An Introduction To Parkinson`s Disease And Its Impact On Driving

My project aims to provide an analysis of many aspects of Parkinson's disease including the prevalence of the disease around the world as well as the possible causes of the disease. It also looks at the symptoms of the disease, the different treatment options available and the side effects these treatments bring with them. It then looks at the potential implications these symptoms and side effects can have on the ability to drive safely. It also includes case studies on Parkinson's patients' personal experiences with driving. In preparing this paper I was fortunate enough to have the opportunity to talk to many Parkinson's patients whilst working at The William Harvey Hospital. They kindly allowed me to discuss with them how the disease has affected their lives.

Background information:

Parkinson's disease is a neurological condition that was first described by Dr James Parkinson in his 1817 paper: "The Shaking Palsy". It is classed as a movement disorder as it affects the motor system. Parkinson's also causes non-motor symptoms, such as depression and sleep difficulties. The symptoms of Parkinson's are caused by the death of dopamine producing nerve cells within the brain, specifically in the substantia nigra. Dopamine is a chemical messenger, which helps to coordinate the bodies' movements. One of the possible factors in the death of these neurons is an accumulation of protein called alpha-synuclein in these cells forming lewy bodies, but the cause of this accumulation of protein is unknown. The symptoms of Parkinson's can make some aspects of everyday life difficult. One of these is driving, as driving requires fast physical and mental reactions, driving can often cause a problem for those with Parkinson's disease. Parkinson's disease has many varied symptoms and every patient is affected differently.

After Alzheimer's disease, Parkinson's is the most common neurodegenerative disease. Parkinson's is much more prevalent in older people with the mean age of developing the disease being 62.4. In the UK each year there are 18 new cases of Parkinson's disease per 100,000 of the population. It is very hard to put an exact number of people with Parkinson's due to difficulty in diagnosing the condition. There is no definitive test for the disease and the fact that Parkinson's in part of a wide spectrum known as Parkinsonism, and its symptoms can be so varied. This can make it difficult to say a how many cases of true Parkinson's there are. It is however estimated that there are between 108-164 people with Parkinson's per 100,000 of the population in the UK. The prevalence around the world seems to vary significantly; in Shanghai (China) there are 18 cases per 100,000 of the population, whereas in Mumbai (India) there are 328 cases per 100,000 of the population. There have been several studies, which say that Parkinson's has gender and ethnicity bias, but there is not currently significant evidence to prove these claims. Currently around 0.3% of the UK population have Parkinson's disease; this number has risen over the last century. This increase is most likely due to the better diagnosis of the disease, but also and the fact that the UK has an ageing population.

Symptoms: Tremor: Around 75% of Parkinson's patients present with a tremor. A tremor is an involuntary movement, which has a regular rhythm, usually with a frequency of 3-7 Hz. Bradykinesia: This is the slowness of starting and executing movement. Rigidity: This is the stiffness of muscles, which causes resistance to passive movement such as arm swing. Hypographia: Small spidering handwriting. Hypomimia: Mask like face. Dysphagia: Swallowing difficulty Hypophonia: Soft speech. Depression: Around 40% of Parkinson's patients present with this is a feeling of hopeless sadness which can make other symptoms such as a tremor more pronounced. Loss of Impulse Control: In some patients there is a loss in impulse control, this is where decisions may be made with little thought of the consequences, e.g gambling and hypersexuality are signs of loss of impulse control. Insomnia: Sleep disturbances occur in almost all Parkinson's patients (~98%). Caused by two conditions, Firstly Rapid eye movement sleep behaviour disorder (RBD); or Restless Legs Syndrome (RLS). Impaired gastrointestinal motility: Parkinson's can cause several problems with bowel function. Constipation is the most common in Parkinson's. Urinary bladder dysfunction: With Parkinson's there are two main problems that affect the bladder. The first is an overactive bladder; this is where the patient feels the need to go to the toilet more frequently, the second problem is difficulty in trying to empty the bladder, due to the bladder muscles not contracting properly.

Drug Treatments: Although there is currently no cure for Parkinson's there are several different groups of drugs that can help to manage the symptoms. It is not known what causes the nerve cells to die in the substantia nigra, but we do know that it is this death of cells that causes the symptoms of Parkinson's, as it leads to a reduced production of Dopamine.

Levodopa Preparations: Dopamine cannot cross the blood brain barrier, so dopamine itself cannot be given as a treatment. Therefore levodopa is given which is converted into dopamine inside the brain.

Dopamine agonists: Dopamine agonists work in a similar way to dopamine within the brain, by stimulating the nerve cells. One of the main benefits of dopamine agonists is that it enables the delay in the use of levodopa treatments, as these often only work for several years. They also cause fewer movement problems such as dyskinesias (involuntary movement) than levodopa preparations.

MAO-B Inhibitors: Dopamine is broken down in the brain by enzymes. One of these enzymes, called monoamine oxidase-B (MAO-B) can be inhibited. This means that less dopamine is broken down and therefore more is available for the coordination of the body.

COMT Inhibitors: COMT Inhibitors work in a similar way to MAO-B inhibitors. Alone they have little or no effect on the symptoms of Parkinson's, but they can make Levodopa treatments more effective as they inhibit another enzyme (Catechol-O-methyl transferase) that breaks down dopamine.

Glutamate antagonist: Amantadine is the only Glutamate antagonist proscribed for the treatment of Parkinson's. It is used with other Parkinson's drugs as it can reduce the amount of dyskinesia caused by other Parkinson's drugs but has little effect on the symptoms of Parkinson's itself. Anticholinergics: work by stopping another chemical messenger within the body, called acetylcholine. Blocking this chemical by the use of anticholinergics can reduce tremors and muscle stiffness.

Methodology:

My research for this project came from several sources. I read many books and medical papers on the subject of neurology and Parkinson's disease, as well as the excellent Parkinson's U.K website. I also sat in on many clinic consultations, taken by a number of different consultant neurologist and nurses. I sat in on medical tests to see whether a patient's medicine was working, this allowed me to see the difference medication can make on a patient in only a few hours I also had the opportunity to assist on home visits during my placement. I also had the opportunity to interview patients to see how the disease has affected them individually. I gained a great deal of patient contact, which greatly helped with my understanding of the disease. I also had access to patient files as well as the Parkinson's database, which allowed me to look for similarities between patients.

Wider impacts: The main impact of my project it would be the increased understanding of Parkinson's disease that it would bring. It aims to make people more accepting of the difficulties the disease can cause, as well as reinforcing the importance of treating a person with Parkinson's disease equally in all aspects of life.

Ethical issues: As I was sitting in on many clinic appointments I was listening to confidential information I had to sign a non-disclosure form meaning that I was no allowed to repeat any information unless I kept their names anonymous. I also briefly talk about stem cell treatments being a possible future treatment for Parkinson's, which raises ethical questions about where the stem cells come from. Conclusions:

A study completed by the Department of Neurology, University Hospital of Oulu, Finland in 1998 created a study into driving with Parkinson's disease. One of the main investigations they carried out was a test into the safety of drivers with Parkinson's against how safe a control group of drivers were. A driving instructor gave each person in the study a mark out of 10 for their driving ability, 10 being the safest and below 4 meaning they were unable to drive safely. The mean score of the 20 people in the control group was 7/10, whereas the mean score of the 20 Parkinson's patients was only 5.1/10. The difference between these scores indicates that on average drivers with Parkinson's are less safe drivers according to this study. The driving ability of the Parkinson's patients was much more widespread than the driving ability of the control group. The standard deviation of the Parkinson's group was 2.00 with a range of 2/10-9/10 whereas the standard deviation of the control group was 0.97 with a range of 6/10-9/10. The number of faults each driver made was also recorded and a mean was calculated. The control group had a mean of 9 faults, but the Parkinson's group had a mean of 13.4 faults, which again showed how on average drivers with Parkinson's were not as safe. Twenty laboratory tests were also conducted looking into memory, motor and cognitive reaction times as well as visual perception and a number of other important faculties needed for driving. In most of these tests the results were very similar but in the memory test, motor reactions and information processing tests the Parkinson's group was greatly outperformed by the control group.

The evidence from the study discussed above does look as though drivers with Parkinson's are at a much higher risk of having a crash. This is probably not the case; in this same study they found that although they generally didn't perform as well in the driving assessments, the number of crashes that drivers with Parkinson's have is only slightly higher than the general public. They also found that almost all of the drivers with Parkinson's were still safe to drive even if they didn't perform as well as the control group. Possibly the most significant finding of this study is the huge variation with how Parkinson's disease affects driving. Many of the people in the Parkinson's group were able to drive as safely as the control group and scored highly on many of the laboratory tests, but some of the group preformed very poorly which influenced the mean scores greatly. This shows how some Parkinson's patients are perfectly able to drive safely, whereas others are not.

It is clear that both the symptoms of Parkinson's and the side effects of the medication taken for it can pose a risk for drivers and therefore it is vital drivers with Parkinson's watch out for new symptoms or side effects of drugs. It is a good idea to not drive for a few days after starting a new drug to make sure the effects on the body are fully understood and to see if it causes sleepiness or any other side effects that could affect driving. Patients should not drive until they have asked their Doctor for advice. If driving is becoming difficult due to something like one-sided rigidity, cars can become adapted to make the driving experience easier. It is vital to never drive when feeling tired, and it is best to avoid rush hour and hours of darkness. In almost all people with Parkinson's there comes a day where they are no longer capable of driving safely. When that day comes, it is important to accept it and stop driving.

Removing the right to drive from a Parkinson's patient too early can greatly reduce their independence and can also be detrimental for their self-confidence and quality of live. Whereas taking away their right to drive too late can be dangerous to both the patient and the general public as it puts them at serious risk of injury or death.

It would not be fair to conclude that everyone, or no one, with Parkinson's is safe to drive. Blanket statements are not easily made with Parkinson's, as there are no two patients with identical cases of Parkinson's. As the disease affects everyone in a different way, it would be very unfair to make judgments about the ability of drivers with Parkinson's without individual assessment. It is true that as a group, drivers with Parkinson's are at more risk of incident, which means that it is important to review these patients regularly to catch any development in their condition that could potentially pose a risk.

In some cases, Parkinson's patients feel that their licenses have been unfairly taken away. The DVLA needs a more comprehensive risk assessment, which takes into consideration symptoms, medication side effects, driving history and other relevant factors. It is also important that it includes the severity of the symptoms and side effects. The current assessment form is in the form of simple yes or no answers, which gives no real insight into the individual patient's condition.

To some the decision to allow people to drive once they have been diagnosed with a condition where the symptoms include tremors, muscle rigidity, depression, hallucinations and dizziness might seem reckless. When the potential side effects of the treatment for that disease include involuntary movement, irregular heartbeat and fainting such a decision becomes even more questionable. The facts however, are that many thousands of Parkinson's sufferers enjoy years of safe driving until eventually their symptoms progress to a point where driving is no longer safe. With regular medical checks and individual driving risk assessments it would help to ensure that all risks to society are reduced to the lowest level possible. It is imperative that any Parkinson's patient who can demonstrate the ability to drive safely should be granted the right to drive, as driving is so important for a person's independence and feeling of self-worth and withdrawing the right before absolutely necessary can leave many people feeling socially isolated.