Identifying factors influencing cognitive outcomes after anodal transcranial direct current stimulation in older adults with and without cognitive impairment: A systematic review

Grace Ky Koo; Amish Gaur; Shankar Tumati; Raphael W Kusumo; Kritleen K Bawa; Nathan Herrmann; Damien Gallagher; Krista L Lanctôt

doi:10.1016/j.neubiorev.2023.105047

Identifying factors influencing cognitive outcomes after anodal transcranial direct current stimulation in older adults with and without cognitive impairment: A systematic review

Neurosci Biobehav Rev. 2023 Mar:146:105047. doi: 10.1016/j.neubiorev.2023.105047. Epub 2023 Jan 14.

Authors

Grace Ky Koo¹, Amish Gaur¹, Shankar Tumati², Raphael W Kusumo², Kritleen K Bawa², Nathan Herrmann³, Damien Gallagher³, Krista L Lanctôt⁴

Affiliations

¹ Neuropsychopharmacology Research Group, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Pharmacology & Toxicology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
² Neuropsychopharmacology Research Group, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada.
³ Neuropsychopharmacology Research Group, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, 250 College Street, 8th floor, Toronto, ON M5T 1R8, Canada.
⁴ Neuropsychopharmacology Research Group, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Pharmacology & Toxicology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Department of Psychiatry, Faculty of Medicine, University of Toronto, 250 College Street, 8th floor, Toronto, ON M5T 1R8, Canada. Electronic address: Krista.Lanctot@sunnybrook.ca.

PMID: 36646259
DOI: 10.1016/j.neubiorev.2023.105047

Abstract

Anodal transcranial direct current stimulation (tDCS) can improve cognition in healthy older adults, those with Alzheimer's disease (AD) and mild cognitive impairment (MCI), albeit with considerable variability in response. This systematic review identifies interindividual factors that may influence tDCS outcomes in older individuals with or without cognitive impairment. Peer-reviewed articles were included if they assessed whether cognitive outcomes (memory or global cognition) after tDCS were associated with pre-intervention factors in healthy older adults or individuals with AD/MCI. We identified eight factors that may affect cognitive outcomes after tDCS. Improved tDCS outcomes were predicted by lower baseline cognitive function when tDCS was combined with a co-intervention (but not when used alone). Preserved brain structure and better baseline functional connectivity, genetic polymorphisms, and the use of concomitant medications may predict better tDCS outcomes, but further research is warranted. tDCS outcomes were not consistently associated with age, cognitive reserve, sex, and AD risk factors. Accounting for individual differences in baseline cognition, particularly for combined interventions, may thus maximize the therapeutic potential of tDCS.

Keywords: Alzheimer’s disease; Global cognition; Interindividual variability; Memory; Mild cognitive impairment; Older adults; Predictors; Transcranial direct current stimulation.

Publication types

Systematic Review
Review
Research Support, Non-U.S. Gov't

MeSH terms

Aged
Alzheimer Disease* / psychology
Brain
Cognition
Cognitive Dysfunction*
Humans
Transcranial Direct Current Stimulation*