A study published in The Journal of the American Medical Association (JAMA) reveals that an increasing number of vascular risk factors such as obesity, high blood pressure, diabetes, high cholesterol, and smoking during midlife contributes to increased brain amyloid levels (protein fragments associated with Alzheimer’s, the most common form of dementia) in later life.
Alzheimer's disease - neurons with amyloid plaques. Credit: Juan Gaertner / Shutterstock.com
Dementia in later life is connected to midlife vascular risk factors. However, whether the risk factors are directly linked to amyloid deposition in the brain, it is not clear. Rebecca F. Gottesman, M.D., Ph.D., of the Johns Hopkins University School of Medicine, Baltimore, and her team studied the data of 346 individuals all dementia-free and evaluated for vascular risk factors and markers. The participants had previously had PET scans as part of the Atherosclerosis Risk in Communities (ARIC)-PET Amyloid Imaging trials in 2012-2013.
The individuals were between 45 and 64 years old when the ARIC study took place, and the risk factors included were body mass index that equals 30 or greater, current smoking, hypertension, diabetes, and total cholesterol of 200 mg/dL or higher. The models evaluated included age, gender, race, APOE genotype, and educational level.
Potential biomarkers such as brain amyloid help in early detection of dementia and provide insights into the role of vascular disease to cognition and amyloid deposition.
The research has identified that a collective number of midlife vascular risk factors are connected with increased brain amyloid, irrespective of race. However, later-life vascular risk factors are not related to later-life brain amyloid deposition. The study outcomes were not significant among individuals who carry or do not carry the Apolipoprotein E (ApoE) ε4 allele—risk factor gene to develop Alzheimer's.
The authors wrote:
These data support the concept that midlife, but not late-life, exposure to these vascular risk factors is important for amyloid deposition… These findings are consistent with a role of vascular disease in the development of AD."