The Neuro-cognitive Profile of Theory of Mind in Healthy Ageing

Abstract

Theory of mind (ToM) is often reported to decline with age. While early studies of ageing ToM produced mixed outcomes, the literature generally reports that ToM declines with ageing. However, many ageing ToM investigations employ paradigms that have sources of interference that are non-social in nature, comprising additional demands on executive function, which also declines with age. Consequently, these tasks may disproportionately disadvantage older adults. As a result, existing work may portray an inflated effect of age. To assess this, a meta-analysis was conducted. This showed that, while an overall age effect emerged, there was significant heterogeneity in the magnitude of the reported effects. The scale of the age effect varied and, in some cases diminished, based on paradigm type and sampling considerations, such as age and education, highlighting the problem of non-uniformity and non-specificity in ageing ToM. Next, using a novel paradigm, in-task manipulations which separated out executive demands that are relevant to ToM – outcome knowledge, self-other and attentional conflict – were examined to observe how these processes differentially affect older versus younger adults. Results showed that individual differences in attention and processing speed best explained the degree of conflict experienced through incongruent self-other perspectives. However, older adults were disproportionately affected by managing attentional conflict, and this source of interference was predicted by spatial working memory, highlighting that non-social demands can partially explain reduced ToM performance in ageing. Finally, fMRI was used to show differentiation in the neural response to social and non-social manipulations embedded within false belief tasks. Age-related differences in the recruitment of cortical regions, as informed by a ToM functional localizer, were also assessed. Overall, these findings bring greater clarity to our understanding of ToM in healthy ageing, disentangling classic experimental parameters to highlight which sources of interference best explain age-related difficulty in ToM reasoning.