Here are extracts from an important link, (unfortunately, the site does not allow me to post links yet) which could be a vital tool in the differentiation between dementia and vitamin B12 deficiency - reading it made me wonder why our family had to fight so hard for our relative to obtain B12 tests and treatment after wrongly diagnosed dementia & ME when this information was out there all along ?! According to the research, B12 deficiency should have been considered earlier, especially with a history of vegetarianism and ME, yet our letters and pleas to the surgery with guidelines and information on B12 def. were ignored and obstructed time after time. This caused delay, worsening symptoms, and risk of permanent damage. Extracts: "Evaluating cognitive dysfunction requires involvement of family or other independent observers (not just the patient). " "We attempt to define and quantify the cognitive impairment, identify any potentially reversible conditions and address comorbidities, such as vascular risk factors in hopes of preventing progression.". "Lab testing B12 levels - Methylmalonic acid/homocysteine levels (confirm vitamin B12 deficiency). Potentially reversible syndromes: - Depression - Medication induced - Metabolic derangements - Vitamin B12 deficiency - Thyroid disorders - Thiamine deficiency - Chronic disease (e.g., renal failure, hepatic failure, malignancy)" "Laboratory testing should be considered to identify potentially reversible conditions that may mimic dementia. Early identification and aggressive management of such disorders may improve a patient’s thinking and daily function. Which laboratory studies to order is controversial. Some clinicians suggest a detailed laboratory evaluation to include complete blood counts (CBC), chemistry panels, erythrocyte sedimentation rate, thyroid function tests (thyroid-stimulating hormone [TSH] and free thyroxine [FT4]), vitamin B12 level, thiamine level and syphilis screening. As tertiary-level neurologists, we tend to agree with this approach for many of our referrals. Others would dispute this assertion from a cost–benefit standpoint, arguing that such evaluations are expensive and usually low yield." Metabolic derangements Vitamin B12 deficiency The classic dementia work-up includes a vitamin B12 assay. Serum folate should also be measured. An estimated 10–15% of individuals over 60 years of age may be deficient . Hematologic abnormalities may not occur with vitamin B12 deficiency, even with nervous system involvement . In deficient states, vitamin B12 supplementation should improve mentation and prevent the disability associated with progressive myelopathy and peripheral neuropathy. Like depression, vitamin B12 deficiency is more common in AD, although it is unclear why . Physicians need to monitor mental status in patients with vitamin B12 deficiency whose clinical profile is otherwise consistent with AD. If cognitive abnormalities progress even after vitamin B12 levels normalize, a diagnosis of both conditions can be made." I hope this information helps others understand, research and ask for the correct tests before a wrong diagnosis is made.