Association between dietary thiamine consumption and cognitive decline

In a recent study published in General Psychiatry, researchers explored the impact of thiamine consumption on cognitive function among older adults in China.

Study: J-shaped association between dietary thiamine intake and the risk of cognitive decline in cognitively healthy, older Chinese individuals. Image Credit: aleksandr talancev/Shutterstock.com

Background

Dementia is a leading cause of disability and mortality, with no treatment. Preventing cognitive decline is critical, particularly by addressing readily modifiable dietary and behavioral variables.

Thiamine, a water-soluble B vitamin, has been proven to enhance cognitive performance in individuals with mild dementia or cognition impairment, maintenance hemodialysis patients, and alcoholics.

However, the relationship between dietary thiamine consumption and cognitive performance among elders is unknown, with most investigations relying on cross-sectional or case-control designs.

The current emphasis on high-dose thiamine supplementation or intramuscular injections has resulted in conflicting data about the relationship between dietary thiamine intake and cognitive performance in the general elderly population.

About the study

The present study investigated whether thiamine intake is associated with cognitive decay among older, cognitively healthy Chinese individuals.

The team subjected 3,106 individuals aged ≥55 years from the China Health and Nutrition Survey (CHNS) to repeated cognitive evaluations using a modified version of the Telephone Interview for Cognitive Status (TICS) tests.

They assessed cognitive decline based on declines in global and composite cognitive scores over five years. They obtained dietary intake data through three-day diet recalls and used a food-weighed approach to evaluate condiment and cooking oil consumption.

The study involved individuals from Liaoning, Heilongjiang, Henan, Shandong, Hubei, Jiangsu, Guizhou, Guangxi, and Hunan. The CHNS team completed the follow-ups in various years, with cognitive assessments in 1997, 2000, 2004, and 2006.

The team excluded individuals with only one survey round of data and those with extremes of dietary calorie intake (above 4200 or below 600 kcal/day for males and above 3,600 or below 500 kcal/day for females).

The researchers performed linear regression modeling for analysis. Study covariates included blood pressure, age, sex, body mass index (BMI), alcohol intake, smoking, occupation, education level, residence type, region, comorbidities, medications, physical activity, and cognition-associated dietary factors (potassium, sodium, fiber, carbohydrate, fat, and protein).

The team performed several sensitivity analyses. They examined the link between energy-adjusted thiamine consumption and cognition to eliminate the confounding effects of total calorie intake.

They also adjusted for the intakes of legumes, whole grains, processed and unprocessed red meat, niacin, and riboflavin to reduce confounding effects. They used the Benjamini-Hochberg technique to derive multiple-test corrected values in the primary and subgroup analyses.

Results

The study participants had a mean age of 63 years and a mean thiamine intake value of 0.9 mg/day. Higher thiamine intake was associated with younger individuals, the male gender, alcohol consumption, farming, and smoking.

It also led to lower systolic blood pressure and higher body mass index, education, physical activity levels, educational attainment, and carbohydrate, fiber, fat, protein, potassium, and sodium intake.

The team followed the study participants for a median of six years. They found a J-shape association between thiamine consumption and the five-year composite and global cognition scores, with a 0.7 mg/day inflection point and a minimum risk among individuals consuming 0.6 to 1.0 mg daily.

Thiamine consumption was unrelated to cognition decay before the inflection point; however, every unit rise in thiamine consumption (mg/day) led to significant reductions in global and composite cognition scores of 4.2 points and 0.5 units, respectively, over five years.

The positive link between thiamine consumption and cognitive decay was more robust among obese and hypertensive non-smoking individuals.

Sensitivity analyses yielded similar results. The mixed linear regressions for individuals subjected to more than two cognitive tests showed the slowest cognition decay among individuals consuming 0.7 to <1.0 mg/day of thiamine. 

Conclusions

The study findings showed a J-shape relationship between thiamine consumption and cognitive deterioration among older, cognitively healthy Chinese individuals.

Thiamine consumption was not significantly associated with cognition before the inflection point of 0.7 mg/day; however, a strong positive correlation increased after the inflection point, particularly in persons with obesity, hypertension, and nonsmokers.

Thiamine insufficiency may result in inadequate energy supply to the brain’s neurons and reduced acetylcholine transmission, limiting cognitive function.

Hypertensive, obese, and non-smoking individuals had a higher positive correlation, indicating that hypertension and obesity had a synergistic effect on cognitive decline risk when combined with high thiamine consumption.

The favorable correlation was reduced among smokers, suggesting that nicotine may mitigate the negative consequences of excessive dietary thiamine consumption.

The ideal thiamine consumption range for older individuals with the lowest cognitive loss risk is 0.6–1.0 mg/day.