Microarchitectural structure of bone mediates the relationship between age and cognition

There is potential endocrine crosstalk between bone and the brain. To elucidate the relationship between age and cognitive decline, it is important to consider microarchitectural structure of bone such as trabecular bone score (TBS), which is more sensitive technique to measure microarchitectural structure of bone than bone mineral density (BMD) and may affect behavior. Therefore, we aimed to investigate if TBS is a mediator of the relationship between age and cognitive decline. Healthy participants (N = 101, 40–90 years) completed the Montreal Cognitive Assessment (MoCA). Body composition, BMD and TBS were measured by dual X-ray absorptiometry. Mediation analysis was conducted to determine if TBS mediates the relationship between age and cognition. Older age was associated with worse cognition (p < 0.001), but this was an indirect effect: older participants had lower TBS, and, in turn, lower TBS was associated with worse MoCA scores. TBS mediates the relationship between age and cognitive decline. Importantly, this relationship was not moderated by age. Moreover, high muscle mass was associated with increased TBS. This relationship between health and TBS may be a possible mechanistic explanation for how health affects cognition in older age.