Individuals with depression are more than two times as likely to be diagnosed with dementia

Penn Medicine research finds the risk of dementia is higher for men than women, and in individuals with multiple inpatient hospitalizations for depression.

Those diagnosed with depression—including young and middle-aged adults—were more than twice as likely to be diagnosed with dementia later in life, as compared to those without depression, according to an analysis conducted in collaboration between researchers at the Perelman School of Medicine and Aarhus University in Denmark. The study marks the largest analysis of its kind with the longest follow-up time to date—with data from 1.4 million Danish citizens over nearly four decades. The findings are published in JAMA Neurology.

A person walking with an elderly person.
Image: iStock/Obencem

“While depression diagnosed later in life is generally thought to be an early symptom of dementia, our results suggest that a depression diagnosis at any point in adulthood increases the risk of dementia later on,” says first author Holly Elser, a neurology resident at Penn. “Previous studies with smaller sample sizes and shorter follow-up times have consistently illustrated the link between dementia and depression diagnosed later in life, but with our long-term analysis, we were able to precisely estimate the association between dementia and depression over an individual’s life span.”

The association between depression and dementia for men and women persisted regardless of whether depression was diagnosed in early, middle, or late life, although the association between depression and dementia among men was stronger. Multiple inpatient hospitalizations for depression were associated with an increased risk of dementia later in life, and the risk increased with each subsequent hospitalization. Researchers found that being prescribed an antidepressant within six months of depression diagnosis had no effect on the rate of dementia diagnosis later in life.

The researchers acknowledge the limitations of the paper and underscore the need to further investigate the link between depression and dementia.

Read more at Penn Medicine News.