Theory of Mind : A Cognitive Marker of Conversion from Mild Cognitive Impairment to Alzheimer Disease? (P4.200)

OBJECTIVE:To investigate the emergence of a social cognition deficit in Mild Cognitive Impairment (MCI) and in early Alzheimer disease (AD), assessing Theory of Mind (TOM). BACKGROUND:TOM refers to the ability to infer other’s mental states (beliefs, knowledge). TOM has been shown to be impaired in AD patients (Le Bouc et al., 2012) and MCI subjects (Baglio et al., 2012) compared to healthy aged controls (HC) but, to date, no study proposed to directly compare TOM deficit in these two conditions. DESIGN/METHODS:We explored TOM in 14 AD patients and 18 MCI subjects compared to 22 HC. The first task was a referential communication task (RCT), an ecological paradigm assessing TOM in a natural situation of conversation (Champagne-Lavau et al., 2009). The second task was a classical belief inference task using video materials in which participants have to detect that someone hold a false belief (Samson et al., 2007). Both tasks were designed to limit cognitive overload. RESULTS:Both MCI and AD patients showed significant difficulties to attribute knowledge to their interlocutor during the RCT compared to HC participants. On the belief inference task, AD patients made significantly more errors in false-belief detection compared to HC participants. MCI participants performed like HC participants on this task but their performances were heterogeneous. Indeed, 7 of them made a number of errors equivalent to AD patients and showed difficulties in belief inference. CONCLUSIONS:A deficit in TOM is present even in the early stages of cognitive impairment. Some MCI participants were as impaired as AD patients and may represent a subgroup at-risk of evolution. Therefore, social cognition deficit may constitute a cognitive risk of conversion from MCI to AD. Disclosure: Dr. Moreau has nothing to disclose. Dr. Rauzy has nothing to disclose. Dr. Viallet has nothing to disclose. Dr. Champagne-Lavau has nothing to disclose.