Relationship Between Type 2 Diabetes Mellitus and Cognitive Change in a Multiethnic Elderly Cohort

Abstract

OBJECTIVES Diabetes may raise dementia risk. However, the pattern of cognitive change over time in non-demented older adults with diabetes, including the onset of cognitive decline, is unclear. We examined the association of diabetes and cognitive functioning at baseline and cognitive change over time in a large, ethnically diverse sample of older adults. DESIGN Prospective cohort study. SETTING Washington Heights-Inwood Columbia Aging Project (WHICAP), a community-based, prospective study of risk factors for dementia. PARTICIPANTS 1,493 met both inclusion and exclusion criteria for this study. MEASUREMENTS Participants underwent baseline and follow-up cognitive and health assessments approximately every 18 months. Generalized estimating equations were used to examine the longitudinal association between diabetes and cognition. RESULTS Diabetes was associated with poorer baseline cognitive performance in memory, language, processing speed/executive functioning, and visuospatial abilities. After adjusting for age, education, sex, race/ethnicity, and apolipoprotein-ε4, participants with diabetes performed significantly worse at baseline relative to those without diabetes in language and visuospatial abilities. There were no differences between those with and without diabetes in terms of rate of cognitive change over a mean follow-up time of six years. CONCLUSION The rate of cognitive change in elderly persons with and without diabetes is similar, although cognitive performance is lower in persons with diabetes. Our findings suggest that cognitive changes may occur early during the diabetes process and highlight the need for studies to follow participants beginning at least in midlife, prior to the typical later-life onset of dementia.

Changes in metabolic risk factors over 10 years and their associations with late‐life cognitive performance: The Multi‐Ethnic Study of Atherosclerosis

“…Other studies have reported that trajectories of insulin and HbA1c are associated lower cognitive performance [21]. In contrast to these findings, associations between diabetes and rate of cognitive change are less consistent [22] and suggest intensive glycemic control in diabetics may not provide additional benefit [23].…”

Effect of a long-term intensive lifestyle intervention on prevalence of cognitive impairment

“…It may be that the legacy of the adverse cognitive effects conveyed by diabetes endures for some time, so that any intervention effects may only be expressed after a long latency period. Cognitive deficits appear early in the development in diabetes 31 ; it may be that Look AHEAD missed a window of opportunity for prevention. Whether our null findings are limited to individuals with diabetes, or extend more generally to other cohorts, is unknown.…”

Glycemia, Diabetes Status, and Cognition in Hispanic Adults Aged 55–64 Years

“…Although diabetes in older age is related to a higher risk of categories of cognitive impairment, when cognitive performance is examined as an outcome in persons aged 65 years and older, diabetes status is related to lower cognitive performance but not to steeper cognitive decline,(21, 22) suggesting that the onset of cognitive impairment related to diabetes begins before the age of 65. However, most cognition studies enroll elderly participants with a mean age around 75 years of age (23), and many studies that relate middle age risk factors such as diabetes to dementia in older age do not have concurrent midlife cognitive data(24–26).…”