Muhammad Ali is one of the most popular boxers, or sportspersons for that matter, of our times.
Shortly after Ali's retirement from boxing in 1981, rumours began circulating about his health.
His speech had become slurred, he shuffled and he was often drowsy.
In 1984, he was diagnosed with Parkinson’s disease.

Yes, my topic is Parkinson’s disease as is obvious. Now this is another neurological disorder (why do I love damaged brains so much?!) and has no real known cause.

Now what happens? There is a part of your brain called the substantia nigra which is a component of the basal nuclei of the brain. This disease causes gradual destruction of the dopaminergic neurons of the substantia nigra.
In simpler words, the dopamine producing neurons gradually degenerate.
Since dopamine promotes motor activity, the decreased dopamine leads to increased effort being needed for movement. This consequently leads to stiffness and rigidity., which are the main symptoms (more on that below)

Causes

It is still unknown as to what exactly causes this condition. However, the following two factors are the most implicated:-

Genetics:- Is it even a surprise here? Of course your genes are responsible. While it has been linked to various genes, it has not been conclusively proven to be entirely genetic in nature.
Environmental factors:- Ol' Muhammmad Ali was rumoured to have been affected due to the blows he received to his head during his career. Some toxins may also lead to parkinsonism though it is uncommon.

Signs and symptoms

Major signs are:-

Tremors in the hand/arm, especially while at rest
Slowness of movement
Muscle rigidity
Loss of postural balance

Other problems may arise as a consequence:-

Mental symptoms such as dementia and depression. The cognitive abilities are affected.
Physical problems such as sleep disorders, sexual dysfunction, bladder problems, difficulty in swallowing, excessive sweating and salivation, impaired smell.

Diagnosis

This condition cannot be diagnosed easily. There are no definite tests for diagnosing it. Hence, a carefully elicited medical history is taken and on its basis, medication is provided. Improvement in symptoms usually confirms the existence of this condition. Other tests such as imaging may be done to rule out other conditions which may cause parkinsonism.

Treatment

This disease has no known cure, however, most symptoms can be controlled. Following are the methods used:-

Medication:- Most effective drug is levodopa, which is converted to dopamine within the body. It can lead to drastic improvement although it shows undesirable side effects with prolonged use.
Surgery:- It is done in those whom medication is not sufficient enough. The common surgical procedure used is deep brain stimulation.
Physiotherapy/exercise:- There is evidence that this helps in improvement of the motor symptoms.