Still no convincing evidence for increasing prospective effects between grip strength and cognitive function: A simulated reanalysis and comment on Zhang et al. (2026)

Based on findings from analyses with cross-lagged panel models, Zhang et al. suggested that muscle strength, measured as grip strength, can protect against cognitive decline among the elderly. Here, we simulated data to resemble the data used by Zhang et al. We fitted complementary models to the simulated data and found contradicting increasing, decreasing, and null effects of initial grip strength on subsequent change in cognitive function and vice versa. Meta-analytic aggregations of these divergent effects were not statistically significant. Hence, it is premature to assume a protective effect of muscle strength on cognitive decline and the conclusion by Zhang et al. in this regard can be challenged. It is important for researchers to be aware that correlations, including adjusted cross-lagged effects, do not prove causality in order not to overinterpret findings, something that appears to have happened to Zhang et al. We recommend researchers to fit complementary models to their data in order to evaluate if observed effects may be due to true causal effects or if they appear to be spurious.