In their analysis of the Malmö Diet and Cancer Study, Dr. Glans et al. evaluated the association between incident dementia and adherence to a modified Mediterranean diet vs conventional dietary recommendations. More than 28,000 individuals were followed over an approximately 20-year period and were asked to report on their dietary habits using a detailed questionnaire, food diary, and clinical interviews. There was no significant association between incident dementia and dietary strategy. Furthermore, the lack of association was observed in various sensitivity analyses—including those with best adherence to a particular diet and when assessing Alzheimer dementia or vascular dementia as secondary outcomes or when isolating a nested cohort (n = 738) with CSF samples for amyloid-β42 accumulation. In response to this analysis, Dr. Brenner emphasizes the potential risk of dementia based on the method of food preparation (rather than simply food content). In particular, there is a relationship between advanced glycation end-products (as seen in patients with diabetes and in patients who prepare foods by grilling or frying methods). Drs. Smith and Refsum also acknowledge the bias of self-reported dietary adherence and suggest that serologic biomarkers of diet be used to support the conclusions of this report. This exchange highlights the value of heterogeneity in study methodology. For conditions such as dementia, Alzheimer disease, and others, which may be causally related to innumerable factors (including dietary content, food preparation, and adherence to a particular regimen), large population-based cohorts may reveal specific, modifiable risk factors. However, definitive associations require validation with objective biomarkers and advanced neurodiagnostic testing, which may be cost-prohibitive for studies of this scale. There is an equal need for both large-scale population-based studies and smaller cohorts, which report highly detailed clinical, physiologic, and neurodiagnostic findings. In their analysis of the Malmö Diet and Cancer Study, Dr. Glans et al. evaluated the association between incident dementia and adherence to a modified Mediterranean diet vs conventional dietary recommendations. More than 28,000 individuals were followed over an approximately 20-year period and were asked to report on their dietary habits using a detailed questionnaire, food diary, and clinical interviews. There was no significant association between incident dementia and dietary strategy. Furthermore, the lack of association was observed in various sensitivity analyses—including those with best adherence to a particular diet and when assessing Alzheimer dementia or vascular dementia as secondary outcomes or when isolating a nested cohort (n = 738) with CSF samples for amyloid-β42 accumulation. In response to this analysis, Dr. Brenner emphasizes the potential risk of dementia based on the method of food preparation (rather than simply food content). In particular, there is a relationship between advanced glycation end-products (as seen in patients with diabetes and in patients who prepare foods by grilling or frying methods). Drs. Smith and Refsum also acknowledge the bias of self-reported dietary adherence and suggest that serologic biomarkers of diet be used to support the conclusions of this report. This exchange highlights the value of heterogeneity in study methodology. For conditions such as dementia, Alzheimer disease, and others, which may be causally related to innumerable factors (including dietary content, food preparation, and adherence to a particular regimen), large population-based cohorts may reveal specific, modifiable risk factors. However, definitive associations require validation with objective biomarkers and advanced neurodiagnostic testing, which may be cost-prohibitive for studies of this scale. There is an equal need for both large-scale population-based studies and smaller cohorts, which report highly detailed clinical, physiologic, and neurodiagnostic findings.