Using smell test for dementia diagnosis

It has been suggested that smell tests could be used for early detection of dementia. The following is a summary of some advantages and disadvantages of using smell test for dementia diagnosis:


Smell test has the potential to be considered as a medicationindependent biomarker for the progression of neurodegenerative diseases. This diagnostic test is an inexpensive, simple, non-invasive, and readily available for use tool that, in combination with neuropsychological tools and neuroimaging, can help with early detection of dementia. This detection allows for treatments that may be effective in preventing the progression of the disease (Dhilla Albers et al., 2016).

The smell test can aid physicians in predicting whether patients have been benefited from the prescribed treatments for their neurodegenerative disease. Researchers at CUMC and NYSPI have found a way to use smell test results to determine if patients with mild cognitive impairment may respond to cholinesterase inhibitor drugs to treat Alzheimer’s disease (Columbia University Medical Center, 2017).

Also, since several diseases often misdiagnosed as AD or PD, such as severe depression or progressive supranuclear palsy, are accompanied by little or no smell loss, performing the smell test can improve the diagnostic procedure.This test could also make it easier and less expensive for clinical trials to develop new dementia drugs by determining who should get a PET scan to look for beta-amyloid plaques (Columbia University Medical Center, 2018).

The smell test is fast; It normally takes 5 to 8 minutes to administer; it can be purchased online and done at home, but currently, its mainly used in research. Taking the test may not be helpful unless you have a doctor to provide you with an interpretation of the results. (Columbia University Medical Center, 2018) Figure 3: The University of Pennsylvania Smell Identification Test (known commercially as the Smell Identification Test) (Doty, Shaman, & Dann, 1984)


Its important to note that there is an association between the loss of smell and dementia, but there is not enough evidence to conclude that olfactory dysfunction can, by itself, predict if the disease is present.Poor sense of smell does not necessarily mean individuals get dementia. Olfactory dysfunction can be caused by many conditions other than dementia, including normal aging, medications, viral illnesses, head injuries, a decreased level of hydration, the thinning of the mucous lining in the nasal passages, and possible exposure to toxic agents or due to nasal conditions.

In fact, many individuals with dementia retain their sense of

smell, so smell test results shouldnt be the only information to rely on for diagnostic purposes of dementia (Dhilla Albers et al., 2016).The smell test can help predict the risk of dementia but it can’t tell which neurodegenerative disease is causing it  (Columbia University Medical Center, 2018). Therefore, clinicians need to consider other factors such as genetic risk factors and family history while examining for causes of olfactory dysfunction.

Since the smell test is inexpensive and accessible, they may want to use it only to help determine if a more expensive, invasive workup is needed  (Columbia University Medical Center, 2018).Another disadvantage of smell tests is that they arent designed based on the fact that variation in an olfactory receptor gene changes odor perception. It is known that the olfactory ability to recognize and discriminate between odors among healthy individuals can vary by as much as 40 times.

In the end, the assessment of olfactory performance might not only be influenced by the performed assessment tasks, but it might also be influenced by brain functions such as memory. For example, age-related difficulties in the activation of odor knowledge (i.e., odor names) might influence the olfaction assessment process (Larsson, Oberg, & Bäckman, 2006).

To conclude, the smell test, in combination with neuropsychological tools and neuroimaging, is most helpful when individuals have concerns about their memory decline and they want to be evaluated. Some context is needed to properly evaluate patients, so someone without a memory complaint or a family history of dementia wouldnt necessarily benefit from the test.