Remotely-supervised Neuromodulation in PPA

The goal of this clinical trial is to learn whether home-based brain stimulation combined with virtual speech-language therapy can improve communication abilities in adults with logopenic variant primary progressive aphasia (lvPPA), a language disorder most often caused by Alzheimer's disease. The main questions the study aims to answer are: * Is combining remotely supervised transcranial direct current stimulation (tDCS) with virtual speech-language therapy feasible and acceptable for people with lvPPA? * Does this combined treatment lead to improvements in communication compared to speech-language therapy with sham (placebo) stimulation? * Do individual brain characteristics help predict who benefits most from this treatment? Researchers will compare participants who receive active tDCS plus virtual speech-language therapy to participants who receive sham (placebo) tDCS plus virtual speech-language therapy to see if active brain stimulation enhances communication outcomes. Participants will: * Complete speech-language therapy sessions delivered by video visit. * Receive either active or sham tDCS that is remotely supervised and completed at home. * Complete language and cognitive testing before and after treatment. * Undergo brain imaging and other assessments to help understand treatment response.

Inclusion Criteria: * Meets diagnostic criteria for primary progressive aphasia (PPA) * Meets diagnostic criteria for logopenic variant PPA * Attains score of 20 or higher on the Mini-Mental State Examination * Has adequate hearing and vision (with hearing or vision aids, if needed) * Is able to travel to research site and undergo MRI brain scan * Has access to high speed internet and basic experience using a computer and the internet * Is a fluent speaker of English * Has a study partner who can co-enroll in the study, attend pre-treatment training at the research site, and be present for teleconference meetings, as needed Exclusion Criteria: * Speech and language deficits better accounted for by another neurological disorder * Does not meet diagnostic criteria for logopenic variant PPA * Scores less than 20 on the Mini-Mental State Examination * Does not have a study partner who can co-enroll in the study * Has contraindications for tDCS or MRI scan (History of seizures, head injury, craniotomy, skull surgery or fracture; History of severe or frequent migraines; Metallic implant in head or any metal in head; Pacemaker or cardioverter-defibrillator or any other stimulator; Chronic skin problems; Pregnancy) * Has a history of stroke, epilepsy, or significant brain injury