Theory of mind, empathy and neuropsychological functioning in X-linked Spinal and Bulbar Muscular Atrophy: a controlled study of 20 patients

Recent studies have described brain involvement, mainly at frontal level, in patients with spinal and bulbar muscular atrophy (SBMA), a rare adult-onset motor neuron disease caused by a CAG repeat in the androgen receptor (AR) gene. The aim of our research was to investigate the poorly characterized neuropsychological and psychological profile of these patients, on the basis of previous literature. We administered a neuropsychological screening and tests relating to cognitive and affective empathy, attributed to the theory of mind (ToM) framework, to 20 males with SBMA, and to age- and education-matched controls. Although patients' neuropsychological performance was unimpaired, a clear dissociation emerged between their cognitive and affective empathy. Patients had distinctive deficits in mentalizing, as assessed with the Faux Pas Test, whilst affective empathy (i.e., sharing experience), assessed with the Reading the Mind in the Eyes test, appeared to be preserved. The likely implications of subtle frontal lobe impairments on the one hand, and a protective influence of androgen insensitivity in these patients on the other, are discussed in the light of our results.