Neurodegenerative diseases are characterized by premature and selective aging of nerve cells. The frequency of these disorders increases with age, while the aging of the population is accelerating. Neurodegeneration can affect the cerebral cortex (Alzheimer disease), deep brain structures (Parkinson disease), the spinal cord (amyotrophic lateral sclerosis).
Multiple sclerosis and inflammatory diseases of the nervous system begin in the young adult and drastically change his future life.
Tumours are sometimes benign and treated by neurosurgery; often malignant, they are generally beyond therapeutic intervention.
Epilepsy, affecting young people, is treated effectively with pharmaceutical agents, but not always.
Stroke, tumours, developmental disorders, metabolic disorders, hereditary disease of the nervous system (Huntington, myopathies), etc, are difficult to accept, notably when they affect children.