Parkinson's

Parkinson’s is a progressive neurological disorder, typically visible at around 50 years. Aging is the largest known risk factor, but others include exposure to toxins and heredity.

Due to age being the largest risk factor, it makes it difficult to be proactive about lifestyle choices, but regular aerobic exercise can help.

There usually aren’t any medical tests to detect Parkinson’s so people often dismiss early symptoms such as loss of smell as normal aging effects.

Parkinson’s happens about 1.5 times more in men than in women.



Symptoms:

  1. Tremor in hands, arms, legs, jaw or head

  2. Stiffness of limbs and trunk, making it difficult to move

  3. Slow movement (Bradykinesia) due to stiffness

  4. Impired balance/coordination → can lead to falls

  5. Others

    1. Depression + emotional changes

    2. Problems with thinking

    3. Difficulty swallowing, chewing and speaking

    4. Urinary problems or constipation

    5. Skin problems

    6. Fatigue and sleep disruptions

The symptoms are progressive and can vary. Early stages are very subtle and occur gradually, often on 1 side of the body.

In later stages, motor symptoms become more obvious and affect both sides. This is the stage when someone would develop bradykinesia. They would also have distinct gait changes.



Parkinson’s disease affects the basal ganglia (a collection of 4 nuclei of neurons). Basal ganglia is important for fine-movement control and selects what behaviour to execute at a given time. It also switches between behaviours. These structures communicate with dopamine (neurotransmitter). 

In Parkinson’s, around 70-80% of dopaminergic neurons in 1 of these nuclei (substantia nigra) is lost.


Loss of dopamine causes other areas to become overactive. Due to overactivation, the output nuclei of the basal ganglia, which are inhibitory, become overactive and reduce the activity of the motor cortex (leading to the symptoms).

There is a degree of tolerance so at least 40% of these neurons must die before symptoms occur.

People with Parkinson’s also lose neurons in a lower brain nucleus (Locus Coeruleus of the Pons). This is where noradrenaline is made, which is used by the sympathetic NS. The sympathetic NS in the ANS controls many autonomic functions so the loss of noradrenaline explains the non-movement features of Parkinson’s.

Cellular death in Parkinson’s may involve external factors, making it pard to pre-determine and treat. Causes can include endogenous (within the body) chemical reactions, exposure to environmental factors and neurotoxins, and genetic predisposition. 



In Parkinson’s, many neurons in the substantia nigra contain Lewy bodies (unusual clumps of the alpha-synuclein protien). Lewy bodies can spread from celll to cell throughout the brain and may play a role in both familial and sporadic cases of Parkinson’s. These protein lumps have been found in many  parts of the body (not just the brain), explaining why Parkinson’s causes so many other symptoms apart from shaking and movement issues.