Depression Increases Risk of Dementia in Patients with Type 2 Diabetes

OAKLAND Calif. — Depression in patients with diabetes is associated with a substantively increased risk of development of dementia compared to those with diabetes alone, according to researchers from the University of Washington and Kaiser Permanente.

The study, among the first (and largest to date) to examine all-cause dementia in diabetes patients with and without depression, appears on the current online issue of the Archives of General Psychiatry.

Patients with Type 2 diabetes who also had depression had a doubling in risk of dementia during years three to five after initial screening, compared to patients with diabetes who did not have depression, said the study’s lead author Wayne Katon, MD, professor and vice chair of the University of Washington department of psychiatry and behavioral sciences. This study was supported by the National Institutes of Health-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 more than 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. This study suggests that having both of these illnesses occurring together is associated with an even greater risk,” said Kaiser Permanente researcher and senior author Rachel Whitmer, PhD.

“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," explained Andrew J. Karter, PhD, co-author from Kaiser Permanente Division of Research and 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,” Katon said.

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.

Additional authors on the study include Courtney R. Lyles, PhD, the University of California, San Francisco; Melissa M. Parker, MS, with the Kaiser Permanente Division of Research; Elbert S. Huang, MD, MPH, with the University of Washington Schools of Medicine and Public Health. Funding for the research was provided by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of Mental Health. Dr. Katon’s relevant financial activities include board membership with Eli Lilly and Wyeth, honorariams for lectures Eli Lilly, Wyeth, Pfizer and Forest.

About University of Washington Medicine
With a mission to improve the health of the public, UW Medicine provides primary and specialty care to patients throughout the Pacific Northwest, trains medical professionals and scientists, and conducts biomedical and health services research. Our system includes Harborview Medical Center, Northwest Hospital & Medical Center, Valley Medical Center, UW Medical Center, UW Neighborhood Clinics, UW Physicians, UW School of Medicine and Airlift Northwest.

Every year, our four hospitals manage more than 65,000 patient admissions and nearly 200,000emergency visits, while our clinics manage more than 1.6 million patient visits. UW Medicine’s 2,100 faculty and more than 6,000 volunteer and part-time clinical faculty include four Nobel Laureates, 32 members of the National Academy of Sciences and 33 members of the Institute of Medicine. U.S. News & World Report has ranked UW’s School of Medicine No. 1 in the nation in primary-care training for the past 18 years. The school is the top public recipient of biomedical research funding from the National Institutes of Health and second in NIH funding among all medical schools, public and private.

UW Medicine is affiliated with Seattle Children’s, Fred Hutchinson Cancer Research Center, the Veteran’s Affairs Healthcare System in Seattle, and the Boise VA Medical Center in Boise, Idaho. We share in the ownership and governance of the Seattle Cancer Care Alliance and Children’s University Medical Group. For more information, visit uwmedicine.washington.edu.

About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well-being and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 400-plus staff is working on more than 250 epidemiological and health services research projects. For more information, visit www.dor.kaiser.org.

About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, our mission is to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We serve approximately 8.9 million members in nine states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to: www.kp.org/newscenter.