Loss of Smell – A Hallmark of Parkinson’s Disease and Lewy Body Dementia

How is Parkinson’s disease related to Lewy body dementia (LBD)? To answer that, you must know the answer to the question, “What is Lewy body dementia?” LBD is a form of dementia caused by a buildup in the brain of abnormal protein structures called Lewy bodies. Parkinson’s disease dementia (PDD) is one form of Lewy body dementia because Parkinson’s disease is also associated with Lewy bodies in the brain. 

Loss of the sense of smell, called hyposmia, can be caused by any number of medical conditions. It can precede other symptoms Lewy body dementia. But because it is also a symptom of Parkinson’s disease (PD) and Alzheimer’s disease (AD), by itself it is not a warning sign of LBD. And of course, not everyone who loses the sense of smell will develop PD or AD. However, most people who have Parkinson’s disease have at least partially lost their sense of smell. Many people come to the realization that they began to lose their sense of smell many years before receiving a diagnosis of PD.

It is not especially common for doctors to ask patients about their sense of smell, nor for patients to volunteer this information. Therefore, hyposmia often goes undetected and thus is under-recognized as a symptom of Parkinson’s disease and LBD. If you are having changes in thinking or movement, and notice that you have trouble smelling foods like bananas, pickles, or licorice, or if you notice this symptom in a person, you know who also has changes in thinking or movement, it is wise to ask a healthcare provider about LBD and Parkinson’s.  Download the LBD Diagnostic Symptoms Checklist

There is not really anything anyone can do about a lost sense of smell. Unfortunately, because smell is linked to taste, losing the sense of smell might cause a loss of appetite as well. This can lead to problems maintaining weight. This is another concern that should be raised with a healthcare provider. If you have recently lost or gained weight unexpectedly, talk to your doctor about diet and nutrition.

Ideally, physicians would inquire about a loss of sense of smell and explore the possibility of Parkinson’s disease by performing or ordering additional tests. The symptom could be a valuable tool for earlier diagnosis, which can lead to therapeutic intervention. Better treatment is possible if PD is diagnosed early on, because of smell loss or another lesser symptom instead of the typical tremor and slowness of movement.

The Lewy Body Dementia Association is a nonprofit organization dedicated to raising awareness of LBD, with a focus on serving all individuals affected by this disease. We work to support people with LBD, along with their families and care partners, through outreach, education, and research. To learn more, contact us through our website, sign up for our email newsletter, or connect with us on Facebook or Twitter.