The association between allostatic load, Alzheimer biomarkers and cognition among patients at the memory clinic: A longitudinal study

Background Various lifestyle and physiological dementia risk factors have been identified. However, little is still known about the role of stress‐related risk factors. Chronic psychological stress affects several systems, such as the immune and cardiovascular systems, and increases the risk for physical, behavioral and mental disorders and reduced cognitive function. The goal of this study is to assess whether allostatic load (AL), a composite biomarker measure of chronic stress, is associated with AD biomarkers and cognitive function among memory clinic patients. Methods Data were derived from the Co‐STAR study at Karolinska University Hospital Memory Clinic, Sweden. Participants underwent baseline assessments including blood tests for AL measures, and cerebrospinal fluid sampling for AD biomarkers (Ab1‐42, total Tau (T‐tau), phosphorylated Tau (P‐tau)), a neuropsychological test battery was performed with measures for the following cognitive domains: general cognition, memory, working memory, processing speed and perceptual reasoning. Multiple linear regressions were conducted, adjusting for age, sex and education. P‐value <0.05 was used to identify significant associations. Results Higher AL was associated with lower CSF Ab1‐42 level (β = ‐0.175, p = 0.025) reflecting higher brain levels of Ab1‐42. Analyses stratified by sex showed that these associations were only present for women, but not for men. AL was not significantly associated with T‐tau level and P‐tau level. Multiple regression analyses showed that there were no significant association between AL and general cognitive functioning, processing speed, working memory, memory, and perceptual reasoning. AL modified the association between Ab1‐42 and perceptual reasoning; the non‐significant association was significant when additionally adjusted for AL (β = 0.157, p< 0.05). Conclusion This study identified a significant negative association between AL and Ab1‐42 among women, and AL modified the association between Ab1‐42 and perceptual reasoning. This suggests that AL may play a role in dementia pathophysiology. Further evidence is needed on whether specific subgroups in memory clinic samples are particularly vulnerable to the effects of high AL burden.