Does Parkinson's disease only affect older populations?

Parkinson's disease is most commonly diagnosed in people over the age of 60 but an estimated 5% of the cases of PD occur in folks younger than 40 (https://parkinsonsdisease.net/special-populations/). Probably the most famous case of young-onset Parkinson's disease (YOPD) is that of the actor Michael J. Fox, who was diagnosed in 1991 at age 29. According to scientists who research PD, there may be a stronger genetic factor leading to the development of YOPD than in other cases (https://parkinsonsdisease.net/young-onset-parkinsons-disease/). The perception that PD only (or at least, most commonly) affects older people can lead to misdiagnosis or a prolonged diagnosis process for young people. If you or a loved one has symptoms of PD (https://parkinsonsdisease.net/symptoms/), we encourage you to ask for a referral to a neurologist specializing in movement disorders for further evaluation (https://parkinsonsdisease.net/diagnosis-treatment/).

Parkinson's disease is commonly thought to be a disease of older adults but can impact those who are younger. Young-Onset Parkinson's disease can affect those under the age of 40, is a small percentage (between 5-10%) of the Parkinson's disease community (reference: http://www.pdf.org/parkinson_young_onset). My husband, Karl has young-onset Parkinson's disease. He was diagnosed twenty-seven years ago, at the age of 23.
You can read more about Young-Onset Parkinson's disease in this article (link to YOPD article)