The study, published in Diabetes Care, included a group of more than 22,000 patients aged 60 or older who were members of the Kaiser Permanente Northern California Diabetes Registry. Dementia was diagnosed in 3,796 patients (17.1 percent of the study cohort) during a follow-up of up to 10 years. Dementia was not present in any of the patients at the start of the study.
Compared to Asian-Americans, Native Americans were 64 percent more likely to develop dementia, and African-Americans were 44 percent more likely. Almost 20 percent (or one in five) African-Americans and Native Americans were diagnosed with dementia during the 10-year study.
"We found that in a population of elderly individuals with type 2 diabetes, there were marked differences in rates of dementia over a 10-year period by racial and ethnic groups," said senior author Rachel Whitmer, PhD, research scientist at the Kaiser Permanente Division of Research. "Moreover, the differences were not explained by diabetes-related complications, glycemic control or duration of diabetes. Nor were they altered by factors of age, gender, neighborhood deprivation index, body mass index, or hypertension."
Among people aged 60 and above, those with type 2 diabetes have double the risk of developing dementia. Certain racial and ethnic groups in the U.S., including Latinos, African-Americans, some Asian American groups, and Native Americans, are disproportionally affected by type 2 diabetes. However, the interplay of type 2 diabetes and race/ethnicity on long-term dementia risk has not been explored previously.
"Since ethnic minorities are the fastest-growing segment of the elderly population in the United States, it is critical to determine if they are at higher risk of dementia, especially among those with type 2 diabetes," said Elizabeth Rose Mayeda, PhD, lead author and postdoctoral fellow at University of California, San Francisco. "It's eye-opening to see the magnitude of ethnic and racial differences in dementia risk in a study where everyone already has type 2 diabetes."
The researchers concluded that more work is needed to identify factors that will reduce dementia risk for those with diabetes, particularly for ethnic and minority groups at highest risk. While future research is greatly needed on potential dementia prevention efforts in general, these findings suggest that certain ethnic groups within the type 2 diabetes population may benefit the most.
This study is part of an ongoing body of work to better understand dementia. Earlier this year, Kaiser Permanente researchers created the first risk score that predicts the 10-year individualized dementia risk for patients with type 2 diabetes.
Kaiser Permanente can conduct transformational health research in part because it has the largest private patient-centered electronic health system in the world. The organization's electronic health record system, Kaiser Permanente HealthConnect®, securely connects 9.1 million patients to 16,000 physicians in 600 medical offices and 38 hospitals. It also connects Kaiser Permanente's research scientists to one of the most extensive collections of longitudinal medical data available, facilitating studies and important medical discoveries that shape the future of health and care delivery for patients and the medical community.
Other authors of the study include: Andrew J. Karter, PhD, and Howard H. Moffet, MPH, of the Kaiser Permanente Division of Research; Mary N. Haan, DrPH, MPH, of the University of California, San Francisco; and Elbert S. Huang, MD, MPH, of the University of Chicago.
The study was supported in part by funding from the National Institute of Diabetes, Digestive and Kidney Diseases [Grant numbers R01DK081796, R01DK080726, R01DK65664], Centers for Diabetes Translation Research at Kaiser Permanente and University of California, San Francisco and the University of Chicago.
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, the Division's 550+ staff are working on more than 350 ongoing research studies in behavioral health and aging, cancer, cardiovascular and metabolic conditions, health care delivery and policy, infectious diseases, vaccine safety and effectiveness, and women's and children's health. 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 currently serve 9.1 million members in eight 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: kp.org/share.
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