PHYSICAL ACTIVITY IS ASSOCIATED WITH LOWER AMYLOID LOAD IN MIDDLE-AGED COGNITIVELY UNIMPAIRED INDIVIDUALS

Abstract

Alzheimer's disease (AD) is becoming increasingly prevalent worldwide and it is hence crucial to identify modifiable risk factors that can lead to prevention of the disease. The effect of several cardiovascular and psychiatric risk factors on cognition and dementia risk is well known, but their impact on the pathophysiology of AD defined by core biomarkers is not yet well established. The aim of this study was to perform an exploratory analysis to assess whether the main cardiovascular and psychiatric AD risk factors are associated with core AD biomarkers in middle-aged cognitively unimpaired individuals. This is a cross-sectional study performed in the ALFA+ (for ALzheimer and FAmilies) cohort comprising middle-aged cognitively unimpaired individuals at risk for AD. We studied the following factors: hypertension, dyslipidaemia, body mass index (BMI), diabetes mellitus, physical activity, depression and anxiety. Core AD biomarkers (Aβ42, t-tau and p-tau) were measured in cerebrospinal fluid (CSF) using Elecsys and subjects were categorized according to whether or not they were amyloid (A) positive (CSF Aβ42 < 1098 pg/mL), tau (T) positive (p-tau > 19.2 pg/mL) and neurodegeneration (N) positive (t-tau > 242 pg/mL). We used logistic regression analyses to test whether the risk factors predict CSF biomarker positivity, adjusted by the effect of age, gender, years of education and APOE-ε4 status. We studied 257 participants, with a mean age of 60.7 years, 64.5% were female, 40.1% APOE-ε4carriers and 29.6% were A+, 26.1% T+ and 23.3% N+. Physical activity was associated with reduced risk of amyloidosis; 46.7% of physically inactive individuals were A+ vs 25.9% of physically active subjects (P = 0.014). No significant associations were found regarding the other risk factors.