Parkinson’s disease is not a fatal illness. However, it’s a degenerative disorder that usually progresses until it leaves its patients completely debilitated. The condition usually worsens over an average of 15 years.

The rate of progression and its course varies among patients. The course is relatively benign in some patients with little disability after twenty years and may be more aggressive among others who may be severely disabled after ten years. Those with an early onset Parkinson’s disease have shorter life spans than those with later-onset disease.

Untreated prognosis

Untreated, Parkinson’s disease worsens over years. Parkinson's may lead to a deterioration of all brain functions and an early death. Life expectancy however is normal to near normal in most treated patients of Parkinson’s disease.

Prognosis with medications

Most people respond to medications. However, the extent of responsiveness and the duration of how long the efficacy of the drug lasts varies from person to person. The side effects of medications are another deterrent in their use.

Movement disorder symptoms differ from person to person. For some they are more bothersome than others depending on what a person normally does during the day. In some the mild symptoms may last for many years while in others they may develop more quickly. Non-motor symptoms may also vary from person to person. They affect most people with Parkinson's at all stages of disease.  Some people with Parkinson's find that symptoms such as depression or fatigue may be more cumbersome to deal with that the movement disorders themselves.

Complications of Parkinson’s

Complications associated with Parkinson’s disease usually lead to a lowered life expectancy rather than the disease itself. PD may cause complications such as choking, pneumonia, and falls leading to severe injury or death.

Stages of Parkinson’s

There are several rating scales that may be used as tools to understand the progression of the disease. The stages of Parkinson's correspond to severity of movement symptoms and to the degree of impairment in a person’s daily activities. 

The most commonly used rating scales are focused on the motor symptoms. Commonly used scales are:-

• Hoehn and Yahr scale that rate symptoms on a scale of 1 to 5.  On this scale, depending on a person’s difficulties, 1 and 2 represent early-stage, 2 and 3 mid-stage, and 4 and 5 advanced-stage Parkinson's.
• United Parkinson’s Disease Rating Scale (UPDRS) scale is more comprehensive than the Hoehn and Yahr scale. It takes into account cognitive difficulties, ability to carry out daily activities, behaviour, mood, and treatment complications along with movement symptoms.