If you like reading Psychology literatures, you've probably already encountered the terms psychosis and neurosis. Both imply an unhealthy psychology. But do you know what they exactly mean?
When you say psychosis, it refers to a mental state where a person experiences hallucination and delusion.
Hallucination may involve any of the senses, such as vision and hearing. A hallucinating person sees, hears, smells, touches, or tastes objects that aren't really existing. Hallucination often occurs when a person is under the influence of drugs. That is why there are often cases when psychosis is induced by substance abuse. But hallucination also occurs due to other mental conditions that aren't substance-related.
On the other hand, delusion is an experience when an existing object is perceived differently. In other words, there is a distortion of reality. Besides the distortion of objects, a delusion may also refer to a distortion of thoughts, perception, and judgment. There are many types of delusions. Examples include delusion of grandeur, where one believes he or she has special powers, talents, or abilities, and delusion of persecution, where one believes he/she is being harmed by someone.
Having these symptoms make a person with psychosis dysfunctional. As being out of touch in reality makes it impossible for the person to function normally in society.
Going on to neurosis, it is a cluster of behaviors that is manifested due to an emotional distress. Unlike psychosis, neurosis is experienced by everyone, with or without a mental illness, and may still be socially acceptable. There are many forms of neurosis, but all forms exist in response to stress or anxiety a person encounters. Examples include depression, aggression, low self-esteem, and phobia. Neurosis may also involve physical symptoms, such as excessive trembling and vomiting. The main difference of neurosis from psychosis is that the person experiencing neurosis is still in touch with reality.