Theory Of Mind In Amnestic Mild Cognitive Impairment

Objective Amnestic mild cognitive impairment(a MCI), which is a subtype of mild cognitive impairment(MCI) featured by memory decline, has been regarded as the early stage of Alzheimer’s disease(AD) because of its high risk of developing into Alzheimer dementia(Petersen et al., 2014) and is a hot spot in recent research. Theory of mind(To M) is the ability of perceiving and understanding others’ mental states, which is an essential part of social cognition for individual social adaptation. Recent studies have proved that in addition to memory decline, AD patients are also impaired in social cognition including To M. It is of great importance to study social cognition in a MCI in order to further understand the behavioral characters of AD as well as helping early detection of this disease. Current research on a MCI has paid little attention to social cognition. This research selected different experimental paradigms to study To M in a MCI patients from multiple dimensions to explore the behavioral representation of social cognition in a MCI.Methods 16 a MCI patients and 15 normal controls matched in age, gender and education underwent a battery of background tests and To M experimental paradigms. The correct number of answers were recorded and conversed to accuracy for the measurement of To M. Data were analyzed using two-way ANOVA and follow-up multiple ANOVA. Spearman’s correlation analyses were administered between impaired To M type and background tests within each of the two groups. Three To M tests were utilized. 1, first- and second-order simple To M tests:the Yoni task were used to test first-order cognitive To M(Cog1), second-order cognitive To M(Cog2), first-order affective To M(Aff1), second-order affective To M(Aff2) together with first-order and second-order physical control conditions. 2, first-order complex To M tasks : We administered RMET to test the subjects’ performance in first-order complex To M(mind reading) and first-order physical control condition. 3, second-order complex To M tasks: the FOR were used to test second-order complex To M(i.e. interpersonal emotion recognition ability) including three subscales of Identification, Envy and Gloat, as well as the physical control condition.Results First- and second-order simple To M test:In the Yoni task, the a MCI group were inferior to the normal controls in Cog2 [F(1, 29) = 6.75, p = 0.015] and Aff2 [F(1, 29) = 15.84, p = 0.000]. There were no differences in Cog1 [F(1, 29) = 1.75, p = 0.196] or Aff1 [F(1, 29) = 0.08, p = 0.774].First-order complex To M test:In RMET,performance of the two groups showed no significant difference.Second-order complex To M test:In FOR, the a MCI patients were outperformed in both Identification [F(1,29)=12.176, p=0.002] and Envy [F(1,29)=14.32, p=0.002], while they marked lower than the control group in Gloat but the difference didn’t reach a statistical significance [F(1,29)=3.52, p=0.071].Within the a MCI group, Spearman’s correlation analysis showed that second-order cognitive To M(Cog2) was positively correlated with global cognitive function MMSE(r = 0.550,p=0.027) and frontal-executive function VFT(r=0.607, p=0.013) while no similar findings were found analyzing the control group. Within the control group, Spearman correlation analysis showed that Envy in second-order complex To M was positively correlated with frontal-executive function VFT(r=0.610,p=0.016) while there was no such result for the a MCI group. These meant that second-order To M ability of a MCI patients might have some connection with their impaired global cognitive function and frontal-executive function.Conclusion This study finds that To M is impaired in a MCI patients. The pattern of To M deficit can be described as follows:1, both cognitive and affective To M are impaired. 2, complex interpersonal emotional recognition ability is impaired. 3, a MCI’s To M ability was mainly affected in second-order To M irrespective of the To M complexty. 4, second-order To M in a MCI might have some connection with the patients’ impaired global cognitive function and frontal-executive function. This alteration of To M may be a behavioral representation of social cognition in a MCI. In comparison with apparent clinical symptoms such as memory decline, the pattern of aberrant social cognition including To M is far unrecognized and underestimated. This study contributes to the exploration of the behavioral feature of To M in a MCI and early AD, which can possibly facilitate the early detection of AD.