Researchers are saying dizziness when standing up from a sitting position is an early sign of mental decline, known as orthotstatic hypotension. [Daily Mail UK Oct 2016] Researchers act as if they are clueless over the cause. But there is clear evidence a deficiency of vitamin B12 is the root cause of this problem. [Texas Heart Institute Journal 2012] There is a buildup of an undesirable protein called homocysteine in the brain when B12 levels are low which has been linked with mental decline. [Neuropsychiatric Disease & Treatment 2010]