Theory of mind in Alzheimer's disease and amnestic mild cognitive impairment: a meta-analysis.

Abstract

The assessment of theory of mind (ToM) performance in Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) remains inconclusive. We conducted a meta-analysis to investigate ToM performance in patients with aMCI and AD. A systematic literature search was performed for eligible studies published up to July 2019 in three international databases (PubMed, Embase, and Web of Science). Due to heterogeneity between studies, a random-effects model was used. Individual ToM tasks were meta-analyzed separately and possible sources of heterogeneity were examined. In total, 36 studies involving 701 individuals with AD and 197 with aMCI were identified. Compared with healthy controls, ToM was impaired in both AD (d = 1.45) and aMCI patients (d = 0.65). In AD patients, ToM was particularly impaired in advanced tasks such as Faux Pas Recognition (d = 1.26). In patients with aMCI, ToM deficits were relatively modest, with the exception of the reading the mind in the eyes task (d = 1.22). ToM was significantly more impaired in AD than that in aMCI (d = 0.88). This is the first meta-analysis examining ToM performance in AD and aMCI simultaneously. The results showed that ToM deficits were more severe in AD than that in aMCI in most individual ToM tasks. Longitudinal studies are warranted to determine whether ToM abilities in aMCI patients can be used for prognostic purposes.