Dementia. A review emphasizing clinicopathologic correlation and brain-behavior relationships.

Numerous pathogenetic mechanisms may lead to the progressive loss of memory and intellectual function known as dementia. Currently, the dementias are classified according to clinicopathologic entities, although for clinical diagnosis, this introduces a degree of uncertainty. Characteristic patterns of behavior and anatomic pathology have been associated with specific clinicopathologic entities. Although somewhat simplistic, classification of the dementias as cortical vs subcortical embodies the precept that brain substrate is intimately tied to behavior. Lessons in brain-behavior relationships are reviewed for four clinicopathologic entities: Alzheimer's disease, Pick's disease, vascular dementia, and Parkinson's disease. Dementing illnesses have contributed significantly to our understanding of brain-behavior relationships. Major progress can be anticipated as diagnostic issues are resolved and biological and state-specific markers emerge.