J-shaped association between dietary thiamine intake and the risk of cognitive decline in cognitively healthy, older Chinese individuals

Abstract

Background: The prospective association of dietary thiamine intake with the risk of cognitive decline among the general older adults remains uncertain.

Aims: To investigate the association between dietary thiamine intake and cognitive decline in cognitively healthy, older Chinese individuals.

Methods: The study included a total of 3106 participants capable of completing repeated cognitive function tests. Dietary nutrient intake information was collected through 3-day dietary recalls and using a 3-day food-weighed method to assess cooking oil and condiment consumption. Cognitive decline was defined as the 5-year decline rate in global or composite cognitive scores based on a subset of items from the Telephone Interview for Cognitive Status-modified.

Results: The median follow-up duration was 5.9 years. There was a J-shaped relationship between dietary thiamine intake and the 5-year decline rate in global and composite cognitive scores, with an inflection point of 0.68 mg/day (95% confidence interval (CI): 0.56 to 0.80) and a minimal risk at 0.60-1.00 mg/day of dietary thiamine intake. Before the inflection point, thiamine intake was not significantly associated with cognitive decline. Beyond the inflection point, each unit increase in thiamine intake (mg/day) was associated with a significant decrease of 4.24 (95% CI: 2.22 to 6.27) points in the global score and 0.49 (95% CI: 0.23 to 0.76) standard units in the composite score within 5 years. A stronger positive association between thiamine intake and cognitive decline was observed in those with hypertension, obesity and those who were non-smokers (all p<0.05).

Conclusions: This study revealed a J-shaped association between dietary thiamine intake and cognitive decline in cognitively healthy, older Chinese individuals, with an inflection point at 0.68 mg/day and a minimal risk at 0.60-1.00 mg/day of dietary thiamine intake.

Keywords: Cognition; Cohort Studies; Diet, Healthy; Epidemiologic Studies; Geriatric Psychiatry.

Figure 1

Flowchart of the study.

Figure 2

Subgroup analyses for the association between dietary thiamine intake and the 5-year decline rate in cognitive scores in participants with dietary thiamine intake higher than the inflection point (0.68 mg/day). (Adjusted, if not stratified, for age, sex, global score, smoking, alcohol consumption, BMI, SBP, DBP, education level, occupation, region, urban or rural residency, self-reported diabetes, antihypertensive medication, physical activity, as well as the intakes of fibre, sodium, potassium, carbohydrate, protein and fat. Hypertension was defined as SBP≥140 mm Hg or DBP≥90 mm Hg, or diagnosed by a physician, or currently under antihypertensive treatment.) BMI, body mass index; CI, confidence interval; DBP, diastolic blood pressure; P-BH, multiple testing corrected p values by Benjamini-Hochberg method; SBP, systolic blood pressure; SD, standard deviation; SU, standard units by averaging z scores.