Rare Diseases with Serious Consequences

Motor Neuron Diseases (MND), including ALS, which accounts for 90% of cases in adults, lead to rapid loss of independence and premature death, often within 2 to 5 years of diagnosis. In the absence of a curative treatment, these conditions pose a major challenge for patients, their caregivers, and the healthcare system.

In France, updated indicators confirm a standardized incidence of 3 to 3.5 cases per 100,000 inhabitants per year—close to European rates—and an equivalent mortality rate, reflecting the high fatality rate of these diseases. Thus, each year, approximately 2,250 people are diagnosed in France and approximately 1,840 people die.

The study conducted by Santé publique France reveals that:

• Incidence and mortality remained stable over the 2010–2021 period, after adjustment for age and sex.

• Men are more affected than women, consistent with international data.

• Regional disparities are observed, with areas of excess incidence identified at the regional, departmental, and even intermunicipal levels, where groups of ^EPCI^1s exhibit locally higher incidence and mortality rates compared to the national average.

Sustained epidemiological surveillance useful for research and the management of these diseases

For the first time, drawing on medical and administrative data from the National Health Data System (SNDS), this study analyzes and compares the incidence and mortality of motor neuron diseases in France over more than a decade, including a detailed mapping of the geographic distribution of affected individuals. The availability of these new indicators and the analysis of their trends over space and time shed light on several key issues:

• For decision-makers and stakeholders in the management of motor neuron diseases (MNDs): by providing health authorities, healthcare providers, and lawmakers with essential local indicators to adapt the provision of healthcare information and medical-social support, and to inform discussions on end-of-life care; and by providing contextual information to address persistent questions regarding spatiotemporal aggregates.

• For research: by providing results to guide investigations into the causes of MMN (including amyotrophic lateral sclerosis, or ALS), as part of Action 5.1 of the 2025–2030 National Plan for Rare Diseases (improving information for professionals, patients, and the general public).

• Thus, Santé publique France recommends furthering investigations in collaboration with expert centers. The objective is twofold: to strengthen epidemiological surveillance in order to inform and improve patient care and support public policies, particularly in the regions most affected, and ultimately to refine our understanding of the determinants of these diseases, particularly within the framework of the 2025–2030 National Plan for Rare Diseases and the National Strategy for Neurodegenerative Diseases.