Age-related changes in responsiveness to non-invasive brain stimulation neuroplasticity paradigms: A systematic review with meta-analysis

Mahima Shah; Suraj Suresh; Johanna Paddick; Maddison L Mellow; Amy Rees; Carolyn Berryman; Tasha R Stanton; Ashleigh E Smith

doi:10.1016/j.clinph.2024.03.002

Age-related changes in responsiveness to non-invasive brain stimulation neuroplasticity paradigms: A systematic review with meta-analysis

Clin Neurophysiol. 2024 Mar 22:162:53-67. doi: 10.1016/j.clinph.2024.03.002. Online ahead of print.

Authors

Mahima Shah¹, Suraj Suresh², Johanna Paddick³, Maddison L Mellow¹, Amy Rees⁴, Carolyn Berryman⁵, Tasha R Stanton⁶, Ashleigh E Smith⁷

Affiliations

¹ Alliance for Research in Exercise, Nutrition and Activity (ARENA) Research Centre, Allied Health and Human Performance, University of South Australia, Adelaide 5000, Australia.
² Brain Stimulation, Imaging and Cognition Laboratory, The University of Adelaide, South Australian Health and Medical Research Institute, Adelaide 5000, Australia.
³ Alliance for Research in Exercise, Nutrition and Activity (ARENA) Research Centre, Allied Health and Human Performance, University of South Australia, Adelaide 5000, Australia; Persistent Pain Research Group, Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI).
⁴ Discipline of Physiology, School of Biomedicine. The University of Adelaide, Adelaide 5000, Australia.
⁵ Brain Stimulation, Imaging and Cognition Laboratory, The University of Adelaide, South Australian Health and Medical Research Institute, Adelaide 5000, Australia; South Australian Health and Medical Research Institute (SAHMRI), North Tce, Adelaide 5000, Australia; IIMPACT in Health, University of South Australia, Adelaide 5000, Australia.
⁶ Persistent Pain Research Group, Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI); IIMPACT in Health, University of South Australia, Adelaide 5000, Australia.
⁷ Alliance for Research in Exercise, Nutrition and Activity (ARENA) Research Centre, Allied Health and Human Performance, University of South Australia, Adelaide 5000, Australia. Electronic address: Ashleigh.smith@unisa.edu.au.

PMID: 38579515
DOI: 10.1016/j.clinph.2024.03.002

Abstract

Objectives: We aimed to summarise and critically appraise the available evidence for the effect of age on responsiveness to non-invasive brain stimulation (NBS) paradigms delivered to the primary motor cortex.

Methods: Four databases (Medline, Embase, PsycINFO and Scopus) were searched from inception to February 7, 2023. Studies investigating age group comparisons and associations between age and neuroplasticity induction from NBS paradigms were included. Only studies delivering neuroplasticity paradigms to the primary motor cortex and responses measured via motor-evoked potentials (MEPs) in healthy adults were considered.

Results: 39 studies, encompassing 40 experiments and eight NBS paradigms were included: paired associative stimulation (PAS; n = 12), repetitive transcranial magnetic stimulation (rTMS; n = 2), intermittent theta burst stimulation (iTBS; n = 8), continuous theta burst stimulation (cTBS; n = 7), transcranial direct and alternating current stimulation ((tDCS; n = 7; tACS; n = 2)), quadripulse stimulation (QPS; n = 1) and i-wave periodic transcranial magnetic stimulation (iTMS; n = 1). Pooled findings from PAS paradigms suggested older adults have reduced post-paradigm responses, although there was considerable heterogeneity. Mixed results were observed across all other NBS paradigms and post-paradigm timepoints.

Conclusions/significance: Whilst age-dependent reduction in corticospinal excitability is possible, there is extensive inter- and intra-individual variability both within and between studies, making it difficult to draw meaningful conclusions from pooled analyses.

Keywords: Aging; Corticospinal excitability; Motor cortex; NBS; Neuroplasticity; Transcranial magnetic stimulation.