Clinical utility of transcranial direct current stimulation and online language training in semantic dementia

Abstract Background Semantic dementia (SD) is a variant of primary progressive aphasia (PPA) which is characterised by impaired confrontation naming, single word comprehension and object recognition with preserved fluency and syntax. Similar to many other neurodegenerative dementias, there is currently no effective treatment for semantic dementia. Neuromodulatory interventions like transcranial direct current stimulation(tDCS) and repetitive transcranial magnetic stimulation(rTMS) along with language training is emerging as a potential treatment strategy for Primary progressive aphasia. Aim: Four patients with semantic dementia were administered concomitant online language training with tDCS to study the feasibility and clinical outcome. Method Four patients (2 males) aged between 50‐63 years, diagnosed with semantic dementia after a comprehensive clinical assessment and Addenbrooke’s cognitive examination and Clinical Dementia Rating(CDR) scale by an experienced geriatric Psychiatrist were included in the case series. Detailed assessment of neurolinguistic skills was done using Western Aphasia Battery (WAB‐Kannada/Hindi) before and after 5‐days of tDCS by qualified speech pathologist. Daily tDCS sessions were delivered using 2mA current with anode over the left dorsolateral prefrontal cortex and cathode over right supraorbital area for 30 minutes, except one female patient with moderate dementia who received 2 session daily at an interval of 3 hours. Online cognitive‐linguistic intervention was provided by the speech pathologist during tDCS sessions. Adverse effects were monitored using structured questionnaire. Result Three Patients had mild dementia and one had moderate dementia as per CDR. tDCS was tolerated well except for burning sensation in two sessions in one patient and all were able to attend the linguistic training. All subjects improved in the domains of Spontaneous speech, Auditory verbal comprehension, repetition and naming on the WAB. Conclusion tDCS can be a potential therapeutic modality in semantic dementia. Randomized Sham Controlled Clinical trials are required to establish the efficacy of tDCS and language training in the treatment of semantic dementia.