Non-motor symptoms may herald Parkinson's disease.

Parkinson's disease is the second most common neurodegenerative disorder, after Alzheimer's disease. It predominantly affects the elderly. Age is the most clearly established risk factor and there is a male:female ratio of 1.5:1. Current incidence in the general population is 8.4-19 per 100,000 population per year with an approximate prevalence of 120 per 100,000 population. NICE recommends that patients with suspected Parkinson's disease should be referred untreated to a specialist with expertise in parkinsonian disorders. The diagnosis is primarily clinical. Parkinson's disease should be suspected in all patients presenting with bradykinesia (which is essential for the diagnosis of any form of parkinsonism, including Parkinson's disease), muscular rigidity, resting tremor (4-6 Hz) and postural instability not caused by a primary visual, vestibular, cerebellar, or proprioceptive dysfunction. At present, there are no specific biochemical, imaging or genetic tests to assist in the diagnosis of Parkinson's disease. Structural brain imaging (MRI or CT) has no role in the diagnosis of Parkinson's disease but may be useful to exclude cerebrovascular disease, hydrocephalus and Wilson's disease in selected cases. Parkinson's disease is a condition that results in both motor and non-motor symptoms. Morbidity associated with non-motor symptoms in Parkinson's disease is becoming increasingly recognised and some non-motor symptoms such as hyposmia, apathy, depression and REM sleep behaviour disorder may precede the onset of motor symptoms.