| خلاصه مقاله | Background
Throughout the life of humans, microbes are colonized within different organs of the body and most colonization occurs in the gastrointestinal. The term microbiota is also a determinant factor in the association between illness and health. Gut dysbiosis is increasing the number of pathogenic species, and decreasing microbial diversity in the intestine. gut dysbiosis can be associated with Alzheimer’s Disease (AD), which is a progressive neurodegenerative disease with cognitive impairment. The main cause of AD is unknown and it is estimated that by 2050 the number of patients will increase up to 3 times. The Gut-brain axis is to link the emotional and cognitive center of the brain with intestinal activities. In this review, we provide an overview of gut microbiota and how their dysregulation in the pathogenesis of AD.
Materials and Methods
“PubMed”, “Google Scholar” and “MedLine” were searched using the MeSH terms “Alzheimer Disease”, “cognitive disorders”, “microbiota”, “gut dysbiosis”, “amyloid-β”, “hypothalamic pituitary adrenal”, “short-chain fatty acid” and “gut-brain axis.
Results
It is estimated that by 2050 the number of AD patients will increase up to 3 times, and on the other hand, by knowing the risk factors and preventing them, the number of patients can be reduced by 8.3% by 2050. In Iran, due to the decrease in birth rate and increase in life expectancy, the number of elderly people in society is increasing. It is estimated that the number of older people over 65 years will increase from 5.7% in 2011 to 25.2% in 2060, and the probability of developing dementia will increase by 6% for each year of age. According studies, the average survival after diagnosis has been reported to be 4-8 years, depending on various causes such as age, gender, physical activity, motor system involvement, comorbidities, and neuropsychiatric symptoms during AD diagnosis. Accordingly, changes in the ratio of firmicutes and Bacteroidetes affect the pathogenic or non-pathogenicity of gut composition. Many factors such as dietary, environmental exposures, sanitation, general and mental stress, chronic inflammatory gut, host genetics, and life-long drug use (most importantly antibiotics) effectively change this ratio. Alterations in the composition of gut microbiota are associated with multiple neurodegenerative disorders. Although a causal relationship between gut dysbiosis and neural dysfunction remains elusive, emerging evidence indicates that gut dysbiosis may promote amyloid-beta aggregation, neuroinflammation, and oxidative stress in the pathogenesis of AD
Conclusion
Illustration of the mechanisms underlying the modification of gut microbiota composition may pave the way for developing novel preventive and therapeutic approach for AD. |