As neurologists often say, not everything that tremors is Parkinson Disease. Especially if the patient presents in an unusual manner. One of the lesser known and often confusing causes of tremor is dystonia, an increase in muscle tone that is abnormal, often painful, and leads to abnormal postures or movements. A famous British actor recently revealed that he was misdiagnosed with PD when, in fact, he had dystonia of the head and neck, called cervical dystonia or spasmodic torticollis if the head is turning uncontrollably.
This is a common question that comes up in the neurologists’ office, regardless of age of the patient. It arises not just from concern for family members, but also as a matter of curiosity, of explanation.
We used to believe that Parkinson Disease was almost entirely caused by environmental factors. 20 years ago, genetic involvement was deemed to be around 2% of cases or less. Through the advent of advanced and increasingly affordable genetic testing, as well as improved collaboration across the globe, we now believe that genes account for at least 8% of PD, perhaps up to 15% based on more recent data. People with Young Onset Parkinson Disease, those with dystonia early on, and those with symmetric (both sides) findings are probably more likely to have a genetic cause than the more typical patients.
Yes, some environmental factors have been linked to increased risk of PD, such as pesticides, herbicides, fungicides, some heavy metals, and, perhaps, living in North America, but the linkage or direct cause is not as obvious as one might hope. To date, the use of surveys and questionnaires has produced few, if any, clues to the causes of PD.
The virtual revolution that has occurred in genetic testing in the past 20-odd years has allowed us to identify quite a few genes that seem to cause PD, perhaps 15 or 20 genes that are under study, with more being identified at an increasing rate. In a recent interview with Medscape Medical News, Owen A. Ross, PhD, a neuroscientist at the Mayo Clinic said ”The idea that [PD] occurs mostly in a random sporadic fashion is changing.” Dr. Ross was part of consortium of PD researchers who published an online report August 31 in Lancet Neurology. The Genetic Epidemiology of Parkinson’s Disease (GEO-PD) consortium reported the identification of both risk and protective variants in the LRRK2 gene, perhaps the most notorious PD gene both for its dominant inheritance (50% of offspring inherit the gene) and for its association with Sergay Brin, the co-founder of Google who inherited LRRK2 from his mother. Dr. Ross and colleagues found that, while some forms seem to carry increased risk of PD, others may protect against PD to some extent.
Obviously, as in many things, our view of the cause of PD is vastly different than it was just 10 years ago. Hopefully, we will be eventually be able to get a handle on prevention of PD as well as a more satisfying treatment or even a cure.
One of the questions we encounter the most in the PD clinic is “What is my prognosis, Doc?” In fact, it’s rare that a patient doesn’t ask this question. If we could predict the date that someone might need a walker, or a wheelchair, or 24-hour care, that would be very useful to everyone involved. As frustrating as it might be, the fact is that we can only make broad, sweeping statements about prognosis in PD. There are many reasons for this.
Not all PD patients are the same; in fact, the general rule is that each patient is different. In a room full of PD patients, no two will be exactly alike. As we learn more about PD, doctors and scientists are able to see that there is a spectrum of changes in multiple systems, such as memory, motor behavior, tremor, gait, autonomic function, gastrointestinal function, mood, and more. We also are learning that there are multiple causes of PD, from genes to pesticides to vascular changes and who knows what else. The end result is that each case, each person with PD, is unlike the others. Thankfully, however, there is enough overlap to allow us to treat most people.
Another problem that confounds prognostication in PD is that there seems to be a spectrum of rate of progression. Person A might have PD for 20 years and have minimal progression, while person B may progress to the same point in just 5 years. We don’t know why this happens overall, other than to say that it gets back to the issue of multiple causes. For instance, if you were exposed to Agent Orange (an herbicide which has been associated with PD), your rate of progression might be related to the amount of Agent Orange that you came in contact with and how long that contact occurred.
Yet another problem is lifestyle. This is the most potentially modifiable factor, in my estimation. By lifestyle, I mean how you treat your body and mind. Exercise, diet, social interactions, control of vascular risk factors – these are all important. From my experience, patients who exercise regularly do the best in the long run. While this is undoubtedly a physical result, it may also be a mental result as well, in that people who exercise are those who take a proactive approach to their PD. They want to continue to do the things they enjoy in life for as long as possible. I would venture to guess that anyone who reads this would agree that if you had a pair of twin 60 year-olds with PD, the twin who exercises for 40 minutes per day, 5 days per week, is going to have better health and less debility over time than the twin who is sedentary.
So, back to the original question…What’s my prognosis, Doc? The answer is “I don’t know.” I do know that PD is a progressive disease for anyone who has it, but there are too many variable involved for me to predict your individual course, for the most part, and that lifestyle and attitude have a significant impact on the whole process, on the whole person. For the patients who we see on a recurrent basis, it may be more obvious to the doctor as to rate of progression. In that case, the answers may be more concrete, but not always. Studies done with oncologists and their cancer patients have shown that giving a definitive prognosis in cancer (“You have 8 months”) is not helpful, often wrong, and may be counterproductive and anxiety producing.
It’s okay to ask about prognosis and you should ask…just be aware that you probably won’t get a clear, satisfying answer!