RESUMEN
Alzheimer's disease (AD) is one of the most complicated neurodegenerative diseases causing dementia in human beings. Aside from that incidence of AD is increasing also its treatment is very complicated. There are several known hypotheses regarding the pathology of Alzheimer's disease, including the Amyloid beta hypothesis, Tau hypothesis, inflammation hypothesis, and cholinergic hypothesis, which are investigated in different researches to completely elucidate the pathology of AD. Aside from these some new mechanisms such as immune, endocrine, and vagus pathways, as well as bacteria metabolite secretions are being explained as other causes that are somehow related to AD pathogenesis. There is still no definite treatment for Alzheimer's disease that can completely cure and eradicate AD. Garlic (Allium sativum) is a traditional herb used as a spice in different cultures and due to the organosulfur compounds like allicin it possesses highly anti-oxidant properties and the benefits of garlic in cardiovascular diseases like hypertension and atherosclerosis is examined and reviewed, although its beneficiary effects in neurodegenerative diseases such as AD is not completely understood. In this review, we discuss the effects of garlic based on its components such as allicin, S-allyl cysteine on Alzheimer's disease and the mechanisms that garlic components can be beneficiary for AD patients, including its effects amyloid beta, oxidative stress, tau protein, gene expression, and cholinesterase enzymes. Based on the literature review we have done, garlic has revealed beneficiary effects on Alzheimer's disease, especially in animal studies; however, more studies should be done on human populations to find the exact mechanism of garlic effects on AD patients.