Depression and dementia have many similarities:

  1. Memory problems;
  2. Excessive sleeping;
  3. Lack of interest in hobbies and activities; and
  4. Social withdrawal.

In fact, there are so many similarities between the two conditions that even physicians may have difficulty differentiating between the two, particularly when they both occur at the same time.  This raises questions about the two conditions:  (1) can a diagnosis of dementia cause someone to become depressed, or (2) is late-life depression a harbinger of the diminished cognitive impairment associated with dementia?

Clinical Studies about Depression and Dementia

Studies about these questions have shed some light on them, but have not confirmed definitive answers.  One study found that the emergence of depressive symptoms in mid-life, late-life, or both was associated with an increased risk of dementia.

Another study found a significant link between vascular dementia, Alzheimer’s, and depression.  When the depression occurred (mid-life or late-life) also appeared to be associated with different kinds of dementia.  For example, those who experienced symptoms of depression in their 40s and 50s and the depression persisted into later life, seemed to have a three-fold increase in the rate of developing vascular dementia.  Vascular dementia is a type of dementia caused by blood vessel injuries or disease within the brain.  This same study also found that those individuals who presented with symptoms of depression later in life were twice as likely as their non-depressed peers to develop Alzheimer’s.

Biological Effects of Depression

Other studies have investigated additional linkages between depression and dementia.  Some have looked at biological effects of depression on the brain.  Depressed individuals tend to produce higher levels of the stress hormone cortisol.  Higher levels of cortisol may impair parts of the brain responsible for short-term memory and learning.

Another biological effect of depression may be increased inflammation.  Depression causes increased inflammation of the immune system which, in turn, can affect all areas of the nervous system.  Long-term inflammation can eventually damage the brain, affecting mood, learning, and memory.

Structural brain damage can also result from prolonged periods of stress.  The hippocampus, the part of the brain responsible for turning information into memories, can be damaged as a result of prolonged periods of stress.  Chronic depression can also lead to damage to other parts of the brain.

Behavioral Effects

Depression can also produce behavioral changes.  One of the primary symptoms of depression can be a loss of interest in social activities.  Other studies have found that loneliness and a lack of social engagement put individuals aged 65 or older at greater risk of developing dementia.

Final Thoughts

Clearly, there is some kind of link between depression and dementia.  In order to diminish negative effects of these two conditions, it is necessary to take immediate steps to identify and treat depression.  If a client is exhibiting symptoms of depression, immediate medical attention should be sought.  In most cases, some combination of psychotherapy and medication can do much to alleviate the symptoms.

Depression is a serious illness, like other serious illnesses.  I must be treated effectively in order to alleviate symptoms.  If there is a link between depression and dementia, the sooner depression can be identified and treated, the better.

About the Author

Cynthia Barnes, PH.D., lives in Denver, Colorado and is an experienced educational and training professional at all educational levels. Dr. Barnes has a background in organizational development and change and systems thinking/operating. She is a published author with exceptional written, oral, and interpersonal relationship skills. Dr. Barnes has consulted with organizations and school systems throughout the United States and in Canada, Germany, Micronesia, and South Africa.

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