Non-Invasive Brain Stimulation in Frontotemporal Dementia: A Systematic Review of Non-Pharmacological Treatment Approaches.

Frontotemporal dementia (FTD) is a heterogeneous disorder for which disease-modifying treatments are lacking. Non-invasive brain stimulation (NIBS) has emerged as a potential therapeutic approach to modulate dysfunctional neural networks and support residual plasticity. This systematic review aims to provide an updated overview of current NIBS applications across the main clinical syndromes associated with FTD, namely behavioral variant FTD (bvFTD), semantic variant of primary progressive aphasia (svPPA), and nonfluent variant of PPA (nfvPPA). According to PRISMA guidelines, twenty-seven studies investigating NIBS interventions in major FTD phenotypes met the inclusion criteria, predominantly employing transcranial direct current stimulation (tDCS) or repetitive transcranial magnetic stimulation (rTMS). tDCS, particularly when combined with language therapy, consistently improved several language abilities in PPA, with some evidence of maintenance over time. Benefits were most consistently reported in nfvPPA, whereas effects in svPPA were more limited and domain-specific. rTMS studies showed short-term improvements in language and executive functions, especially following stimulation of left frontal regions. In bvFTD, findings were heterogeneous, with social-cognitive outcomes appearing more sensitive to stimulation, whereas global cognitive measures showed more variable effects. NIBS, particularly tDCS combined with behavioral interventions, shows symptomatic potential in selected FTD phenotypes, but methodological heterogeneity and small samples warrant larger, well-controlled trials.