A new study found that dementia risk more than doubled in men and women with depression compared to those without depression. The link was higher in men, but the risk for dementia remained whether people had depression earlier in life, during the middle of their life, or later in life.
The study examined more than 1.4 million adult Danish citizens. Researchers followed them from 1977 to 2018. Of the people studied, 246,499 had depression and 1,190,302 people didn’t. The median age was about 50, and about 65% of the participants were women. Most people with depression knew they had it before they were 60 years old.
“The persistent association between dementia and depression diagnosed in early and middle life suggests that depression may increase dementia risk,” the authors wrote.
People with depression were 2.41 times more likely to develop dementia than those without it, Holly Elser, MD, PhD, a resident at the Hospital of the University of Pennsylvania in Philadelphia, one of the researchers, said.
“Our study leverages data from more than 1.4 million Danish citizens followed from 1977 onward and demonstrates that there is a persistent association of dementia with depression diagnosed in early, middle, or late life,” Elser said in another outlet. “There is a clear need for future research that examines potential mechanisms that relate depression earlier in adulthood to subsequent onset of dementia.”
The most common comorbidity was cardiovascular disease, which occurred in 19.8% of people with a depression diagnosis and 11.8% without it. Substance use disorders were the second most common comorbidity. Of people with depression, 11.7% experienced it compared to 2.6% without it.
Among people with depression, 5.7% later received a dementia diagnosis during the follow-up period; 3.2% without depression wound up with dementia. There was a greater hazard for vascular dementia and a smaller hazard for Alzheimer’s disease, the authors reported.
