What is Psychosis?

Please note this section is currently under review.

To download our full document on psychosis please click here.

Psychosis is not a single entity, rather it is an umbrella term describing a group of loosely related abnormalities of thinking, perceiving, communicating and behaving. These experiences are very common in society and at any one time it is estimated that 8% of the population have had psychotic experiences. Only a small percentage of these people develop a psychotic disorder requiring treatment. In general, a person can only be said to be suffering from a psychotic disorder if these experiences are prominent, persistent or are causing the person distress and difficulties in every day functioning.

A recent study found that 3.5% of the population experience a psychotic disorder at some time in their lives. Psychosis commonly emerges early on in life, often in the late teens or twenties. People suffering with psychosis can experience a loss of touch with reality, and develop symptoms such as hallucinations and delusions.

Hallucinations occur when someone experiences a sensation without any stimulus. Hallucinations can be normal occurrences, for example when drifting off to sleep or waking up. People with hearing difficulties can experience auditory hallucinations, and similarly people with visual difficulties may experience visual hallucinations, without this being indicative of any mental illness. Use of drugs such as LSD, and extreme lack of sleep may also induce experiences like hallucinations.

Hallucinations may also be indicative of mental illness and in this instance they tend to be more complex, intense and persistent. Hallucinations can occur in any of the 5 sensations; auditory (hearing), visual (seeing); gustatory (tasting), haptic (touching) and olfactory (smelling). Hallucinations can be very simple i.e. noises or flashes of light, or can be more complex i.e. hearing voices or seeing fully formed objects. Auditory hallucinations are the most commonly described in mental illnesses such as schizophrenia, and usually consist of hearing noises or voices when there is nothing to be heard.

This video from TEDx gives one woman’s experience of hallucinations which are a feature of her diagnosis of schizophrenia:

Delusions are another common symptom of psychosis, and consist of false beliefs held with complete conviction. An example would be holding a belief that people are against you or wish to harm you. False beliefs may not appear understandable to others, however may be understandable in terms of what the patient is experiencing. For example people with psychosis may interpret events in their environment incorrectly such as believing that someone who is looking at them in a normal manner, may be looking at them in a threatening manner.

In addition people with psychosis can experience a loss of motivation to function in daily living. Poor energy and loss of enjoyment may also occur. These type of symptoms of are often referred to as negative symptoms.

Symptoms Description
Hallucinations Hearing, seeing, smelling, tasting or feeling things without there being anything there
Delusions Fixed false beliefs not consistent with cultural beliefs
Thought Disorder Disorganised thinking
Blunted Affect Loss of Emotional Expression
Avolition/Anhedonia Loss of Energy/Drive/Enjoyment
Depressed Mood Subjective sadness, hopelessness
Cognitive Deficits Sometimes present as subtle difficulties such as decreased attention or concentration

The content of psychotic experiences may be affected by culture. For example the content of paranoid delusions may relate to issues of the day; in Ireland in the 1970s and 1980s paranoid delusions regarding the IRA were common, but with the end of the “troubles” these ideas have become much less common. Knowledge of an individual’s social and cultural background is essential before a diagnosis of psychosis can be made.

The term “psychotic” is frequently misapplied to people or behaviours without any understanding of what this term means. The term psychotic does not imply that a person is dangerous or liable to behave bizarrely. Somebody who is “psychotic” is suffering from psychosis. Most people who have had psychosis at one time in their lives are very well at present and without any ongoing problems. Often they will have experienced hallucinations, delusions or thought disorder at one or more times in their lives, but now may be fully recovered or just have mild symptoms.

There are a great many conditions in which psychosis can feature, sometimes alongside other difficulties such as depressed mood, anxiety or memory difficulties. Conditions in which psychosis features include schizophrenia, depression, dementia, brain injuries, alcohol misuse, drug misuse and many other conditions. Although it may appear from diagnostic classification systems that these conditions are distinct there can often be some overlap between these conditions.

Diagnosis Common Symptoms
Schizophrenia Delusions, Hallucinations, Loss of motivation
Bipolar Affective Disorder Elated mood, Delusions, Hallucinations,
Severe Depression Depressed mood, Delusions, Hallucinations
Alcohol/Drug Induced Psychosis Alcohol/Drug misuse, Delusions, Hallucinations
Delusional Disorder Delusions, often long-term
Organic Psychosis Delusions, Hallucinations caused by a biological illness/brain injury
Brief Psychotic Disorder Delusions/Hallucinations of short duration

(See other pages on this website by clicking highlighted conditions in the above table )

The actual cause of psychosis is complex, and it is often difficult to find a single underlying cause. For most of the psychotic disorders, it is thought to be a combination of a genetic predisposition, abnormalities in the development of the growing brain, and environmental stresses.

Treatment for psychosis involves providing a comprehensive treatment package suited to the needs of each individual. Successful recovery from an episode of psychosis usually involves treatment, at least for a period of 1-2 years, with antipsychotic medications. However, it is important to emphasise that medication only ever plays a part in the recovery process and that other psychological treatments, rehabilitative interventions, lifestyle, family support, environmental and other changes are also of critical importance. In addition to antipsychotic medications there are other medications and supplements that can sometimes be helpful in the treatment of psychosis.

There are numerous medications which can be used for psychosis, each of which may have different benefits and potential side effects. There is no single antipsychotic medication which is most effective for everyone, and the choice of medication is usually made following discussions between the patient and prescribing doctor.

Cognitive behavioural therapy is a helpful talking therapy which is used for recognising symptoms of psychosis, identifying relapse triggers, and learning to cope with symptoms of psychosis. Family education can also be hugely beneficial in assisting recovery from psychotic illnesses, and occupational therapy often plays a crucial role in rehabilitation.

Similar to many other medical illnesses, early detection and treatment of psychosis leads to better outcomes. Early intervention strategies are gaining recognition as a crucial aspect of the management approach to psychosis. Efforts at educating the public, and others likely to come into contact with people developing psychosis, such as General Practitioners, teachers, counsellors, and gardai, has been shown to improve the long term outcome of psychotic illnesses, by leading to earlier identification and treatment of these illnesses. The reason for this better outcome isn’t fully clear, but it is believed to occur by reducing the toxicity caused to people suffering with psychosis. For example it is possible that psychotic symptoms may cause biological damage to the brain, or that the experience of psychotic symptoms may damage thought processes in the brain. It is also thought that the social consequences of symptoms early on in psychotic illnesses, such as loss of a job, or damage to relationships may have a detrimental effect on long term outcome.

The HSE has a clinical programme on Early Intervention in Psychosis in partnership with the College of Psychiatrists of Ireland. For more information on the programme, click here.


Psychosis is a treatable mental illness which individuals can experience by itself, or as an aspect of Schizophrenia, Bipolar I, depression, dementia, brain injuries, alcohol misuse, drug misuse and many other conditions. When a person is going through an episode of psychosis they can experience delusions, hallucinations, or paranoia. These can sometimes lead to the individual isolating themselves from others. Hallucinations occur when someone experiences a sensation such as seeing or hearing something which others do not. Delusions consist of personal beliefs, held with complete conviction, that are true for the individual but seem strange or untrue to others. Not everyone will experience the same symptoms of psychosis. Some people will find an episode of psychosis stressful, while others may not. Early intervention is key to supporting the individual in their recovery, dealing with symptoms, and leading the life they wish.

When reporting on psychosis, the expression “a person with psychotic symptoms” or “Tom experiences psychosis” is preferable to ‘Tom is psychotic’. The term psychotic does not imply that a person is dangerous or liable to behave bizarrely.


Psychopathy (including psychopathic and psychopath) is a completely different term. It is a forensic term used to describe a personality with no empathy, a lack of remorse for any crime committed, and a lack of emotions.  Psychopathy is not considered to be a mental illness and is therefore not treatable alone within the mental health services. When psychopathic traits become dysfunctional in a person it is termed psychopathic personality disorder.

The word “psycho” is often confused as referring to psychosis in reports about violent personalities or crime. People experiencing psychosis are no more prone to violence than the general population.

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