Dementia of the Alzheimer Type: Challenges of Definition and Clinical Diagnosis

Abstract

Dementia of the Alzheimer type (DAT) has become the focus of increasing interest and study in recent years. This intensified attention reflects the increased prevalence of dementia in a society with a rapidly expanding geriatric population and the fact that DAT is among the most common causes of intellectual deterioration in the aged. As clinicians have devoted more study to DAT and to other etiologies of acquired intellectual decline, many conceptual and definitional problems have emerged and currently remain unresolved. Among the most pressing of these issues are the following: Are the clinical manifestations of DAT sufficiently uniform to allow accurate clinical identification? What clinical features should be present before a diagnosis of DAT is warranted? How accurate are current clinical criteria in predicting a pathological diagnosis of DAT? What correlations exist between the pathological alterations of DAT and the clinical manifestations? Is DAT a single disease or should it be regarded as a clinical syndrome with a few or many etiologies? Answers to these questions are crucial to an understanding of DAT and dementia. Accurate prevalence figures cannot be obtained until criteria for the clinical diagnosis of DAT are agreed upon. The prognosis of individual patients with dementia cannot be determined unless the etiology of their dementia can be correctly established. Research regarding the treatment, progression, laboratory correlates, and neuropsychological manifestations of DAT are meaningless if homogenous groups of DAT patients cannot be identified in life. Conclusions based on clinically diagnosed DAT patients must be regarded skeptically if the correlation between clinical and pathological diagnosis is poor.