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olfaction & Alzheimer's disease

Epidemiology: - men with Alzheimer's disease (AD) more likely to have olfactory dysfunction than women [1] Pathology: - worse visuospatial functioning associated with olfactory dysfunction [1] - the primary olfactory cortex is the only primary cortex affected early during the course of Alzheimer's disease. - olfactory bulb & olfactory tract effected as early as entorhinal cortex [3] - olfactory bulb & olfactory nerve involvement begins in Braak stage 2 Special laboratory: - UPSIT odor test may predict development of AD inpatients with mild cognitive impairment (MCI) & correlate with measures of amyloid plaques* & neurofibrillary tangles (see UPSIT) * seems inconsistent with Braak staging Radiology: - olfactory bulb volume may serve as a preclinical marker for adults at risk for developing Alzheimer's disease later in life [5] Notes: - also see anatomic predilection of Alzheimer's pathology

Related

Alzheimer's disease (AD) olfaction (smell) Pennsylvania smell identification scale (UPSIT)

References

  1. Westerfelt HJ et al, Presentation of Alzheimer's disease in patients with and without olfactory deficits. Arch Clin Neuropsychol 2007, 22:117 PMID: 17156971
  2. Albers MW et al Olfactory dysfunction as a predictor of neurodegenerative disease. Curr Neurol Neurosci Rep 2006, 6:379 PMID: 16928347
  3. Christen-Zaech S, Kraftsik R, Pillevuit O, Kiraly M, Martins R, Khalili K, Miklossy J. Early olfactory involvement in Alzheimer's disease. Can J Neurol Sci. 2003 Feb;30(1):20-5. PMID: 12619779
  4. Attems J, Jellinger KA, Olfactory tau pathology in Alzheimer disease and mild cognitive impairment. Clin Neuropathol. 2006, 25:265 PMID: 17140156
  5. Lu R, Aziz NA, Reuter M et al Evaluation of the Neuroanatomical Basis of Olfactory Dysfunction in the General Population. JAMA Otolaryngol Head Neck Surg. Published online August 26, 2021 PMID: 34436517 https://jamanetwork.com/journals/jamaotolaryngology/article-abstract/2783603