Dementia and Systemic Disorders

This chapter provides an overview of the relationship between systemic disorders and cognitive dysfunction. While systemic disorders can be associated with cognitive impairment and dementia, they can also lead to encephalopathy or delirium. The chapter focuses primarily on systemic illnesses that can cause a dementia or a dementia-like illness, rather than delirium. It reviews the interaction of systemic diseases and degenerative dementias and outlines the approach for the patient with a cognitive complaint. Systemic disorders discussed here include endocrine disorders, electrolyte disorders, autoimmune disorders, organ dysfunction and failure, and cancer and paraneoplastic disorders. Finally, the chapter presents a discussion on the infectious diseases that can cause cognitive impairment, and on the complications due to transplantation and critical medical illness.