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Psychosis and schizophrenia

Psychosis refers to a collection of symptoms associated with certain mental disorders. Psychosis involves a temporary loss of contact with reality and is characterized by disturbances in:

  • perception, such as auditory or visual hallucinations
  • thinking, such as false beliefs or problems communicating
  • behaviour

Psychosis may be a sign of an underlying mental disorder. Examples are schizophrenia, schizophreniform disorder, schizoaffective disorder, organic psychoses, delusional disorder and drug-induced psychosis. Symptoms of psychosis may also be associated with severe depression and bipolar disorder.

Schizophrenia is the most common disorder with symptoms of psychosis.


  • 80% of patients present between the ages of 16 – 30
  • women tend to present at higher ages than men and seem to be more susceptible when they are premenstrual, menopausal and immediately post-partum



Delusions are fixed beliefs that are not changeable in light of conflicting evidence. There are several types of delusions:

  • Persecutory - the most common type of delusion, where the person believes that they will be harmed.
  • Referential - the belief that gestures or comments are directed toward the person.
  • Grandiose - when the person believes they have exceptional talent, abilities, fame or wealth.
  • Erotomanic - when the person believes falsely that someone is in love with them is important to consider cultural differences in beliefs.
  • Nihilistic - when the person believes a major catastrophic event will happen. 
  • Somatic delusions - when a person is overly occupied with their health.


Hallucinations are hearing or seeing things that other people don't experience. The most common hallucinations in schizophrenia and related disorders are auditory hallucinations – hearing voices.

Disorganized thinking

This is usually manifested by erratic speech where the person jumps from one topic to another or provides answers unrelated to the questions. Sometimes it is so disorganized it is known as "word salad".

Negative symptoms

These are more commonly associated with schizophrenia and less so with other psychotic disorders. They include reduced expression of emotion, reduced motivation for activities and an apparent lack of interest in social interactions.

Cognitive symptoms

Some people may experience changes in memory or other aspects of thinking. These changes can be difficult to recognize and may include difficulty with:

  • understanding information and using information to make decisions
  • focusing and paying attention
  • using recently-acquired information


While the exact cause of psychosis is still unclear, studies point to several genetic and environmental risk factors.

In a series of videos Dr. Kwame McKenzie, psychiatrist at the Centre for Addiction and Mental Health (CAMH), explains current thinking about 

  • causes of psychosis
  • psychosis and cannabis
  • psychosis and genetics
  • psychosis and stress
  • psychosis and cities


Early intervention with proper supports and medications improves the prognosis for people with symptoms of psychosis.

More information about treatment of psychosis and schizophrenia.

Evidence summary

Diaz, P. (2012). Psychosis. In A. Khenti, J. Sapag, S. Mohamoud & A. Ravindran (Eds.), Collaborative Mental Health: An Advanced Manual for Primary Care Professionals (pp. 127–142). Toronto: Centre for Addiction and Mental Health.

Foussias, G. & Daskalakis, Z.J. (2011). The patient who is psychotic. In D. Goldbloom & J. Davine (Eds.), Psychiatry in Primary Care: A Concise Canadian Pocket Guide (pp. 113–128). Toronto: Centre for Addiction and Mental Health.

Fraser Health Authority. (n.d.).Dealing with psychosis: A toolkit for moving on with your life. Surrey, B.C.: Author.

Douglas Mental Health University Institute. Schizophrenia: causes, symptoms and treatments

American Psychiatric Association. (2013).Diagnostic and Statistical Manual of Mental Disorders (5th ed. Arlington, VA: Author.  Retrieved from

Baker, S. Martens, L. (2010). Promoting Recovery from First Episode Psychosis: A Guide for Families. Toronto: Centre for Addiction and Mental Health. 

Psychosis – Diagnosis and management.

DSM-5 – Schizophrenia spectrum and other psychotic disorders

Schizophrenia for Primary Care Providers: how to contribute to the care of a vulnerable patient population.