In humans, evidence regarding the relationship between obesity and dementia or other neural risks is conflicting: some studies suggest these risks are greater in APOE4 carriers (Mole et al., 2020; Osiecka et al., 2023), while others indicate a more robust effect in APOE4 non-carriers (Coad et al., 2022; Shinohara et al., 2023; Zhao et al., 2023). Here, APOE is linked to obesity due to melanocortin 4 receptor deficiency.