When dopamine dies off

A CHRONIC progressive neurodegenerative movement disorder that is usually characterised by tremors, rigidity, slow movement, poor balance and difficulty in walking, Parkinson’s disease (PD) can also present through a number of non-motor impairment symptoms ranging from constipation, lack of smell, depression to dementia and visual hallucinations. The disease made headlines earlier this year when actor Robin Williams committed suicide. He had been diagnosed with Parkinson’s and it is believed the actor was suffering from depression at least in part as a result of the disease.
While not life-threatening in the early stage, Parkinson’s disease cannot be cured and the symptoms will inevitably increase over time. However, early diagnosis and proper treatment can help alleviate most symptoms and possibly slow down progression of the disease, allowing patients to enjoy a better quality of life.
Neurologist Associate Prof Dr Roongroj Bhidayasiri, the director of Chulalongkorn University Hospital's Parkinson’s Disease and Related Disorders Centre and Visiting Associate Professor of David Geffen School of Medicine at UCLA in Los Angeles, says that the perception of and knowledge about the disease among Thais has greatly improved in recent years. Usually found in those over 55 years old though young people are sometimes affected, about 70,000 PD patients are currently registered in the Thai PD registry database and prevalence is estimated at around 400 in every 100,000 population. Some five million people are dealing with PD worldwide.
However, the figure is likely under-reported, as many sufferers are not aware they have PD or else live far away from treatment options.
The disease can be detected by examination by a doctor or a specialist like a neurologist. The most common symptom and the one that is found in every patient is slowness of movement and is often initially put down to ageing.
If necessary, A FDOPA-PET scan can be used to check the levels of dopamine in the brain, but this is costly.
Dr Roongroj adds that once a patient is diagnosed with PD, he or she often report preclinical symptoms as olfactory loss, sleeping disorders or constipation, all of which are reasonably common and may also occur in normal individuals, not only in PD patients.
While these symptoms alone can’t be used for diagnosis, Dr Roongroj says research is underway to see how such preclinical symptoms can help in early detection of the disease.
The disease is caused by a gradual loss of neurons that release dopamine, a neurotransmitter which stimulates the motor nerve cells that control the muscles. When dopamine production is depleted by 60 per cent or more, the motor nerve cells are unable to control movement and coordination and the motor symptoms start to appear.
The exact cause of nerve cell degeneration is unknown. Many factors are involved such as ageing, environmental toxins and cumulative brain trauma (as in boxers).Genetics now account for at least five per cent of PD populations as different familial forms of PD are being recognised.
While medications can radically improve symptoms, opinion often varies between doctor and patient as to the level of such improvement. In addition, not all patients are concerned about motor symptoms like tremors or rigidity but they may find nonmotor symptoms like constipation, depression, dementia or delusion more troublesome. Some patients may also experience hallucinations – these are visual rather than auditory – often refuse medication even though this is vital to controlling the hallucinations.
PD is also considered by many of those suffering from it as a social stigma. A recent study revealed that as many as 60 per cent of Thai PD patients felt inferior because of PD. This is of concern to Dr Roongroj who says people shouldn’t consider PD as a “miserable” disease and points out it is one of very few neurological ailments where much improvement can be seen in patients who receive treatment.
“But it’s human nature to focus on the bad side rather than the bright side. It’s just like we are immediately drawn to headlines announcing bad news than items bearing good news,” he says.
Part of the problem, he acknowledges, is the perception of other patients. For example, he has observed that in the waiting room of the clinic, people tend to stare at patients with the tremors and see themselves getting to the stage rather than looking at those whose symptoms are under control thanks to the treatment.
The Parkinson’s Centre at Chulalongkorn hospital today has around 4,000 patients spread between various clinics. “There are more options for treatment of Parkinson’s too these days,” says the neurologist. “These range from taking pills, to injections and skin pads or even surgery depending on the patient’s symptoms.