Olfactory dysfunction in dementia

Table 1 Table of main findings (comparing findings in different dementias)

Type of dementia	Profile/main findings	Differences between dementias (extent/degree/severity of impairment)
Alzheimer	Odor identification deficit, is a widely acknowledged feature of Alzheimer’s	Mixed findings: AD > VD[6,23]; AD = VD[25] AD = PD[26]; mild DLB > MCI/AD[27] FTD < AD[54] FTD = AD[55] Legend: > more impaired; < less impaired; = similar
VD	Olfactory performance below normative scores; Unclear differential profile with other dementias
PD	Decreased odor identification, which may precede the development of clinical PD
FTD	FTD patients demonstrate preserved odor discrimination abilities, Impairments in odor naming and odor-picture

AD: Alzheimer’s disease; VD: Vascular dementia; PD: Parkinson’s disease; FTD: Frontotemporal dementia; DLB: Dementia with Lewy bodies; MCI: Mild cognitive impairment.