Psychosis is a symptom of mental illness rather than the name of a medical condition itself.
Broadly speaking, it means a loss of contact with reality, and generally there are two types of psychiatric disorder that produce psychotic symptoms: schizophrenia, and mood disorders such as bipolar disorder.
This page offers a full description of what psychosis is and how it is caused, including links to complete information on the individual disorders that give people psychotic symptoms.
Contents of this article:
What is psychosis?
Psychosis is a symptom of psychiatric illness; it is not itself the name of a mental disorder.4
Psychosis means experiencing things and believing them to be real when they are not; in other words, losing contact with reality. This happens in two broad forms:1-4
- Hallucination - hearing, seeing or feeling things that are not there
- Delusion - holding unusual beliefs not shared by other people.
At a general level, two types of psychiatric disorder produce psychosis: schizophrenia, and mood or affective disorder. Specific diagnoses and subtypes can display psychotic symptoms, and there is also some overlap.1-3,5,6
Psychosis is classically associated with schizophrenia disorders, and while there are other symptoms, schizophrenia is defined by psychosis.4 Other disorders also have psychotic symptoms. The full list includes:1,2,4-6
Some mothers who have just given birth can experience psychosis in a severe form of postpartum depression.
- Schizoaffective disorder and other subtypes of schizophrenia
- Persistent delusional disorders
- Acute and transient psychotic disorders
- Bipolar disorder (also known as manic depression)
- Major depressive disorder with psychotic features
- Postnatal psychosis (a severe form of postnatal depression in some mothers with newborns)
- Substance-induced psychosis (including alcohol, certain illegal drugs and some prescription drugs, such as steroids and stimulants)
- Some personality disorders.
These are the primary causes of psychotic symptoms, but psychosis can also be secondary to other disorders and diseases, including:1,2,5
- Brain tumor or cyst
- Dementia (Alzheimer's disease, for example)
- Neurological illness, such as Parkinson's disease and Huntington's disease
- HIV and other infections that may affect the brain
- Some types of epilepsy
To learn more about causes, use the hyperlinks above to pages about individual conditions and disorders that may produce psychosis. The causes section of the Medical News Today schizophrenia page may be particularly relevant.
The major psychotic illnesses of schizophrenia and bipolar disorder show patterns of family history and they are among the most heritable common disorders.7 Research has found that these two disorders may share a common genetic cause.7,8 Molecular genetic research also suggests that schizophrenia may overlap with developmental disorders such as autism.9
Such findings raise questions about the validity of diagnostic approaches that classify distinct types of psychotic illnesses. The research coincides with debate and refinement of the criteria used to determine what diagnosis is lying behind someone's psychosis.10,11
There are structural and chemical changes in the brains of people with a psychotic disorder.
Alterations in brain structure and changes in dopamine neurotransmission (a chemical important for communication between brain cells) are found in people who have psychosis.9,12 The dopamine changes are directly related to hallucinations and delusions.9
Dopamine levels are thought to be too high during psychosis and to affect:12
- Social behaviour
Brain scans have revealed reduced grey matter in the brains of some people who have had a history of psychosis, which may explain effects on thought processing.12
Recent developments on psychosis causes from MNT news
Psychosis may be triggered by antibody reaction to brain protein - a new study published in the journal Biological Psychiatry investigates the role antibodies may play in cases of psychosis, suggesting that psychosis symptoms such as hallucinations and delusions may be triggered by an antibody response to a protein in the brain.
Symptoms of psychosis
Psychosis is a symptom rather than a medical condition - it is not itself a psychiatric diagnosis, but a sign of a mental disorder. Psychotic symptoms may be separated out and given specific descriptions.
The classic hallmarks of psychosis are:1,4
- Hallucinations - hearing, seeing or feeling things that do not exist; perceptions without external stimuli
- Delusions - false beliefs, especially based on fear or suspicion of things that are not real.
Psychotic symptoms in disorders such as schizophrenia may also include:1,4
- Disorganized thought, speech or behavior
- Disordered thinking (jumping between unrelated topics, making strange connections between thoughts)
- Catatonia (unresponsiveness).
One example of a psychotic delusion of grandeur is an impossible but unshakeable belief in being a monarch or ruler of a country.
Depending on the cause, psychosis can come on quickly or slowly. The same is the case in schizophrenia, although symptoms are more likely to have a slow onset and begin with milder psychosis, which in some cases does not convert to the full disorder.4
In those people who do go on to display clear-cut psychosis, the slow onset, or prodromal phase of schizophrenia, is often found later to have gone without recognition by the patient or their family and friends.4
Prodromal psychosis goes on untreated for an average of two years, and even fully psychotic symptoms can be untreated for a number of years, too.4
The milder initial symptoms of psychosis might include:4
- Feelings of suspicion
- Distorted perceptions
- Depression and suicidal feelings
- Obsessive thinking
- Sleep problems.
An online resource developed by psychiatrists gives a list of questions based on the sort of symptoms that, particularly when clustered together and getting worse, may be a signal of psychosis or schizophrenia.13
The full test produces a score based on self-reported ratings of delusional and hallucinatory experiences.
The examples tested include belief in possession of magical powers that other people do not have, and belief that other people are plotting against the person. Other items rate how much trust the person has in the reality of their thoughts, and how much control they feel they have over their thoughts.
Hallucinations can affect any of the senses (sight, sound, smell, taste and touch) in the person with psychosis, but in about two-thirds of patients with schizophrenia, hallucinations are auditory - hearing things and believing them to be real when they do not exist, there is no actual external noise to produce the stimulus.4
The following auditory hallucinations are common in schizophrenia:4
- Hearing several voices talking, often negatively, about the patient
- A voice giving a commentary on what the patient is doing, or
- Repeating what the patient is thinking.
Delusions are defined as beliefs that are not supported by the cultural or religious context and there is clear evidence that they are false - nevertheless, they are strong convictions that the patient believes in completely.4,14
The type of delusion differentiates the psychosis of schizophrenia from that of other delusional disorders:4
- Non-bizarre delusions - false but feasible beliefs
- Bizarre delusions - impossible, such as contrary to the laws of physics.
Bizarre delusions are experienced during psychosis.4
Examples of psychotic delusions include the paranoid type - more likely to be associated with schizophrenia5 - and delusions of grandeur.15
Paranoid delusions: these may cause the person with psychosis to be unduly suspicious of individuals or organizations, believing them to be plotting to cause them harm. Such delusions can be very frightening and may result in unusual behavior to avoid things - for example, staying out of a room with certain devices in it, believing them to be controlling thoughts, or locking up the front door with an excessive number of padlocks.3,15
Delusions of grandeur: clearly false but strongly held belief in having a special power or authority - the person with psychosis may, as examples, believe that they are a world leader, very rich, that they are able to bring dead people back to life, or that they can control the weather.3,15
While the classic hallmarks of psychosis are hallucination and delusion, other symptoms persist in disorders such as schizophrenia - known as negative symptoms. That is, cognitive and motivational impairments, which can be disabling and do not respond to drug treatment.9
The UK mental health charity Rethink Mental Illness has listed examples of negative symptoms of schizophrenia:16
- Lack of motivation
- Slow movement
- Change in sleep patterns
- Poor grooming or hygiene
- Difficulty in planning and setting goals
- Not saying much
- Changes in body language
- Lack of eye contact
- Reduced range of emotions
- Tendency not to interact with other people
- Little interest in having hobbies
- Little interest in sex.
On the next page we look at the ways in which psychosis can be diagnosed. On the final page we discuss the available treatments for psychosis and the link between psychosis and the use of illegal substances such as cannabis.