Depression in patients with type 2 diabetes was associated with greater cognitive decline in a study of almost 3,000 individuals who participated in a clinical trial.
Depression and diabetes are among the most common illnesses in older primary care populations, according to background information in the study, which was published Aug. 14 on the website of JAMA Psychiatry. Up to 20% of adult patients with type 2 diabetes meet the criteria for major depression. Both depression and diabetes appear to be associated with an increased risk for dementia.
“Depression has been identified as a risk factor for dementia among patients with type 2 diabetes mellitus but the cognitive domains and patient groups most affected have not been identified,” wrote Mark D. Sullivan, MD, PhD, of the University of Washington, Seattle, and colleagues.
The study included 2,977 patients with type 2 diabetes at high risk for cardiovascular disease who were participants in the Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes trial. Researchers used tests to gauge cognition and a questionnaire to assess depression.
Patients with scores indicative of depression showed greater cognitive decline during the 40-month follow-up on all tests. The effect of depression on risk of cognitive decline did not differ according to previous cardiovascular disease; baseline cognition or age; or intensive vs. standard glucose-lowering treatment, blood pressure treatment, lipid treatment or insulin treatment, the researchers reported.
In summary, the authors wrote, “depression is associated with cognitive decline in all domains assessed” and “this effect does not differ in clinical subgroups.
“This suggests that a potentially reversible factor may be promoting general cognitive decline in the broad population of patients with type 2 diabetes. Since dementia is one of the fastest growing and most dreaded complications of diabetes, our findings may be important for public health.”
Study abstract: http://archpsyc.jamanetwork.com/article.aspx?articleid=1727436.