Public awareness of Parkinson’s has been heightened in recent years by the impact of the disease on high-profile personalities, including the actor Michael J. Fox, the boxer, Mohammed Ali and, most recently, the comedian, Billy Connolly.
Parkinson’s is more common in older people, most cases occurring after the age of 50. It is estimated that around four in every 1,000 people in Australia have Parkinson’s, and one in every 100 over the age of 60. There are approximately 80,000 people living with Parkinson’s in Australia, with one in five being diagnosed before the age of 50.
The main motor symptoms are collectively referred to as parkinsonism. Parkinson’s disease is an idiopathic disorder (having no known cause), although there is increasing recognition of the importance of genetic factors and there are reported links with exposure to certain types of environmental toxins. In a minority of cases PD is hereditary, with either a dominant or recessive pattern of inheritance, and disease-causing mutations have been found in many different genes. There is no diagnostic test for Parkinson’s disease and the diagnosis is made on the history and examination findings, after excluding other causes of parkinsonism.
Increasingly recognized are the ‘non-motor’ symptoms of the disease, such as loss of the sense of smell (‘anosmia’), dream enactment during sleep (‘REM sleep behaviour’), depression, constipation, pain, and speech and swallowing difficulties. These are equally important as they can cause significant impairment to quality of life and so warrant exploring and treatment.
The motor symptoms of Parkinson’s appear when about 70% of the dopamine-producing cells cease to function normally. However, some non-motor symptoms can predate the motor symptoms by several years; this time period is referred to as the “prodromal” phase of the disease and provides a unique opportunity to utilise disease-modifying treatment that may arrest or reverse the degenerative process. A number of clinical trials of potentially neuroprotective drugs are currently investigating the prospect of altering the disease process in the prodromal phase.
Presently, there are no available treatments to cure Parkinson’s disease and treatment consists of managing the motor and non-motor symptoms. The best pharmaceutical treatment available is Levodopa which has been used for decades, and effectively replaces the lost dopamine in the brain to normalise motor control. PD patients often refer to ‘ON’ and ‘OFF’ states, the ‘ON’ state being the time period when the drugs are working and controlling the motor symptoms and the ‘OFF’ state the period when the effects of the drugs are wearing off. A number of other drug types are also used, including dopamine agonists (Sifrol), COMT inhibitors (COMTAN), MAO-B inhibitors (Azilect) and anticholinergic medications (Artane). These pharmaceutical treatments may also improve some of the non-motor symptoms.
As the disease progresses and dopamine nerve cells continue to be lost, treatment becomes less effective. Increasing quantities of medication are required to control the symptoms and side-effects become more troublesome, including excessive involuntary writhing movements (‘dyskinesias’). Changes in medication may overcome some of these complications but ultimately an Advanced Therapy may need to be considered. There are three main Advanced therapies; 1) Deep brain stimulation (DBS), 2) Duodopa (Levodopa-carbidopa intestinal gel), and 3) Apomorphine infusion.
At the Perron institute, we provide medical input into the diagnosis and treatment of Parkinson’s disease. We offer individualised patient-centred care and assist in managing the motor and non-motor symptoms of the disease. We have access to all the Advanced therapies and provide long-term support for patients with PD.