Early Depression Diagnosis Linked to Higher Rate of Dementia

A recent study published in JAMA Neurology on July 24, 2023, linked depression diagnoses to dementia diagnoses later in life. Researchers’ analysis revealed that early- and middle-life depression diagnoses correlated with a higher risk of dementia later in life.

The study focused on a cohort of Danish patients, collecting data from April 2022 to March 2023. Researchers evaluated data from participants between 1977 and 2018 using the Danish National Patient Registry (DNPR) and the Danish Psychiatric Central Research Register (DPCRR).

The study used data from 246,499 individuals with depression and 1,190,302 without depression. The majority of patients with depression were diagnosed before the age of 60.

According to the study, across all patients, those with depression were 2.41 times more likely to be diagnosed with dementia later in life than those without depression.

A depression diagnosis early in life, between 18 and 44, was associated with the highest risk of dementia later in life, with a 3.08 times greater probability compared to those who did not have a depression diagnosis. Meanwhile, a depression diagnosis in middle life —ages 45 to 59 — was linked to a 2.95 times greater probability of dementia. The final age bracket, which had a depression diagnosis starting at age 60 or older, had a 2.31 times greater risk of dementia than their counterparts without depression.

While the dementia rate was higher for anyone with a depression diagnosis, regardless of age, the risk was significantly higher for those diagnosed with depression earlier in life.

Beyond analyzing risk by age, the researchers also evaluated the impact of gender, finding that men with depression were at a higher risk for dementia than women with depression, with a hazard ratio of 2.95 and 2.31, respectively.

“Results suggest that the risk of dementia was more than doubled for both men and women with diagnosed depression. The persistent association between dementia and depression diagnosed in early and middle life suggests that depression may increase dementia risk,” concluded researchers in the study.

Although the insights from this study provide potential hypotheses on the link between mental health and dementia, additional clinical research on a broader patient population is necessary for definitive conclusions.