JAMA: Depression and type 2 diabetes mellitus were each associated with an
increased risk for dementia and that risk was even greater among
individuals diagnosed with both depression and diabetes compared with
people who had neither condition, according to an article published
online by JAMA Psychiatry.
Diabetes and major depression are common in Western populations and
as many as 20 percent of people with type 2 diabetes mellitus also have
depression.
Dimitry Davydow, M.D., M.P.H., of the University of Washington School
of Medicine, Seattle, and coauthors examined the risk for dementia
among individuals with depression, type 2 diabetes or both compared with
individuals with neither condition in a group of more than 2.4 million
Danish citizens, who were 50 and older and free from dementia from 2007
through 2013.
Overall, 19.4 percent of individuals in the group had a diagnosis of
depression (477,133 individuals), 9.1 percent had type 2 diabetes
(223,174 individuals), and 3.9 percent (95,691 individuals) had
diagnoses of both diabetes and depression. The average age at initial
diagnosis of type 2 diabetes was 63.1 years old and the average age at
initial diagnosis of depression was 58.5 years old.
The authors found that during the study period, 2.4 percent of
individuals (59,663 people) developed dementia and the average age at
diagnosis was nearly 81 years. Of those individuals who developed
dementia, 15,729 people (26.4 percent) had depression alone and 6,466
(10.8 percent) had type 2 diabetes alone, while 4,022 (6.7 percent) had
both conditions.
The results of the study indicate that type 2 diabetes alone was
associated with a 20 percent greater risk for dementia and depression
alone was associated with an 83 percent greater risk, while having both
depression and type 2 diabetes was associated with a 117 percent greater
risk. The risk for dementia appeared to be even greater among those
study participants younger than 65.
“In light of the increasing societal burden of chronic diseases,
further research is needed to elucidate the pathophysiologic mechanisms
linking depression, DM [type 2 diabetes mellitus] and adverse outcomes
such as dementia and to develop interventions aimed at preventing these
dreaded complications,” the study concludes.
(JAMA Psychiatry. Published online April 15, 2015. doi:10.1001/jamapsychiatry.2015.0082. Available pre-embargo to the media at http://media.jamanetwork.com.)
Editor’s Note: The
study was supported by an unrestricted grant from the Lundbeck
Foundation and by a grant from the National Institutes of Health. Please
see the article for additional information, including other authors,
author contributions and affiliations, financial disclosures, funding
and support, etc.
Commentary: Promoting Healthy Brain Aging
In a related commentary, Charles F. Reynolds III, M.D., of the
University of Pittsburgh Medical Center, writes: “In conclusion, the
study by Katon and colleagues illustrates the need for convergent
scientific approaches to meet the challenge of promoting healthy brain
aging and cognitive fitness into the last years of life. The convergence
of expertise from epidemiology, behavioral and basic science in the
biology of aging and brain health are all necessary ‘to move the needle’
in the demographic challenge that confronts the entire globe.”
(JAMA Psychiatry. Published online April 15, 2015. doi:10.1001/jamapsychiatry.2015.0174. Available pre-embargo to the media at http://media.jamanetwork.com.)
Editor’s Note: The
author made conflict of interest and funding/support disclosures. Please
see the article for additional information, including other authors,
author contributions and affiliations, financial disclosures, funding
and support, etc.