Longitudinal Associations Between Gut Microbiome Diversity and Emotional Well-Being

Objective: While a significant link between emotional well-being (EWB) and the gut microbiome has been reported recently, their temporal relationships remain elusive. This study aims to fill this gap by examining the longitudinal associations between EWB and the Shannon Index (SI), an indicator of gut microbiome diversity. Method: The analysis focused on a dataset that collected participants' current EWB and fecal samples in both 2019 and 2022 (N = 57, 56.1% female, M-age = 52.47 years, SD = 12.65). Gut microbiome profiles were generated by sequencing the 16S rRNA gene, from which SI was subsequently calculated. Results: The cross-lagged panel analysis revealed significant positive cross-sectional associations between EWB and SI in both 2019 (beta = .296, SE = 0.121, p = .014) and 2022 (beta = .324, SE = 0.119, p = .006). However, no significant longitudinal associations were found between 2019 EWB and 2022 SI (beta = .068, SE = 0.138, p = .623), nor between 2019 SI and 2022 EWB (beta = -.016, SE = 0.13, p = .899). Conclusions: Our findings indicate that emotional happiness may be associated with gut microbiome profiles at a particular time point, but they may not serve as predictive factors for each other over time. Future research is needed to establish causal relationships between them.