Parkinson’s disease is a neurodegenerative disorder that causes difficulty with walking and coordination. It occurs when the brain can no longer produce enough dopamine, one type of chemical in the brain. A progressive disease, Parkinson's starts gradually and gets worse with time.

The most common symptoms of Parkinson's disease are stiffness in different parts of the body, shaking (particularly in the hands, legs, and face), difficulty with balance and coordination, difficulty walking and slow movements. As the disease advances, muscle pain and cramps, problems with sleep, memory impairment, depression, and behavioral changes may set in, too.

The Hoehn and Yahr scale is used to stage Parkinson’s disease according to the order in which symptoms appear and gradually worsen. There were previously five stages in the Hoehn and Yahr scale, but over time it was modified—stages 1.5 and 2.5 were added to it.

Stage 1

Stage 1 is the earliest stage of Parkinson’s disease. In it, the symptoms you experience are very mild and do not cause any disability or interference with day to day living. The symptoms also affect only one side of the body—an occurrence known as unilateral involvement. The most common symptoms at this stage are tremors (usually in one hand or leg), and slight changes in posture, movement, and facial expressions.

Due to how mild the symptoms are, it is usually very difficult for a doctor to make a definitive diagnosis of Parkinson's disease during stage 1.

Stage 1.5

This stage is not very different from the first stage except that the neck and spine are now involved.

Stage 2

In the second stage of Parkinson’s disease, the symptoms affect both sides of the body (bilateral involvement), but your balance is not impaired. It may take months or years for you to move from the first stage to the second stage. Changes in posture and your gait are now more apparent. You may start experiencing problems with speech such as slurring your words, being unable to control the tenor of your voice.

Increased stiffness, loss of facial expression control are seen in this stage, too. All of these symptoms will have some, albeit minimal, disabling effect and cause interference to your day to day living. This stage still isn't easy to diagnose, as sometimes the symptoms are simply attributed to being part of aging.

Stage 2.5

In this stage, you start to experience a mild impairment of balance, but still no loss of balance. The "pull test" is usually performed to see the extent to which your balance has been affected. The test involves a doctor standing behind you and asking you to maintain your balance when he pulls you back.

Taking three or more steps to recover your balance when you are pulled backward is indicative of having reached this stage

Stage 3

In this third stage, Parkinson's disease significantly advances, and it is often considered mid-stage in the entire progression of the disorder. Loss of balance is finally experienced and the pull test is performed to check. If you don't regain your balance and the doctor has to catch you to prevent a fall, it is said that your balance is impaired.

Your body movements also start to slow down noticeably during the third stage—a manifestation medically referred to as bradykinesia.

Your doctor will find it easy to make a definite diagnosis when you have gotten to this stage of Parkinson’s disease. Disability is apparent at this stage, and you may find it more difficult to perform basic tasks like dressing and eating.

It is, however, still possible to be able to carry out your daily activities without external help. Depending on the kind of work you do and how much physical dexterity it requires, you may also still be able to remain employed.

Stage 4

Your symptoms become severe in this stage. You become unable to perform your daily tasks without assistance, or if you can, it will be very challenging, making independent living almost impossible. Your body parts and the slowness of movement becomes significantly worse. It is still possible to stand and walk by yourself, but it may be difficult and using a walker may make it easier.

Stage 5

This is the most advanced stage of Parkinson's disease, as most (or all) other symptoms previously experienced worsen. It becomes impossible for you to move around unaided and a wheelchair is necessary. You’ll also be unable to perform your daily living tasks such as eating, dressing up, and bathing by yourself.

Due to this, constant nursing care is necessary to prevent falls and other accidents from happening. Some people also experience delusions, dementia, hallucinations, and confusion at this stage.

It is important to know that Parkinson's disease, unlike some other conditions, is a highly individual one, and the way people experience its symptoms can vary wildly.

For example, some people may never reach stage 5 of Parkinson’s disease. In uncommon cases, a person’s symptoms may become severe but still be limited to just one side of the body.

Medically, these stages are used as a loose guide, and in fact, they make up one of the sections in the Unified Parkinson's Disease Rating Scale (UPDRS). The UPDRS is the widely accepted method of classifying, monitoring, and managing the progress of Parkinson's disease.

A Word From Verywell

Parkinson's disease can be a very debilitating disorder, however, you are not alone. Consider joining a support or community group with other people affected by Parkinson's. It may help you be better prepared for the changes you may experience as your condition progresses. If you can afford it or can find free resources around you, do not feel embarrassed to get counseling or mental health support. It will play a huge role in helping you cope better if depression sets in, and with the condition as a whole.

There are many therapies that exist to slow down the progression of the disease and ease its symptoms, so be sure to explore your options extensively with your doctor.

Diagnosing Parkinson's