Nerve and mental diseases. Nervous system diseases and mental disorders are called the plague of the XXI century. Prolonged depressions became a common phenomenon all over the world. Mental health of modern man is significantly spoiled by all kinds of neuroses. Doctors define neurosis as a mild form of mental illness which sometimes causes an inability to live a normal life. Most often neurosis is a person’s predisposition to respond too emotionally to stress. Mental disorders are more severe forms of mental illnesses than neuroses. Mental disorders appear when an individual loses his contact with a real life. It is believed that psychoses develop due to the violation of the brain chemical equilibrium or the damage of its part. It may be quite easy to manage symptoms using drugs but the mental disorder that hides behind the symptoms may remain incurable and lasts until the very death.