Psychosis
Psychosis
Psychosis is a mental state in which a person loses touch with external reality. It can involve seeing, hearing, smelling, or feeling things that are not there, or holding fixed beliefs that persist despite clear evidence to the contrary. Thinking and speech can also become disorganised.
Psychosis is not a diagnosis in itself but a symptom that can occur on its own, as part of a psychiatric condition such as schizophrenia, or as a consequence of a neurological or medical condition, substance use, or medication. It is increasingly understood to sit on a spectrum, ranging from mild and transient perceptual disturbances to persistent, functionally disabling episodes.
Psychosis can be triggered by a wide range of underlying factors, including genetics, neurotransmitter imbalances, brain injury, inflammation, infection, and severe stress. Identifying the underlying cause is a key part of determining appropriate treatment.
Psychosis should be assessed promptly by a medical professional, as early treatment is associated with better outcomes, and some underlying causes require urgent medical attention.
Symptoms of Psychosis
Psychosis can look different from person to person, and its symptoms can come on suddenly or build up gradually over weeks. It is often described in terms of “positive” symptoms (experiences added on top of ordinary functioning) and “negative” symptoms (a loss or reduction of normal functioning).
Mental and perceptual symptoms
- Hallucinations – seeing, hearing, smelling, tasting, or feeling things that are not actually there; hearing voices is the most common form
- Delusions – fixed, false beliefs that persist even when shown clear evidence to the contrary, such as believing one is being watched, persecuted, or controlled by an outside force
- Disorganised or racing thoughts, and speech that becomes difficult to follow
- Reduced insight – difficulty recognising that the hallucinations or beliefs are not real
- Paranoia and heightened suspicion of others
- Difficulty concentrating or a marked change in memory
- Emotional flatness, or emotions that seem disconnected from the situation
- Loss of motivation and withdrawal from friends, family, and previously enjoyed activities
- Confusion about what is real
Physical and behavioural symptoms
- Disturbed sleep
- Changes in appetite
- Neglect of personal hygiene and self-care
- Restlessness or agitation
- Unusual or repetitive movements, or, at the other extreme, remaining very still (catatonia)
- Changes in energy levels, from marked lethargy to hyperactivity
The combination of hallucinations, delusions, and disorganised thinking is often referred to as a psychotic episode.
Different types of psychosis
Psychiatry increasingly views psychosis as sitting along a spectrum rather than as a single, fixed diagnosis. The type diagnosed depends on how long symptoms last, which symptoms are present, and whether they can be explained by another physical or psychiatric cause.
At the mildest end of the spectrum, schizotypal disorder involves odd beliefs, unusual perceptual experiences, and social discomfort, but without the full loss of reality testing seen in more severe psychotic disorders.
Characterised by one or more delusions lasting a month or more, without the prominent hallucinations, disorganised speech, or negative symptoms seen in schizophrenia.
A short episode of delusions, hallucinations, disorganised speech, or disorganised behaviour lasting at least a day but less than a month, with a full return to normal functioning afterwards. It’s sometimes triggered by a major stressor or can occur around childbirth.
Symptoms resembling schizophrenia, lasting between one and six months.
A more persistent condition, with symptoms present for six months or more, that significantly affects a person’s ability to function at work, in relationships, or in day-to-day self-care.
A combination of psychotic symptoms alongside a major mood episode (depressive or manic), where psychosis also occurs independently of mood disturbance for a meaningful stretch of time.
Some people experience psychosis only during an episode of severe depression, mania, or bipolar disorder, in which case the psychotic symptoms are usually thematically linked to the prevailing mood (for example, delusions of guilt during depression, or grandiose delusions during mania).
Psychotic symptoms can develop during intoxication or withdrawal from alcohol or recreational drugs, or as a side effect of certain prescribed medications, and in some cases can persist beyond the substance’s immediate effects.
Psychosis can also arise as a direct consequence of an underlying neurological or medical condition rather than a primary psychiatric illness. This is sometimes called secondary or “organic” psychosis, and it’s an important category for anyone experiencing a first episode of psychosis to have ruled out, since treating the underlying condition can resolve the psychosis. Conditions associated with secondary psychosis include:
- Traumatic brain injury, particularly injuries involving the temporal or frontal lobes
- Stroke, especially affecting the right temporo-parietal region
- Epilepsy, particularly with a left-sided temporal focus
- Dementia, including Alzheimer’s disease, dementia with Lewy bodies, frontotemporal dementia, and Parkinson’s disease dementia
- Autoimmune and paraneoplastic encephalitis, such as anti-NMDA receptor encephalitis
- Brain tumours, particularly those affecting the temporal lobes, limbic system, or pituitary/suprasellar region
- Multiple sclerosis and other white matter disease
- Huntington’s disease and Wilson’s disease
- HIV and other infections affecting the brain
Diagnosing psychosis
Diagnosis begins with ruling out delirium and any medical, neurological, or substance-related cause, since these require different and often urgent treatment. A doctor will usually take a detailed history (from the person themselves and, where possible, from family or friends who know them well), alongside a physical and neurological examination.
Structured tools that clinicians may use to assess psychosis include:
Clinician-administered scales that rate the severity of hallucinations, delusions, disorganisation, and other symptoms.
A structured interview with a close friend or family member, often used when assessing psychosis alongside dementia.
Introduced in the DSM-5, this eight-item scale rates the severity of hallucinations, delusions, disorganised speech, abnormal movement, negative symptoms, and co-occurring cognitive, depressive, and manic symptoms, and can help track change over time.
Cognitive and functional assessments, ideally carried out by a neuropsychologist or occupational therapist, are also useful for understanding how psychosis is affecting day-to-day life.
Investigations and tests
There is no single blood test that can diagnose a primary psychotic disorder such as schizophrenia. However, because psychosis so often has an identifiable and treatable underlying cause, a thorough medical work-up is an essential part of a proper diagnosis, especially for a first episode.
Used to screen for thyroid dysfunction, vitamin deficiencies (such as B12), electrolyte disturbances, infections, and autoimmune markers that could be contributing to or mimicking psychosis.
Checks for recreational drugs, prescription medications, and other substances that can trigger psychotic symptoms.
Used to look for structural causes such as tumours, stroke, traumatic brain injury, or white matter disease, particularly when psychosis develops suddenly, later in life, or alongside other neurological symptoms.
Can help identify epilepsy-related psychosis, particularly when episodes are brief and recurrent.
Sometimes used, especially when autoimmune or infectious encephalitis is suspected.
In integrative and functional medicine, additional testing – such as stool testing for gut dysbiosis, inflammatory markers, or nutritional and toxicology panels – may also be used to help identify biochemical imbalances that could be contributing to psychotic symptoms.