The central framework for the project is a double-blind, sham-controlled, crossover study in which subjects with the non-fluent/agrammatic and logopenic variants of primary progressive aphasia (naPPA and lvPPA, respectively) will undergo language testing and structural and functional brain imaging before and after receiving 10 semi-consecutive daily sessions of real or sham high definition transcranial direct current stimulation (HD-tDCS) paired with modified constraint-induced language therapy (mCILT). Language testing and brain imaging will be repeated immediately after completion of and 3 months following completion of treatment.~Subjects with naPPA and lvPPA will be randomized to one of two study arms: HD-tDCS+mCILT or sham stimulation+mCILT paired with pre- and post-stimulation imaging and behavioral measures. Equal numbers of subjects with naPPA and lvPPA will be randomized to the HD-tDCS + mCILT and sham + mCILT study arms. The study is double-blinded, in that neither the subject nor the study personnel administering HD-tDCS or sham stimulation will know which arm of the study the subject has been randomized into. Study coordinators will administer HD-tDCS by entering a pre-determined code that has been programmed into the device by another member of the study team. Data will be digitally audio-recorded and analyzed off-line, such that study team members performing data coding and analysis will likewise be blinded to the treatment condition of each subject.~Subject participation in this protocol will occur during 27 planned visits that will span approximately 8 months. The events of the study visits are described below:~VISIT 1:~a Informed consent and screening b. Baseline language assessment #1 c. Baseline MRI scanning~VISIT 2:~Baseline language assessment #2~VISITS 3-11:~HD-tDCS+mCILT OR sham stimulation+mCILT, depending on the study arm to which they had been randomized.~VISIT 12:~Final session of HD-tDCS+mCILT or sham stimulation+mCILT~Follow-up language assessment~Follow-up MRI~VISIT 13:~6-Week follow-up language assessment~VISIT 14:~12-week follow-up language assessment~12-week follow-up MRI~**CROSSOVER**~VISIT 15:~Crossover baseline language assessment #2~VISITS 16-24:~HD-tDCS+mCILT or sham stimulation+mCILT~VISIT 25:~10th session of HD-tDCS+mCILT or sham stimulation+mCILT~Follow-up language assessment~Follow-up MRI~VISIT 26:~6 Week follow-up language assessment:~VISIT 27:~12-week follow-up language assessment~12-week follow-up MRI
This is a double-blind, sham-controlled, crossover study in which subjects with the non-fluent/agrammatic and logopenic variants of primary progressive aphasia (naPPA and lvPPA, respectively) will undergo language testing and structural and functional brain imaging before and after receiving 10 semi-consecutive daily sessions of real or sham high-definition transcranial direct current stimulation (HD-tDCS) paired with modified constraint-induced language therapy (mCILT). Language testing and brain imaging will be repeated immediately after completion of and 3 months following completion of treatment. The 3-month follow-up will be the primary endpoint. The investigators will examine changes in language performance induced by HD-tDCS + mCILT compared to sham HD-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.