Selective theory of mind impairment and cerebellar atrophy: a case report

Abstract

The cerebellum is recognized as an affect and cognition modulator, besides the traditional role of movement coordinator [1]. Bidirectional connections exist between the cerebellum and cortical structures involved in the regulation of different cognitive and emotional processes [1–3]. Stoodley and Schmahmann [3] supported a functional dichotomy of the cerebellum: the anterior portion would control the sensory-motor system, while the posterior portion would control the cognitive–affective functions. Schmahmann and Sherman [4] defined the ‘‘cerebellar cognitive affective syndrome’’ (CCAS) as a pattern of deficits in language, visuospatial abilities, executive functioning and affective regulation. The affective component includes changes in personality, lack of inhibitory regulation, inappropriate behaviour, altered mood regulation, blunting of affect, obsessive–compulsive tendencies, and psychotic thinking [4]. These symptoms may be secondary to an impairment of social cognition, the capacity to construct mental representations of social relations and to flexibly use them in the social environment. Social cognition comprehends theory of mind (ToM), one’s perspective taking, empathy, the appreciation of behavior appropriateness, and the understanding of conventional and moral rules, resulting an important prerequisite to successful behavior [5]. ToM, the reading of others’ mental states (beliefs, intentions, desires), allows distinguishing mental states that have a basis in reality from lies, metaphors, persuasion, or delusion [6]. Indeed, in psychiatric patients, some psycho-behavioural symptoms were related to ToM deficit [6]. Functional imaging and clinico-pathological studies indicated that a widely distributed neuronal system underlies ToM, especially the anterior paracingulate cortex, superior temporal sulci, temporal poles, and the dorsolateral and ventromedial prefrontal cortex [7–11]. A study of autism and abnormalities of the cerebellar hemispheres, vermis, and lobules, suggested an involvement of the cerebellum [12]. The cerebellum is linked, through different neural pathways, to the associative and paralimbic cortex that are linked to the regulation of the emotions and social behaviour [4]. Research on connectivity also evidenced that bi-directional pathways link the left lateral cerebellum and the right posterior superior temporal sulcus, supporting a role for the cerebellum in a wide range of social cognitive functions [13]. Few clinical studies addressed the relationship between the cerebellum and ToM, reporting conflicting results: ToM impairment in the absence of emotion attribution and appreciation of social situation deficits in patients with cerebellar siderosis or atrophy [12, 14, 15] or normal ToM functions in patients with cerebellar stroke [16]. Given the differences in the patient samples and ToM tasks, these results are scarcely comparable, preventing general conclusions. Within this research framework, it is interesting to evaluate the case of a right-handed, 65-year-old patient with 8-year education, who was admitted to hospital due to progressive gait and limb ataxia and dysarthria. Neurologic symptoms began at age 63, with progressive walking A. Parente, V. Manfredi, and A. Tarallo have contributed equally to this work.