Can Smell tests help in early identification of Alzheimer’s disease? Current Opinion. March.2015


Alzheimers disease (AD)  has an insidious symptom onset.Though biomarker research has advanced, they are not yet readily available  for clinical use. Are there any simple clinical test that can reveal the onset of AD?

Latha Velayudhan reviews this question in current opinion.

Almost all studies in this area have shown that AD patients always have smell defects. Defects in smell identification ( example :  University of Pennsylvania smell identification test (UPSIT)) is shown to correlate with MMSE scores. Smell identification tests have been able to differentiate AD from controls.

A three item olfactory identification test could differentiate between AD and depression.

It is also shown that such changes in olfaction can help in predicting conversion from  MCI (Mild cognitive impairment )  to AD when combined with other measures like functioning report,  verbal memory, and hippocampal- entorhinal cortex volumes. 

Olfactory function is overlooked by clinicians and by patients. Patients are largely unaware of their deficits. Low olfaction score patients, especially those unaware of smelling problems, are most prone to developing Alzheimer’s disease.Olfactory identification and recognition are the most interesting candidates to be included in a battery to detect subclinical cases in Alzheimer’s disease.

These tests are inexpensive, simple and can be applied bedside. Day to day utility in clinical practice  is yet to be established.

Summary of the article:

Smell identification function and Alzheimer’s disease: a selective review.

Velayudhan L. Curr Opin Psychiatry. 2015 Mar;28(2):173-9


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