Baseline Functional Connectivity Predicts Who Will Benefit From Neuromodulation: Evidence From Primary Progressive Aphasia
Year: 2026
Type: article
Abstract: BackgroundUnderstanding individual variability in response to interventions is essential for developing personalized treatment strategies. In rare and clinically heterogeneous conditions like primary progressive aphasia (PPA), predicting treatment response is particularly challenging due to varying clinical manifestations. In this study, we aimed to identify and analyze predictors of individual language response to transcranial direct current stimulation (tDCS) of the left inferior frontal gyrus (IFG), using a novel, robust analytic approach focused on treatment effect heterogeneity.MethodsWe compared the ability of predicting individual effect (active vs sham tDCS during 20-minute sessions on weekdays for 3 weeks; active: 2 mA current across electrodes; sham: current ramped down after 30 seconds), using demographic and clinical patient characteristics (eg, PPA variant and disease progression, baseline language performance) or volumetric fMRI data versus functional connectivity (from resting-state fMRI) in the cohort of 36 patients.ResultsFunctional connectivity alone had the highest predictive value for outcomes, explaining 62% of the variance of the tDCS effect in generalization (semantic fluency) and 75% of the main outcome (written naming), contrasted with <15% (for semantic fluency) and <23% (for written naming) of variance predicted by demographic and clinical patient characteristics or volumetric data. Patients with higher baseline functional connectivity within the left IFG (between pars opercularis and pars triangularis) were most likely to benefit from tDCS both in generalization (semantic fluency) as well as in the main outcome (written naming). In addition, patients with higher baseline FC between the middle temporal pole and superior temporal gyrus, were most likely to show generalization effects of tDCS.ConclusionsThe present study showcases the importance of a baseline functional connectivity scan in predicting tDCS outcomes, and points toward a precision medicine approach in neuromodulation studies. The study has important implications for clinical trials and practice, providing a statistical method that addresses heterogeneity in patient populations and allowing accurate prediction and enrollment of those who will most likely benefit from specific interventions.
Language: English
Subfield: Neurology
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Awards: Rehabilitation and Prophylaxis of Anomia in Primary Progressive Aphasia, Transcranial direct current stimulation in typical and atypical Alzheimer's disease, G2788811118, Effects of tDCS on spoken and written production in Primary Progressive Aphasia, Phase II clinical trial of transcranial direct current stimulation in the treatment of primary progressive aphasia, Neural Basis of Language in Acute Stroke and Recovery, Center for the Study of Aphasia Recovery (C-STAR), Targeting language-specific and executive-control networks with transcranial direct current stimulation in aphasic AD
OpenAlex ID: W7119488852