Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is linked to cognitive dysfunction, hippocampal atrophy and an increased risk for Alzheimer’s disease (AD). Less is known of the role of cortisol levels in the prediction of cognitive decline or in moderating the effect of beta-amyloid in preclinical AD. Researchers evaluated 401 cognitively normal adults enrolled in the Australian Imaging Biomarker & Lifestyle Flagship Study of Ageing (AIBL) who had undergone beta-amyloid neuroimaging at a single time point. Subjects also underwent comprehensive neuropsychological assessment. After 54 months, results showed that higher plasma cortisol levels at baseline were associated with a 2.2 times greater risk of having beta-amyloid presence. Higher cortisol levels were also associated with increased declines in global cognition in general. Compared with older adults with low cortisol and beta-amyloid deposits, those with high cortisol and beta-amyloid showed faster declines in various measures. Researchers concluded that in cognitively normal older adults, high plasma cortisol levels are associated with greater decline in global cognition, and accelerate the effect of beta-amyloid on decline in global cognition, episodic memory and attention over a 54 month period. The results suggest that therapies targeted toward lowering plasma cortisol and beta-amyloid levels may help mitigate cognitive decline in the preclinical phase of AD.
Pietrzak RH, et al. Plasma Cortisol, Amyloid-BETA, and Cognitive Decline in Preclinical Alzheimer’s Disease. (Abstract A 10218) Alzheimer’s Asso International Conf. Toronto 2016 July 22=-28.