What is psychosis?

Psychosis is a set of symptoms in which a person loses touch with shared reality. Someone experiencing psychosis may believe, see, or hear things that others don't, and may struggle to tell the difference between what's real and what isn't.¹

Core Symptoms

Psychosis generally involves one or more of the following:

Delusions — fixed, false beliefs held with strong conviction, even in the face of clear evidence against them.¹ Common types include:

  • Persecutory delusions — believing one is being watched, followed, or targeted

  • Grandiose delusions — believing one has exceptional power, talent, wealth, or identity

  • Delusions of reference — believing ordinary events, media, or objects carry hidden personal messages

  • Somatic delusions — false beliefs about one's body or health

  • Delusions of guilt or sin — believing one is responsible for a terrible wrongdoing

Hallucinations — perceiving something that isn't actually there.¹ These can involve any of the senses:

  • Auditory (hearing voices or sounds) — the most common type

  • Visual (seeing things)

  • Tactile (feeling sensations on or under the skin)

  • Olfactory or gustatory (smelling or tasting things that aren't present)

Disorganized thinking and speech — thoughts that lose logical connection to one another, which can show up as jumping between unrelated topics, giving tangential answers, or, in severe cases, speech that becomes very difficult to follow.²

Disorganized or abnormal motor behavior — this can range from unpredictable agitation to catatonia, a state involving decreased responsiveness, unusual posturing, or lack of movement.²

Not everyone experiencing psychosis has all of these symptoms — the specific combination and severity vary widely from person to person and episode to episode.²

What Causes Psychosis

Psychosis can arise from a wide range of causes, which is part of why a thorough medical and psychiatric evaluation matters whenever it appears:

Primary psychiatric disorders²

  • Schizophrenia

  • Schizoaffective disorder

  • Bipolar disorder (during severe manic or depressive episodes)

  • Major depressive disorder with psychotic features

  • Brief psychotic disorder and schizophreniform disorder (shorter-duration conditions)

  • Delusional disorder (persistent delusions without the broader symptom profile of schizophrenia)

Substance-related causes³

  • Intoxication from substances such as methamphetamine, cocaine, cannabis (particularly high-potency forms), hallucinogens, or high doses of alcohol

  • Withdrawal from alcohol or sedatives (such as in delirium tremens)

  • Certain prescription medications, especially at high doses or in vulnerable individuals

Medical conditions⁴

  • Neurological conditions, including epilepsy, brain tumors, stroke, and neurodegenerative diseases like Parkinson's or Alzheimer's disease

  • Autoimmune conditions (such as autoimmune encephalitis, including anti-NMDA receptor encephalitis, which can produce prominent psychiatric symptoms)⁵

  • Severe infections affecting the brain (encephalitis, meningitis)

  • Metabolic disturbances (severe electrolyte imbalances, thyroid dysfunction, vitamin deficiencies)

  • Extreme sleep deprivation

Other triggers

  • Severe, prolonged psychological stress or trauma

  • Postpartum psychosis, a rare but serious condition that can emerge in the days or weeks after childbirth⁶

Because the underlying cause has such a direct bearing on treatment, clinicians typically work to rule out substance use and medical conditions before attributing psychosis solely to a primary psychiatric disorder — especially when psychosis appears suddenly or in someone with no prior psychiatric history.²

How Common Is It

Estimates suggest that around 3% of people will experience some form of psychosis in their lifetime, though this includes brief or isolated episodes as well as those tied to a chronic underlying illness.⁷ A large Finnish general-population study using comprehensive diagnostic methods found the lifetime prevalence of all psychotic disorders combined to be just above 3%, rising slightly further when register-based diagnoses were included.⁸ Psychotic disorders as a category (schizophrenia, schizoaffective disorder, and related conditions) are less common individually — the same study found lifetime prevalence of 0.87% for schizophrenia and 0.32% for schizoaffective disorder specifically, with other national surveys finding overall psychotic-disorder prevalence in a broadly similar 1–3% range.⁸ ⁹

The Early Warning Signs (Prodrome)

Psychosis often doesn't appear suddenly out of nowhere — it's frequently preceded by a "prodromal" period of subtler changes that can last weeks, months, or even a couple of years.¹⁰ Recognizing these signs early has become a major focus in mental health care, since early intervention is associated with better long-term outcomes.¹⁰ Warning signs can include:

  • Social withdrawal or declining interest in relationships

  • A noticeable drop in functioning at work, school, or in daily responsibilities

  • Increasing suspiciousness or unfounded worry that others intend harm

  • Unusual or overly intense new beliefs, even if not yet fully fixed delusions

  • Difficulty concentrating or a sense that thoughts feel disorganized

  • Perceptual changes that feel "not quite right," even before clear hallucinations emerge

  • Flattened emotional expression or reduced motivation

These changes can be easy to mistake for typical stress, depression, or (in younger people) ordinary developmental changes, which is part of why professional evaluation matters when several of these signs appear together and persist.¹⁰

Diagnosis

There's no lab test or brain scan that identifies psychosis directly — evaluation relies on:

  • A clinical interview assessing current symptoms in detail

  • A thorough history, including onset, duration, and any relationship to substance use, medical illness, or mood symptoms

  • Physical examination and often lab tests or brain imaging, specifically to rule out a medical or substance-related cause

  • Input from family or close contacts, since people experiencing psychosis don't always recognize their own symptoms as unusual (a feature called impaired insight, distinct from denial)¹¹

The goal of evaluation isn't just to confirm that psychosis is present, but to identify why — since the underlying cause fundamentally shapes treatment.²

Treatment

Treatment depends heavily on the underlying cause, but common approaches include:

Antipsychotic medication — the primary treatment for psychosis regardless of cause, used to reduce hallucinations, delusions, and disorganized thinking. Choice of medication and dosing depends on the underlying condition, side-effect considerations, and individual response.²

Treating the underlying cause — for substance-induced psychosis, this means addressing the substance use; for medical causes, treating the underlying condition (e.g., an autoimmune or neurological disorder) is essential and may resolve the psychosis entirely.²

Hospitalization — often necessary during an acute psychotic episode, both for safety and to allow for thorough evaluation and treatment initiation.

Psychosocial support, once acute symptoms stabilize:¹²

  • Cognitive behavioral therapy for psychosis (CBTp)

  • Family education and support

  • Coordinated specialty care programs for first-episode psychosis, which combine medication, therapy, social support, and education/employment assistance

  • Social skills training and case management

Early intervention programs have become a major focus in mental health systems, since treating a first episode of psychosis promptly — ideally within the first weeks to months — is strongly associated with better long-term functional outcomes.¹³ The National Institute of Mental Health's RAISE (Recovery After an Initial Schizophrenia Episode) initiative found that people who received coordinated specialty care stayed in treatment longer and experienced greater improvement in symptoms, relationships, and quality of life, along with more involvement in work and school, compared with typical community care.¹³ A separate evaluation of New York State's OnTrackNY coordinated specialty care program found that participation in work or school rose from 40% to 80% within the first six months of treatment, while hospitalization rates dropped from 70% to 10% within the first three months.¹⁴

Outlook

The course of psychosis varies enormously depending on its cause. A single episode tied to substance use or severe sleep deprivation may resolve completely once the trigger is addressed. Psychosis tied to a chronic condition like schizophrenia typically requires ongoing, long-term management.² Regardless of the underlying cause, early recognition and prompt treatment are consistently linked to better outcomes, which is why increasing public understanding of psychosis's warning signs has become a public health priority.¹³

References

  1. National Institute of Mental Health (NIMH). Understanding Psychosis. nimh.nih.gov

  2. American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.).

  3. National Institute on Drug Abuse (NIDA). Substance-Induced Psychosis. nida.nih.gov

  4. Freudenreich, O., Brown, H. E., & Holt, D. J. (2019). Psychosis, mania, and catatonia due to medical and substance-related causes. Focus, 17(2), 108–115.

  5. Dalmau, J., et al. (2011). Clinical experience and laboratory investigations in patients with anti-NMDAR encephalitis. Lancet Neurology, 10(1), 63–74.

  6. VanderKruik, R., et al. (2017). The global prevalence of postpartum psychosis: A systematic review. BMC Psychiatry, 17, 272.

  7. Perälä, J., Suvisaari, J., Saarni, S. I., et al. (2007). Lifetime prevalence of psychotic and bipolar I disorders in a general population. Archives of General Psychiatry, 64(1), 19–28.

  8. Same as [7]; see also McGrath, J. J. (2007). The surprisingly rich contours of schizophrenia epidemiology. Archives of General Psychiatry, 64(1), 14–16.

  9. Kendler, K. S., Gallagher, T. J., Abelson, J. M., & Kessler, R. C. (1996). Lifetime prevalence, demographic risk factors, and diagnostic validity of nonaffective psychosis as assessed in a U.S. community sample: The National Comorbidity Survey. Archives of General Psychiatry, 53(11), 1022–1031.

  10. Fusar-Poli, P., et al. (2013). The psychosis high-risk state: A comprehensive state-of-the-art review. JAMA Psychiatry, 70(1), 107–120.

  11. Amador, X. F., et al. (1993). Assessment of insight in psychosis. American Journal of Psychiatry, 150(6), 873–879.

  12. National Institute of Mental Health (NIMH). Coordinated Specialty Care for First Episode Psychosis. nimh.nih.gov/health/topics/schizophrenia/raise

  13. Kane, J. M., Robinson, D. G., Schooler, N. R., et al. (2016). Comprehensive versus usual community care for first-episode psychosis: 2-year outcomes from the NIMH RAISE early treatment program. American Journal of Psychiatry, 173(4), 362–372.

  14. Center for Health Care Strategies. Results of a Coordinated Specialty Care Program for Early Psychosis and Predictors of Outcomes (OnTrackNY evaluation). chcs.org