medwireNews: The global burden of Parkinson’s disease has more than doubled over the past 26 years, show findings from the Global Burden of Disease Study 2016.
“[T]his increase was not solely due to increasing numbers of older people because age-standardised rates also increased in most regions”, note E Ray Dorsey (University of Rochester, New York, USA) and co-researchers.
The team carried out a systematic analysis and identified 127 epidemiological data sources on Parkinson’s disease, including 91 on prevalence covering 16 world regions, 34 on incidence covering nine world regions and 11 sources on mortality risk covering two world regions.
Using various methods of analysis, they estimated that between 1990 and 2016, the number of people worldwide with Parkinson’s disease increased 2.4-fold, from 2.5 million to 6.1 million.
The researchers comment in The Lancet Neurology that, while aging populations were a major contributing factor to that growth in numbers, as crude prevalence rates increased by 74.3% during the 26 years, age-standardised prevalence rates also increased by 21.7%.
Parkinson’s disease was the cause of 211,296 deaths in 2016 and was responsible for 3.2 million disability-adjusted life–years (DALY), which was 2.6 and 2.5 times higher, respectively, than in 1990. Again, these differences were not solely explained by an increasing number of older people, with age-standardised rates for both increasing by about 22% between 1990 and 2006, and they generally increased across the Socio-demographic Index.
Possible other reasons for the growth in Parkinson’s disease include longer disease duration as a result of longer life expectancy and environmental factors linked to growing industrialisation, suggest the investigators.
Indeed, they found that Parkinson’s disease prevalence and rates of death and DALY increased with time across all global regions, but most notably in China, which the team points out “has undergone rapid industrial growth since 1990.” The only regions to not show an increase in Parkinson’s disease prevalence and burden were southern Latin America, eastern Europe and Oceania.
Another possible factor contributing to the findings is the decline in rates of smoking, consider Dorsey and colleagues, as “[t]he risk of Parkinson’s disease is decreased approximately 40% among smokers.”
The study confirmed that Parkinson’s disease is about 1.4 times more frequent in men than women, which may be related to “[e]nvironmental (eg, occupational) exposures to which men are more frequently exposed”, the researchers propose, and this difference did not change substantially between 1990 and 2016.
They stress that “[a]s the population ages and life expectancy increases, the number of individuals with Parkinson’s disease will continue to increase as well as the duration of the disease, leading to more patients with advanced Parkinson’s disease. To address this burden, primary prevention strategies based on the underlying causes of Parkinson’s disease and more effective treatments than are currently available are required.”
Agreeing with this sentiment, Walter Rocca (Mayo Clinic, Rochester, Minnesota, USA) says in a related commentary: “A relatively conservative projected doubling of the number of patients over the next 30 years would yield more than 12 million worldwide by about 2050.
“However, if population aging continues, medical management keeps improving survival, and environmental or social risk factors remain stable or increase, we can expect an even greater increase in the number of patients.”
He adds that different preventive strategies might need to be considered separately for men and women and tailored to specific countries or regions of the world.
By Lucy Piper
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