Depression in patients with diabetes is associated with a substantively increased risk of development of dementia compared to those with diabetes alone, according to Andrew Karter, PhD and Rachel Whitmer, PhD. The researchers collaborated with the University of Washington on a study – among the first (and largest to date) to examine all-cause dementia in diabetes patients with and without depression. The study appeared in the Archives of General Psychiatry.
Patients with type 2 diabetes who also had depression had a doubling in risk of dementia during years 3 to 5 after initial screening, compared to patients with diabetes who did not have depression, said the researchers.
This study was supported by the NIH-funded Diabetes & Aging Study, which focuses on the special health problems of older patients with diabetes, and its parent study, Diabetes Study of Northern California (DISTANCE) which collected surveys from over 20,000 adults with diabetes who are patients from the Kaiser Permanente Northern California Diabetes Registry.
“Prior research has shown that both depression and diabetes are risk factors for dementia,” said senior author Whitmer. “This study suggests that having both of these illnesses occurring together is associated with an even greater risk.”
“Since depression affects up to 20 percent of diabetic patients, it is critical to understand this relationship and further evaluate whether depression interventions have an impact on dementia risk in patients with diabetes, added Karter, the principal investigator for the Diabetes & Aging and DISTANCE Studies.
Earlier onset of diabetes in patients with depression and greater risk of dementia in younger (compared to older) patients with depression and diabetes underscore the importance of evaluating the potential for early depression interventions to reduce the incidence of dementia, emphasized the researchers.
Of the 20, 188 consenting adults in the DISTANCE Study, 19.6 percent of the patients with diabetes met criteria for clinically significant depression.
Among patients with diabetes, depression is associated with poorer adherence to diet and exercise programs, increased smoking and poorer blood sugar control as well as psychobiologic changes such as increases in cortisol and increased sympathetic nervous system tone which could worsen the course of diabetes and increase the risk of dementia associated with depression, they added.