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

Ashley D Harris; Zeyi Wang; Bronte Ficek; Kim Webster; Richard Ae Edden; Kyrana Tsapkini

doi:10.1016/j.neurobiolaging.2019.03.011

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

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

Authors

Ashley D Harris¹, Zeyi Wang², Bronte Ficek³, Kim Webster⁴, Richard Ae Edden⁵, Kyrana Tsapkini⁶

Affiliations

¹ Department of Radiology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada. Electronic address: ashley.harris2@ucalgary.ca.
² Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
³ Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA.
⁴ Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA; Department of Otolaryngology Head & Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA.
⁵ Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
⁶ Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA; Department of Cognitive Science, Johns Hopkins University, Baltimore, MD, USA.

PMID: 31029018
PMCID: PMC6591063
DOI: 10.1016/j.neurobiolaging.2019.03.011

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.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Aged
Aphasia, Primary Progressive / metabolism*
Aphasia, Primary Progressive / psychology
Aphasia, Primary Progressive / therapy*
Female
Follow-Up Studies
Humans
Language Therapy*
Learning
Magnetic Resonance Spectroscopy
Male
Middle Aged
Neuronal Plasticity
Time Factors
Transcranial Direct Current Stimulation*
gamma-Aminobutyric Acid / metabolism*

Substances

gamma-Aminobutyric Acid

Abstract

Publication types

MeSH terms

Substances

Grants and funding