Association of Alzheimer’s Plasma Biomarker Concentrations with Body Mass Index in Older Adults
Serena Hoost1, Adam Brickman2, Annie Lee2, Yian Gu2, Danurys Sanchez3, Dolly Reyes-Dumeyer2, Lawrence Honig2, Jennifer Manly2, Rafael Lantigua4, Min Suk Kang2, Jeffrey Dage5, Richard Mayeux2
1Department of Neurology, 2Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, and the G.H. Sergievsky Center, 3Department of Neurology, and the G.H.Sergievsky Center, 4Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, and the Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, and the New York Presbyterian Hospital, 5Stark Neurosciences Research Institute, the Department of Neurology, and the Indiana Alzheimer's Disease Research Center, Indiana University School of Medicine
Objective:
To evaluate the relationship of chronic medical conditions and other characteristics, including body mass index (BMI), vascular risk factors, depression, head injury and education, with cognitive impairment and blood-based biomarkers of Alzheimer’s pathology, phosphorylated tau (P-tau 181, P-tau 217), in a multi-ethnic cohort.
Background:
Studies suggest that comorbidities may influence the levels of blood-based biomarkers for Alzheimer’s disease and their interpretation; however, these relationships must be further explored in ethnically diverse cohorts. In our recent multi-ethnic cohort study, 47% of cognitively impaired participants had low P-tau concentrations, and 31% of unimpaired participants had high P-tau concentrations. We sought to determine whether differences in risk factor profiles may help to explain the discordant groups in the same cohort.
Design/Methods:
Three hundred participants aged 65 and older were selected from a prospective community-based cohort for equal representation among three racial/ethnic groups: non-Hispanic White, Hispanic/Latino and African American/Black. Participants were classified into four diagnostic groups based on absence (Asym)/ presence (Sym) of cognitive symptoms and low(-)/high(+) P-tau, determined in the same cohort: (Asym/P-tau-, Asym/P-tau+, Sym/P-tau-, Sym/P-tau). We examined differences in participant characteristics across the four groups. For significant factors, we also examined two-group differences according to cognitive symptoms (Asym/Sym) and P-tau (P-tau+/P-tau-).
Results:
BMI was lower in individuals with high P-tau 217 and 181 concentrations (25.7 vs. 27.9 kg/m2; 25.3 vs. 27.9 kg/m2, respectively) but did not differ across dementia groups. Education was lower in individuals with dementia compared to those without (9.1 vs. 12.5 years), and it did not vary according to P-tau level. Frequencies of hypertension, diabetes, heart disease, smoking, head injury and depression did not differ between the four groups.
Conclusions:
Lower BMI is associated with higher P-tau concentrations but not with the presence or absence of dementia. This finding suggests that Alzheimer’s pathology may be accompanied by metabolic changes regardless of cognitive status.