The Link Between Depression, Dementia, and Alzheimers

Depression is common among older adults, who may experience symptoms as they enter retirement and experience other significant changes to their lifestyles. The loss of a spouse, lack of support from family and friends and the increasing physical challenges may contribute to the development of depression symptoms. A new study says that loved ones should be careful to watch for signs of depression in older family members. The onset of depression may be a predictor of both Alzheimer’s disease and vascular dementia, which is caused when blood flow is blocked from entering the brain, keeping oxygen and nutrients from entering as well. The study appears in a recent issue of the British Journal of Psychiatry, providing a summary of 23 total studies examined in the meta-analysis. The studies involved a total of 50,000 older adults, who were followed over a median time period of five years. The analysis showed that adults over the age of 50 who met the criteria for depression were more than twice as likely to go on to develop vascular dementia and 65 percent more likely to meet criteria for Alzheimer’s disease when compared with older adults who had not experienced depression. The analysis was conducted by researchers at the University of Pittsburgh. Co-author Meryl Butters, PhD., an associate professor of psychiatry in the School of Medicine, explains that the findings do not illustrate a cause-and-effect relationship, but the study does support the belief that depression contributes to the development of vascular dementia and Alzheimer’s disease. The findings lend support to the idea that depression is damaging to the brain, possibly leading to the development of degenerative processes. In the results, 36 out of 50 participants diagnosed with depression in older adulthood were later diagnosed with vascular dementia. In addition, 31 out of 50 participants diagnosed with depression could eventually be diagnosed with Alzheimer’s disease. While earlier research has shown a connection between depression and Alzheimer’s disease, this is the first study to show that the connection may be even more robust between depression and vascular dementia. One theory that is being explored to explain the connection relates to cortisol, a stress hormone that can negatively affect the hippocampus. The hippocampus is largely responsible for the functions of the brain related to learning new things and processing short-term memory tasks. Individuals experiencing the symptoms of depression tend to have an elevated level of cortisol, as well as a smaller hippocampus, which is especially critical for memory processing. Another theory maintains that depression is associated with chronic inflammation that could cause damage to the blood vessels that carry oxygen to the brain. This could then lead to permanent deterioration in the neural connections. The study authors note that the results warrant immediate attention given to older adults exhibiting signs of depression. They caution that if an older adult is depressed, they need immediate treatment.