The Effects of Combined Dietary and Exercise Interventions on Neurocognitive Function -A Systematic Review and Meta-Analysis

Background: Recent studies have shown that the modification of lifestyle, including diet and exercise, can help to prevent neurocognitive decline. However, there is a lack of comprehensive systematic reviews on the effects of combined diet and exercise interventions on neurocognitive function.

Methods: Pubmed, Web of science, Embase, and Google Scholar were searched for randomized controlled trials (RCTS) on the effects of combined dietary and exercise interventions on neurocognitive function up to November 1, 2024. Randomized controlled trials (RCTS) on the effects of combined diet and exercise intervention on neurocognitive function were included. Standardized mean difference (SMD) and 95% confidence interval (CI) were used to express the specific effect size. The final result was a meta-analysis of the included literature data using a random effects model to analyze the specific effects of the combined diet and exercise intervention on the neurocognitive function of the participants. The quality of evidence was assessed by Grading of Recommendation, Assessment, Development, and Evaluation (GRADE).

Results: A total of 12 randomized controlled trials were included, with a total of 3603 subjects, including 2028 females (56.28%) and 1575 males (43.71%). The risk of bias in the included studies was low. Moderate-quality deterministic evidence showed that the combined diet and exercise intervention, compared with the control group, improved participants' global cognitive scores (SMD = 0.10, 95%CI: 0.03 to 0.17, p = 0.003, [I squared = 0%, p = 0.97]), memory (SMD = 0.29, 95% CI: 0.16 to 0.41, p < 0.001, [I squared = 17%, p = 0.29]) and executive function (SMD = 0.49, 95% CI: 0.29 to 0.69, p < 0.001, [I squared = 53%, p = 0.02]) has significant positive effect. The results of subgroup analysis showed that the combined intervention of diet and exercise had no significant effect on improving participants' overall cognitive function compared with either diet or exercise alone. The overall risk of bias of the included studies was low and the possible risk of publication bias was excluded.

Conclusion: The combined intervention strategy of diet and exercise has positive effects on improving neurocognitive function, especially on global cognitive function, memory function and executive function. However, there was no significant difference in cognitive intervention effect between the combined intervention strategy and the single intervention strategy. This means that the combined intervention of diet and exercise may not have a positive additive effect, which needs to be further verified by high-quality randomized controlled trials.