The growing number of people living with Parkinson's disease (PD), multiple sclerosis (MS) and motor neuron disease (MND) is being driven by different underlying factors, according to new research due to be presented at the European Academy of Neurology (EAN) Congress 2026 and published in Neurology.1,2
Researchers from France and Sweden analysed nationwide health data covering the entire populations of both countries to examine trends in the prevalence, incidence and life expectancy of people living with PD, MS and MND between 2003 and 2022. While the number of people living with all three conditions increased, the factors driving these trends differed substantially between diseases.
MS prevalence appears to be increasing largely because people are living longer after diagnosis, likely reflecting advances in treatment and care. In contrast, MND was the only condition to show rising age-adjusted incidence, suggesting factors beyond population ageing may be contributing. For Parkinson's disease, age-adjusted incidence declined over time, indicating that historical increases in prevalence have been driven mainly by improved survival rather than increasing disease risk.
While crude incidence of PD and MS remained largely stable throughout the study period, both crude and age-adjusted incidence increased for MND. Life expectancy also improved for people living with MS and MND. For PD, life expectancy increased between 2003 and 2013 before declining in later years.
Lead author Dr Thomas Nedelec, from Sorbonne University and the Paris Brain Institute, said, "The fastest-growing disease in terms of prevalence is multiple sclerosis. Importantly, this rise does not appear to be driven by increasing incidence, but by improved life expectancy among patients."
Discussing the possible reasons behind improved MS survival, Dr Nedelec added, "For multiple sclerosis, advances in immunosuppressive and immunomodulatory therapies may have contributed substantially by reducing disease activity and improving long-term outcomes."
For MND, researchers say population ageing explains much of the increase in incidence, but not all of it. Greater awareness and improvements in diagnosis may have contributed to more cases being identified, although the possibility of changing environmental or lifestyle-related risk factors cannot yet be ruled out.
For PD, the picture appears more complex. Once the effects of population ageing were taken into account, the number of new cases declined over time. Researchers suggest this pattern may reflect better disease management and improved treatment of related health conditions, particularly cardiovascular disease.
Dr Nedelec explained, "There are several important messages here. The number of people living with these neurological conditions continues to rise substantially, but this does not appear to be driven by a major increase in new cases. That is reassuring from a public health perspective, as it suggests we are not seeing a dramatic rise in population-level risk."
The findings highlight the importance of understanding the different mechanisms driving disease prevalence, as rising survival and increasing incidence have very different implications for healthcare planning, service provision and disease prevention.
Looking ahead, the research team are calling for a coordinated European effort to better understand long-term neurological disease trends.
"We see a clear need for a large-scale European initiative that reproduces this type of analysis across the continent," Dr Nedelec concluded. "This would help us better understand differences between countries and improve our understanding of the factors driving these diseases."
