Benefits and risks of folic acid to the nervous system

During three decades of neurological practice I have witnessed a remarkable change in attitudes to the benefits and risks of folic acid therapy in nervous system disorders. In the 1960s all that was known and taught was that folic acid was harmful to the nervous system, especially in precipitating or exacerbating the neurological complications of vitamin B12 deficiency. So deeply held was this view that the possibility of neuropsychological benefits from this vitamin was initially viewed with considerable scepticism.