Allostatic load and cardiometabolic health in a young adult South African population: the African-PREDICT study

Abstract

Sustained stress, assessed as a high allostatic load score (ALS), is an independent cardiovascular disease (CVD) risk factor in older adults but its associations in young people are undefined. Since neurological maturation impacts stress adaptation and CVD risk, we assessed the relationship of ALS with CVD profile by using a tiered approach stratified by age [emerging adults (EA) aged 20-24 yr vs. young adults (YA) aged 25-30 yr] and ALS (high vs. low). In 1,054 healthy participants of the African Prospective Study on Early Detection and Identification of Cardiovascular Disease and Hypertension (African-PREDICT), we determined: 1) ALS in EA versus YA; 2) the relationship between ALS and cardiovascular (CV) health, and 3) the odds of high ALS > 4 to identify masked hypertension (HT) and prediabetes as cardiometabolic outcomes. A nine-component, four-domain ALS was compiled: neuroendocrine [dehydroepiandrosterone (DHEA), cortisol], inflammatory [interleukin-6 (IL-6), C-reactive protein (CRP)], cardiovascular [systolic blood pressure (SBP) and diastolic blood pressure (DBP)], and metabolic [total cholesterol, high density lipoprotein cholesterol (HDL-cholesterol), body mass index (BMI)]. Retinal vessel caliber, pulse wave velocity (PWV), and cardiac structure and function were assessed. Median ALS was 3 (range: 1-9). A high-ALS > 4 was more common in YA versus EA (47 vs. 35%, P = 0.032). Higher ALS associated with narrower retinal arteries (P < 0.01), greater PWV (P ≤ 0.01), lower diastolic function (P < 0.01), and left ventricular (LV) function (P < 0.01). High-ALS increased the odds of having masked hypertension, prediabetes, narrower retinal arteries, higher LV mass, poorer diastolic and ventricular functions (all P ≤ 0.01), in EA and YA independent of traditional CVD risk factors. The composite ALS identified early-stress dysregulation in cardiometabolic health and higher odds for masked hypertension and prediabetes in young adults. Cumulative stress may be a modifiable, independent cardiometabolic risk factor in younger populations that needs further investigation.NEW & NOTEWORTHY This is the first study to assess the effect of stress, as a composite allostatic load score, on micro-, macrovascular, and central cardiac features in healthy emerging and young adults, independent of traditional cardiovascular risk markers. It exemplifies independent stress-induced changes throughout the cardiovascular tree, which may increase the risk of cardiometabolic complications, masked hypertension, and prediabetes. Sustained stress may be a key etiological factor in cardiometabolic disease development in a young population.

Keywords: South Africa; allostasis; cardiometabolic health; neurological age; stress.