Parkinson’s disease, documented by James Parkinson in 1817, is the second common chronic neurodegenerative disease after Alzheimer’s disease and it is progressive and disabling in its development. It is characterised by the degeneration of neurones in the basal ganglia, which synthesise and store the neurotransmitter dopamine. It is thought at diagnosis, the person with Parkinson’s will have already lost between 60-80% of their dopamine neurons. Dopamine is thought to be responsible for the initiation, planning and execution of movement, as well as motivation and thinking.

Parkinson’s disease affects approximately 9,000 people in Ireland, 1.2 million people in Europe, and 6.3 million worldwide. It is estimated that Parkinson’s disease affects 1-2:1,000 of the general population, affecting more men than women. This can be further broken down to 2:100 of the elderly, and 1:10 nursing home residents.  According to the World Health Organization, Parkinson’s is just one of many neurodegenerative disorders, which will surpass cancer as the most common group of medical conditions by 2040.

The cause of Parkinson’s disease is generally unknown, but there have been links identified to genetic disposition, environmental toxins, drugs, viruses or head injury.  Parkinson’s disease is slow and insidious in its progression and it always presents asymmetrically, but both sides of the body will be affected as the condition advances. NICE guidelines state that a person with suspected Parkinson’s disease should be referred to a neurologist or geriatrician for a confirmed diagnosis.

Although Parkinson’s disease is classified as a movement disorder, we know there are two aspects to the disease, the motor symptoms and the non-motor symptoms. Motor symptoms are the cardinal features of Parkinson’s disease. For a diagnosis (as defined by the UK Brain Bank criteria), bradykinesia must be present along with at least one of the following: muscle rigidity; resting tremor; and/or postural instability. Only approximately 70% of people with the disease will have a tremor. 

There are many non-motor symptoms (NMS), which often dominate the clinical picture, these include constipation, depression, bladder problems, sweating, REM sleep behaviour disorder, sexual dysfunction, anosmia (lack of a sense of smell), fatigue and insomnia to name but a few. These are often present for years prior to diagnosis. 

There is no cure for Parkinson’s disease, so treatment is symptom management through lifestyle and medication. There are different forms of treatment – Levodopa is the gold standard and has been used for more than 40 years. This replaces the lost dopamine. Dopamine agonists stimulate the dopamine receptors directly, COMT inhibitors boost the function of dopamine, and MAO-B inhibitors try to keep the remaining dopamine working to its full potential. It often takes eight to 10 weeks after starting treatment to see an improvement of symptoms.

The addition of dopaminergic medications usually benefit the motor symptoms, but a recent study showed that very few NMS are positively affected by these therapies¹. 

The iceberg (see Fig 1) is commonly used to illustrate the ratio of motor to non-motor symptoms, as often the number of non-motor symptoms far exceeds the motor symptoms, and can be hidden or not initially associated with Parkinson’s disease. NICE guidelines state that the identification and treatment of these non-motor symptoms are an important aspect of care, although they are frequently untreated.

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Non-motor symptoms

NMS, such as anxiety and communication difficulties, can have a serious impact on the quality of life for people with Parkinson’s disease. The presence of NMS can be a contributing factor for admission to hospitals and nursing homes. This is particularly true in later stages of the disease, as the symptoms such as postural hypotension worsen (which can leads to falls) and neuropsychiatric symptoms creep in.

Constipation and fatigue

Constipation is extremely common in Parkinson’s disease, and is often one of the symptoms present before diagnosis. Constipation is a product of a decrease in gut motility and a decrease in overall activity, which result in a lack of stimulation. As Levodopa is absorbed in the bowel, constipation can cause delay or failure of medication, which can lead to unpredictable OFFs, a worsening of symptoms, both motor and non-motor. Some people may be able to manage their constipation through diet and exercise, but the majority of people will require a laxative to ensure they go regularly.

Fatigue can be described as a feeling of exhaustion, a lack of energy and overall tiredness. It is one of the non-motor symptoms of Parkinson’s disease that is difficult to manage, as the medication does little to combat fatigue, and can often be part of the cause. It is thought that fluctuations in the motor symptoms may contribute to the level of fatigue, or may be related to the medication and timing. People with Parkinson’s disease may describe feeling that they have no reserve energy. Fatigue can also be experienced as a symptom of depression, which is another common NMS. 

Apathy, which is described as a state of indifference, is under-recognised as a symptom of Parkinson’s disease as it can also be misdiagnosed as fatigue. Because of this, apathy is poorly managed, and may lead to increased level of disability, carer burden and stress, as well as reducing overall quality of life.

Speech and language difficulties

Speech and language problems are varied between dysarthria and dysphasia. People with Parkinson’s disease will frequently have a soft voice, and are likely to lack expression in their voice. They may also experience festination of speech or a hesitancy of initiating words. These issues may be worse during periods when the medication is not working or ‘wearing off’. Speech and Language difficulties can have a huge negative impact on a person’s life, and may lead to social isolation. The therapy known as LSVT (Lee Silverman voice treatment) was specifically developed for people with Parkinson’s disease to help them improve their speech by teaching them to ‘think loud’. The four-week course of classes is conducted by qualified STLs and can be very successful.

Postural hypotension

Postural hypotension (defined as a drop of 20mmHg in systolic or a drop of 10mmHg in diastolic BP) in Parkinson’s disease can be difficult to manage, due to the fact that both Parkinson’s disease and the medications used to treat it, all contribute to orthostatic hypotension. This NMS is often the cause of falls, which can lead to a loss of patients’ confidence in walking, and an increase in their level of dependence. 

This loss of independence can result in hospital and nursing home admissions. The Parkinson’s Disease Nurse Specialist Association made new recommendations around checking for postural drop in Parkinson’s disease – the patient is to sit or lie comfortably for five minutes, check BP, then patient is to stand and check BP at one minute, three minutes and five minutes. Treatment of postural hypotension may vary from increasing fluids and sodium intake, stopping anti-hypertensive medications and prescribing steroids. Often physiotherapists can give advice to people about standing up safely after lying or sitting for long periods.

Dementia

Dementia in Parkinson’s disease, sometimes called PDD, can be relatively common. According to a recent study² in Australia, 83% of people with Parkinson’s disease will develop a form of dementia. Typically, dementia may present itself eight to 10 years after onset of motor symptoms, and manifests as a severe disturbance of the ability to plan, cognitive dysfunction and reduced intellect. Often the spouse or partner will describe how they have taken over the household duties such as paying bills, shopping and organising outings. If symptoms of dementia appear within a year of the onset on Parkinson’s disease, it is likely that the diagnosis is actually Lewy Body Dementia (LBD). Cognitive impairment along with visual hallucinations, impaired visuospatial awareness and a fluctuating disease course are clear indicators of LBD. 

Anosmia and hyposmia 

Anosmia and hyposmia (reduced sense of smell) have been identified as possible pre-clinical features of Parkinson’s disease. Often people with Parkinson’s disease will report that they have never had a good sense of smell, or that it disappeared years ago. It has been suggested that anosmia may be used, along with other tests, to screen for Parkinson’s disease.³ There is a standardised smell test, the UPSIT, but it not frequently used in treatment centres in Ireland.

Assessment tool

Due to the vast array of possible non-motor symptoms, there have been calls to develop a standardised assessment tool. Parkinson’s UK have developed a questionnaire that asks clients to tick the boxes of any of the listed symptoms which have occurred in the last month, and they fill this in prior to their clinic visit. This questionnaire is an effective way to identify and address the issues they are having problems with. These forms are available online from www.parkinsons.org.uk

We know that Parkinson’s disease is slow in progression, so if an acute deterioration occurs (over a few days or weeks), it is most likely due to a secondary cause. The Dublin Neurological Institute produced a ‘Top 10 Causes of Sudden Deterioration’ poster which was devised by Brian Magennis, a Parkinson’s disease nurse specialist. The poster lists the most likely causes of the condition, including constipation, infection, stress and pain. It notes that any of these problems could result in an increase in motor symptoms and/or non-motor symptoms, such as confusion, hallucinations and increased day time sleepiness. 

The poster recommends that once the cause of the deterioration has been identified and treated, symptoms should return to the baseline, usually without any changes to the Parkinson’s medications. The poster is available from the Parkinson’s Association of Ireland. For more information, Tel: 1800 359 359.

References

1. Erro R et al. Non-motor Symptoms in Early Parkinson’s Disease – A 2-Year Follow-Up Study on Previously Untreated Patients. Journal of Neurology, Neurosurgery and Psychiatry 2013; 84(1): 14-17
2. Hely MA, Reid WG, Adena MA, Halliday GM, Morris JG. The Sydney multicenter study of Parkinson’s disease: the inevitability of dementia at 20 years, Movement Disorders 2008;  23(6): 837-44
3. Haehner A, Hummel T, Hummel C, Sommer U, Junghanns S, Reichmann H. Olfactory loss may be a first sign of idiopathic Parkinson’s disease. Mov Disord 2007; 22: 839-842