Parkinson’s is a progressive illness, with symptoms gradually growing worse over time. This process is usually very gradual. Many people with Parkinson’s believe they had the condition for some time – often two to three years – before they sought a formal diagnosis. Often it is only when symptoms become obvious or start to interfere with daily life that people visit the doctor.
Symptoms and responses to treatment vary from person to person, so it is not possible to accurately predict how Parkinson’s will progress. For some people it may take many years for the condition to develop, for others it may take less time.
A number of rating scales are used to measure progression in Parkinson’s, for example the Hoehn and Yahr scale which categorises the severity of motor symptoms based on how they affect an individual’s mobility. Often more than one scale is used to give a broader picture. Motor (movement) scales are the best-known and most widely used, but non-motor symptom scales are equally important.
See also, Rating scales.