Abstract
The clinical problems associated with vitamin B_1(B_1), vitamin B_<12> (B_<12>) and folic acid deficiencies have been reported. Recently, B_1 deficiency has been observed in aged people with diabetes mellitus or in patients with gastrectomy. Other vitamins as well as B_1 should be supplied for treatment of these patients. Wernicke's encephalopathy is an acute neuropsychiatric syndrome resulting from B_1 deficiency. Even if patients are diagnosed as hiving Wernicke's encephalopathy, insufficient treatment of the disorder is followed by mental sequelae such as Korsakoff syndrome. The guideline of treatment of Wernicke's encephalopathy has to be established in Japan. B_<12> deficiency induces peripheral neuropathy, subacute combined degeneration of spinal cord or encephalopathy. B_<12> is one of the drugs for treatment of amyotrophic lateral sclerosis (ALS), which is a neurodegenerative disease, and treatment of ALS with ultrahigh dose B_<12> has been tried. Serum homocysteine (Hcy) is increased in the deficient state of B_<12>, B_6 or folic acid. The detailed mechanism for the effect of Hcy on cognitive function is unknown. However, it has been reported that Hcy induces apoptosis of neuronal cells directly or activates the N-methyl-D-aspartate (NMDA) receptors. Many clinical studies on the therapeutic effects of B_<12>, B_6, and folic acid on disorders with cognitive dysfunction as well as Alzheimer's disease have been reported.
