NEW YORK Diabetic adults with depression are twice as likely to develop dementia, according to a new study published in the Journal of General Internal Medicine.
To test the idea that the development of dementia -- which causes progressive decline of thinking and reasoning abilities -- may be caused by both factors, researchers (that included Group Health Research Institute in Seattle and the Veterans Affairs Puget Sound Health Care System) led by Wayne Katon, professor of psychiatry and behavioral sciences at the University of Washington, tracked the outcomes of adults from the Group Health Cooperative's diabetes registry who agreed to participate.
Over the five-year period, 36 of 455 patients, or 7.9%, of the diabetes patients with major depression were diagnosed with dementia. Among the 3,382 patients with diabetes alone, 163 patients, or 4.8%, developed dementia.
The researchers calculated that major depression with diabetes was associated with a 2.7-fold increase of dementia, compared with diabetes alone. Because the onset of dementia sometimes can be marked by depression, the researchers also adjusted their hazard model to exclude patients who developed dementia in the first two years after their depression diagnosis. The team's previous findings from earlier studies showed that depression increases the mortality rate among people with diabetes, as well as the rate of such complications as heart, blood vessel, kidney and vision problems.
"It seems prudent for clinicians to add effective screening and treatment for depression to other preventive measures such as exercise, weight control, and blood sugar control to protect against the development of cognitive deficits in patients with diabetes," researchers said.
Grants from the National Institute of Mental Health and National Institutes of Health, supported the study.