Parkinson's disease has several non-motor symptoms, researchers have claimed, which often remain unrecognised.
Most people associate the disease with tremors and slow, rigid movements, yet some other symptoms can be even more disturbing for sufferers, particularly if they go untreated.
According to a survey cited in the Harvard Women's Health Watch newsletter, 88 per of those with Parkinson's disease experienced at least one non-motor symptom.
These include changes in taste and smell, hallucinations and delusions, sexual problems, cognitive problems and depression, which is often mistakenly thought to be a response to the illness rather than a symptom in its own right.
In addition, some sufferers experience uncharacteristic compulsive behaviour, such as shopping or gambling, which can be a side effect of some medications used to treat the disease, the newsletter reported.
It is vital that people with Parkinson's disease are adequately treated for all of their symptoms, to ensure they have the highest quality of life possible.