Noémie Moreau

Determinants of Theory of Mind performance in Alzheimer’s disease: A data-mining study

Whether theory of mind (ToM) is preserved in Alzheimers disease (AD) remains a controversial subject. Recent studies have showed that performance on some ToM tests might be altered in AD, though to a lesser extent than in behavioural-variant Frontotemporal Dementia (bvFTD). It is however, unclear if this reflects a genuine impairment of ToM or a deficit secondary to the general cognitive decline observed in AD. Aiming to investigate the cognitive determinants of ToM performance in AD, a data-mining study was conducted in 29 AD patients then replicated in an independent age-matched group of 19 AD patients to perform an independent replication of the results. 44 bvFTD patients were included as a comparison group. All patients had an extensive neuropsychological examination. Hierarchical clustering analyses showed that ToM performance clustered with measures of executive functioning (EF) in AD. ToM performance was also specifically correlated with the executive component extracted from a principal component analysis. In a final step, automated linear modelling conducted to determine the predictors of ToM performance showed that 48.8% of ToM performance was significantly predicted by executive measures. Similar findings across analyses were observed in the independent group of AD patients, thereby replicating our results. Conversely, ToM impairments in bvFTD appeared independent of other cognitive impairments. These results suggest that difficulties of AD patients on ToM tests do not reflect a genuine ToM deficit, rather mediated by general (and particularly executive) cognitive decline. They also suggest that EF has a key role in mental state attribution, which support interacting models of ToM functioning. Finally, our study highlights the relevancy of data-mining statistical approaches in clinical and cognitive neurosciences.

Different Patterns of Theory of Mind Impairment in Mild Cognitive Impairment

Theory of Mind refers to the ability to infer other’s mental states, their beliefs, intentions, or knowledge. To date, only two studies have reported the presence of Theory of Mind impairment in mild cognitive impairment (MCI). In the present study,we evaluated 20 MCI patients and compared them with 25 healthy control participants using two Theory of Mind tasks. The first task was a false belief paradigm as frequently used in the literature, and the second one was a referential communication task,assessing Theory of Mind in a real situation of interaction and which had never been used before in this population. The results showed that MCI patients presented difficulties inferring another person’s beliefs about reality and attributing knowledge to them in a situation of real-life interaction. Two different patterns of Theory of Mind emerged among the patients. In comparison with the control group, some MCI patients demonstrated impairment only in the interaction task and presented isolated episodicmemory impairment, while others were impaired in both Theory of Mind tasks and presented cognitive impairment impacting both episodic memory and executive functioning. Theory of Mind is thus altered in the very early stages of cognitive impairment even in real social interaction, which could impact precociously relationships in daily life.

Characteristics of current tasks that contribute to mentalizing judgments: does the engagement of the participants in the social interaction matter? Comment on Achim et al. (2013).

In a recent article, Achim et al. (2013) discussed the different sources of information that contribute to mentalizing judgments in current theory-of-mind (ToM) tasks. The authors rightly emphasized the dynamic aspect of real-life social interaction, suggesting that taking account of the ongoing changes occurring during social interaction would make ToM tasks more ecological. They proposed a framework (i.e., the Eight Sources of Information Framework) that specifies the 8 sources of information we get from the environment and/or from our memories to attribute mental states to others. Nevertheless, we believe that a central aspect of ToM is missing in this framework: the engagement (or not) of the participant in the social interaction during ToM assessment. Indeed, this framework fails to consider how the participant who takes part in the ToM task manages this information, depending on the fact that he or she is involved in the interaction or not and how the information concerning the agent may impact the participant attribution of mental states. We reviewed several arguments and results from the ToM literature suggesting that merely observing a social interaction is not equivalent to participating in an interaction in terms of cognitive processes involved in the attribution of mental states to others.