Female rodents are not more variable than male rodents: A meta-analysis of preclinical studies of fear and anxiety

Summary

This 2022 meta-analysis of preclinical rodent studies challenges the widely held assumption that female rodents are inherently more behaviourally variable than males in fear and anxiety tasks. By synthesising data across multiple studies, Kaluve, Le and Graham appear to demonstrate that sex-based differences in variability are not statistically supported, suggesting that exclusion of female subjects from research designs on grounds of greater variability lacks empirical foundation. The findings have implications for research design transparency and the generalisability of preclinical findings across sexes.

Regional applicability

As a preclinical methodology paper, the findings are applicable to UK laboratory neuroscience and animal research standards, potentially influencing institutional guidance on sex representation in rodent studies. The work supports alignment with UK and EU regulatory frameworks (e.g. NC3Rs guidance) that increasingly mandate consideration of sex as a biological variable in experimental design.

Key measures

Behavioural variability (as suggested by variance or coefficient of variation), effect sizes across fear and anxiety paradigms in rodent models

Outcomes reported

The study synthesised data from preclinical rodent studies to examine whether female rodents show greater behavioural variability than males in fear and anxiety tasks. The meta-analysis evaluated effect sizes and variability metrics across multiple published experiments to challenge the common assumption that females are more variable subjects.

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