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Can Poor Sense of Smell Be a Precursor to Parkinson's?

An impaired sense of smell may end up being an important telltale sign of Parkinson's disease. There is a lot of evidence still being studied that point to the fact that a diminished sense of smell (called hyposmia) or total loss of smell (called anosmia) may show up in the earliest stages of the disease, several years before motor coordination is affected. This is big news in the medical community as new tests can be created related to sense of smell that can then predict the disease. Early intervention can help greatly in controlling symptoms of the disease.

Doctors have concurred that one of the earliest symptoms of Parkinson's is indeed loss of smell or the inability to recognize particular odors. In test studies, participants were graded on their sense of smell with a variety of items with each item garnering them a point. Flash forward a few years and a percentage of these participants developed Parkinson's' disease. Virtually of these people had scored lower on the smell test than others did.

Understanding how it works

Both the diminished capacity to smell and loss of smell are the result of the same chemical processes in the brain that leads to impaired motor function. A decrease of dopamine producing cells is the major culprit. Dopamine is the chemical that the nerve cells produce which carries communication to the rest of the brain, specifically the area that control movement.

What is interesting is that doctors have figured out a way to measure the nerve cells that product dopamine by evaluating the actions of a particular protein found in the cells that carry the dopamine chemical. These proteins are called dopamine transporters or DAT. The levels of DAT in the test subjects who eventually developed Parkinson's and had diminished smell capacity were lower than the others, several years before the diagnosis and motor impairment started to occur.

During these test studies for the smell-Parkinson's tie-in, other factors were considered and dismissed such as age of the subject as well as their lifestyle choices such as smoking, which can and often does affect sense of smell. It is important to note also that most lab studies have focused solely on men, not women. So until more definitive testing occurs with women as the focus, not much is known about how their sense of smell will relate to diagnosing Parkinson's early.

Passing the smell test is literally becoming a new favorite way to diagnose Parkinson's disease but there is still a long way to go regarding the efficacy of the situation. However, it can serve as a wake-up call to people who may have Parkinson's in the family or perhaps feel that something is "not quite right" with them physically. If sense of smell and taste is altered in any way, it might a signal to get some testing done to see if an early diagnosis of Parkinson's disease is necessary. Other conditions do affect sense of smell, so obviously doctors will look for other warning signs and as-yet undiagnosed symptoms.