Dietary Patterns and Nutritional Interventions for Cognitive Impairment in Parkinson’s Disease: A Critical Narrative Review

Background/Objectives: Cognitive impairment affects most people with Parkinson’s disease (PD); mild cognitive impairment is present in 25–40% of people with PD without dementia, and nutritional advice often exceeds the evidence. We reviewed the human evidence that dietary patterns or nutritional supplements improve cognition in established PD, separating objective cognitive outcomes from patient-rated and biomarker outcomes.