Faster Increase in Symptom Severity Tied to Older Age at Disease Onset
Older age at disease onset among people with Parkinson’s is associated with a more rapid increase in the severity of motor symptoms, as well as a faster decline in health-related quality of life, a new study found.
According to investigators, understanding the factors underlying the development of symptoms “is useful both on the individual level and for clinical research.”
“On the individual level, prognostic information can be useful for guiding treatment choices and for planning for the future, which is identified as a key need for patients and care partners,” they wrote.
Parkinson’s is often considered an age-related disease, as older age is a risk factor for the neurodegenerative disorder. However, the age at onset of Parkinson’s symptoms can vary by decades from person to person. The ways in which Parkinson’s progression tends to differ among people with an earlier or later age at the first signs of disease remain incompletely understood.
Now, a group of researchers in Europe conducted an analysis using data from the Swedish National registry for Parkinson’s Disease, dubbed PARKreg. The analysis included data for 1,436 patients, followed for an average of 1.7 years.
The median age upon inclusion in the registry was 72 years, and the median time since onset of Parkinson’s motor symptoms was just over six years. The majority of patients had relatively mild disease, the researchers noted.
The team conducted a battery of statistical analyses, looking at differences in trends for a variety of clinical factors based on variances in age at onset.
Broadly, the results showed that people with an older age at onset tended to have a more rapid worsening in motor symptoms. Generally, the team noted that the magnitude of the difference was relatively small.
Notable exceptions were for dyskinesia, or uncontrolled movements, and dystonia, or abnormal muscle tone, where an older age at the time of the first symptoms was generally associated with less severe progression.
An older age at first symptoms also was associated with greater severity in certain non-motor symptoms, including unexplained weight change, hallucinations, and double vision. Other non-motor symptoms like sexual health problems and constipation showed no association with age at onset.
“Higher age at onset was associated with a more severe course of disease,” the researchers wrote.
Over time, health-related quality of life (HRQoL) tended to get worse for all patients, though some differences were seen based on age at onset. Patients with a younger age when symptoms first occurred tended to experience a more pronounced decrease in HRQoL early on, with milder changes as the disease progresses. By contrast, an older age at onset was associated with a less substantial immediate change, but a greater decline in HRQoL over time.
These findings suggest “that earlier onset was associated with lower HRQoL or a greater initial impact on HRQoL than later onset,” the researchers wrote. “However, later onset was associated with faster worsening of HRQoL as measured by most of the outcomes.”