Hidden in plain sight: under-recognized risks of dementia and underweight in younger acute myocardial infarction patients

This invited commentary refers to ‘Synergistic effects of underweight and dementia on in-hospital mortality during acute myocardial infarction’, by K. Ishihara et al., https://doi.org/10.1093/eurjcn/zvaf158. Ishihara et al.1 provide compelling evidence on the impact of two frequently overlooked vulnerabilities, dementia and underweight status, on in-hospital outcomes for patients admitted with acute myocardial infarction (AMI). Drawing from a large, nationwide Japanese dataset, the authors demonstrate that patients with both dementia and underweight status experienced the highest in-hospital mortality (17.5%) and poorest functional outcomes, despite incurring the lowest hospital costs. This paradox presents critical clinical, behavioural, and methodological implications. A particularly novel finding is the ‘age paradox,’ where patients under 75 years with both dementia and underweight status faced significantly higher in-hospital mortality (OR 2.56) compared to those without either condition. This counters the common belief that such vulnerabilities predominantly affect the oldest. It also raises concerns that these risks may be hidden in plain sight in younger patients with fewer comorbidities, making dementia and malnutrition stand out more sharply as risk amplifiers.