Treating Primary Progressive Aphasia (PPA) Using tDCS

This is a double-blind, sham-controlled, crossover study in which subjects with the non-fluent/agrammatic and semantic variants of primary progressive aphasia (naPPA and svPPA, respectively) will undergo language testing and structural and functional brain imaging before and after receiving 10 semi-consecutive daily sessions of real or sham transcranial direct current stimulation (tDCS) paired with modified constraint-induced language therapy (mCILT). Language testing and brain imaging will be repeated immediately after completion of and up-to 24 weeks following completion of treatment. The investigators will examine changes in language performance induced by tDCS + mCILT compared to sham tDCS + mCILT. The investigators will also use network science to analyze brain imaging (fMRI) data to identify network properties associated with baseline PPA severity and tDCS-induced changes in performance. This study will combine knowledge gained from our behavioral, imaging, and network data in order to determine the relative degrees to which these properties predict whether persons with PPA will respond to intervention.