Evaluating the gut microbiome, dietary patterns, and cognition: a sub-study protocol from the brain health and the gut microbiome study in cognitive decline (bMicrobiome study).

The aim of this study is to describe the development and implementation of a novel Readiness to Change Nutritional Habits (RCNH) survey for use along with dietary assessment and gut microbiome profiling in a proof-of-concept study in individuals with early Alzheimer's disease dementia (eAD), mild cognitive impairment (MCI), and healthy controls (HC). Overall, this methods paper contributes to emerging research examining how behavioural readiness for change can be integrated with dietary assessment and gut microbiome profiling to better understand the microbiome's influence on the nervous system. This is a sub-study embedded within a multi-prong proof-of-concept, observational study mapping the gut microbiome in 45 participants (15 HC, 15 MCI, 15 eAD) at baseline, 3 months, and 6 months. The parent study collects gut microbiome profiles, dietary patterns, and cognitive assessments. The sub-study develops and administers the 32-item RCNH survey to characterize participants' readiness to adopt nutritional change. This manuscript reports the RCNH survey, its development process, the sub-study protocol including data collection procedures, and planned exploratory analyses. This protocol presents a novel intervention to assess the gut microbiome, individual dietary patterns, and readiness to make lifestyle changes related to diet.