Comorbid Diabetes and Depression Boost Dementia Risk

Adults age 50 and older diagnosed with both diabetes and depression are at 117% greater risk of developing dementia than their peers without diabetes and depression, according to a study in the April 15, 2015 online JAMA Psychiatry.

While previous studies have suggested that depression and type 2 diabetes independently increase dementia risk, this is the first to investigate the effect of comorbid depression and diabetes, according to researchers. The study spanned more than 2.4 million adults age 50 and older in Denmark, including 477,133 people with depression, 223,174 people with type 2 diabetes, and 95,691 people with both depression and diabetes.

All were free of dementia at the study’s start. But over the course of 6 years, 59,663 (2.4%) of participants developed dementia at an average age of almost 81, researchers found.

“Depression and type 2 diabetes mellitus were independently associated with a greater risk for dementia,” researchers reported in the study, “and the combined association of both exposures with the risk for all-cause dementia was stronger than the additive association.”

Compared with the 117% increased risk of developing dementia associated with comorbid diabetes and depression, researchers found that type 2 diabetes alone was associated with a 20% greater risk for dementia, while depression alone was associated with an 83% increased risk. Furthermore, dementia risk seemed to be heightened among participants younger than 65, the study showed.

"In light of the increasing societal burden of chronic diseases, further research is needed to elucidate the pathophysiologic mechanisms linking depression, type 2 diabetes mellitus, and adverse outcomes such as dementia,” researchers concluded, “and to develop interventions aimed at preventing these dreaded complications.”—Jolynn Tumolo

References

1. Katon W, Pedersen HS, Ribe AR, et al. Effect of depression and diabetes mellitus on the risk for dementia: a national population-based cohort study. JAMA Psychiatry. 2015 April 15. [Epub ahead of print].
2. Depression, diabetes associated with increased dementia risk [press release]. EurekAlert!: Washington, DC; April 15, 2015.