Sudeep S. Gill, MD, FRCP(C), Research Fellow, Division of Geriatric Medicine, University of Toronto and Kunin-Lunenfeld Applied Research Unit, Baycrest Centre for Geriatric Care, Toronto, ON.
Shabbir M.H. Alibhai, MD, MSc, FRCP(C), Staff Physician, Department of Medicine, University Health Network, Toronto, ON.

Folate deficiency is relatively common in older adults. There is now growing interest in the roles played by folate and B vitamins in the metabolism of homocysteine. Recent studies have suggested a link between elevated levels of homocysteine and the risk of Alzheimer disease. In this article, we will focus on the physiology and pathophysiology related to folate and homocysteine metabolism. We have also included a discussion of the laboratory evaluation of these compounds. Finally, we review the evidence supporting the relationships between folate deficiency, hyperhomocysteinemia and the development of dementia.
Key words: folic acid, vitamin B12, deficiency diseases, homocysteine, dementia.

12 Deficiency in the Elderly

Sudeep S. Gill, MD, FRCP(C), Research Fellow, Division of Geriatric Medicine, University of Toronto and Kunin-Lunenfeld Applied Research Unit, Baycrest Centre for Geriatric Care, Toronto, ON.
Shabbir M.H. Alibhai, MD, MSc, FRCP(C), Staff Physician, Department of Medicine, University Health Network, Toronto, ON.

Vitamin B12 deficiency is a common disorder in older adults, but its diagnostic work-up and management can be complex. In this article, we review the metabolic pathways involving vitamin B12 and the various pathologies that can interfere with these pathways. This discussion provides a framework to understand the following section, which outlines an approach to the clinical examination, laboratory evaluation and treatment of subjects with suspected vitamin B12 deficiency.
Key words: vitamin B12, folic acid, deficiency diseases, dementia, aging.