Parkinson's: A Deeper Dive
Parkinson’s: A Deeper Dive, provides an overview of the disease, with scientific and medical expressions explained in simple terms.
Parkinson’s disease is a progressive neurological disorder. This means that brain function will become more and more affected over time, leading to a whole range of bodily signs and symptoms.
What causes Parkinson’s disease?Parkinson’s disease is caused by an increasing impairment of specific neurons (nerve cells in the brain). When these neurons work, they produce a chemical called dopamine. Dopamine acts as a chemical messenger, passing electronic messages that allow the different areas of the brain to communicate. This communication is what enables smooth muscle movement and the successful completion of action. For instance, reaching out and picking up a cup of tea requires the synchronised movement of an arm to reach, a hand to grip, and messages from the optic nerve in the eyes to communicate the distance from your hand to the cup. A lack of dopamine leads to unusual nerve function, which causes a lack of control over the movements of the body. . The actual cause of Parkinson’s disease hasn’t yet been discovered, but some avenues of thought include:
Genetic factorsIn a number of families where young people are diagnosed with Parkinson’s, genetic factors have been identified, but as yet those genetic factors appear in a very small number of people with Parkinson’s, so this cause isn’t yet confirmed.
Environmental factorsSome sources suggest that external or internal toxins may lead to the destruction of dopamine producing cells in the brain. These toxins include:
- Manganese - an essential mineral found in all living organisms, but in large amounts it can cause damage to the brain
- Carbon monoxide - is a neurotransmitter that helps to control inflammatory responses in the body, but in large amounts causes carbon monoxide poisoning
- Carbon disulfide - is highly toxic, used in fumigation processes, and causes many dangerous side effects
- Some pesticides - chemical compounds used to kill insects, rodents, fungi, etc.
A brief history of Parkinson’s
- James Parkinson first observed the condition in “An essay on the shaking palsy”, published in 1817.
- In 1919 it was discovered that people with Parkinson’s disease lose cells in the substantia nigra, the part of the midbrain where dopamine neurons originate.
- In 1957, Carlsson discovered that dopamine was a ‘putative neurotransmitter’ (a neurotransmitter transmits signals between nerve cells in the brain).
- In 1960, Ehringer and Hornykiewicz discovered that there’s much less dopamine in patients with Parkinson’s disease.
- In 1961, after the Ehringer and Hornykiewicz discovery, trials of levodopa (the main medication used to treat Parkinson’s) began. Levodopa is a chemical building block that your body can transform into dopamine. This amazing progress won Carlsson the Nobel Prize for Medicine in 2000.
It took 183 years, from the discovery of Parkinson’s disease to the discovery of a treatment, and a cure is yet to be found.
The signs and symptomsThere are four main symptoms of Parkinson’s disease, known as TRAP features: ....Tremor at rest ....Rigidity ....Akinesia (or bradykinesia) ....Postural instability Two more, flexed posture and freezing, are also considered ‘classic’ features of Parkinson’s.
Tremor at restThis is the most common and easily recognised symptom of Parkinson’s disease. Hand tremors often spread from one hand to the other, but rest-tremor can involve lips, chin, jaw, and legs. Typically this type of tremor disappears when the affected area is being used, for instance, a lip tremor will typically disappear when the patient is speaking. Tremors also stop during sleep.
RigidityThis means ‘increased resistance’. It can be described as an ‘involuntary push’ against a force. For instance, if a doctor is trying to bend your arm at the elbow, your joint will resist whether you want it to or not. This usually includes the ‘cogwheel’ phenomenon, which means that your arm will be shaking while the doctor is bending it. Rigidity can appear in the neck, shoulders and hips, as well as the wrists and ankles. This symptom can cause pain, and pain in the shoulder is a very typical initial sign of Parkinson’s disease. Because shoulder pain is such a general symptom, it can be misdiagnosed as arthritis or a number of other conditions.
Akinesia (bradykinesia)Simply put, this means slowness of movement. It’s very common in conditions related to the area of the midbrain affected by Parkinson’s disease, and can cause:
- Difficulties with planning
- Beginning and ending movement
- Performing more than one task in a row or at the same time
- Loss of movements and gestures
- Drooling (due to trouble with swallowing)
- Monotonic and hypophonic dysarthria - which means a level and toneless voice and an expressionless face
- Less blinking
- Stiff arms while walking
Postural instabilityThis usually happens during the later stages of Parkinson’s disease, after other signs and symptoms have been recognised. Postural instability is the most common cause of falls, and fear of falling also increases the likelihood of taking a tumble. There are various treatment options, which can ease postural instability a little:
- Dopaminergic therapy - regulation of dopamine levels.
- Pallidotomy - a surgical procedure where an electrical probe is placed in the brain and heated to destroy a specific area of brain cells.
- Deep brain stimulation - a surgical procedure where two tiny electrodes are placed in the brain, connected by a wire under the skin to a battery. This device can be called a brain pacemaker, as it delivers electrical pulses that block the brain signals causing certain symptoms.
FreezingCausing loss of movement, freezing is one of the most disabling symptoms of Parkinson’s and usually happens later in the disease. Freezing is not something everyone with Parkinson’s experiences; of 6,620 patients asked, during one study by the German Parkinson’s Association, 47% reported freezing. It usually causes a sudden inability to move, lasting under and up to 10 seconds. Categories include:
- Start hesitation
- Turn hesitation
- Hesitation in tight quarters
- Destination hesitation
- Open space hesitation
How is Parkinson’s diagnosed?As yet there are no tests that can specifically diagnose Parkinson’s disease. The diagnosis is based on symptoms, medical history, and a thorough physical examination. The examination will include talking about the problems facing the patient and performing simple mental and physical tasks. In the early stages it can be difficult to say for sure if the symptoms are related to Parkinson’s. If the GP suspects Parkinson’s, then a referral will follow, and the patient will usually see a specialist within 6 weeks. They will commonly see:
- A neurologist - a specialist in conditions affecting the brain and nervous system
- A geriatrician - a specialist in conditions affecting the elderly
- Specialist nurses
- Speech and language therapists
The comorbiditiesA comorbidity is the name given to another disease, condition or state that can appear as a result of the initial disease. For instance, the most common comorbidities of chronic disease are mental health problems, back problems, asthma and arthritis. Parkinson’s disease can cause all of these, alongside:
DementiaThe Sydney Multicenter Study of Parkinson’s Disease found that 84% of patients evaluated showed cognitive decline, and that 48% met the diagnostic criteria for dementia after 15 years of follow-up. It has been estimated that people with Parkinson’s are 6 times more likely to develop dementia.
Hedonistic homeostatic dysregulationObsessive-compulsive and impulsive behaviour, including:
- Binge eating
- Pathological gambling
- Punding - which is intense fascination and repetitive handling and arranging of objects.
Sleep disordersOnce thought to be a side-effect of the medications prescribed to combat the symptoms of Parkinson’s disease, sleep disorders are now believed to be an integral part of the disease. Rapid eye movement sleep behaviour disorder - which is now considered to be an early sign of Parkinson’s disease - includes:
- Increased violent dream content
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What is an ‘on’ or ‘off’ state?The medical dictionary defines the ‘on-off’ phenomenon as:
A refractoriness to the ability of Levodopa to control the smooth skeletal musclemovement in Parkinson’s disease, where periods of excess abnormal movements - ‘on’, alternate with periods of prolonged immobility or freezing - ‘off’; ‘on-off’ also refers to the waxing and waning of parkinsonism itself.This simply means that while levodopa will help the brain by providing the building blocks from which it can produce more dopamine, the rate at which the brain does this will be higher on some days than on others. It also means that the symptoms of Parkinson’s disease appear worse at some times than at others. The ‘on-off’ phenomenon has been described by patients as the equivalent of switching ‘on’ a lightbulb, and the ‘off’ state being a return to darkness. As one patient described in a 1989 edition of the Journal of Neurology, Neurosurgery, and Psychiatry:
'On' is quite simply normal; I can survive a dinner party, drive a car, write a fair, round hand, my voice is normal. I can fall asleep rather easily unless I am trying not to. 'Off', on the other hand, is very unpleasant. I lose almost all motor power in my legs; and this paralysis increasingly now spreads to my arms. Sometimes odd pains and cramps move round the body. There is no position in which I am comfortable. I can't write, I can't type, my speech is slurred and low-powered.This is almost always a result of long-term levodopa use. Swings can last for between 1 and 3 hours, but sometimes 2-3 rapid swings can happen in just 30 minutes. Fragmentation of dosing can help to regulate these swings, and involves more frequent, lower doses of levodopa. This tactic is normally backed-up by the use of other treatments: