Late-Life Depressive Symptoms Linked to Higher Dementia Risk: JAMA

A nationwide study conducted from April 2020 to March 2023 in Denmark has shed light on the potential association between depressive symptoms at different stages of life and the risk of subsequent dementia diagnosis. The findings published in JAMA Neurology indicate that late-life depression may serve as an early symptom or response to preclinical dementia. 

The study by Holly Elser and team included a staggering 246,499 Danish citizens with diagnosed depression and 1,190,302 individuals without depression, matched by sex and birth year. Participants were followed up from 1977 to 2018. Individuals followed for less than a year, those under 18 years old, or those with baseline dementia were excluded from the analysis.

The researchers defined depression using diagnostic codes from the International Classification of Diseases (ICD) obtained from the Danish National Patient Registry (DNPR) and Danish Psychiatric Central Research Register (DPCRR). Incident dementia was defined using ICD diagnostic codes within the DPCRR and DNPR.

The results revealed that the hazard of dementia among individuals diagnosed with depression was 2.41 times that of the comparison cohort. Remarkably, this elevated risk persisted even when the time elapsed from the index date was longer than 20 to 39 years. Additionally, the association between depression and dementia was observed in individuals diagnosed with depression in early, middle, or late life.

Those diagnosed between 18-44 years had a hazard ratio of 3.08, while those diagnosed between 45-59 years had a hazard ratio of 2.95. Even those diagnosed with depression at the age of 60 or older had a significantly increased hazard ratio of 2.31.

When examining the data by sex, the study found that the overall hazard ratio for dementia was greater for men (HR, 2.98) compared to women (HR, 2.21).

The researchers underscore the importance of these findings, as they suggest that the risk of dementia is more than doubled for both men and women diagnosed with depression. Furthermore, the persistence of this association when depression is diagnosed in early and middle life implies that depression may play a role in increasing the risk of dementia.

Reference:

Elser, H., Horváth-Puhó, E., Gradus, J. L., Smith, M. L., Lash, T. L., Maria Glymour, M., Sørensen, H. T., & Henderson, V. W. (2023). Association of early-, middle-, and late-life depression with incident dementia in a Danish cohort. JAMA Neurology. https://doi.org/10.1001/jamaneurol.2023.2309