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.

Methods

Critical narrative review reported according to SANRA. Sources were PubMed, Embase, Web of Science and Cochrane CENTRAL (inception to 29 September 2026) and reference lists. Controlled intervention studies in established idiopathic PD with an objective cognitive outcome or a specifically rated cognitive symptom formed the evidence set, appraised on risk-of-bias domains and classified by an explicit rule.