Depression - Causes Of Memory Impairment: Improving Memory Understanding Age Related Memory Loss

Content provided by the Faculty of the Harvard Medical School

Depression

The relationship between depression and memory loss is complex. Depression can be a cause as well as an effect of memory dysfunction. Severe, ongoing, and untreated depression can make people forgetful by interfering with their ability to concentrate, pay attention to details, and process information. This is particularly true in the elderly. In fact, doctors have coined the term "depressive pseudo-dementia" to describe elderly patients with severe memory impairment based on depression. Once their depression is treated, their memory returns to baseline.

Research suggests that long-term depression may result in a loss of neurons in structures within the limbic system of the brain, including the hippocampus and amygdala. For example, one imaging study found that these structures were smaller in women with a history of major recurrent depression than in people who had not experienced depression. In the same study, women with a history of depression did not perform as well as other women on tests of verbal memory.

Depression might also increase the risk of Alzheimer's disease. A study in the Archives of Neurology in 2003 compared the history of depression in two groups: 1,953 patients with Alzheimer's and 2,093 unaffected relatives. The study found that a history of depression was more common among the Alzheimer's patients than among their relatives. The association was strongest — nearly five times stronger — among the patients who had had depression within the year preceding the appearance of Alzheimer's symptoms.

Although depression can be a symptom of early Alzheimer's disease, there are key differences in the memory loss experienced by people suffering from depression alone and people experiencing depression in conjunction with Alzheimer's disease. In people with depression alone, cognitive function usually fluctuates with mood. When mood improves — usually in response to treatment with medication, psychotherapy, or both — cognitive function generally improves as well. By contrast, someone with Alzheimer's disease will experience no such improvement in cognitive function when the depression lifts.

Last updated:	January 23, 2007