Diet Effects on Cerebrospinal Fluid Amino Acids Levels in Adults with Normal Cognition and Mild Cognitive Impairment

Background: Exploration of cerebrospinal fluid (CSF) amino acids and the impact of dietary intake on central levels may provide a comprehensive understanding of the metabolic component of Alzheimer's disease. Objective: The objective of this exploratory study was to investigate the effects of two diets with varied nutrient compositions on change in CSF amino acids levels in adults with mild cognitive impairment (MCI) and normal cognition (NC). Secondary objectives were to assess the correlations between the change in CSF amino acids and change in Alzheimer's disease biomarkers. Methods: In a randomized, parallel, controlled feeding trial, adults (NC, n = 20; MCI, n = 29) consumed a high saturated fat (SFA)/glycemic index (GI) diet [HIGH] or a low SFA/GI diet [LOW] for 4 weeks. Lumbar punctures were performed at baseline and 4 weeks. Results: CSF valine increased and arginine decreased after the HIGH compared to the LOWdiet in MCI (ps = 0.03 and 0.04). This pattern was more prominent in MCI versus NC (diet by diagnosis interaction ps = 0.05 and 0.09), as was an increase in isoleucine after the HIGH diet (p = 0.05). Changes in CSF amino acids were correlated with changes in Alzheimer's disease CSF biomarkers A beta(42), total tau, and p-Tau 181, with distinct patterns in the relationships by diet intervention and cognitive status. Conclusion: Dietary intake affects CSF amino acid levels and the response to diet is differentially affected by cognitive status.

Automated summary

This study aimed to investigate the impact of diets with different nutrient compositions on cerebrospinal fluid amino acid levels, finding that a high saturated fat/glycemic index diet can lead to changes in amino acid levels in individuals with mild cognitive impairment. The response to diet intervention varies according to cognitive status.