Parkinson’s disease (PD) impacts people in different ways. Not everyone will experience all the symptoms of Parkinson’s, and if they do, they won’t necessarily experience them in quite the same order or at the same intensity. There are typical patterns of progression in Parkinson’s disease that are defined in stages.

Stage One
During this initial stage, the person has mild symptoms that generally do not interfere with daily activities. Tremor and other movement symptoms occur on one side of the body only. Changes in posture, walking and facial expressions occur.

Stage Two
Symptoms start getting worse. Tremor, rigidity and other movement symptoms affect both sides of the body. Walking problems and poor posture may be apparent. The person is still able to live alone, but daily tasks are more difficult and lengthy.

Stage Three
Considered mid-stage, loss of balance and slowness of movements are hallmarks. Falls are more common. The person is still fully independent, but symptoms significantly impair activities such as dressing and eating.

Stage Four
At this point, symptoms are severe and limiting. It’s possible to stand without assistance, but movement may require a walker. The person needs help with activities of daily living and is unable to live alone.

Stage Five
This is the most advanced and debilitating stage. Stiffness in the legs may make it impossible to stand or walk. The person requires a wheelchair or is bedridden. Around-the-clock nursing care is required for all activities. The person may experience hallucinations and delusions. The Parkinson’s community acknowledges that there are many important non-motor symptoms as well as motor symptoms.

Watch this video for more information about the forms and stages of Parkinson’s.

Rating Scales
Your doctor may refer to a scale to help them understand the progression of the disease. Parkinson's stages correspond both to the severity of movement symptoms and to how much the disease affects a person’s daily activities. The most commonly used rating scales focus on motor symptoms. They are the:

Hoehn and Yahr stages follow a simple rating scale, first introduced in 1967. Clinicians use it to describe how motor symptoms progress in PD.

Rates symptoms on a scale of 1 to 5. On this scale, 1 and 2 represent early-stage, 2 and 3 mid-stage, and 4 and 5 advanced-stage Parkinson's.

The Unified Parkinson’s Disease Rating Scale (UPDRS) is a more comprehensive tool used to account for non-motor symptoms, including mental functioning, mood and social interaction.

Accounts for cognitive difficulties, ability to carry out daily activities and treatment complications.
New scales include information on non-motor symptoms (such as sense of smell).

While symptoms and disease progression are unique to each person, knowing the typical stages of Parkinson’s can help you cope with changes as they occur. Some people experience the changes over 20 years or more. Others find the disease progresses more quickly.

Theory of PD Progression: Braak’s Hypothesis
The current theory (part of the so-called Braak's hypothesis) is that the earliest signs of Parkinson's are found in the enteric nervous system, the medulla and the olfactory bulb, which controls sense of smell. Under this theory, Parkinson's only progresses to the substantia nigra and cortex over time.

This theory is increasingly borne out by evidence that non-motor symptoms, such as a loss of sense of smell (hyposmia), sleep disorders and constipation may precede the motor features of the disease by several years. For this reason, researchers are increasingly focused on these non-motor symptoms to detect PD as early as possible and to look for ways to stop its progression.