I know everyone keeps playing the guessing game but I still can't figure out if I am suffering from B12 deficiency or hypothyroidism. I am having memory issues along with cognitive decline and am still quiet far from a diagnosis. I tested for AMA antibodies (Anti-TPO) and they came out at 122 IU/ml (negative for < 34) . My TSH is at 6.7 and B12 was at 180 hence I have been supplementing with methylcobalamin for the past 8 months with my current b12 level at 1000+. My question to the experts here is whether a 6.7 level TSH cause brain fog/cognitive issues without any other visible symptoms for hypothyroidism? Also how does one arrive at the diagnosis of B12 vs thyroidism?