve energy and reduce anxiety and negative thoughts. There are several classes of these drugs; it is important to work closely with the healthcare provider during the process of finding the best medication for each patient. This may take several months.

Many older adults avoid seeking help for depression. They may have a generational attitude of self-sufficiency and keeping one's problems to oneself. To help overcome that preconception, seniors should be encouraged to understand that treating depression is no different than treating any other illness. Professional help can let them get their lives back on track. And now we know it may very well also protect their brains!

Better treatment of depression and understanding of the connection between depression and dementia is not only important for senior patients; it is vital for our nation's healthcare system as well. According to University of Pittsburgh School of Medicine professor Meryl Butters, Ph.D., "An understanding of how late-life depression increases the risk of dementia could lead to better prediction and prevention mechanisms. Early diagnosis and prevention of depression could have a major dual public health impact as they could also potentially prevent or delay cognitive decline and dementia in older adults."

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