Corticospinal activity during dual tasking: A systematic review and meta-analysis of TMS literature from 1995 to 2013

• Eleven dual task studies were pooled for meta-analysis.
• TMS studies indicate corticospinal excitability and inhibition.
• Variables of age, task type, and task prioritisation were investigated.
• Results showed reduced corticospinal inhibition during a dual task.
• Randomisation and blinding within a dual task procedure are raised and discussed.

This systematic review and meta-analysis was conducted across studies using transcranial magnetic stimulation to investigate corticospinal excitability and inhibition in response to a dual task (DT). Quantitative analysis was performed on eleven controlled studies that had included healthy participants over the age of 18 years. Results showed a small effect size for increased corticospinal excitability for DT conditions (SMD = 0.207; p = .217, and a small effect size (SMD = −0.253) demonstrating a significant decrease in corticospinal inhibition for DT conditions (p = .019). Meta-regression demonstrated that neither age, task type, or task prioritisation accounted for the high variability in effect sizes between studies. A number of possible sources of within study bias are identified, which reduced the level of evidence for study findings. The results show overall changes in corticospinal responses between ST and DT conditions; however further research is necessary to investigate variables that could account for differences in corticospinal responses between studies.