Detecting any illness early can make a huge difference in how it ultimately affects you, whether that means improving symptoms or potentially even saving your life. And that’s the case with Parkinson’s disease, which affects nearly one million people in the U.S., according to the Parkinson’s Foundation. In the past two decades, death rates for Parkinson’s among adults 65 and older has increased 57 percent, according to the Centers for Disease Control and Prevention (CDC). But the good news is, there are some ways to detect the disease much earlier and better your chances of controlling it. In fact, research has shown there’s one sign of Parkinson’s disease that affects 96 percent of patients and it can appear a decade before any of the more well-known symptoms occur. To see the common early sign of Parkinson’s that you should watch out for, read on.RELATED: 40 Subtle Signs Your Body Is Telling You Something’s Seriously Wrong. Loss of smell is one of the most common and earliest signs of Parkinson’s disease. According to a 2011 study published in the journal Parkinson’s Disease, more than 96 percent of Parkinson’s patients have significant olfactory dysfunction. But it often goes unnoticed because it’s not accompanied by other more typical symptoms. “It can come on many years, up to decades before the other symptoms start,” certified neurologist Huma U. Sheikh, MD, told Best Life.According to The Michael J. Fox Foundation for Parkinson’s Research, most people don’t notice a diminished or lost sense of smell at first, but later, when they develop more well-known symptoms of Parkinson’s, they recall “years or even decades earlier their ability to smell decreased.”Noticing and reporting a loss of smell earlier on can benefit you and help your health provider address your condition. Sheikh notes that your smell may not completely disappear but just decrease, so any diminished ability to smell is worth bringing up to your doctor. Some experts believe Parkinson’s begins in the nose. Experts have long suggested that loss of smell is an early sign of Parkinson’s because that’s where the disease begins. An Aug. 2020 study published in the journal Brain Pathology gathered evidence that seems to support this. “Olfactory dysfunction may not just be a sign of broader neural damage, but rather may have a more direct linkage to the generation of the disorder itself,” the study authors from Florida Atlantic University said in a statement.The olfactory system is exposed to various toxins in the environment from bacteria, viruses, mold, dust, pollen, and chemicals. These toxins can result in an inflammatory response in the nose and from there, the inflammation can spread and activate inflammatory cells deep in the brain. And that inflammation can contribute to the development and progression of Parkinson’s and other degenerative diseases. The Michael J. Fox Foundation suggests that clumps of the protein alpha-synuclein, a trademark of Parkinson’s, likely first form in the olfactory system before migrating to the brain.RELATED: If You Can’t Smell This, It Could Be an Early Sign of Dementia, Study Says. Additional subtle signs of Parkinson’s affect other areas of your face. While a loss of smell is likely to occur much earlier than other symptoms of Parkinson’s, it’s worth keeping an eye out for other common symptoms of the disease, like tremors, a fixed facial expression, small handwriting, and not blinking as often, according to Sheikh. She adds that a loss of taste can occur but is less common.According to the Parkinson’s Foundation, other more obvious signs include trouble walking, constipation, low voice, dizziness, fainting, and hunching over. If you notice any of these symptoms, bring them up to your doctor. RELATED: For more up-to-date information, sign up for our daily newsletter. A loss of smell doesn’t necessarily mean you have Parkinson’s. While most people with Parkinson’s have a loss of smell, that doesn’t mean most people with diminished smell have Parkinson’s. As we know now with COVID-19, a loss of smell can be the result of many illnesses, so it’s worth talking to your doctor before jumping to conclusions.The Mayo Clinic lists dozens of reasons your sense of smell could be obstructed, including smoking, a deviated septum, nasal polyps, aging, diabetes, poor nutrition, various medications, and multiple sclerosis.RELATED: If You Lose This Feeling, It May Be an Early Sign of Dementia, Study Says.