Non-pharmacological neurostimulatory techniques show mild cognitive improvements in cancer survivors with CRCI

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Frontiers in Medicine Published June 2, 2026 Medically reviewed June 2, 2026 DOI ↗ By Dr. Ji-eun Park, MD · Brain, Mind & Pain

Key Takeaway

Consider the mild cognitive improvements noted but recognize the evidence is limited by methodological flaws.

This is a systematic review of 17 studies that synthesized evidence on non-pharmacological neurostimulatory interventions for chemotherapy-related cognitive impairment in cancer survivors. The authors reviewed 77 papers from 2,708 screened manuscripts, focusing on techniques such as transcranial direct current stimulation, transcranial magnetic stimulation, multisensory stimulation, Flexyx neurotherapy system, acupuncture, and electroacupuncture.

The main synthesized finding was that mild improvements in some cognitive outcome measures were observed across all studies. The review did not report effect sizes, p-values, or confidence intervals for these outcomes. Secondary outcomes included memory, sustained attention, executive function, overall performance, working memory, processing speed, and quality of life.

The authors acknowledged substantial limitations, including insufficient statistical power, insufficient testing, lack of a control group, lack of randomization, lack of blinding, incorrect statistical methods, small sample sizes, biased study designs, and only a handful of trials reporting cognitive outcomes. Safety data were not reported.

The review provides rationale for assessing these techniques in large-scale randomized controlled trials. Practice relevance is limited by the evidence quality, and clinicians should interpret the mild improvements cautiously given the methodological gaps.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedJun 2026

View Original Abstract ↓

BackgroundChemotherapy-related cognitive impairment (CRCI) represents an increasingly recognized problem in the growing cancer survivor population within the US and worldwide. CRCI is characterized by deficits in memory, sustained attention, and executive function, which significantly worsens the cancer survivors’ quality of life. An increasing number of studies have been conducted using novel intervention approaches aimed at mitigating CRCI. In this systematic review, we sought to summarize the current evidence of cognitive improvement in cancer survivors receiving non-pharmacological interventions with neurostimulatory effects following chemotherapy.MethodsWe screened five databases (Embase, MEDLINE, PubMED, Scopus, and PsycINFO) for original articles reporting the administration of any type of brain stimulation or complementary/alternative therapies targeting the central and/or peripheral nervous system to improve cognitive outcomes in cancer survivors reporting CRCI. We systematically extracted information from each eligible study using participant, intervention, comparison, outcome(s), and study design (PICOS) framework according to Cochrane recommendations. We used the critical appraisal tool by Joanna Briggs Institute to assess the risk of bias.ResultsAfter screening 2,708 manuscripts, we performed a full-text review of 77 papers and identified 17 studies that met our inclusion criteria: nine randomized controlled trials, four case reports, one case series, two quasi-experimental study, and one cohort study. We identified seven studies which focused on CRCI and 10 others where cognitive function was properly reported for inclusion. Subjective and objective cognitive outcome measures reflecting overall performance, attention, working memory, processing speed, and quality of life with separate cognitive function reporting were assessed in patient(s) treated with transcranial direct current stimulation, transcranial magnetic stimulation, multisensory stimulation, Flexyx neurotherapy system, acupuncture, and electroacupuncture. Mild improvements in some of the cognitive outcome measures were observed in all studies. The weaknesses of these studies can be attributed to insufficient statistical power and testing, lack of a control group, randomization, blinding, and incorrect statistical methods.Discussion and conclusionWe found only a handful of trials reporting cognitive outcomes in CRCI interventions, with small sample sizes and biased study designs limiting the validity of the statistically significant findings. Our systematic review provides rationale for assessing the impact of non-pharmacological neurostimulatory techniques on CRCI in large-scale randomized controlled trials.