Abstract
Background/Aim: Studies have indicated a relationship between either gene polymorphism or in vivo B vitamins’ nutritional status with cognition in the elderly. However, the combined effects of MTHFR and SLC19A1gene polymorphism with serum folate and vitamin B12 levels on cognition in Chinese adult population remain unclear. Methods: Demographic information of 426 Chinese adults aged from 55 to 90 were collected by a well designed self-administered questionnaire. The Montreal Cognitive Assessment test was utilized to evaluate the cognition status of the participants. MTHFR and SLC19A1 genotyping was analyzed using polymerase chain reaction-ligase detection reaction (PCR- LDR) method. Serum folate, vitamin B12 and homocysteine (Hcy) levels were detected by commercial assay kits. Pearson’s correlation was used for data analyses and statistical significance was set at p < 0.05. Results: Serum Hcylevels demonstrated a negative correlation with serum folate (r = −0.301) and vitamin B12 (r = −0.292) levels. The negative correlation found between serum Hcy levels and attention ability was observed in all 426 studied subjects (r = −0.122). Subjects with MTHFR 677 T/T and 1298 A/A genotypes demonstrated a higher serum Hcy levels (p < 0.05). Carriers of MTHFR (1298 A/C + C/C and 1793 G/A) and SLC19A1 80 G/G genotypes showed lower abstraction and delayed memory ability, respectively (p < 0.05). Subjects with MTHFR 1793 G/A genotype along with low serum folate concentration demonstrated the lowest name and orientation abilities. The effects of MTHFR 1793 G/A genotype on cognitive performance were dependent on the status of serum vitamin B12. Conclusion: Cognition of adults was associated with MTHFR, SLC19A1 gene polymorphism and serum Hcy levels. This study clearly establishes a combined effect of MTHFR gene polymorphism and serum B vitamins levels on cognition in Chinese adults.
Highlights
Alzheimer’s disease (AD) is recognized as the most common entity of dementia in the elderly.Mild cognitive impairment (MCI) is regarded as an early stage of AD, which results in memory loss beyond the expected for age and learning [1,2,3]
Cognitive function was assessed by Montreal Cognitive Assessment (MoCA), which consists of seven cognitive domains including visual-spatial and executive ability, namely, attention, attraction, language, delayed memory and orientation functions
MoCA, Montreal Cognitive Assessment; SLC19A1, RFC. p value < 0.05 was considered as significance. a,b : significantly different for multiple comparisons among different SLC19A1 G80A genotypes, p < 0.05. This present study is the first to explore the relationship between serum folate, vitamin B12, Hcy levels, folate metabolism related enzyme gene polymorphisms and cognitive function in Chinese adults
Summary
Alzheimer’s disease (AD) is recognized as the most common entity of dementia in the elderly. A recent clinical trial has demonstrated that treatment with B-group vitamins significantly halted the progression from MCI to AD [13] This implies that low serum folate and vitamin B12 levels and elevated Hcy levels might be potential risk factors contributing to the development of MCI and AD in the elderly. Given the role of brain DNA methylation in memory and AD [15], confirmation of the epigenetic impacts associated with MTHFR and SLC19A1/RFC1 gene mutations as markers for MCI or AD could open new potential research domains for the prevention and treatment of dementia in the elderly [16]. Limited studies have explored the interactions of serum folate, vitamin B12 and Hcy levels with respect to MTHFR and SLC19A1 gene polymorphism on cognitive function in the elderly. The results of the present study will provide a theoretical basis and foundation for uncovering the potential interactions that exist between nutritional and genetic backgrounds of cognition in adults
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