Anosognosia for Theory of Mind deficit: a single case study

Objective Theory of Mind (ToM) refers to the ability to understand and predict others’ mental states, emotions, intentions and beliefs. Deficits in ToM have been reported in adult following brain lesions involving the anterior cingulate and orbitofrontal cortices. Although these disorders impact on patients’ social life, the issue regarding their awareness of deficits is to date unresolved. Anosognosia is the lack of awareness regarding an individual’s deficits. In this study, we investigated the anosognosia for deficits in ToM. Participants and Methods A.P. is a middle-aged male, who suffered from a traumatic brain injury. The cognitive and affective components of ToM were investigated through ToM-test, Faux Pas, Eye Reading and Irony-Comprehension test. Furthermore, the awareness was assessed in three ways: i) a non-structured interview; ii) the DEX, and iii) the PCRS tests. By means of a neuroanatomical study, we investigated the regions and the main white matter tracts associated with the patient’s specific deficits. Results A shortfall of patient’s performance was observed during the ToM assessment (both cognitive and affective ToM). Moreover, he presented a selective impairment in awareness for ToM deficits. His performance in the other cognitive functions, in particular, executive functions (BADS), did not result defective. The lesion analysis showed bilateral lesions in the orbitofrontal and lateral basal-temporal regions. The explorative DTI suggested a disconnection of the arcuate fasciculus and the anterior cingulum. Conclusions We reported a specific deficit in awareness regarding ToM deficits in a traumatic brain injured patient. The lesion analysis is consistent with the previously described neural bases of ToM and supports the hypothesis of modularity in anosognosia, according to which there is a certain degree of awareness that is specific for different cognitive functions (Mograbi & Morris, 2013). Further investigations are needed in order to better understand the networks involved in deficits of awareness