APOB and early-onset autosomal dominant Alzheimer disease: In humans, mutations in APOB and circulating levels of ApoB have been associated with cognitive impairment: (i) loss of function mutations in APOB are among the causes of familial Alzheimer's disease (Aumont-Rodrigue et al. 2024), (ii) high serum ApoB levels are connected to greater risk of dementia (Gong et al. 2022), and (iii) a high ratio of ApoB/ApoA1 in circulation predicts the extent of diminished mental capacity in stroke patients (Lee et al. 2023).