Theory of mind in multiple sclerosis: Three-month follow-up effects after double-blind tDCS and video-training, a pilot study

Objective: Theory of Mind (ToM) deficits are common in people with Multiple Sclerosis (PwMS). This pilot study evaluated the feasibility of an ecologically valid ToM training in PwMS and examined whether experimental transcranial direct current stimulation (tDCS) intervention targeting the prefrontal cortex could enhance its effects on cognitive and affective ToM components across verbal and nonverbal modalities. Methods: Two studies were conducted. Study 1 employed a single-case design with three PwMS undergoing a 16-week video-based ToM training. ToM performance was assessed at baseline, post-intervention, and 3-month follow-up. Study 2 included 12 PwMS randomly assigned to receive ToM training with either active tDCS (dlPFC or vmPFC) or sham stimulation. tDCS was delivered twice weekly (2 mA, 20 minutes) over 16 weeks. Results: In Study 1, participants showed improvements in cognitive ToM (verbal and nonverbal), and selective improvement in verbal affective ToM. In Study 2, both active tDCS groups exhibited improvements in cognitive and affective ToM compared to the sham group. Conclusions: ToM training seems to be useful in improving cognitive and verbal affective ToM in PwMS, especially when combined with prefrontal tDCS. However, nonverbal affective ToM appears resistant to intervention, suggesting the need for targeted strategies. These preliminary findings support a personalized, multimodal approach to social cognitive rehabilitation in MS.