Primary progressive aphasia (PPA) is a neurodegenerative syndrome associated with Alzheimer’s disease and frontotemporal degeneration. Non-invasive brain stimulation (NIBS) is a promising treatment, especially associated with language therapy, but comparative efficacy and long-term effects between the different techniques (transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS)) remain unknown. The present study aims to investigate the effects of non-invasive brain stimulation, alone or associated (tDCS/TMS/tDCS plus TMS) combined with language therapy delivered during a period of 6 months, in the progression of language impairment in PPA, compared with sham stimulation combined with language therapy.

The study is a randomised, double-blinded, parallel, sham-controlled clinical trial. Patients with PPA in early stages (global Clinical Dementia Rating equal to or less than 1) are eligible. They are to be randomised to one of the four treatment arms of the study (active tDCS-active TMS, active tDCS-sham TMS, sham tDCS-active TMS, sham tDCS-sham TMS). All patients will receive language therapy immediately after each session of NIBS, for 6 months. The primary outcome is the Mini-Linguistic State Examination. The secondary outcomes are naming of trained items, Addenbrooke’s Cognitive Examination, Interview for Deterioration in Daily Living Activities, Clinical Dementia Rating including behaviour and language domains, Neuropsychiatric Inventory and regional brain metabolism. Exploratory substudies will be conducted including blood biomarkers, quantitative electroencephalography and spontaneous speech assessment.

The study is registered (ClinicalTrials.gov: NCT07158216) and approved by the Ethics Committee of the Hospital Clinico San Carlos (code 25/309-IC_P_CE). Patients will be enrolled after signing an informed consent form. Study outcomes will be disseminated through presentations at scientific conferences, publications in peer-reviewed journals and other academic forums.

NCT07158216.