Alzheimer’s Disease

Abstract

Alzheimer’s disease (AD), a progressive degenerative dementia, causes suffering for millions of patients as well as their caregivers. Among the elderly, the prevalence of AD increases dramatically with age: it is about 5% to 7% in people 65 years of age and older and rises to 40% to 50% in those older than 90 years of age (Rabins, Lyketsos, and Steele, 1999). AD typically affects short-term memory first; over time, impairment in language, praxis, recognition, and executive function occur. In the late stages, patients become completely dependent on others. In addition to this cognitive and physical burden, psychiatric signs and symptoms are nearly universal. These psychiatric phenomena, which include depression, delusions, hallucinations, apathy, and aggression, affect as many as 90% of patients with dementia over the course of their illness (Steinberg et al., 2003). Psychiatric phenomena often present differently in patients with AD than in the population without dementia. Uncertainty remains regarding how to best classify many of these phenomena. For example, delusions can be described as occurring in isolation, or as part of a psychotic syndrome, with associated features such as irritability and agitation. Delusions can also occur as part of a depressive syndrome or delirium. Little research is currently available to guide treatment. Nevertheless, many syndromes can be accurately diagnosed and can respond to a variety of pharmacologic and nonpharmacologic treatments. Depressive phenomena are common in AD. Estimates for the prevalence of major depression in patients with AD are 20% to 25%, (Lyketsos et al., 2003). Due to their dementia, patients with AD are often poor historians. They may not be aware of Depressive phenomena or able to recall them, and their aphasia may make describing symptoms difficult. Therefore, information from a reliable caregiver is crucial for making a proper diagnosis. Depressive disorders in AD are often somewhat different from those occurring in the absence of dementia. In particular, patients with AD may not endorse hopelessness, suicidal thoughts, or worthlessness (Zubenko et al., 2003). Patients with AD, however, express symptoms such as anxiety, anhedonia, irritability, lack of motivation, and agitation (Rosenberg et al., 2005).