CADASIL: yesterday, today, tomorrow.

BACKGROUND AND PURPOSE: In 2019, the Brain Prize crowned the discovery of CADASIL in the 1990s and research efforts on this archetypal small vessel disease of the brain over 40 years. METHODS AND RESULTS: The hereditary origin of this arteriolopathy was discovered from a first clinical case and detailed observation of the patient's family. Thereafter, the role of causative mutations within the NOTCH3 gene were identified, allowing the development of a genetic test and then of an animal model of the disease. These crucial steps led to the discovery progressively that CADASIL is the most common genetic cerebral small vessel disease, to describing for the first time the natural history of a cerebral ischaemic small vessel disease from silent cerebral tissue lesions up to severe motor disability and dementia at the end stage, to demonstrating the central role of matrix proteins in its pathophysiology and to opening the door to the discovery of several other genes involved in monogenic cerebral small vessel diseases. DISCUSSION: Today, CADASIL is known to every neurologist, but the disease has not yet revealed all its secrets. A lot of effort is still needed to understand the intimate mechanisms of the disease and the most efficient targets or approaches for the development of efficient therapeutics. The history of CADASIL will be further enriched by multiple ongoing research projects worldwide, at clinical and preclinical level, and will continue to enlighten research in the field of cerebral small vessel disorders.