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. 2019 Jul:79:75-82.
doi: 10.1016/j.neurobiolaging.2019.03.011. Epub 2019 Mar 27.

Reductions in GABA following a tDCS-language intervention for primary progressive aphasia

Ashley D Harris  1 , Zeyi Wang  2 , Bronte Ficek  3 , Kim Webster  4 , Richard Ae Edden  5 , Kyrana Tsapkini  6
Affiliations

Reductions in GABA following a tDCS-language intervention for primary progressive aphasia

Ashley D Harris et al. Neurobiol Aging. 2019 Jul.

Abstract

Transcranial direct current stimulation (tDCS) has shown efficacy in augmenting the effects of language therapy in primary progressive aphasia (PPA). The mechanism of action of tDCS is not understood, but preliminary work in healthy adults suggests it modulates γ-aminobutyric acid (GABA) levels to create an environment optimal for learning. It is unknown if this proposed mechanism translates to aging or neurodegenerative conditions. This study tested the hypothesis that tDCS reduces GABA at the stimulated tissue in PPA. We applied GABA-edited magnetic resonance spectroscopy to quantify GABA levels before and after a sham-controlled tDCS intervention with language therapy in PPA. All participants showed improvements but those receiving active tDCS showed significantly greater language improvements compared to sham both immediately after the intervention and at 2-month follow-up. GABA levels in the targeted tissue decreased from baseline after the intervention and remained decreased 2 months after the intervention. This work supports the hypothesis that tDCS modulates GABAergic inhibition to augment learning and is clinically useful for PPA combined with language therapy.

Keywords: Anodal tDCS; GABA-edited MRS; Language therapy; Learning; Neural plasticity; Neurodegenerative disorder.

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Conflict of interest statement

Disclosures

The authors have no conflicts of interest relevant to the subject matter of this manuscript.

Figures

Figure 1.
Figure 1.
Exemplar voxel placement and GABA spectra for the IFG voxel and the SM voxel.
Figure 2.
Figure 2.
Language scores at pre-intervention (base), following the tDCS protocol (post) and at 2-months follow-up (follow-up). Scores are presented as a percentage of the possible points for each patient.
Figure 3.
Figure 3.
GABA levels in the IFG voxel for each patient at pre-intervention (base), following the tDCS protocol (post) and at 2-months follow-up (follow-up).
See this image and copyright information in PMC

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