Résumé
Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS) often exhibit a prolonged presymptomatic phase during which neuropathological changes silently progress. Recent advances in biomarker research have revealed molecular and imaging signatures that precede clinical onset by years, offering a critical window for early intervention. This review synthesizes current knowledge on the most promising presymptomatic biomarkers across these conditions, highlighting their biological origins, diagnostic performance, and clinical utility. Particular emphasis is placed on the development and validation of biomarker panels, which combine multiple markers to enhance diagnostic sensitivity and specificity, enabling more accurate detection of disease in its earliest stages. Minimally invasive approaches, such as blood-based assays, are also discussed for their potential to facilitate widespread screening and longitudinal monitoring. As these biomarkers begin to integrate into clinical workflows, particularly in AD and MS, international collaboration will be essential to standardize methodologies and ensure equitable implementation. Ultimately, presymptomatic biomarkers hold transformative potential for shifting neurology toward a proactive and precision-based paradigm.