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In Alzheimer’s disease and olfaction can be impaired. Indeed this is so characteristic that Solomon et al (1998) [1] suggested that the Pocket Smell Test could be used as a diagnostic tool to distinguish between the condition and major depression.

Hyposmia - decreased ability to smellEdit

Doty[2] reviewed 13 studies investigating olfaction in Alzheimer's patients compared to age-matched controls and identified that the majority of studies found significantly decreased function in Alzheimer's patients.

Nordin and Murphy[3] also documented impaired olfaction in patients with possible Alzheimer's.

Morgan et al.[4] reported that odor identification tasks could be useful in diagnosing Alzheimer's and that possible language deficits in this group were not responsible for the difficulties in smell identification.

Anosmia - lack of ability to smellEdit

For some people wih Alzeimers the sense of smell can disappear completely.[5]


A postmortem study by Reyes et al (1993) [6] has demonstrated increased numbers of neurofibrillary tangles and neuritic plaques in the olfactory cortex of Alzheimer's patients versus age-matched control subjects. Doty[7] has suggested that the magnitude of the olfactory deficit parallels the progression and severity of the Alzheimer's process.


  1. Solomon, Gary S.; Petrie, William M. Hart, James ; Brackin, Henry B. Jr. (1998). Olfactory Dysfunction Discriminates Alzheimer's Dementia From Major Depression. The Journal of Neuropsychiatry and Clinical Neurosciences ;10:64-67.
  2. Doty RL: Olfactory dysfunction in neurodegenerative disorders, in Smell and Taste in Health and Disease, edited by Getchell TV. New York, Raven, 1991, pp 735—751
  3. Nordin S, Murphy C: Impaired sensory and cognitive olfactory function in questionable Alzheimer's disease. Neuropsychology 1996; 10:113—119
  4. Morgan CD, Nordin S, Murphy C: Odor identification as an early marker for Alzheimer's disease: impact of lexical functioning and detection sensitivity. J Clin Exp Neuropsychol 1995; 17:793—803
  5. Solomon GS (1994). Anosmia in Alzheimer's disease. Percept Mot Skills ; 79:1249—1250,
  6. Reyes PF, Deems DA, Suarez MG: (1993). Olfactory-related changes in Alzheimer's disease: a quantitative neuropathological study. Brain Research Bulletin  ; 32:1—5
[[category:Olfactory perception]
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