Diabetes, Cardiovascular Risk Factors Linked to Early Declines in Cognition

Kristine Yaffe, MD

The latest analysis of the CARDIA study is detailing a troubling link between presence of diabetes and hypertension with cognitive declines in middle age.

Results of the analysis, which assessed adults aged 50 years and older without dementia at baseline, indicate hypertension increased likelihood of accelerated cognitive decline by 87% while a diagnosis of diabetes more than tripled a person’s risk of accelerated cognitive decline.

“Cardiovascular risk factors, especially high blood pressure and diabetes, become more common in midlife. We found those two risk factors, as well as smoking, are associated with higher odds of having accelerated cognitive decline, even over just a short span of five years,” said lead investigator Kristine Yaffe, MD, of the University of California, San Francisco (UCSF) and a member of the American Academy of Neurology (AAN), in a statement from the AAN.

While previous studies have established associations between midlife cardiovascular risk factors and risk of dementia, few have examined whether these risk factors influence cognition in midlife. With this in mind, Yaffe and a team of colleagues hoped to examine potential associations between risk factors, including hypertension, dyslipidemia, diabetes, and obesity, on declines in midlife cognitive abilities from patients in the Coronary Artery Risk Development in Young Adults (CARDIA) study.

For the purpose of analysis, investigators only included participants who completed cognitive testing at year 25 of the study, which was considered baseline for the current analysis, and 5 years later. In total, investigators identified 2675 middle-aged adults for inclusion in their study. The mean age of patients included in the study was 50.2±3.6 years, 57% of participants were female, and 45% were black.

Among the study population, 31% had hypertension, 11% had diabetes, 43% were considered obese, 9% had high cholesterol, and 15% were current cigarette smokers at baseline. For the purpose analysis, patients were categorized into groups based on the number of risk factors present—defined as 0, 1, 2, and 3 or more.

Over the follow-up period, which lasted a mean of 5.02±0.34 years, accelerated decline occurred in 143 participants. Upon analysis, investigators found diabetes (aOR, 2.45; 95% CI, 1.54-3.88), hypertension (aOR, 1.87; 95% CI, 1.26-2.75), and smoking (aOR, 1.65; 95% CI, 1.00-2.71) were associated with increased likelihood of accelerated decline in multivariable adjusted analyses. Conversely, obesity and high cholesterol did not appear to be associated with increased risk of accelerated decline.

“Surprisingly, people who were considered obese and those with high cholesterol did not have a greater risk of cognitive decline,” Yaffe added, in the aforementioned statement. “Other studies have shown a link between obesity and dementia, but mostly in older adults. Meanwhile, the studies that examine high cholesterol and dementia have had mixed results, so our research adds to those studies.”

When examining likelihood of accelerated decline based on number of risk factors present, investigators found presence of 1-2 risk factors (aOR, 1.77; 95% CI, 1.02-3.05) and presence of 3 or more risk factors (aOR, 2.94; 95% CI, 1.64-5.28) were both associated with increased likelihood compared to those with 0 risk factors. Additionally, results of the analysis indicated a Framingham Coronary Heart Disease Risk Score of 10 or more was also associated with increased likelihood (aOR, 2.29; 95% CI, 1.21-4.34).

Investigators noted multiple limitations to consider. Limitations included inability to assess every cognitive domain, the Framingham Coronary Heart Disease Risk score was developed in a more homogeneous cohort, and characterization of cognitive change in middle-aged adults is not well-defined.

This study, “Cardiovascular Risk Factors and Accelerated Cognitive Decline in Midlife: the CARDIA Study,” was published in Neurology.