What is Psychosis?

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Psychosis is a word used to describe a group of experiences that affect a person’s:

  • Perceptions. Perceptions are about how people see, hear or experience things through their senses. Some people have experiences called hallucinations. Hallucinations are when someone sees, hears or feels things that aren’t there.
  • Thinking. People’s thinking can become disorganised and they can find it hard to stay focused. They can also experience delusions. Delusions are unusual and false beliefs.
  • Behaviours. This is about how people act and what they do. The behaviour of some people changes when they experience psychosis. For example, some people with psychosis do less of the things they used to do before.
  • Communication. This is about how people express themselves and communicate with others. Some people with psychosis find it hard to express themselves and communicate with other people.

Hallucinations and delusions are often called psychotic experiences.

Psychotic experiences are very common. About 1 in 12 of people will experience hallucinations or delusions at some time in their life. For most people, the experiences don’t last and are not a symptom of a psychotic disorder. Childhood is the most common time to have psychotic experiences.

A psychotic disorder is a medical diagnosis. About 1 in 100 people will be diagnosed with a psychotic disorder at some time in their life. People with a psychotic disorder experience hallucinations and/or delusions.  They can also have difficulties with their thinking and behaviour. These experiences:

  • Happen over time
  • Happen often
  • May be distressing for the person
  • Negatively affect the person’s life

Negatively affect a person’s relationships with other people

Research suggests that the cause of psychosis is complex. Here are some of the main things that can increase someone’s risk of developing a psychotic disorder.

Genetic vulnerability

This refers to inherited genetic characteristics passed on from parents to children.

Delayed childhood development

A risk factor for some people who develop psychosis is delayed childhood development.

Being a victim of trauma, violence or abuse

In particular, childhood experiences of trauma or abuse.

Early experiences of stress

This can include stressful life events. It can also refer to environmental stress, like growing up in poverty.

Drug use

Certain drugs are associated with higher risk of psychosis. Cannabis is has been found to increase people’s risk of psychosis. Drug use during adolescence is particularly problematic.

Poor mental health

Having mental health difficulties can increase someone’s risk of having psychotic experiences.

People with a psychotic disorder can experience one or more of the following symptoms.


Hallucinations are when someone sees, feels or senses things that aren’t there. They can involve any of the 5 senses:

  • Hearing. When someone hears sounds or voices that aren’t there. These are called auditory hallucinations.
  • Seeing. When someone sees things (objects, people or images) that aren’t there. These are called visual hallucinations.
  • Taste. When someone tastes things that they haven’t eaten. These are called gustatory hallucinations.
  • Touch. When someone senses someone or something touching them when nothing is near them. These are called haptic hallucinations.
  • Smell. When someone smells something that isn’t around. These are called olfactory hallucinations.


Not all hallucinations are a sign of mental ill-health. Hallucinations can be normal occurrences. For example, people can think they hear someone calling their name when they’re going to sleep.

When someone has a psychotic disorder, their hallucinations are usually intense and persistent. Persistent means they keep happening over time. Hearing voices or seeing things can be very upsetting. It can also be very distracting. That can affect how someone feels and how well they can relate to other people.

In the video below Eleanor Longden talks about her experience of hearing voices.

Difficulties related to people’s thinking

Some people with a psychotic disorder experience problems with their thinking.

  • They may lose their ability to concentrate
  • They may struggle to learn things as well as they did before
  • They may find it hard to make decisions
  • Their thoughts can become jumbled up. That can affect how they express what they’re thinking and feeling.
  • They can experience delusions



Delusions are false beliefs a person holds with strong conviction.

When someone has a delusion, it’s hard to convince them their beliefs aren’t true. They hold the belief even when there’s no evidence to support it.

There are lots of false beliefs people can have. Some examples include when a person believes:

  • That people are against them or wish to harm them
  • They have extra special powers that no one else has
  • They are being spied on in their home
  • Another force is trying to control them

Being very suspicious of people and believing that people are against you are called paranoid beliefs.  These beliefs can affect how people feel about themselves and the world around them. For example, they may not feel safe in certain places. That could even include their own home.

Some delusions happen when a person misinterprets what’s happening around them. For example, someone with delusions might believe:

  • Topics on the news have special meaning for them
  • Certain gestures by strangers are signs that they are under threat


Emotional difficulties

People who have a psychotic disorder can experience different kinds of emotional difficulties.

  • How they feel and express their emotions may change
  • They may lose pleasure in things they used to enjoy. This is called anhedonia.
  • They may find it hard to express their emotions.
  • They may feel sad
  • They may experience depression
  • They may seem emotionally flat. This is called having blunted affect.
  • Some people with a psychotic disorder can feel very hopeless. People with psychotic disorders are at higher risk of suicide


Changes in behaviour

There are lots of ways people’s behaviour can change when they have a psychotic disorder. Things may change in:

  • What they do. For example,
    • They can have low energy and may not be motivated to do anything. When they have no motivation, it’s called avolition.
    • They may withdraw from contact with other people.
    • They may find it difficult to keep up with their education or work.
    • They may withdraw from their hobbies and interests
  • How they communicate with people. For example,
    • They may struggle to express what they are thinking or feeling.
    • They may lose interest in communicating with people.
    • Their speech can slow down.
    • They may talk very little with others.
    • When they talk, what they’re saying may seem jumbled up
    • They may become very focused on their own experiences. This can often happen when a person has delusional beliefs.
  • How well they manage their day-to-day functioning
    • They may not function as well as they used to in their day-to-day life.
    • They may lose interest in looking after themselves.
    • They may not look after their home.

They may not want to take medication if it has been prescribed for them.

Psychotic disorders are mental health conditions where psychotic experiences are the main symptom. The main types of psychotic disorder are:


Schizophrenia usually involves a combination of all of the symptoms above. They include:

  • Hallucinations
  • Delusions
  • Difficulties related to people’s thinking
  • Behaviour changes


Delusional disorder

Delusional disorder is when the main symptom someone has is delusional beliefs.


Schizoaffective disorder

Schizoaffective disorder involves a combination of psychotic experiences and mood problems. The two main mood problems people experience are:

  • Depression is when someone’s mood is low. When someone is depressed, they can:
    • Experience intense feelings of sadness. They may also feel angry.
    • Feel very numb. It’s like their emotions have shut down and they feel nothing at all.
    • Lose motivation and interest in things
    • Have problems sleeping and eating
  • Mania. When someone experiences mania, they can:
    • Experience an extreme sense of well-being
    • Have excessive energy
    • Feel very high in mood. This is also called elation
    • Act impulsively. For example, they may spend a lot of money on things they don’t need.
    • Speak very fast.


Brief psychotic episode

Some people have a single, short episode where they experience psychosis. Sometimes, it may happen at a time of stress.


Drug-induced psychosis

When someone takes high levels of some drugs, they can develop psychosis. That’s because toxic levels of some drugs can cause people to experience hallucinations and delusions. Cannabis is a drug that can put people at risk of psychosis. For many people, the psychosis will pass. For others, it can be the start of a long-term psychotic disorder.


There can be overlap between some of these conditions.

Some people experience psychotic symptoms that are related to other conditions. These include:


Bipolar disorder.

Bipolar disorder is when someone’s mood changes. Sometimes their mood is very low. Other times, it is very high.



Dementia is a progressive brain condition. It causes damage to a person’s brain. The damage can affect a person’s memory, thinking and language. It can make it hard for the person to manage day-to-day activities. Some people with dementia can experience delusional beliefs. For example, they may experience paranoia.


Autism Spectrum Disorders

People with Autism Spectrum Disorders (ASD) can experience psychotic experiences. ASD is a group of conditions that affect people’s ability to:

  • Communicate with other people
  • Form relationships with others
  • Interpret social cues from other people
  • Use or make sense of language.


Brain injuries

Some brain injuries can cause people to develop psychosis. This can depend on the area of the brain that has been damaged.

For more resources on psychiatry and mental illness, click here.