Clinical Aspects of Alzheimer Disease

The clinical diagnosis of Alzheimer disease (AD) has been well established, but there is a widespread misunderstanding about the relationship between dementia (a syndrome) and AD (a cause of dementia). AD is the most common etiology that causes dementia in mid- and late life. The prototypical clinical presentation is that of a gradually worsening problem with learning new information, that is, a short-term memory deficit, accompanied by cognitive impairment in other domains, including language, spatial cognition, and executive functioning, as well as changes in personality and behavior. A key element of the diagnosis of dementia is that daily functioning is impaired. The concept of mild cognitive impairment (MCI) as the earliest symptomatic presentation of a dementing illness is now widely accepted. MCI due to AD typically presents with isolated problems with learning and memory without substantial loss of ability to function in daily life. Less common variants of AD are now recognized and include a disorder in which spatial and visual cognitive dysfunction occurs or in which word-finding problems predominate at the onset of symptoms. Although AD as a cause of dementia is the most common among etiologies, AD often co-occurs with other neurodegenerative diseases and with cerebrovascular disease. The presence of multietiology dementia in which AD is a contributor is particularly common in the eighth decade of life and beyond. Key words: Alzheimer disease, cognitive impairment, dementia, mild cognitive impairment