Causes

Psychosis can be caused by a mental (psychological)condition,a general medical condition, or a substancesuch as alcohol or drugs.

These three main causes are described in more detail below.

Psychological causes

The following conditions have been known to trigger psychotic episodes in some people:

  • Schizophrenia a mental health condition that causes hallucinations and delusions
  • bipolar disorder a person with bipolar disorder can have episodes of low mood (depression) and highs or elated mood (mania)
  • severe stress or anxiety
  • severe depression feelings of persistent sadness, including postnatal depression ,which some women experience after having a baby
  • lack of sleep

The underlying psychological cause often influences the type of psychotic episode someone experiences.

For example, a person with bipolar disorder is more likely to have grandiosedelusions. Someone with depression or schizophrenia is more likely to develop persecutory delusions.

General medical conditions

The following medical conditions have been known to trigger psychotic episodes in some people:

  • HIV and AIDS
  • malaria
  • syphilis
  • Alzheimer's disease
  • Parkinson's disease
  • hypoglycaemia (an abnormally low level of glucose in the blood)
  • lupus
  • multiple sclerosis
  • brain tumour

Substances

Alcohol misuse and drug misuse can trigger a psychotic episode.

A person can also experience a psychotic episode if they suddenly stop drinkingalcohol ortaking drugs after using them for a long time. This is known as withdrawal.

It's also possible to experience psychosis after drinking large amounts of alcohol or if you're high on drugs.

Drugs known to trigger psychotic episodes include:

  • cocaine
  • amphetamine (speed)
  • methamphetamine (crystal meth)
  • mephedrone (MCAT or miaow)
  • MDMA (ecstasy)
  • cannabis
  • LSD (acid)
  • psilocybins (magic mushrooms)
  • ketamine

In rare situations, psychosis can also occur as a side effect of some types of medication or as a result of an overdose of that medication.

Never stop taking a prescribed medication unless advised to do so by your GP or another qualified healthcare professionalresponsible for your care.

See your GP if you're experiencing psychotic side effectscaused by medication.

The brain

There's been a great deal of research into how psychosis affects the brain and how changes in the brain can trigger symptoms of psychosis .

Dopamine

Researchers believe dopamine plays an important role in psychosis.

Dopamine is a neurotransmitter,one of many chemicals the brain uses to transmit information from one brain cell to another.It's associated with how we feel whether something is significant, important, or interesting.

Disruption to these important brain functions may explain the symptoms of psychosis.

Evidence for the role of dopamine in psychosis comes from several sources, including brain scans andthe fact medicationsknown to reduce the effects of dopamine in the brain also reduce thesymptoms of psychosis.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 4 Jan 2017