Emerging role of sulfur-containing amino acids in the etiology of neurological disorders

Neurological disorders are an important cause of disability and death worldwide. In the recent years hyperhomocysteinemia (hHcy) has gained a great deal of interest in the scientific society because of its high prevalence about 5% in the general population. Numerous evidences suggest relationship between high circulating homocysteine (Hcy) level and the development of brain disorders. Hcy may promote its detrimental effect by more than one mechanism. In this review we discuss the role of sulfur containing amino acids and especially hHcy as a risk factor, marker or both in the etiology and pathogenesis of Alzheimer 's disease (AD) and a stroke. We present the contribution of hHcy in AD generation in different animal studies, with emphasis on the main etiopathogenic AD hallmarks, such as amyloid-beta and tau protein. We also focus on the hHcy involvement in the methylation hypothesis of AD pathogenesis. In addition, we describe detrimental effect of hHcy in ischemic animal models.