Overview 

Psychosis and schizophrenia are two distinct terms that are often intertwined and misunderstood, yet have gathered attention and study in psychiatry and psychology. The terms are often incorrectly used interchangeably due to exhibiting shared symptoms and having similar diagnostic and treatment overlap. Understanding the difference between psychosis and schizophrenia is crucial as it allows mental health professionals to accurately diagnose, which influences treatment and leads to improved outcomes.

This article aims to explore the difference between psychosis and schizophrenia by understanding how they are distinct concepts, the different symptoms experienced, the main causes of how they emerge, and how they are both diagnosed and treated. This can help promote awareness and support for those who are affected by psychosis or schizophrenia.

What is psychosis? 

Psychosis is a condition of the mind that is characterised by a significant disruption in a person’s ability to accurately perceive thoughts and perceptions, resulting in a loss of contact with reality.¹ A psychotic episode (also known as a ‘psychotic break’) refers to a period of psychosis marked by symptoms such as hallucinations, delusions, and disorganised thinking, emotion, and behaviour. Psychosis can be a symptom of schizophrenia but also occurs separately. These psychotic episodes may arise from various mental health issues, and medical conditions, or occur independently.¹ 

What is schizophrenia?

Schizophrenia is a chronic and severe mental health condition that encompasses a variety of symptoms, including psychosis.² People with schizophrenia will often face challenges that can impair daily functioning in everyday life including cognitive impairments and social withdrawal.^2,3 Symptoms of schizophrenia can be persistent, involving recurrent episodes of psychosis and long-term impairments that contribute to the chronic nature of the disorder.⁴ Therefore, long-term treatment and support are essential to enable individuals with schizophrenia to live fulfilling lives. 

Symptoms 

Both psychosis and schizophrenia involve symptoms that affect perception, thinking, emotions, and behaviour. However, they differ in terms of duration, severity, and how the symptoms emerge. 

Symptoms of psychosis

Positive symptoms refer to the presence of abnormal or unusual thoughts, perceptions, or experiences that are associated with loss of contact with reality.⁵ The intensity and duration of positive symptoms can vary greatly depending on the underlying cause and the person who is experiencing them.

Positive symptoms of psychosis include:

• Hallucinations: perceiving things that aren't actually there, such as hearing voices, seeing images, or experiencing sensations like taste, touch, or smell that others do not experience 
• Delusions: having fixed false beliefs that are not based on reality, reasoning, or evidence, such as believing one is being controlled or has extraordinary abilities 
• Disorganised thinking and speech: thoughts may become illogical making it difficult to express them coherently or maintain a train of thought
• Disorganised behaviour: odd or unpredictable behaviour, actions or gestures, such as responding to or being preoccupied with hallucinations, which leads to difficulties in following social norms or carrying out daily tasks or goals

Symptoms of schizophrenia 

Schizophrenia encompasses a broader range of symptoms beyond the positive symptoms of psychosis. People with schizophrenia will also experience negative symptoms and cognitive impairments. 

Negative symptoms describe deficits or reductions in normal emotional, behavioural, and cognitive processes.⁵ In schizophrenia, negative symptoms may persist after treatment of psychotic symptoms, and contribute to the chronic nature and poor functional outcome in those with the condition.⁶

Negative symptoms of schizophrenia include:

• Anhedonia: a loss of pleasure and interests that were once enjoyable or rewarding
• Affect flattening: reduced emotional expression that is reflected by a lack of facial expression, vocal tone and gestures
• Alogia: poverty of speech and language disturbance resulting from reduced or impaired speech and/or slowed verbal response
• Avolition: decreased motivation to accomplish a task or goal
• Asociality: a lack of desire to form or maintain social interactions, relationships or activities 
• Cognitive dysfunction: refers to challenges in mental processes that are essential for acquiring knowledge, thinking and perceiving sensory information. This includes impairments in attention, reasoning, memory and problem-solving

Causes 

Psychosis is not a diagnosis or a disorder in itself but rather is a symptom of various mental and medical conditions that profoundly impact the way the person interacts with the world around them. While psychosis has unique causes, it is not clear why schizophrenia develops but it is thought to stem from biological and environmental factors.⁷ 

Causes of psychosis 

• Mood disorders: psychosis can appear in major depressive disorder and bipolar disorder, primarily during severe manic or depressive episodes^8,9
• Medical conditions: some medical conditions such as epilepsy, traumatic brain injury, Alzheimer's disease and lupus can cause psychosis due to their effects on brain function^{1,10,11,12,13} 
• Substance use: intoxication or withdrawal from certain drugs such as cannabis, amphetamines and methamphetamines can mimic psychotic symptoms when the drug is active in their system¹
• Stress: chronic or severe stress can trigger the release of stress hormones like cortisol, which may lead to physiological changes in the brain and body and increase the risk of experiencing psychotic symptoms¹⁴
• Trauma: negative experiences, especially early in life, can interfere with normal brain development and cause changes in brain regions. This can cause psychosis to appear later in life¹⁵
• Sleep deprivation: going without sleep for long periods of time can impair cognition and cause psychotic symptoms to emerge¹⁶

Causes of schizophrenia 

• Genetic factors: schizophrenia has a strong genetic component, with heritability estimated to be around 60-80%. Having a family background of schizophrenia can increase the chance of developing the disorder¹⁷
• Brain abnormalities: abnormal brain structure and function such as reduced brain volume, fluctuations in neurotransmitter systems (chemical messengers such as, dopamine, glutamate and serotonin), and disrupted neural connectivity are present in those with schizophrenia¹⁸
• Prenatal and perinatal factors: complications during pregnancy or birth such as maternal infections, prenatal exposure to toxins, stress or complications during delivery have been associated with an increased risk of developing schizophrenia later in life¹⁹
• Environmental factors: stressful life events including childhood trauma, social isolation, and cannabis use during adolescence can increase the risk of developing schizophrenia in those who are genetically susceptible²⁰ 

Diagnosis 

In general, diagnosing a mental health condition involves a comprehensive evolution by a mental health professional such as a psychiatrist, psychologist or mental health nurse. It begins with a careful evaluation of whether the mental health condition may be caused by underlying medical issues or external factors such as substance use. Once alternative causes have been ruled out, clinicians use the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) or ICD-10 (International Classification of Diseases, Tenth Revision).

The DSM-5 and ICD-10 contain guidelines and criteria necessary for diagnosing certain mental health conditions. Following these guidelines can assist mental health professionals to assess the symptoms present, their duration and the level of intensity experienced. This ensures that the affected person receives an accurate diagnosis and appropriate treatment. 

Diagnosis of psychosis 

According to the DSM-5, to meet the criteria for various mental health disorders associated with psychosis, a person typically exhibits one or more positive symptoms (hallucinations, delusions, disorganised thinking, speech, and/or behaviour) for at least one month. Mental health disorders that can involve psychotic symptoms can include schizophrenia, schizophreniform disorder, schizoaffective disorder, brief psychotic disorder and mood disorders like major depression and bipolar disorder with psychotic features.¹

Diagnosis of schizophrenia 

The DSM-5 has certain outlines and criteria for a mental health clinician to diagnose schizophrenia. These symptoms include exhibiting two or more positive symptoms (hallucinations, delusions, disorganised speech and behaviour) and negative symptoms (alogia, avolition, affect flattening, asociality) for the majority of at least one month within a six-month period.

This duration should include at least one month of active-phase symptoms (i.e., delusions, hallucinations, disorganised speech) and may also include prodromal (early signs) or residual symptoms. These symptoms must cause impairments in various aspects of life such as social functioning, and occupational or academic achievement.¹ 

Treatment 

The treatment for both psychosis and schizophrenia can overlap as both conditions share similar symptoms. Treatment can vary depending on individual factors such as the cause and intensity of symptoms experienced, and a patient’s response to treatment. Therefore, treatment will involve a combination of medication, therapies and supportive services that meet the person's needs.

Different treatments include:

• Medications: antipsychotic medications are used to address psychotic symptoms by regulating neurotransmitter activity (chemical messengers such as dopamine, glutamate and serotonin) in the brain. Typical (first-generation) and atypical (second-generation) are commonly prescribed²¹
• Therapies: different therapeutic interventions such as individual, family and group therapy along with cognitive behavioural therapy (CBT) can help people improve social and communication skills and behaviour²² 
• Family support: including family members or caregivers in treatment can help them understand the affected person’s condition, enhance communication and learn coping techniques²²
• Supportive services: providing help in housing or employment can help with stability and overall functioning²² 

Summary 

In summary, psychosis and schizophrenia are overlapping but distinct terms. Psychosis is not a diagnosis or a disorder itself but rather a collection of symptoms that cause a person to lose contact with reality. Psychosis involves positive symptoms such as hallucinations, delusions, and disorganised thinking, speech and behaviour.

Experiencing a psychotic episode can vary greatly depending on the underlying cause and the person who is having the psychotic episode. For example, appearing as a symptom of other mental health issues or medical conditions or after being triggered by substance use. Schizophrenia is a chronic and severe mental health condition, where an affected person may experience positive symptoms of psychosis.

In addition to positive symptoms, schizophrenia is characterised by negative symptoms such as affect flattening, asociality, alogia, anhedonia, avolition, and cognitive dysfunction. While psychosis and schizophrenia are intertwined they greatly differ in regard to how they are diagnosed.

Psychosis can occur in the context of mental or medical issues or on its own due to stress, substance use or sleep deprivation. Additionally, to meet the criteria for a disorder associated with psychosis one or more symptoms should be present for at least one month, while for a schizophrenia diagnosis, two or more symptoms should be present for at least one month within 6 months.