An Overview of Primary Dementias as Clinicopathological Entities

Arash Salardini, MD


Semin Neurol. 2019;39(2):153-166. 

In This Article


  • Dementia is a syndrome of functional and cognitive decline regardless of pathophysiology. For example, an individual may be said to have dementia due to late-stage multiple sclerosis.[5]

  • The term dementia can also be used to refer to a specific category of neurological disease in which cognitive decline is the main feature of organic brain disease. AD is an example of such a disease. The term "primary dementia" is a more precise term for the category of disease which presents cognitively.

  • Mild cognitive impairment (MCI) is a state of cognitive decline where independent functioning is relatively preserved. MCI is synonymous with prodromal dementia.[6]

  • Rapidly progressive dementias (RPDs) are defined as dementias which progress from normal cognition to severe dementia in less than 2 years. The definition of RPDs is unofficial.[7]

  • A biomarker, for our purposes, is a biological measurement which helps distinguish between several conditions which may have similar presentations.[8]

  • Cognitive domains: Similar cognitive abilities are grouped together into "cognitive domains." This is useful clinically because members of a cognitive domain share anatomical substrates and have similar pathological vulnerabilities. Cognitive domains include memory, perceptual motor, social cognition, complex attention, executive function and language domains. Some definitions of dementia require the involvement of more than one cognitive domain.[9]