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Parkinson's - some questions and answers
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What is Parkinson’s?
Parkinson’s is a progressive, degenerative disorder of the
brain which arises as a consequence of the loss of specialised
nerve cells and their connections, mainly within certain areas
of the brain called the substantia nigra and locus
ceruleus. These cells produce vital chemicals called dopamine,
which is involved in many functions especially those concerned
with movement control and co-ordination, and noradrenaline,
which is involved with aspects of arousal and consciousness.
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What effect does Parkinson’s have?
The onset of Parkinson’s is often gradual and it may be two to three years before medical help is sought. During that time, the individual may have become quite disabled without realising it. Initial symptoms may be vague – little more than physical tiredness or ‘slowing-down’ – but as time passes, about 70 per cent of people with Parkinson's develop a rhythmical muscular shaking. Pain, difficulty in initiating movement, slowness in everyday activities and a characteristic shuffling walk, in which the body, knees and hips are bent, causing short and increasingly rapid steps, may also appear. Muscular rigidity may lead to a loss of facial expression. Other symptoms often associated with more advanced illness are depression, speech difficulty, constipation and swallowing problems. During the last century, people with Parkinson’s often developed a bent posture, but with medical control this is now avoidable.
It is important to understand that individual people with Parkinson’s may show very different symptoms and that the rate of progression of the illness varies widely, from 3 to 30 years. Not all people with Parkinson’s go on to have severe symptoms and many enjoy years of high quality life.
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Is Parkinson’s a single disorder?
The existence of two main types of Parkinson’s has been suggested. ‘Classical’ Parkinson’s tends to appear before the age of 60 and progresses slowly, while another, late onset, form usually develops after the age of 70, progresses rapidly and is associated with a 15 to 20 per cent incidence of senile dementia, which is not evident in the classical form. Generally, the symptoms are similar for the different types of Parkinson’s and will not be discussed separately in this booklet.
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What is the difference between parkinsonism and Parkinson’s?
There are several other disorders which cause loss of movement
(akinesia) and muscular rigidity, collectively called
‘parkinsonism’. Such conditions can arise as side effects
of some medicines, from some brain infections, as the cumulative
effect of a series of minor strokes, or as a result of other
unrelated diseases. During diagnosis, it is important to eliminate
these other possibilities.
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How can we be sure that a person has Parkinson’s?
There are no biochemical tests for Parkinson’s. Changes in
the brain (loss of pigmented cells and the presence
of small granules called Lewy bodies in brain cells)
cannot be seen except in a post-mortem examination. Hence
the doctor will diagnose Parkinson’s on the basis of the clinical
symptoms. Two criteria are essential for diagnosis: slowness
of movement (called hypokinesia) and rigidity of posture.
The third sign, shaking, is not essential for an accurate
diagnosis and some people develop it without underlying disease
(called essential tremor). Besides essential tremor,
the doctor will need to rule out some other uncommon diseases,
but these are usually distinguishable on the basis of the
individual’s medical history.
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How many people have Parkinson’s?
About 110,000 people in Britain have Parkinson’s, and it ranks as the fourth most frequent disorder of the nervous system, after epilepsy, cerebrovascular disease and Alzheimer’s. About 10,000 people in Britain are newly diagnosed every year.
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Who does Parkinson’s affect?
Classical Parkinson’s affects men slightly more often than women, while the frequency of late onset Parkinson’s is similar between the two sexes. The number of cases is strongly linked with age. Below the age of 50, there are only 80 new cases per million people, but this rises to 22,000 per million in the over-70s. The average age at onset is about 60, and half of all deaths in which Parkinson’s plays a part occur in the over-80s.
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Is Parkinson’s inherited?
Until quite recently, Parkinson’s was not thought to run in families, and this probably remains true for the majority of cases. However, a small number of families were identified who clearly had an inherited form that led to early onset of the illness. One of the responsible genes in this group has now been identified and others are being sought. Until this work is complete, we cannot be entirely sure about the precise role that inheritance plays.
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What causes Parkinson’s?
All of us lose brain cells throughout our lives. Loss of those producing the chemical messenger dopamine can be seen in successive positron emission tomography (PET) scans of the brain . Interestingly, we are all born with a considerable excess of dopamine-producing cells and the symptoms of Parkinson’s do not develop until we have lost 70 to 80 per cent of them.
So why do these cells die more rapidly in some people than others? Perhaps they do not – some people may have fewer to start with (Figure 6). Alternatively, it has been suggested that a particular life event may accelerate dopamine cell death. Tantalising evidence that this might be so comes from an intriguing disorder very similar to Parkinson’s caused by a chemical substance called MPTP.
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What is MPTP and how does it shed light on Parkinson’s?
The remarkable story of MPTP began in 1982. A group of students
in California developed severe Parkinson’s-like symptoms almost
overnight after they had taken a ‘designer drug’ with heroin-like
effects. Chemical detective work established that the offending
agent was not the drug itself, but a contaminant called MPTP.
But the story did not stop there, because it emerged that
MPTP is strongly attracted to the dark pigment found in dopamine-producing
cells in the brain and tends to collect in them at high concentrations.
Once inside, MPTP is converted by an enzyme called monoamine
oxidase (MAO) into another substance which kills the cells
containing it, causing the Parkinson’s-like symptoms.
Though a tragic story for those involved, it provided support
for the theory that Parkinson’s may be caused by a similar
harmful chemical affecting the brain. So far, the search for
such a compound has been unsuccessful, but the MPTP story
raises the possibility that stopping the action of MAO (called
an inhibitor) may prevent the formation of harmful
chemicals and slow the progression of Parkinson’s.
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Can Parkinson’s be cured?
A number of new medicines are being tested which may slow down Parkinson’s. However it is too soon to say whether they work and a cure is not yet possible. If susceptible people could be identified (i.e. those who have almost lost the critical 70 to 80 per cent of their dopamine-producing cells), it might be possible to delay the onset of Parkinson’s. PET scanning can visualise living brain tissue and assess the dopamine level. Using this technology, it may be possible to identify susceptible people, but the method is too complex to form the basis of a widespread screening test.
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What forms of treatment exist for people with Parkinson’s?
Anticholinergics are one of the earliest types of medicine for Parkinson’s. Though they are not used as much as they used to be, they can be prescribed alone if shaking is the dominant symptom, or in combination if other symptoms are also present. Since around 1970, the mainstay of treatment has been levodopa, which is converted to dopamine in the brain, but many other medicines are now available. They fall into a number of distinct groups, namely:
- Compounds that prevent levodopa breakdown in the intestinal
wall, liver, blood and other organs outside the brain (called
dopa decarboxylase inhibitors).
- Compounds that extend the activity of dopamine in the
brain and other tissues by blocking its breakdown into inactive
molecules (called monoamine oxidase [MAO] inhibitors
and catechol-O-methyl transferase [COMT] inhibitors.
- Compounds that mimic the action of dopamine (called dopamine
agonists).
- Other compounds acting through different mechanisms.
The choice of initial treatment will vary according to the individual’s age at diagnosis and how far the illness has progressed. Young people with Parkinson’s or those at an early stage may need no medicines for some time or may be started on a dopamine agonist. Current medical opinion favours delaying the use of levodopa in the early years when symptoms are minimal. This is because levodopa loses its effectiveness after five to ten years, after which a number of complications begins to emerge – notably ‘on-off’ fluctuations. In an ‘off’ period, the individual will find it almost impossible to start any action and can remain ‘frozen’ for long periods until helped out of the ‘off’ state. By this time, most people require several medicines, but their introduction will be carefully staged and the dose adjusted to suit individual patient requirements.
Another treatment available for a minority is stereotactic
brain surgery. This is performed to bring about a change in
a part of the brain called the thalamus, which can
relieve severe shaking. Alternatively, surgery on the globus
pallidus can have beneficial effects on the ‘off’ states,
when the patient cannot initiate voluntary movements (akinesia).
These operations are not without risk and will only be considered
for people with more serious disabilities who are responding
poorly to medicines. Notably, they do not prevent the disease
getting worse.
Deep brain stimulation – electrical stimulation of part of the thalamus or globus pallidus by an implanted electrode and electrical pulse generator - also has a beneficial effect on shaking and some other Parkinsonian symptoms.
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Loss of dopamine-producing cells with age
in relation to the development of symptoms A: A sudden loss may precipitate
Parkinson’s B: Some people have fewer dopamine cells to begin with
C: Most people do not reach the threshold for Parkinson’s -
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What impact is Parkinson’s likely to have on the individual and the family?
As with any chronic and incurable condition, a diagnosis
of Parkinson’s can have an immediate and profound effect on
all concerned. The initial reaction is often to think the
worst. At this stage, it is important that the nature and
likely future course of the illness (the prognosis)
is explained, that information is made available, and that
the people concerned are given support and reassurance. The
initial anxiety will often pass once it is understood that
Parkinson's can be controlled and that near-normal life can
continue for many years. This kind of support can help reduce
the risk of depression, which may be encountered in late-stage
Parkinson’s.
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What support other than medication is available?
It is important to emphasise that Parkinson’s is very ‘individual’ in its nature. No two people will develop the same set of symptoms or at the same rate – factors which bear considerably on treatment and self-management. Because of this, the advice and assistance given to people with Parkinson’s is vitally important.
As well as the medical and surgical treatments available to treat Parkinson’s, a number of other therapies have an important role to play in the management of the condition. These include physiotherapy, speech and language therapy and occupational therapy. Early referral to therapists for help and advice is recommended.
Physiotherapy means treatment using physical means
such as exercise and manipulation. Physiotherapists can help
people to retain good posture and give advice on the correct
approach to walking, sitting, turning and other activities
which can make a great difference to independence and confidence.
Regular exercise is also helpful.
Speech and language therapists treat problems associated
with speech and swallowing. They can suggest ways of improving
speech quality and help to minimise such problems as low volume
or lack of clarity.
The special skill of occupational therapists lies in assessing a person’s home or work situation and then devising ways to make them more manageable and less hazardous. This can help to maximise independence and lessen frustration. Sometimes, a new way of arranging furniture or approaching a task can make all the difference. They also advise on other aspects of work and leisure.
Many of these aspects are covered by the services and useful literature available from the Parkinson’s Disease Society. The Society provides sources for contact with other people with Parkinson’s or carers through local support groups which encourage learning and sharing of achievements and disappointments. The address and phone number of the Parkinson’s Disease Society are listed at the end of this booklet.
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Factors which affect the risk of getting
osteoporosis -
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