Research Progress Of The Relationship Between Blood Homocysteine And Dementia

Objective This paper reviews the damage of homocysteine(Hcy)to brain tissue,the relationship between Hcy and dementia,the pathogenesis of dementia,and the effect of reducing Hcy on cognitive function,in order to improve people's understanding of Hcy-related dementia and attach importance to hyperhomocysteinemia.Method The related literatures were consulted and reviewed.Results Hcy is a non-essential alpha-amino acid containing thiol group,which is produced by demethylation of methionine in food and does not participate in the synthesis of proteins.The main causes of elevated Hcy are genetic and dietary,such as gene mutation or enzyme deficiency of5,10-methylenetetrahydrofolate reductase,methionine synthase and cystathionine beta synthase,and deficiency of folic acid,vitamin B12,vitamin B6 in diet or excessive intake of animal protein.Increased Hcy can cause several effects,such as increased White Matter Damage in the Brain,increased density of neurofibrillary tangles in the brain,and increased rate of atrophy in the brain,Which promote the occurrence of cognitive impairment in the elderly,increase the incidence of dementia and AD in a population,promote conversion from mid cognitive impairment todementia,and accelerate the decline of cognitive function in AD patients.The mechanism of dementia caused by elevated Hcy is still unclear,which may be related to the injury of cerebrovascular,the subsequent increase of neurotoxicity and oxidative stress,the enhancement of neurotoxicity of beta-amyloid protein,the promotion of tau protein phosphorylation and the inhibition of methylation reaction.There are many clinical studies about using B vitamins(vitamin B6,folic acid,and vitamin B12)to reduce Hcy which in order to improve cognitive function.However,most studies have shown that reducing Hcy does not improve cognitive function or delay the progress of disease.Only a few studies believe that using B vitamins to reduce Hcy can delay or improve cognitive function.Conclusion Hyperhomocysteine is closely related to cognitive decline,dementia and AD,but the mechanism remains to be elucidated.Some clinical studies strongly support that lowering tHcy in B vitamin therapy may be beneficial to delaying cognitive decline,but most studies show that lowering Hcy does not improve cognitive function or delay the progress of disease.Therefore,a large number of more comprehensive and well-designed epidemiological studies,clinical intervention trials and animal trials are needed to further explore the effects of lowering tHcy on cognitive function and dementia.