Age-related Inhibitory Decline: Examining Inhibition Sub-Components and their Impact on Sustained Attention in Healthy Ageing

ObjectiveThe inhibition deficit hypothesis postulates that inhibitory functioning declines with age, which negatively impacts other cognitive abilities. Yet still, the impact of healthy ageing on inhibitory functioning remains unclear, with the multifaceted nature of inhibition often an overlooked factor. Moreover, no prior study has empirically tested whether inhibitory sub-components explain differential age-effects in sustained attention - an open question that this work aims to address. MethodIn this cross-sectional study, we investigated the inhibition deficit hypothesis in a sample of eighty healthy older adults (mean age = 67.78 years, 44f). We utilised the PsyToolkit platform to administer three inhibition tasks (i.e., flanker, Stroop, and go/no-go), each targeting a distinct sub-component process, along with the Sustained Attention to Response Task (SART). ResultsSemi-partial correlations (rho) of the three inhibition sub-component measures (correcting for gender and education) with age resulted in significant positive relationships with task performance on the Stroop and go/no-go, such that older individuals had more pronounced Stroop effects and worse go/no-go accuracy, respectively. Lastly, go/no-go performance completely mediated the relationship between ageing and sustained attention performance, whilst Stroop effects partially mediated this association. ConclusionAge-related declines were observed in specific inhibition tasks, which speaks against a general inhibition deficit in healthy ageing and cautions against conflating these sub-components into a generalised concept of inhibition. The mediation findings demonstrate that inhibitory sub-components account for age-related declines in sustained attention, over and beyond ageing itself via an indirect path, representing an important cognitive domain to maintain throughout ageing. Key pointsO_ST_ABSQuestionC_ST_ABSAre different inhibitory sub-components associated with age, and do they mediate age-related changes in sustained attention? FindingsDifferent inhibition tasks were uncorrelated, demonstrating specific relationships with age and providing evidence that select inhibition tasks can explain differential age-effects in sustained attention. ImportanceThis study lends support for the inhibition deficit hypothesis and underlines the importance of considering inhibitions multifaceted nature. Next stepsFuture research should adopt longitudinal designs to examine causal relationships