Parkinson’s disease is a complex condition, writes Louis Roller

Parkinson’s disease is a slowly progressive degenerative neurological disorder characterised by resting tremor, pill rolling of the fingers, a mask-like facies, shuffling gait, forward flexion of the trunk, loss of postural reflexes, and muscle rigidity weakness. It is usually an idiopathic disease of people over 60 years. However, it may occur in younger people.

Similar changes are seen after acute encephalitis or carbon monoxide or metallic poisoning, particularly by phenothiazine drugs. Typical changes are destruction of neurons in basal ganglia, loss of pigmented cells in the substantia nigra, and depletion of dopamine in the caudate nucleus, putamen and palladium structures in the neostriatum that normally contain high levels of the neurotransmitter dopamine.

Parkinson’s disease is second to dementia as the most common neurological condition in Australia and its cause is poorly understood. There is a lack of awareness in the health and general community of the challenges and needs of those suffering from this complex and disabling condition, as well as community stigma and constraints in the delivery of health and social support services.

Consequently, people with PD experience more DALYs (Disability Adjusted Life Years) per person over their lifetime compared to many other diseases and injuries, especially since sufferers live with the disease for a relatively long time.

PD usually affects people 50-75 years, but can start earlier. There are around 9,000 new cases annually, and the median time from onset to death is 12.2 years. Between 55,000 and 77,000 Australians currently have PD.

It is not considered to be genetic, though 10% of cases have a familial incidence. Men and women appear to be affected equally.

Typical pathological changes are destruction of neurons in basal ganglia, loss of pigmented cells in the substantia nigra, and depletion of dopamine in the caudate nucleus, putamen, and pallidum, structures in the neostriatum that normally contain high levels of dopamine.

When approximately 70% of the dopamine-producing cells are damaged, the symptoms of PD appear. There are no laboratory tests for the condition.

PD is a chronic, progressive, incurable, complex and disabling neurological condition. The presentation of symptoms varies greatly between individuals diagnosed and no two people will be affected in the same way. The three symptoms used for diagnostic purposes are:

  • Tremor (shaking, trembling) is the most well known symptom of PD, but is absent in one third of people when the condition is first diagnosed.
  • Rigidity or stiffness of the muscles is a very common early sign of PD whereby the muscles seem unable to relax and are tight, even at rest.
  • Bradykinesia (slowness of movement) occurs because the brain is not able to control smooth and delicate movements.

Additionally, swallowing difficulties occur increasingly as the disease progresses and tablets may need to be crushed where appropriate.

Treatment alleviates symptoms but it does not halt or slow the progression of the illness. Too often pharmacists focus only on the medicines for PD but there are many complex issues which impact on the individual should be taken into account. These include:

  • Physical functional mobility and the ability to perform all activities of daily living independently becomes more difficult. Unpredictable fluctuations in motor movement and “freezing”. Tremor or physical abnormality of movement causes embarrassment and can cause social isolation. Falls are frequent due to postural instability and loss of balance and postural hypotension. 
  • Bodily Functions – general slowing of muscle activity can lead to problems with temperature regulation, ingestion and digestion of food/fluids, elimination, sleep and sexual relationships.
  • Emotional – every person with PD experiences an increased level of anxiety related to the unpredictable nature of motor fluctuations and an uncertain future. It is estimated that approximately 90 per cent of people with PD also suffer from depression.
  • Social: difficulties with communication eg. mask-like face, soft voice, diminished non-verbal gestures, and indiscernible hand-writing, limit the person’s ability to socialise. Increased physical incapacitation will increase dependence on others, and negative stigma about the illness from the community all contribute to social isolation.
  • Cognitive: during the advanced stages of the illness, some are affected by dementia associated with the degenerative processes of PD, although most retain intellectual functioning. Difficulty with tasks involving sequential steps, or activities which require use of short term memory also occur.
  • Abrupt withdrawal of some antiparkinsonian drugs has been associated with symptoms resembling the neuroleptic malignant syndrome; reduce dose gradually.

Dopaminergic drugs (particularly dopamine agonists) may cause impulse control disorders in patients with Parkinson’s disease. Some examples include pathological gambling, hypersexuality, overspending and inappropriate internet use. Patients and carers should be warned of this possibility and behaviour should be monitored. If impulse control disorders develop, dopamine agonists should be tapered off gradually.

Domperidone, a dopamine antagonist that does not cross the blood–brain barrier helps to reduce nausea and vomiting; avoid agents such as prochlorperazine and metoclopramide (central dopamine antagonist activity)

PD can affect a person’s role within a family, and therefore alter the roles and responsibilities of other family members. Leisure activities, household duties, driving, and the capacity to maintain current income can be disrupted or limited. The socially isolating effect of PD can limit the social activities of the whole family.

Pharmacists can play a pivotal role in:  

  • recognising the typical symptoms of Parkinson’s disease;
  • referring a person with suspected Parkinson’s disease to a GP in the first instance;
  • understanding where the patient is at with respect to his/her disease;
  •  advising on the appropriate use of medications; and
  •  checking for any adverse effects and/or interactions.

See http://www.parkinsons.org.au/

The 2015 Deliotte Access Economics report. https://shakeitup.org.au/understanding-parkinsons/

Associate Professor Louis Roller, from the Faculty of Pharmacy and Pharmaceutical Sciences Monash University, was the 2014 recipient of the PSA Lifetime Achievement Award.