TUESDAY, June 23, 2026 (HealthDay News) -- The prevalence rates of multiple sclerosis (MS), motor neuron diseases (MNDs), and Parkinson disease (PD) are increasing over time, with different factors accounting for the increases, according to a study published online June 5 in Neurology to coincide with annual congress of the European Academy of Neurology, being held June 27 to 30 in Geneva.Octave Guinebretiere, from Sorbonne University and the Paris Brain Institute, and colleagues conducted two nationwide, population-based, retrospective cohort studies in Sweden and France to examine the temporal trends in prevalence, incidence, and life expectancy at diagnosis of PD, MS, and MNDs.The researchers found that in the pooled model, there was a significant increase in the annualized prevalence of PD, MS, and MNDs between 2003 and 2022 (prevalence ratio per year: 1.014, 1.029, and 1.028, respectively). Over time, the crude incidence of both PD and MS remained nearly stable (incidence rate ratio [IRR] per year, 0.998 and 0.992, respectively), while there was a more marked decrease for PD in standardized incidence (IRR, 0.986) but almost no change for MS (IRR, 0.995). Both the crude and standardized incidence of MNDs increased over time (IRR, 1.018 and 1.008, respectively). Between 2003 and 2013, there was an increase in life expectancy at diagnosis of PD (+0.95 months per calendar year), followed by a decrease from 2013 to 2022 (−1.20 months); for MS and MNDs, significant increases were seen during the entire study period (+2.35 and +0.34 months, respectively)."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," lead coauthor Thomas Nedelec, Ph.D., also from Sorbonne University, said in a statement.Several authors disclosed ties to the biopharmaceutical industry.Abstract/Full Text (subscription or payment may be required)Editorial (subscription or payment may be required).Sign up for our weekly HealthDay newsletter