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Schizophrenia and other psychotic disorders


Psychosis is a syndrome observed in a number of mental illnesses such as schizophrenia, severe depressive episodes and mania. Some illicit drugs and alcohol can also cause psychotic symptoms (see below). Psychotic symptoms can also result from medication (anti-Parkinsonian) and consequences of medical illnesses. Examples of psychotic symptoms include:

  • Delusion – an unshakeable belief that is false, maintained despite lack of proof or evidence to the contrary, and which is not culturally-bound or accepted by their religious background. Beliefs tend to be of a persecutory (being followed), conspirational (part of a conspiracy), or referential (others talking about them) nature, of grandiosity (being someone of great importance), or bizarre (where the content is so non-credible as for the clinician not to require evidence to disprove it).
  • Hallucination – a false perception, either visual, auditory, tactile, gustatory or olfactory, which is registered by the individual in the absence of an object giving rise to them. The experience of an hallucination strongly suggests the presence of an abnormal mental state and some types of hallucinations are only seen in certain disorders.
  • Disorders of thought – the ability to construct thought patterns is disturbed. The individual may jump from topic to topic without clear association between the two.
  • Passivity experiences – the belief that thoughts are being implanted into or taken from one’s mind, or that they are being ‘broadcast’ through some media, or that emotions and actions are being controlled by something/someone external to themselves.
  • Other disturbances – psychotic symptoms are often accompanied by changes in mood, which may be excessively high or depressed, and in movement that can range from excessive activity to immobility. A person may also have the experience of their thoughts being too fast or slow. This can lead to them having difficulties expressing ideas or maintaining a single spoken topic. In some cases, for example in schizophrenia, the sufferer’s personality, social and vocational functioning may be disturbed beyond the period of time that the patient suffers psychotic symptoms. On other occasions, the patient may experience more drawn out deficits in motivation, volition, mood and poverty of thought, that may further impair overall functioning.

Psychosis is a broad term – an individual may experience a selection or all of the symptoms listed. Common to all of the symptoms is that they can be highly distressing for sufferers and their families. Because of the distressing content and nature of the symptoms, people with psychotic illnesses are sometimes at risk of behaviour that may cause harm to themselves or others.


There are a number of factors that contribute to the development of a psychotic illness.

  • Biological – it is likely that there is some inherited vulnerability to psychotic illness. Although other neurotransmitters have been implicated in the production of psychotic symptoms, there is evidence that dopamine has a primary role in people with some psychotic illnesses.
  • Psychosocial – people with psychotic disorders show evidence of a number of difficulties with thinking and perceptions that may help explain the symptoms that they experience. Many people who suffer with psychotic illnesses experience some kind of stressful or traumatic event although such events are more likely to trigger relapses than to cause the disease in the first place.
  • Treatment

    Depending on the severity of the symptoms, people with psychotic illnesses may receive inpatient or outpatient treatment.

    • Medication – anti-psychotic medication is the first-line treatment and is necessary in almost all cases where an individual suffers these symptoms, e.g. psychotic depression, mania with psychosis and schizophrenia. Only in the rare occasions when the symptoms have resolved spontaneously after a few hours or days can the clinician consider not starting medication. Anti-psychotics act on neurotransmitter systems to re-establish the appropriate balance in, for example, an over-active dopamine system.
    • Psychological therapies – cognitive behavioural therapy (CBT) has been shown to be an effective means of helping people to cope with psychotic symptoms when these are not entirely responding to medication alone. For example, they may learn to recognise that voices they hear cannot harm them or to question beliefs that they are at risk or being persecuted.
    • Social & occupational therapies – it is sometimes necessary to rehabilitate patients with severe psychotic disorders to re-learn social and vocational skills.
    Substance-induced psychotic disorders

    Some illicit drugs and alcohol can also cause psychotic symptoms in the absence of the individual suffering these mental illnesses. Whilst these symptoms may begin when a person is under the influence, a psychotic illness is only diagnosed in relation to illicit drugs or alcohol, when the effects of the drug itself have worn off yet psychotic symptoms remain.

    • Causes – the key cause of substance-induced psychotic illness is the use of drugs (most commonly cannabis, amphetamines and cocaine) and alcohol in excess. Such disorders have become more common with the increase in illicit drug and alcohol misuse but other factors are likely to contribute to the development of these disorders. It is likely that there is some inherited vulnerability to psychotic illness. Drugs interfere with chemicals in the brain, such as dopamine, that are also involved in the development of psychosis.
    • Treatment – most cases of drug-induced psychosis would resolve spontaneously after some days or weeks unless their misuse has exposed an underlying vulnerability to a more severe mental illness. Where a person is suffering with substance-induced psychosis, it is often necessary to manage both the withdrawal from the substance misuse as well as the psychotic symptoms, as these can often be very distressing and can be associated with very serious consequences if left untreated. Depending on the drug of misuse, a detox usually using sedatives such as benzodiazepines may be needed to treat the withdrawal symptoms. These can often also treat the disturbances in movement and arousal associated with psychosis but anti-psychotics may also be required to treat psychotic symptoms more effectively.

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