What is Parkinson's disease?
Parkinson’s disease (PD) is a progressive neurodegenerative disorder. Nerve cells in a part of the brain called the substantia nigra are damaged and lost. These nerve cells are responsible for producing dopamine, and therefore, their loss results in a lack of dopamine production and availability.
Dopamine is a neurotransmitter (a chemical messenger that helps our brain and nervous system communicate with each other). It plays an important role in controlling and coordinating many physical and behavioural functions. With Parkinson’s disease and the corresponding lack of dopamine, individuals experience both motor (movement) and non-motor (cognitive and autonomic) symptoms.
Each year, approximately 17500 people in the UK over the age of 45yrs receive a diagnosis of Parkinson’s disease. It is more common in men, and due to our ageing population, these numbers are expected to increase. PD is the second most prevalent neurodegenerative disease, behind Alzheimer’s.
Symptoms and features
Symptoms can vary between individuals and at different stages of the disease process.
Common motor symptoms of Parkinson’s disease are:
- Bradykinesia (slow movement)
- Tremor (often at rest)
- Rigidity (resistance to movement)
Other common physical features of PD include:
- Muscle weakness
- Postural instability
- Gait disturbances and increased falls risk
Non-motor symptoms are varied and include:
- Cognitive impairment and dysfunction (a key feature of PD)
- Dementia (prevalence of dementia is considerably higher among those with PD)
- Autonomic dysfunction (inability to control blood pressure, heart rate etc)
- Gastrointestinal dysfunction
- Depression and anxiety
- Sleep disorders
Diagnosis and treatment
It is not fully understood why those with PD experience a loss of dopamine producing nerve cells in the brain. Advanced age is a risk factor, as is family history of PD. It is also believed certain environmental factors may contribute.
Diagnosis for Parkinson’s disease is clinical.
There are no conclusive medical tests or scans that show somebody has PD, although scans can be used to rule out other conditions. If your Doctor suspects PD due to current symptoms (physical and cognitive), you will be referred to a specialist, commonly a neurologist. They will then observe features of movement, perform physical tests to assess motor skills, perform certain cognitive tests, and consider all of your symptoms.
Currently there is no cure for PD, however, treatments are available to help relieve symptoms and maintain quality of life. Pharmacological treatment of PD is based on the replacement of dopamine levels in the brain. Levadopa is the most commonly prescribed medication.
Together with a good medication regime, physical activity and exercise can help with symptoms, enhance quality of life, and help maintain independence.
Role of physical activity and exercise
Research into the benefits of exercise for PD supports its role as an adjunct treatment. Significant benefits are demonstrated for both movement and cognitive symptoms. It has been demonstrated that exercise can play a preventative role in symptom progression through neuro-protective mechanisms, as well as delay the onset of PD in those at greater risk.
Exercise is promoted at any stage of PD, however, it is advised that an exercise program begins as soon as possible after diagnosis. It is recommended that exercise modalities are varied and contain activities that challenge both motor skills and cognitive processes (challenge the brain, the body, and the neural interaction between them). Combining this within a program of aerobic, strength, and balance exercise appears to be most effective.
Exercise for PD should be tailored to the individual, and be safely prescribed to target specific symptoms and daily challenges. Common types of exercise that have been studied and shown efficacy include:
- Combining exercises with cognitive tasks to engage cognitive circuitry
- Dual tasking (doing two things at once)
- Learning new physical skills, activities, and movements
- Stationary cycling
- Strength training
- Gait and balance drills
Individuals who are pushed beyond their own self-selected training intensity by an appropriate exercise professional show:
- improvements in motor skills
- reductions in tremor, rigidity, and bradykinesia
- Improvements in strength and cardiovascular fitness
- Improvements in posture and gait
- Decreased risk of falls
- Improved bone mineral density
It is also observed that exercise programs promote the preservation or improvement of cognitive processes, including:
- executive function
- processing speed
- mental flexibility
Exercise can also have a positive impact on mood, risk of depression, fatigue levels, and provide quality social engagement.
Currently there are no set clinical guidelines for the precise frequency, duration and intensity of exercise for PD. Evidence suggests a minimum of 2.5 hours a week that includes all of the components mentioned above, taking into account each individual’s current stage of the disease and their capabilities. Higher relative intensities appear to elicit greater benefit.