Parkinson's disease plays out differently for all of the approximately 145,000 UK residents living with this incurable, progressive neurological disorder.

With as many as 40 reported symptoms, including the hallmark tremors in hands and arms, Parkinson's is the fastest-growing neurological condition globally. Just over 1% of those with the disease are under the age of 50.

People with Parkinson's don't have enough of the chemical dopamine in their brain, because some of the nerve cells that make it have stopped working. The three main symptoms are tremors, slowness of movement, and muscle stiffness.

But there are also lesser-known indicators that may manifest long before more noticeable issues emerge. Dr Beckie Port, the lead for research communications at Parkinson's UK, previously told the Liverpool ECHO: "Parkinson's is complex.

"There are over 40 symptoms which vary from freezing and rigidity to anxiety and sleeping problems. It affects everyone differently and no two people present with the same symptoms. Many people tell us, they experience symptoms related to their Parkinson's for a number of years before a formal diagnosis, but the dots were never connected."

Aside from the three main warning signs, the NHS says  many people develop anosmia (a loss of sense of smell) before any other symptoms occur. This "sometimes occurs several years before other symptoms develop".

Parkinson's UK states that up to 95% of those with the condition experience a loss or reduction in their sense of smell "to some degree". Although it's somewhat of a 'hidden' symptom, it becomes noticeable when people can no longer smell their food, which can have subsequent effects.

The charity explained: "Loss of smell can impact people in various ways. Our sense of smell contributes to our ability to taste food, so a diminished sense of smell can lead to weight loss or gain. It can also influence your mood, relationships and overall quality of life. Moreover, loss of smell can pose safety risks – for instance, not being able to detect burning food. It does not respond to Parkinson's medication, so it's unlikely to improve even with treatment."

Other Parkinson's symptoms include:

• depression and anxiety
• balance problems (this may increase the chances of a fall)
• problems sleeping (insomnia)
• memory problems

Anyone concerned about potential Parkinson's disease symptoms should consult a GP and may be directed to a specialist for more detailed assessments.