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Abstract
- Psychosis can be broadly defined as a family of symptoms in which the patient’s experience is outside the normal experience of reality. This includes delusions and hallucinations. Patients may also lack insight, meaning the patient will not entertain the idea that these beliefs are false.
- Psychosis can have organic (physical) causes: delirium, post-ictal, encephalitis, or drug intoxication.
- Psychosis can also have a functional cause i.e. there is no underlying physical cause.
- An example of a psychotic disorder is schizophrenia, a condition in which patients interpret reality abnormally. Symptoms of schizophrenia can be categorised by Schneider’s First Rank Symptoms: delusional perception, third-person auditory hallucinations, somatic hallucinations, thought interference, and passivity phenomenon.
- There are multiple hypotheses for the pathophysiology of schizophrenia including dopamine and autoimmune.
- Drug treatment of schizophrenia is achieved through antipsychotics: first-generation antipsychotics block D2 receptors with high affinity, and second-generation antipsychotics block D2 receptors, but with lower affinity, reducing side effects.
- Drug-induced psychosis is a temporary psychosis that occurs during or within two weeks of the use of a psychoactive substance, lasting between 48h and six months.
- Affective psychosis involves psychotic symptoms developing that are congruent with the mood disorder also present in the patient.
- Post-partum psychosis occurs within four weeks of birth and is an obstetric emergency.
Core
Psychosis is a collection of symptoms characterised by the patient having experiences outside the normal experience of reality. This includes delusions and hallucinations. Psychosis is not a diagnosis in itself.
Hallucinations are a sensory perception without a stimulus. They can be in any sensory modality. Hallucinations can be normal, for example, hypnogogic hallucinations occur just before falling asleep.
Delusions are fixed firmly held beliefs which are usually falsely held by the patient that are outside of cultural norms and unshakable (i.e. cannot be reasoned away even with evidence). It is important that these beliefs are outside of cultural norms – some might classify religious beliefs as delusional, but as these are within the cultural norms of the patient, they are normally not considered as such.
Insight is the degree to which a patient is aware of their condition and its relation to their symptoms. In psychotic disorders, a lack of insight is common.
Psychosis can occur due to organic, physical causes. It is therefore important when a patient presents to healthcare services to investigate and treat these physical causes first.
- Delirium – an acute confusional state which may include psychotic symptoms. Can be caused by many things, including infection, constipation, hypoxia, and electrolyte disturbances.
- Delirium Tremens – a condition caused by withdrawal of alcohol.
- Post-ictal Psychosis – occurs following a seizure.
- Encephalitis – an infection of the brain tissue.
- Drug Intoxication – multiple prescription and illicit drugs can induce psychosis.
Schizophrenia is a condition in which patients interpret reality abnormally. It may result in hallucinations, delusions, disordered thinking and abnormal behaviours that impair daily functioning.
Like all psychiatric disorders, risk factors for schizophrenia can be categorised into predisposing, precipitating and perpetuating factors.
Predisposing
Predisposing factors are factors that the patient cannot change and that accumulate to increase the likelihood of schizophrenia. They include:
- Genetics – family history
- Childhood abuse
- History of substance misuse
- Age 15 – 35
Precipitating
Precipitating factors are factors that exist in the patient’s life that, combined with predisposing factors, encourage the presentation of schizophrenia at that point. Examples include:
- Use of cannabis or psychostimulants
- Adverse life events such as the death of a parent
Perpetuating
Perpetuating factors are factors that encourage the persistence of the symptoms of schizophrenia once it is already established. They are often seen as barriers to successful treatment. Examples include:
- Continued substance misuse
- Poor social support
- Poor compliance with medication
Schizophrenia has a number of symptoms that were first described in 1959 by Dr Kurt Schneider. They are known as Schneider’s First Rank Symptoms, and they are more specific to schizophrenia than other psychotic illnesses.
- Delusional Perception
- Third-Person Auditory Hallucinations – hallucinations that are heard in the third person, often in the form of running commentary, for example “he’s brushing his teeth, now he is turning on the tap”
- Physical (Somatic) Hallucinations – mimic feelings from inside the body, like feeling bugs on the skin
- Thought Interference
- Thought Broadcast – thoughts are being made known to others, e.g. being played on the radio
- Thought Withdrawal – thoughts are being taken out of the brain
- Thought Insertion – thoughts are being implanted into the brain and the patient can differentiate between external thoughts inserted and original thoughts
- Passivity Phenomenon – actions or feelings are being caused by an external force, e.g. “the police have been moving my leg"
Pathophysiology of Schizophrenia
Nobody knows the exact pathophysiology of schizophrenia, but there are a number of abnormalities that are thought to contribute.
Dopamine Hypothesis
The mesolimbic cortical pathway uses dopaminergic neurones to connect the midbrain to the limbic system in a pathway that manages reward and pleasure. This is thought to be overactive in schizophrenia.
The mesocortical pathway uses dopaminergic neurones to connect the midbrain to the frontal cortex and the cingulate gyrus in a pathway that manages cognition and emotional response. This is thought to be underactive in schizophrenia.
Autoimmune Hypothesis
A condition called Anti-NMDA encephalitis can also present similarly to schizophrenia. This is a condition where the body produces antibodies against its own NMDA receptors, which normally respond to the excitatory neurotransmitter glutamate. The loss of function of these receptors results in lower functioning of these receptors (causing symptoms like schizophrenia) and brain swelling (encephalitis).
In the past, patients with Anti-NMDA encephalitis would have been diagnosed and treated like schizophrenia. However, new trials are indicating that this condition is curable with the right immunomodulation, and there are questions being asked about whether screening for this may offer a cure to some patients otherwise diagnosed with schizophrenia.
Drug Treatment of Schizophrenia
Pharmacological treatment is the mainstay management of schizophrenia through antipsychotics.
Typical antipsychotics were the first antipsychotics developed and block D2 receptors in the dopaminergic pathways in the body; this makes them very effective, but they have severe side effects when other dopamine pathways are blocked. This is especially noticeable when blocking the nigrostriatal pathway in the brain, resulting in symptoms of Parkinsonism – slowed movements, tremors and muscle rigidity.
Atypical (second-generation) antipsychotics also act on D2 receptors in dopaminergic pathways but have a lower affinity for these receptors; this makes them effective, but less likely to cause other side effects as they dissociate quicker from the receptors.
Drug-induced psychosis is a temporary psychosis that occurs during or within two weeks of the use of a psychoactive substance. The psychotic symptoms must last more than 48 hours, but not more than six months. If the psychosis lasts more than six months, it is considered to be a more permanent form of psychosis, such as schizophrenia. This is a key distinction to make, as the use of psychoactive substances can trigger more chronic conditions such as schizophrenia.
Examples of substances that can induce psychosis include; cannabis, cocaine, LSD, ecstasy, methamphetamine, ketamine, and many more.
Affective psychosis is a condition resulting in psychotic experiences that are congruent with the patient’s mood.
For example, a manic patient may have grandiose delusions and hear the voice of God talking to them, or a depressed patient may have delusions of guilt or blame.
For more information on mood disorders, please see our article on the topic.
Post-partum psychosis is a rare syndrome affecting mothers that develops within four weeks of birth. It is a psychiatric emergency due to high rates of maternal suicide and/or infanticide, and new mothers exhibiting symptoms of psychosis should be assessed as an inpatient as soon as possible. Mothers diagnosed with this condition are usually cared for in specialist ‘mother and baby’ units.
The condition is more common in patients with a family history of post-partum psychosis, or with a personal history of psychotic illness, but it can occur in patients with no previous psychiatric history.
Edited by: Dr. Ben Appleby
Reviewed by: Dr. Thomas Burnell
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