Plant Based Dietary Patterns and Alzheimer Disease Risk

Key Takeaways

• Plant-based dietary pattern quality was evaluated in association with incident Alzheimer disease and related dementias (ADRDs).
• Dietary change over time was also analyzed in relation to later ADRD risk.
• The authors framed the findings within an observational, non-causal interpretation.

Investigators asked whether baseline diet quality aligned with incident ADRDs and whether later shifts in diet quality related to subsequent risk. In the source summary, these questions are presented as linked but analytically distinct parts of the same observational investigation. No intervention, treatment assignment, or experimental comparison is described in the abstract. The report is framed as an observational look at how nutrition patterns intersect with cognitive health outcomes.

The study is described as a cohort analysis centered on plant-based dietary pattern quality and incident ADRDs. The main exposure framework focused on diet quality, including overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI), while the primary outcome was ADRD onset during follow-up. The analysis included 92,849 participants for baseline diet and 45,065 participants for the 10-year dietary change. A second analysis considered dietary change over time to assess whether evolving patterns were also related to later ADRD risk. These elements set up a two-part analytic frame spanning baseline diet quality and longitudinal dietary change.

The authors report an association between baseline plant-based dietary pattern quality and incident ADRDs. Higher adherence to overall and healthful plant-based diets was associated with lower risk, while higher adherence to unhealthful plant-based diets was associated with higher risk. Specifically, comparing the highest versus lowest quintiles, PDI and hPDI were associated with 12% and 7% lower risk of ADRDs, respectively, whereas uPDI was associated with a 6% higher risk. This baseline analysis is presented as the study’s initial exposure–outcome comparison.

Longitudinal change in diet quality was examined as a separate analysis tied to later ADRD risk. This repeated-measures lens is presented as distinct from the baseline comparison rather than a restatement of the initial finding. The strongest association was observed for changes in the unhealthful plant-based diet index (uPDI). Compared with stable dietary patterns, a large increase in uPDI was associated with a 25% higher risk of ADRDs, while a large decrease was associated with an 11% lower risk. The authors note that the findings remain observational, keeping interpretation at the level of association rather than proof of cause. Overall, the results are framed as descriptive evidence on diet patterns and ADRDs within a cohort setting.