Home-Based Transcranial Direct Current Stimulation in Primary Progressive Aphasia: A Pilot Study

Area of Science:

• Neuroscience
• Cognitive Psychology
• Speech and Language Pathology

Background:

• Primary progressive aphasia (PPA) is a neurodegenerative disorder affecting language abilities.
• Verbal short-term memory/working memory (vSTM/WM) deficits are common in PPA.
• Non-invasive brain stimulation techniques are being explored for cognitive enhancement.

Purpose of the Study:

• To evaluate the efficacy of home-based anodal transcranial direct current stimulation (a-tDCS) combined with a vSTM/WM intervention (RAM) in PPA patients.
• To determine if a-tDCS over the left supramarginal gyrus (SMG) enhances vSTM/WM performance compared to sham stimulation.
• To investigate the generalization of tDCS effects to other language and cognitive functions.

Main Methods:

• A double-blind, within-subject design was used with seven PPA participants.
• Participants received both active a-tDCS and sham-tDCS, each coupled with the RAM treatment in separate conditions.
• The RAM treatment involved repeating word spans; transfer effects were assessed using near and far transfer tasks.

Main Results:

• Anodal tDCS significantly improved vSTM abilities, specifically word span backward performance.
• The benefits of a-tDCS generalized to other language skills, including spelling of real words and pseudowords.
• Improved learning, retention, and delayed recall were also observed, indicating broader cognitive benefits.

Conclusions:

• Home-based a-tDCS, when combined with vSTM/WM intervention, shows potential for improving cognitive function in PPA.
• The findings suggest that tDCS over the left SMG can augment targeted memory training.
• This approach offers a promising avenue for non-pharmacological cognitive rehabilitation in PPA.