Higher sodium intake is associated with episodic memory decline in cognitively unimpaired older males: A 6-year longitudinal study

Recent evidence has suggested an association between high sodium intake and development of cognitive impairment. However, while animal studies demonstrate consistent relationships between sodium intake and cognitive impairment, this relationship remains less clear in humans. Our aim was to investigate the relationship between self-reported baseline sodium intake and cognitive decline over 72 months. Cognitively unimpaired participants (n = 1208) from the Australian Imaging, Biomarkers and Lifestyle study were included (70.87 years of age; 41 % male). Participants completed a food frequency questionnaire to quantify sodium intake and underwent comprehensive neuropsychological assessment at baseline and four additional timepoints, 18 months apart. Scores for six cognitive composite domains were generated. Linear mixed models examined associations between baseline sodium intake and cognitive decline including potential confounders in the cohort as a whole and when stratified by sex and Apolipoprotein E status. Following false discovery rate adjustment, there was a negative association between sodium intake and change in the episodic recall composite in males (β=-0.00002; SE=0.00001; FDR adjusted p = 0.044), such that males with higher sodium intake showed faster decline in episodic recall. No associations were observed in the cohort as a whole or in females. No associations were observed when the cohort was stratified by Apolipoprotein E status. Further investigation, including sex-specific approaches, is required to evaluate how sodium intake could be incorporated as one modifiable lifestyle factor aimed at delaying Alzheimer's disease onset.