A degenerative brain disorder that sufferers must learn to live with
Parkinson’s disease has no cure, but treatments can extend quality of life
Michael J. Fox remembers that the first sign of what was to come was that his little finger seemed independently animated. He was 29, had been married for three years, his son – the first of four children – was two, and his life was full and successful. He appeared to be the picture of health.
Except that he wasn’t. When the tremor in his finger didn’t cease, a neurologist revealed a shattering diagnosis: early onset Parkinson’s disease.
Although reference to what we call Parkinson’s disease today was made centuries ago – in Indian texts from around 1000 BC as well as ancient Chinese writings – it was first described as a neurological disorder by British doctor James Parkinson in 1817.
In an essay he published on the “shaking palsy”, Parkinson wrote: “Involuntary tremulous motion, with lessened muscular power, in parts not in action and even when supported; with a propensity to bend the trunk forward, and to pass from a walking to a running pace: the senses and intellects being uninjured.”
Parkinson’s disease develops when the brain produces insufficient dopamine, a result of the cells responsible for the chemical’s production having died or become impaired.
You might know of dopamine as the “feel good” hormone – we produce it in response to socialising, sex and even eating. It prompts a sensation of pleasure and drives us to do the things that give us pleasure, even when they aren’t necessarily good for us – such as gambling. It’s part of our reward system.
Dopamine also plays a crucial role in movement, both voluntary, such as that of our arms and legs as we walk, and involuntary, such as that of our bowels.
Parkinson’s is often called a “movement disorder” – symptoms include tremors, slowness, stiffness, and walking and balance problems. But it goes beyond “movement”: it can cause depression, memory problems and other non-movement symptoms – even, for example, the loss of smell. It is a degenerative disorder; it gets worse over time.
There are an estimated 6 million people worldwide living with the disease – including about 13,000 Hong Kong residents.
Professor Ho Shu-leong, chief of the University of Hong Kong’s neurology division, first became interested in Parkinson’s while training as a junior doctor in Britain. A mentor sparked his initial interest in the late 1980s, which, he recalls, “was a period of exciting discoveries and debates on potential causes of Parkinson’s and possible treatment strategies”.
The causes of the illness are unclear. Fox – who launched the Michael J. Fox Foundation for Parkinson’s Research in 2000 – has been quoted as saying, “There’s so many ways that you can – that I could have – hurt myself. I could’ve hit my head. I could have drunk too much at a certain developmental period.”
Fox believes the disease is a combination of genetic and environmental factors.
Ho says Parkinson’s is not one disease, but a spectrum of disorders with possibly different disease-causing mechanisms presenting with what appear to be similar symptoms.
Age certainly seems to play a role in the disease’s development. Ho says while there are some patients who develop Parkinson’s in their forties or even earlier, as Fox did, most patients develop symptoms in their sixties or later.
Although Parkinson’s and Alzheimer’s share some characteristics – age is a risk factor for both – there doesn’t appear to be a link. Both, however, are more prevalent than you might imagine.
Alzheimer’s disease accounts for the vast majority of dementia cases; worldwide, a dementia diagnosis is delivered every three minutes, while a diagnosis of Parkinson’s occurs every six.
Cognitive decline is common in both diseases, though it is much less common in Parkinson’s. Up to half of Parkinson’s patients develop cognitive difficulties, which can range from mild forgetfulness to full-blown dementia.
Parkinson’s is not a killer, but it is life-limiting. Fox, who has just produced a film about his life, Still, says, he won’t die of the disease, but he will die with it. At 61, he says he does not expect to see his 80th birthday.
Many who are diagnosed don’t live beyond another 10 or 20 years. It has been more than three decades since Fox was diagnosed, but he was very young – and early onset Parkinson’s is rare.
There is no cure for Parkinson’s, Ho says, and most treatment alleviates the symptoms of the disease without evidence that it actually slows or halts its progressive nature.
He says treatment does significantly improve the quality of life and extend patients’ lifespan.
For more than 20 years, Ho says, research has explored medicines that can modify the course of the disease to extend quality of life, so those diagnosed in their sixties – most patients – can expect to enjoy a reasonable quality of life into their 80s.
Ho is hopeful that pharmaceutical companies’ clinical trials on novel drugs will prove successful. Many of them target the mechanisms that cause Parkinson’s.
Researchers are seeking to identify biomarkers to personalise treatment for individual patients in a way that is similar to the effective and encouraging targeted treatments being harnessed in breast and lung cancers.
Sometimes, as Fox has been quoted as saying, it takes time to fine-tune treatment regimes.
“It’s not like I take two pills and then at 10am I take another two. It really depends on what chemicals are brewing in my brain that day,” he said in 2010.
“I’m always trying to find the perfect cocktail of medication and I think now I’ve found it,” he said in 2012.
When Ho qualified as a doctor, the profession was focused on the motor disability caused by Parkinson’s – treating it as a movement disorder only and targeting tremors and “poverty of movement”.
But over the past 20 or 30 years, he says, they have learned that non-motor disabilities, anxiety, depression, Parkinson’s psychosis, Parkinson’s dementia, apathy and poor sleep quality are more disabling to patients, and significantly worsen their motor disabilities and quality of life.
Treatment strategies have evolved and improved to address this, and even in the absence of a cure, Ho says: “This is a powerful and positive development.”