Can a vitamin b12 deficiency bring around ocd?

Amazingly, yes: Hermesh et al published in 1988 about 20% of an ocd group having unusually low levels of b12. http://www.ncbi.nlm.nih.gov/pubmed/3176999 there was another report by sharma & biswas, 2012 - a cae of a middle-aged man with ocd, low serum b12, and a + family hx of B12 deficiency who responded to B12 replacement. I would definitely get that level, as well as a methylmalonic acid level, checked.