Psychosis is a mental state in which the individual’s cognitive judgment and contact with reality are disturbed. Hallmark symptoms of psychosis include hallucinations and delusions. Psychosis can result from a psychiatric disorder, such as schizophrenia, but it can also be caused by substance abuse, a brain tumor or neurodegenerative disease. Psychosis is a condition that affects the way your brain processes information. It causes you to lose touch with reality. You might see, hear, or believe things that aren’t real. Psychosis is a symptom, not an illness. A mental or physical illness, substance abuse, or extreme stress or trauma can cause it.Psychotic disorders, like schizophrenia, involve psychosis that usually affects you for the first time in the late teen years or early adulthood. Young people are especially likely to get it, but doctors don’t know why. Even before what doctors call the first episode of psychosis (FEP), you may show slight changes in the way you act or think. This is called the prodromal period and could last days, weeks, months, or even years. Psychosis is characterized by an impaired relationship with reality. It’s a symptom of serious mental disorders. People who are experiencing psychosis may have either hallucinations or delusions. Hallucinations are sensory experiences that occur within the absence of an actual stimulus. For example, a person having an auditory hallucination may hear their mother yelling at them when their mother isn’t around. Or someone having a visual hallucination may see something, like a person in front of them, who isn’t actually there.