You'd be forgiven for thinking that Parkinson's is only an older person's disease.

Many people with Parkinson's, a progressive disease of the nervous system, are indeed at retirement age. So the world was shocked when Back to The Future actor Michael J. Fox revealed he was diagnosed with Parkinson's disease at only 29 years old.

But Fox's case isn't unique. It's believed that 1 in 10 people with Parkinson's develop the disease some time before their 40^th birthday. About 1 in 5 Australians with Parkinson's are at 'working age' (under 65).

And a person can live with symptoms for many years before a diagnosis of Parkinson's is made.

To mark World Parkinson's Day, Thursday April 11, here's what you need to know about the early signs of this insidious neurological disease.

Early symptoms of Parkinson's can be overlooked

Symptoms of Parkinson's disease are divided into 2 groups: motor symptoms and non-motor symptoms.

Early non-motor symptoms can be subtle and it's possible to overlook them as signs of Parkinson's: for example, anxiety and depression, fatigue, loss of smell, speech problems, difficulty sleeping, erectile dysfunction, incontinence and constipation. Another sign of Parkinson's is handwriting that becomes smaller.

Motor symptoms of Parkinson's can include tremor (shakiness), slowness of movement (called 'Bradykinesia'), muscle rigidity and instability (falls).

It's possible for non-motor symptoms to start occurring up to a decade before any motor symptoms emerge. Years can pass before symptoms are obvious enough to make a person to go to the doctor.

There's no 'one size fits all' when it comes to Parkinson's disease — different people will experience different symptoms, and of varying severity. One in 3 people, for example, won't experience tremor.

On average, 37 people are diagnosed with Parkinson's every day in Australia. —Parkinson's Australia   

Parkinson's disease is difficult to diagnose

Parkinson's is a challenge to diagnose since there is no definitive test for it. Blood tests and scans are usually run just to rule out other causes of the symptoms.

If a GP suspects a patient could have Parkinson's, they may refer them to a neurologist (a specialist) who can make a diagnosis based on medical history, a review of the signs and symptoms and a physical examination. It can help to keep a diary of symptoms leading up to the appointment.

Diagnosing Parkinson's disease in some people can be a long process.

Is there a way to slow the progress of Parkinson's?

Parkinson's disease is a progressive disorder, which means its symptoms worsen slowly over time. There is no cure for Parkinson's disease yet and no known way to slow its progress.

But there are treatments and medications that can control or reduce the symptoms and help people live productive lives. Some research suggests that regular exercise may slow the progress of Parkinson's. Physical activity can also alleviate stiffness and other symptoms.

There are other things a person can do to feel better after a diagnosis of Parkinson's, such as joining social support groups and learning as much as possible about the disease. It's also important to make the home safer and less cluttered, since a person with Parkinson's is more likely to fall.

While it's not always easy, neurologists say a positive mindset can also help.

Where to get more information

• If you're experiencing any symptoms and are concerned, see your GP.
• To learn more about Parkinson's disease and to find support, visit Parkinson's Australia or call the Info Line on 1800 644 189.
• The Shake It Up Australia Foundation partners with The Michael J. Fox Foundation to help raise awareness and funds for Parkinson's disease research.
• The Garvan Institute of Medical Research is working hard to find ways to diagnose Parkinson's earlier and repurpose existing drugs to slow its progress. Find out more here.
• The Young Onset Parkinson’s Exchange is an app and online resource for people living with young onset Parkinson’s.