Research evaluation and diagnosis of possible Alzheimer's disease over thelast two decades: II

Objective: To describe the experience of a research clinic diagnosing possi ble AD during the last two decades. Background: The National Institute of N eurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for possible AD are generally used t o indicate that a patient has AD in association with another disease proces s that could by itself cause dementia. There are no studies describing how these criteria should be applied, and there are no descriptions of function al and cognitive progression or survival in possible AD. Methods: The autho rs examined the clinical characteristics of 267 patients diagnosed with pos sible AD at the AD Research Center of Pittsburgh from 1983 to 2000 and the likelihood of arriving at four endpoints: Mini-Mental State Examination sco re of less than or equal to 9, Blessed Dementia Rating Scale for activities of daily living score of greater than or equal to 12, nursing home admissi on, and death. Results: The possible AD classification has been simplified in six categories: possible AD with cerebrovascular disease (CVD) (69%), wi th history of alcohol abuse (15%), with history of depression (7%), with th yroid disease (4%), with history of head trauma (6%), with vitamin B12 defi ciency (6%), and with other disease process that may have affected the clin ical presentation of AD (4%). The presence of CVD, history of alcohol abuse , and history of depression concomitant with the onset of dementia were ass ociated with time to death. Neither thyroid disease, history of head trauma , nor vitamin B12 deficiency were associated with any of the four endpoints . Conclusion: This cohort showed that comorbid conditions that can affect c ognition delineate clearly defined subgroups in AD. The presence of environ mental or other brain disorders sufficient to produce dementia appears to a ffect physical survival in patients with AD, but not functional and cogniti ve decline or institutionalization.