Smell Loss

Smell and Parkinson’s Disease: What you should know and what you can do

Early detection is a crucial step to understanding the causes of and developing better treatments for Parkinson’s disease (PD). Even before the typical tremor and slowness of movements occur in PD, it may be possible to detect early changes in the brain and symptoms that are associated with PD. Loss of sense of smell is a common but little noticed symptom that may occur years before the onset of motor symptoms or a PD diagnosis.

What You Can Do

While most people with a reduced sense of smell will not develop Parkinson’s disease, loss or reduction of the ability to smell is common in people with PD. Get involved by taking the smell survey.


Be one of 10,000 people to follow your nose to PD research!  Learn More

With this simple decision to take the survey or share it, you commit to help us speed scientific progress toward cures for diseases that touch countless lives.

— Michael J. Fox

An often overlooked symptom of Parkinson’s disease

While most people with a reduced sense of smell will not develop Parkinson’s, the majority of Parkinson’s disease patients do have reduced sense of smell. Loss of sense of smell is often overlooked by diagnosing physicians as an early sign of PD. There are of course many other reasons a person may be experiencing a loss in sense of smell.

If you believe that you may have trouble with smell, consult your doctor.

Why am I losing my sense of smell?

Little is confirmed about what causes the early, pre-motor symptoms of Parkinson’s, such as hyposmia, this loss of smell. But one prevalent theory in Parkinson’s research about disease progression has to do with the protein alpha-synuclein, whose clumping is found in all people with the disease.

This theory, based on the research of Heiko Braak, MD suggests that the disease may start not in the substantia nigra (the region of the brain where loss of nerve cells leads to the dopamine deficit experienced by people with PD) but in the gastrointestinal system and the olfactory bulb, the part of the brain that controls sense of smell. Researchers have hypothesized that the alpha-synuclein clumps found in all people with Parkinson’s may form in these parts of the body first, before migrating to other parts of the brain. Should this turn out to be true, and if researchers can find the clumps and break them up before they reach the brain, it may become possible to treat Parkinson’s before major neurological damage occurs.

According to a recent survey conducted by The Michael J. Fox Foundation, only half of U.S. adults are aware that reduced sense of smell can be a precursor to brain disease.

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