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Psychosis is a psychiatric classification for a mental state in which the perception of reality is distorted. Persons experiencing a psychotic episode may experience hallucinations (often auditory or visual hallucinations), hold paranoid or delusional beliefs and exhibit disorganized thinking (see thought disorder). This is often accompanied by a lack of insight into the unusual or bizarre nature of their behaviour.

Psychosis is one of the symptoms of severe mental illness such as schizophrenia and bipolar disorder (manic depression). It may also occur in severe cases of depression, brain injury, drug overdose or unusual negative reaction to drugs (particularly amphetamines and hallucinogenic drugs such as LSD or mescaline), or extreme personal stress. Psychosis triggered by stress in the absence of any other mental illness is known as brief reactive psychosis.

The term psychosis should be distinguished from the concept of insanity, which is a legal term denoting that a person should not be criminally responsible for his actions. It should be distinguished from the state of delirium, in that a psychotic individual may be able to perform actions that require a high level of intellectual effort in clear consciousness. Finally, it should be distinguished from mental illness. Persons with schizophrenia can have long periods without psychosis and persons with bipolar disorder and depression can have mood symptoms without psychosis. Conversely, psychosis can occur in persons without chronic mental illness as a result of drug overdose or extreme stress, although psychosis is considered by most mainstream mental health practictioners to be a sign of mental pathology.

Psychosis has been of particular interest to critics of mainstream psychiatric practice who argue that it may simply be another way of constructing reality and is not necessarily a sign of illness. For example, R. D. Laing has argued that psychosis is a symbolic way of expressing concerns in situations where such views may be unwelcome or uncomfortable to the recipients. Thomas Szasz has focused on the social implications of labelling people as psychotic, a label which he argues unjustly medicalises different views of reality so such unorthdox people can be controlled by society.

Etymology: The word psychosis comes from the Greek psykhe (mind) and osis (diseased or abnormal condition). It is believed the word was first coined in 1846 and is derived from the term neurosis. the

Table of contents
1 Psychotic experience
2 Medical understanding of psychosis
3 See also
4 External links
5 Further reading: Medicine
6 Further reading: Personal accounts
7 References

Psychotic experience

A psychotic episode can be significantly coloured by mood. For example, people experiencing a psychotic episode in the context of depression may experience persecutory or self-blaming delusions or hallucinations, whilst people experiencing a psychotic episode in the context of mania may form grandiose delusions or have an experience of deep religious significance.

Although usually distressing and regarded as an illness process, some people who experience psychosis find beneficial aspects and value the experience or revelations that stem from it.

Hallucinations in psychosis

Hallucinations are defined as sensory perception in the absence of external stimuli. Psychotic hallucinations may occur in any of the five senses and take on almost any form, which may include simple sensations (such as lights, colours, tastes, smells) to more meaningful experiences such as seeing and interacting with fully formed animals and people, hearing voices and complex tactile sensations.

Auditory hallucinations, particularly the experience of hearing voices, is a common and often prominent feature of psychosis. Hallucinated voices may talk about, or to the person, and may involve several speakers with distinct personas. Auditory hallucinations tend to be particularly distressing when they are derogatory, commanding or preoccupying.

Delusions and paranoia

Psychosis may involve delusional or paranoid beliefs. Karl Jaspers classified psychotic delusions into primary and secondary types. Primary delusions are defined as arising out-of-the-blue and not being comprehensible in terms of normal mental processes, whereas secondary delusions may be understood as being influenced by the person's background or current situation.

Thought disorder

Thought disorder describes an underlying disturbance to conscious thought and is classified largely by its effects on speech and writing. Affected persons may show pressure of speech (speaking incessantly and quickly), derailment or flight of ideas (switching topic mid-sentence or inappropriately), thought blocking, rhyming or punning.

Lack of insight

One important and puzzling feature of psychosis is usually an accompanying lack of insight into the unusual, strange or bizarre nature of the person's experience or behaviour. Even in the case of an acute psychosis, the sufferer may seem completely unaware that their vivid hallucinations and impossible delusions are in any way unrealistic. This is not an absolute, however; insight can vary between individuals and throughout the duration of the psychotic episode.

In some cases, particularly with auditory and visual hallucinations, the patient has good insight and this makes the psychotic experience even more terrifying in that the patient realizes that he should not be seeing demons and angels or hearing voices, but does.

Medical understanding of psychosis

There are a number of possible causes for psychosis. Psychosis may be the result of an underlying mental illness such as Bipolar disorder (also known as manic depression), and schizophrenia. Psychosis may also be triggered or exacerbated by severe mental stress and high doses or chronic use of drugs such as amphetamines, LSD, PCP, cocaine or scopolamine. However, as can been seen from the wide variety of illness and conditions in which psychosis has been reported to arise (including for example, AIDS, leprosy, malaria and even mumps) there is no singular cause of a psychotic episode.

The division of the major psychoses into bipolar disorder and schizophrenia was made by Emil Kraepelin, who attempted to create a synthesis of the various mental disorders identified by 19th century psychiatrists, by grouping diseases together based on classification of common symptoms. Bipolar disorder is characterised by problems with mood control and the psychotic episodes appear associated with disturbances in mood, and patients will often have periods of normal functioning between psychotic episodes even without medication. Schizophrenia is characterized by psychotic episodes which appear to be unrelated to disturbances in mood, and most non-medicated patients will show signs of disturbance between psychotic episodes.

Psychotic episodes may vary in duration between individuals. In "brief reactive psychosis", the psychotic episode is related directly to a specific stressful life event so patients may spontaneously recover normal functioning within two weeks. Patients who are undergoing brief reactive psychosis due to drugs or stress generally appear with the same symptoms as a person who is psychotic as a result of a mental illness, and this fact has been used to support the notion that mental illness has a biological basis.

Psychosis and Brain Function

The first brain image of person with psychosis was completed as far back as 1935 using a technique called pneumoencephalography1 (a painful and now obselete procedure where cerebrospinal fluid is drained from around the brain and replaced with air to allow the structure of the brain to show up more clearly on an X-ray picture).

Pneumoencephalogram of person with psychosis, 1935

Modern brain imaging studies, investigating both changes in brain structure and changes in brain function of people undergoing psychotic episodes have shown mixed results.

A 2003 study investigating structural changes in the brains of people with psychosis showed there was significant grey matter reduction in the cortex of people before and after they became psychotic2. Findings such as these have led to debate about whether psychosis is itself neurotoxic and whether potentially damaging changes to the brain are related to the length of psychotic episode. Recent research has suggested that this is not the case3 although further investigation is still ongoing.

Functional brain scans have revealed that the areas of the brain that reacts to sensory perceptions are active during psychosis. For example, a PET or fMRI scan of a person who claims to be hearing voices may show activation in the auditory cortex, or parts of the brain involved in the perception and understanding of speech.

On the other hand, there is not a clear enough psychological definition of belief to make a comparison between different people particularly valid. Brain imaging studies on delusions have typically relied on correlations brain activation patterns with the presence of delusional beliefs.

One clear finding is that persons with a tendency to have psychotic experiences seem to show increased activation in the right hemisphere of the brain4. This increased level of right hemiphere activation has also been found in healthy people who have high levels of paranormal beliefs5 or in people who report mystical experiences6. It also seems to be the case that people who are more creative are also more likely to show a similar pattern of brain activation7. This is no way suggests that paranormal, mystical or creative experiences are in any way a symptom of mental illness, as it is still not clear what makes some such experiences beneficial whilst others lead to impairment or distress.

Psychosis has been traditionally linked to the neurotransmitter dopamine, particularly an excess of dopamine in the limbic system (a structure deep within the brain). The development of effective antipsychotic medication played a large part in the success of this view, as the first effective antipsychotic drugs were dopamine blockers. In addition, drugs that increase the concentration of dopamine tend to trigger psychotic episodes.

Nevertheless, the connection between dopamine and psychosis is generally believed to be complex. First of all, while anti-psychotic drugs immediately block dopamine receptors, they usually take a week or two to reduce the symptoms of psychosis. Moreover, newer and equally as effective antipsychotic drugs actually block slightly less dopamine in the brain than older drugs whilst also affecting serotonin levels, suggesting the 'dopamine hypothesis' is vastly oversimplified. Psychiatrist David Healy has criticised pharmaceutical companies for promoting particular scientific theories that favour their medication and encouraging a purely biological account of mental illness8.

Some theories regard many psychotic symptoms to be a problem with the perception of ownership of internally generated thoughts and experiences9. For example, the experience of hearing voices may arise from internally generated speech that is mislabelled by the psychotic person as coming from an external source.

It has also been argued that psychosis exists on a continuum as everybody may have some unsual and potentially reality-distorting experiences in their life. This has been backed up by research showing that experiences such as hallucinations have been experienced by large numbers of the population who may never be impaired or even distressed by their experiences10. In this view, people who are diagnosed with a psychotic illness may simply be one end of a spectrum where the experiences become particularly intense or distressing.

Cannabis and Psychosis

There is now growing evidence for a small but significant link between cannabis use and vulnerability to psychosis11. Some studies indicate that cannabis use correlates with a slight increase in psychotic experience, which may trigger full-blown psychosis in some people. Early studies have been criticized for failing to consider other drugs (such as LSD) that the subjects may also have used before or during the study, as well as other factors such as possible pre-existing mental health issues. However, more recent studies with better control have still found a small increase in risk for psychosis in cannabis users. It is still not clear whether this is a causal link, and it may be that cannabis use only increases the chance of psychosis in people already predisposed to it. The fact that cannabis use has increased over the past few decades, whereas the rate of psychosis has not, suggests that a direct causal link is unlikely for all users.

See also

External links

Further reading: Medicine

  • Sims, A. (1995) Symptoms in the mind: An introduction to descriptive psychopathology. Edinburgh: Elsevier Science Ltd. ISBN 0702026271

Further reading: Personal accounts

  • Dick, P.K (1981) VALIS. London: Gollancz. [Semi-autobiographical] ISBN 0679734465
  • Jamison, K.R (1995) An Unquiet Mind: A Memoir of Moods and Madness. London: Picador.
    ISBN 0679763309
  • Wikipedia entry for James Tilly Matthews
  • Schreber, D.P. (2000) Memoirs of My Nervous Illness. New York: New York Review of Books. ISBN 094032220X


1Moore, MT, Nathan, D, Elliot, AR & Laubach, C. (1935) Encephalographic studies in mental disease. American Journal of Psychiatry, 92 (1), 43-67.
Pantelis C, Velakoulis D, McGorry PD, Wood SJ, Suckling J, Phillips LJ, Yung AR, Bullmore ET, Brewer W, Soulsby B, Desmond P, McGuire PK. (2003) Neuroanatomical abnormalities before and after onset of psychosis: a cross-sectional and longitudinal MRI comparison. Lancet, 25, 361 (9354), 281-8.
3Ho, B. C., Alicata, D., Ward, J., Moser, D. J., O'Leary, D. S., Arndt, S., et al. (2003) Untreated initial psychosis: relation to cognitive deficits and brain morphology in first-episode schizophrenia. American Journal of Psychiatry, 160(1), 142-148.
4Lohr JB, Caligiuri MP (1997) Lateralized hemispheric dysfunction in the major psychotic disorders: historical perspectives and findings from a study of motor asymmetry in older patients. Schizophrophrenia Research, 30, 27(2-3), 191-8.
5Pizzagalli, D., Lehmann, D., Gianotti, L., Koenig, T., Tanaka, H., Wackermann, J., et al. (2000) Brain electric correlates of strong belief in paranormal phenomena: intracerebral EEG source and regional Omega complexity analyses. Psychiatry Research, 100(3), 139-154.
6Makarec, K., & Persinger, M. A. (1985) Temporal lobe signs: electroencephalographic validity and enhanced scores in special populations. Perceptual and Motor Skills, 60(3), 831-842.
7Weinstein, S., & Graves, R. E. (2002) Are creativity and schizotypy products of a right hemisphere bias? Brain and Cognition, 49(1), 138-151.
8Healy, D. (2002) The Creation of Psychopharmacology. Cambridge, MA: Harvard University Press. ISBN 0674006194
9Blakemore SJ, Smith J, Steel R, Johnstone CE, Frith CD. (2000) The perception of self-produced sensory stimuli in patients with auditory hallucinations and passivity experiences: evidence for a breakdown in self-monitoring. Psychological Medicine, 30 (5), 1131-9.
10Johns LC, van Os J. (2001) The continuity of psychotic experiences in the general population. Clinical Psychology Review, 21 (8), 1125-41.
11Degenhardt, L. (2003) Editorial: The link between cannabis use and psychosis: furthering the debate. Psychological Medicine, 33, 3-6.