I worry about how many people are diagnosed with dementia when, in fact, they could be deficient in Vit B12. Several prescribed medications can cause absorption problems, including Metformin! Doctors don't seem to be very knowledgeable about B12 Deficiency, don't test for it (although testing isn't very reliable anyway), don't listen to symptoms, don't follow NICE guidelines and maybe try to treat some of the symptoms, rather than look for the root cause.
In fact, my GP did request B12 blood test for me but, when the results came back, below the normal range, just said that was fine. I did a lot of research, decided I probably was deficient, GP was adamant I wasn't so wouldn't treat me for it so I eventually went about self-injecting. After a few months, I was feeling better than I had felt for a long time. A year on, ie now, I feel a different person. My GP has seen the difference and he knows I'm self injecting so he has to realise that I was deficient after all. Still, it's not expensive to self inject and 'I'm' in control of this!!!