New study reveals different drivers behind the rising numbers in Parkinson’s, multiple sclerosis and motor neuron disease. The growing number of people living with Parkinson’s disease, MS and motor neuron disease is being driven by different underlying factors, according to new research.

Researchers from France and Sweden analyzed nationwide health data covering the entire populations of both countries to examine trends in the prevalence, incidence, and life expectancy of people living with MS, PD, 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 greatly 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 MS and PD 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.

According to researchers from Sorbonne University and the Paris Brain Institute, the fastest-growing disease in terms of prevalence is MS. Importantly, this rise does not appear to be driven by increasing incidence, but by improved life expectancy among patients. They noted the possible reasons behind improved MS survival may be that advances in immunosuppressive and immunomodulatory therapies 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 considered, 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.

The researchers said 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.

The findings will be presented at the European Academy of Neurology Congress 2026 and published in the journal Neurology.