A Proposed Longitudinal Study of Sleep Quality Diurnal Cortisol Plasma Aβ42-Aβ40 and Cognitive Change in Postmenopausal Women
Year: 2026
Type: article
Study design: Study Protocol
Abstract: Sleep problems may occur before cognitive changes associated with Alzheimer’s disease (AD) become noticeable. However, it is still unclear how disrupted sleep relates to biological changes linked to the early stages of the disease. This proposed study would follow 800 cognitively unimpaired postmenopausal women aged 50 to 70 at enrolment. Participants would attend assessments at baseline then months 18, 36, 54, 72, and 90. Sleep would be assessed using the Pittsburgh Sleep Quality Index (PSQI), alongside wrist-worn actigraphy to objectively measure sleep patterns. Saliva samples would be collected over two weekdays to estimate diurnal cortisol slope. Plasma Aβ42/Aβ40 would be measured using the Sysmex HISCL-5000 platform. Cognitive performance would be assessed with the Preclinical Alzheimer Cognitive Composite (PACC). The main analyses would use mixed-effects models to test whether poorer sleep quality, indicated by higher PSQI scores, predicts later changes in cortisol slope, plasma Aβ42/Aβ40, and cognitive performance. Sleep efficiency measured through actigraphy would be examined separately. Exploratory analysis would assess whether the cortisol slope at month 54 serves as the biological link between baseline sleep quality and plasma Aβ42/Aβ40 at month 90. It is hypothesised participants with poorer sleep may show a flatter diurnal cortisol slope over time, together with a lower plasma Aβ42/Aβ40 ratio. If observed, these findings would be consistent with a possible relationship between sleep disruption, cortisol regulation, and amyloid-related change. The proposed study would clarify the timeline linking sleep and early AD pathology, providing timelines for future sleep-based preventative interventions.
Author: Chad, Marcus
Language: English
Topic: Sleep and related disorders
Subfield: Experimental and Cognitive Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W7223289217