Diagnosis, classification and natural history of degenerative dementias.

The release of the first approved medications for the treatment of Alzheimer's disease in Canada has highlighted the renewed need and importance of diagnostic accuracy and understanding of the spectrum of the dementias. The epidemiological scope of the problem of dementia in Canada including risk factors, caregiving patterns and costs of care have been well-characterized through the Canadian Study of Health and Aging (CSHA 1991-1996) with some of the key findings reviewed here. Beyond Alzheimer's disease the phenotypes and genotypes of the other degenerative dementias have been emerging with proposed operational diagnostic criteria that should facilitate their recognition in clinical practice. This paper reviews the clinical phenotypes of the most common causes of dementia with a proposed classification scheme and with discussion of their relevance from a differential treatment standpoint. This paper served as a background document for the working group of the Consensus Conference on Dementia (C3D) in February 1998 and has been revised subsequently for this publication.