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Psychosis

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"Psychotic" redirects here. For articles with similar names, see Psychosis (disambiguation).
Psychosis
Classifications and external resources
ICD-9 290-299
OMIM 603342 608923 603175 192430
MedlinePlus 001553
MeSH F03.700.675

Psychosis is a generic psychiatric term for a mental state in which thought and perception are severely impaired. Persons experiencing a psychotic episode may experience hallucinations, hold delusional beliefs (e.g., grandiose or paranoid delusions), demonstrate personality changes and exhibit disorganized thinking (see thought disorder). This is often accompanied by lack of insight into the unusual or bizarre nature of such behaviour, difficulties with social interaction and impairments in carrying out the activities of daily living. A psychotic episode is often described as involving a "loss of contact with reality".

Contents

[edit] Classification

Psychosis is considered by mainstream psychiatry to be a symptom of severe mental illness, but is not a diagnosis in itself.<ref name=Tsuang_et_al_2000> Tsuang, Ming T., William S. Stone, Stephen V. Faraone (July 2000). "Toward Reformulating the Diagnosis of Schizophrenia". American Journal of Psychiatry 157 (7): 1041-1050. PubMed. Retrieved on 2006-08-19.</ref> Although it is not exclusively linked to any particular psychological or physical state, it is particularly associated with schizophrenia, bipolar disorder (manic depression) and severe clinical depression. There are also detectable physical pathologies that can induce a psychotic state, including brain injury or other neurological disorder, drug intoxication and withdrawal (especially alcohol,<ref name=>Soyka, Michael (March 1990). "Psychopathological characteristics in alcohol hallucinosis and paranoid schizophrenia.". Acta Psychiatrica Scandanavica 81 (3): 255-9. PubMed.</ref><ref name=Gossman_2005>Gossman, William (November 19, 2005). Delirium Tremens. eMedicine. WebMD. Retrieved on October 16, 2006.</ref> barbiturates,<ref name=de_Paola_et_al_2004>de Paola, Luciano, Maria Joana Mäder, Francisco M.B. Germiniani, Patrícia Coral, Jorge A.A. Zavala, Djon J. Watzo, Jorge Kanegusuku, Carlos E.S. Silvado, and Lineu C. Werneck (June 2004). "Bizarre behavior during intracarotid sodium amytal testing (Wada test): Are they predictable?". Arquivos de Neuro-Psiquiatria 62 (2B): 444-448. DOI:10.1590/S0004-282X2004000300012. PubMed. Retrieved on 2006-10-15.</ref><ref name=Sarrecchia_et_al_1998>Sarrecchia, C., P. Sordillo, G. Conte, and G. Rocchi (October-December 1998). "[Barbiturate withdrawal syndrome: a case associated with the abuse of a headache medication]". Annali Italiani di Medicina Interna 13 (4): 237-239. PubMed.</ref> and sometimes benzodiazepines<ref name=White_et_al_1982>White, M. C., J. J. Silverman, and J. W. Harbison (February 1982). "Psychosis associated with clonazepam therapy for blepharospasm". Journal of Nervous and Mental Disease 170 (2): 117-9. PubMed.</ref><ref name=Jaffe_et_al_1986>Jaffe, R., E. Gibson (June 1986). "Clonazepam withdrawal psychosis". Journal of Clinical Psychopharmacology 6 (3): 193. PubMed.</ref><ref name=Hallberg_et_al_1964>Hallberg, R. J., K. Lessler and F. J. Kane (August 1964). "KORSAKOFF-LIKE PSYCHOSIS ASSOCIATED WITH BENZODIAZEPINE OVERDOSAGE" (PDF). American Journal of Psychiatry 121 (2): 188-189. DOI:10.1176/appi.ajp.121.2.188. PubMed. Retrieved on 2006-10-15.</ref>), lupus,<ref name=Lupus_Psychosis_India>Robert, M., R. Sunitha, and N. K. Thulaseedharan (March 2006). "Neuropsychiatric manifestations systemic lupus erythematosus: A study from South India". Neurology India 54 (1): 75-77. PubMed. Retrieved on 2006-09-29.</ref> electrolyte disorders such as hypocalcemia,<ref name=Rossman_1956>Rossman, Phillip L., Robert M. Vock (September 1956). "Postpartum Tetany and Psychosis Due to Hypocalcemia" (PDF). California Medicine 85 (3): 190-193. PubMed. Retrieved on 2006-10-16.</ref> hypernatremia,<ref name=Jana_1973>Jana, D. K., L. Romano-Jana (October 1973). "Hypernatremic psychosis in the elderly: case reports". Journal of the American Geriatrics Society 21 (10): 473-477. PubMed.</ref> hyponatremia,<ref name= Haensch_et_al_1996>Haensch, C. A., G. Hennen and J. Jorg (April 1996). "[Reversible exogenous psychosis in thiazide-induced hyponatremia of 97 mmol/l]". Der Nervenarzt 67 (4): 319-322. PubMed.</ref> hypokalemia,<ref name=Hafez_et_al_1984>Hafez, H., J. S. Strauss, M. D. Aronson, and C. Holt (June 1984). "Hypokalemia-induced psychosis in a chronic schizophrenic patient". Journal of Clinical Psychiatry 45 (6): 277-279. PubMed.</ref> hypomagnesemia,<ref name=Konstantakos_2006>Konstantakos, Anastasios K.; Enrique Grisoni (May 25, 2006). Hypomagnesemia. eMedicine. WebMD. Retrieved on October 16, 2006.</ref> hypermagnesemia,<ref name=Velasco_et_al_1999>Velasco, P. Joel, Manoochehr Manshadi, Kevin Breen, and Steven Lippmann (December 1999). "Psychiatric Aspects of Parathyroid Disease". Psychosomatics 40 (6): 486-490. PubMed. Retrieved on 2006-10-17.</ref> hypercalcemia,<ref name=Rosenthal_et_al_1997>Rosenthal, M., I. Gil and B. Habot (1997). "Primary hyperparathyroidism: neuropsychiatric manifestations and case report". Israel Journal of Psychiatry and Related Sciences 34 (2): 122-125. PubMed.</ref> and hypophosphatemia.<ref name=Nanji_1984>Nanji, A. A. (November 1984). "The psychiatric aspect of hypophosphatemia". Canadian Journal of Psychiatry 29 (7): 599-600. PubMed.</ref>

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. Similarly, it should be distinguished from psychopathy, a personality disorder often associated with violence, lack of empathy and socially manipulative behavior.<ref name=hare1>Hare, R. D. Psychopathy and Antisocial Personality Disorder: A Case of Diagnostic Confusion, Psychiatric Times, February 1996, XIII, Issue 2 Accessed June 26, 2006</ref> Despite the fact that both are colloquially abbreviated to "psycho", psychosis bears little similarity to psychopathy's core features, particularly with regard to violence, which rarely occurs in psychosis,<ref name=Milton_et_al_2001>Milton, John, Shazad Amin, Swaran P. Singh, Glynn Harrison, Peter Jones, Tim Croudace, Ian Medley, and John Brewin (May 2001). "Aggressive incidents in first-episode psychosis". British Journal of Psychiatry 178: 433-440. PubMed. Retrieved on 2006-10-21.</ref><ref name=Foley_et_al_2005>Foley, Sharon R., Brendan D. Kelly, Mary Clarke, Orfhlaith McTigue, Maurice Gervin, Moyyad Kamali, Conall Larkin, Eadbhard O'Callaghan, and Stephen Browne (January 1, 2005). "Incidence and clinical correlates of aggression and violence at presentation in patients with first episode psychosis". Schizophrenia Research 72 (2-3): 161-168. DOI:10.1016/j.schres.2004.03.010. PubMed. Retrieved on 2006-10-21.</ref> and the distortion of perceived reality, which rarely occurs in psychopathy.<ref name=Nestor_et_al_2002>Nestor, Paul G., Matthew Kimble, Ileana Berman, and Joel Haycock (January 2002). "Psychosis, Psychopathy, and Homicide: A Preliminary Neuropsychological Inquiry". American Journal of Psychiatry 159 (1): 138-140. PubMed. Retrieved on 2006-10-21.</ref>

Psychosis should also 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 in general. Psychosis may be regarded as a symptom of other mental illnesses, but as a descriptive concept it is not considered an illness in its own right. For example, 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 an adverse drug reaction or extreme stress. <ref name=Jaunch_1988>Jauch, D. A., William T. Carpenter, Jr. (February 1988). "Reactive psychosis. I. Does the pre-DSM-III concept define a third psychosis?". Journal of Nervous and Mental Disease 176 (2): 72-81. PubMed.</ref>

[edit] Causes

Psychosis can be a feature of several diseases, often when the brain or nervous system is directly affected. However, the fact that psychosis can occasionally arise in parallel with a number of ailments (including diseases such as flu<ref name=Steinberg_et_al_1959>Steinberg, D., S. R. Hirsch, S. D. Marston, K. Reynolds, and R. N. Sutton (May 1972). "Influenza infection causing manic psychosis". British Journal of Psychiatry 120 (558): 531-535. PubMed.</ref><ref name=Maurizi_1985>Maurizi, C. P. (February 1985). "Influenza and mania: a possible connection with the locus ceruleus". Southern Medical Journal 78 (2): 207-209. PubMed.</ref> or mumps<ref name=Keddie_1965>Keddie, K. M. (August 1965). "Toxic psychosis following mumps". British Journal of Psychiatry 111: 691-696. PubMed.</ref> for example) suggests that a variety of nervous system stressors can lead to a psychotic reaction. Psychosis arising from non-psychiatric conditions is sometimes known as 'secondary psychosis'. The mechanisms by which this happens are still not clear, but the non-specificity of psychosis has led Tsuang and colleagues to argue that "psychosis is the 'fever' of mental illness—a serious but nonspecific indicator".<ref name=Tsuang_et_al_2000/>

Non-psychiatric conditions which are particularly linked to psychosis include brain tumour,<ref name=Brain_tumor>Lisanby, S. H., C. Kohler, C. L. Swanson, and R. E. Gur (January 1998). "Psychosis Secondary to Brain Tumor". Seminars in clinical neuropsychiatry 3 (1): 12-22. PubMed.</ref> dementia with Lewy bodies,<ref name=DLB>McKeith, Ian G. (February 2002). "Dementia with Lewy bodies". British Journal of Psychiatry 180: 144-147. PubMed. Retrieved on 2006-09-27.</ref> hypoglycemia,<ref name=hypoglycemia>Padder, Tanveer, Aparna Udyawar, Nouman Azhar, and Kamil Jaghab (December 2005) "Acute Hypoglycemia Presenting as Acute Psychosis" in Psychiatry online. Retrieved on 2006-09-27 </ref> intoxication,<ref name=alcohol>Larson, Michael (2006-03-30). Alcohol-Related Psychosis. eMedicine. WebMD. Retrieved on September 27, 2006.</ref> multiple sclerosis,<ref name=multiple_sclerosis>(Spanish) Rodriguez Gomez, Diego, Elvira Gonzalez Vazquez and Óscar Perez Carral (August 16-31, 2005). "Psicosis aguda como inicio de esclerosis multiple / Acute psychosis as the presenting symptom of multiple sclerosis / Psicose aguda como inicio de esclerose multipla". Revista de Neurología 41 (4): 255-256. PubMed. Retrieved on 2006-09-27. </ref> Systemic Lupus Erythematosus,<ref name=Lupus_Psychosis_India/> sarcoidosis,<ref name=Sarcoidosis>Bona, Joseph R., Sondralyn M. Fackler, Morris J. Fendley and Charles B. Nemeroff (August 1998). "Neurosarcoidosis as a Cause of Refractory Psychosis: A Complicated Case Report". American Journal of Psychiatry 155 (8): 1106-1108. PubMed. Retrieved on 2006-09-29.</ref>, mumps,<ref name=DELAGE_1995>DeLage, J. (February 1955). "[Moderate psychosis caused by mumps in a child of nine years.]". Laval Médical 20 (2): 175-183. PubMed.</ref> AIDS,<ref name=>Evans, Dwight L., Karen I. Mason, Jane Leserman, Russell Bauer And John Petitto (2002-02-01). “Chapter 90: Neuropsychiatric Manifestations of HIV-1 Infection and AIDS”, Kenneth L Davis, Dennis Charney, Joseph T Coyle, Charles Nemeroff: Neuropsychopharmacology: The Fifth Generation of Progress, 5th, Philadelphia: Lippincott Williams & Wilkins, 1281-1301. ISBN 0-7817-2837-1. Retrieved on 2006-10-16.</ref> malaria,<ref name=Tilluckdharry_et_al_1996>Tilluckdharry, C. C., D. D. Chaddee, R. Doon, and J. Nehall (March 1996). "A case of vivax malaria presenting with psychosis". West Indian Medical Journal 45 (1): 39-40. PubMed.</ref> and leprosy.<ref name=Lowinger_1959>Lowinger, Paul (July 1959). "LEPROSY AND PSYCHOSIS". American Journal of Psychiatry 116 (1): 32-37. DOI:10.1176/appi.ajp.116.1.32. PubMed. Retrieved on 2006-10-17.</ref><ref name=Ponomareff_1965>Ponomareff, G. L. (June 1965). "PHENOMENOLOGY OF DELUSIONS IN A CASE OF LEPROSY" (PDF). American Journal of Psychiatry 121 (12): 1211. PubMed. Retrieved on 2006-10-17.</ref>

Psychological stress is also known to contribute to and trigger psychotic states. Both a history of traumatic incidents experienced throughout the life-span, and the recent experience of a stressful event, is thought to contribute to the development of psychosis. Short-lived psychosis triggered by stress is known as brief reactive psychosis, so patients may spontaneously recover normal functioning within two weeks.<ref name=Jaunch_1988/> In some rare cases, individuals may remain in a state of full-blown psychosis for many years, or perhaps have attenuated psychotic symptoms (such as low intensity hallucinations) present at most times.

Psychotic states occurring after drug use may be particularly linked to drug overdose, chronic use and drug withdrawal. Certain compounds may be more likely to induce psychosis and some individuals may show greater sensitivity than others. Certain "street" drugs, such as cocaine,<ref name=>Brady, K. T., R. B. Lydiard, R. Malcolm, and J. C. Ballenger (December 1991). "Cocaine-induced psychosis.". Journal of Clinical Psychiatry 52 (12): 509-512. PubMed.</ref> amphetamines, PCP<ref name=psychotic_PCP_rats>Reynolds, Lindsay M., Susan M. Cochran, Brian J. Morris, Judith A. Pratt and Gavin P. Reynolds (March 1, 2005). "Chronic phencyclidine administration induces schizophrenia-like changes in N-acetylaspartate and N-acetylaspartylglutamate in rat brain". Schizophrenia Research 73 (2-3): 147-152. DOI:10.1016/j.schres.2004.02.003. PubMed. Retrieved on 2006-09-29.</ref> and hallucinogens are particularly linked to the development of psychosis. Anticholinergic drugs (atropine,<ref name=Bergman_et_al_1980>Bergman, K. R., C. Pearson, G. W. Waltz, and R. Evans III year = 1980. "Atropine-induced psychosis. An unusual complication of therapy with inhaled atropine sulfate" (Infotrieve). Chest 78 (6): 891-893. PubMed. Retrieved on 2006-10-15.</ref><ref name=Varghese_et_al_1990>Varghese, S., N. Vettath, K. Iyer, J. M. Puliyel, and M. M. Puliyel (June 1990). "Ocular atropine induced psychosis--is there a direct access route to the brain?". Journal of the Association of Physicians of India 38 (6): 444-445. PubMed.</ref> scopolamine,<ref name=Barak_and_Weiner_2006>Barak, Segev, Ina Weiner (September 13, 2006). "Scopolamine Induces Disruption of Latent Inhibition Which is Prevented by Antipsychotic Drugs and an Acetylcholinesterase Inhibitor". Neuropsychopharmacology. DOI:10.1038/sj.npp.1301208. PubMed. Retrieved on 2006-10-15.</ref> Jimson weed<ref name=Kurzbaum>Kurzbaum, Alberto, Claudia Simsolo, Ludmilla Kvasha and Arnon Blum (July 2001). "Toxic Delirium due to Datura Stramonium" (PDF). Israel Medical Association Journal 3 (7): 538-539. PubMed. Retrieved on 2006-10-17.</ref>), and many antihistamines can also induce psychosis at high enough dosages.<ref name=diphenhydramine_trip_therapeutic>Sexton, J. D., D. J. Pronchik (September 1997). "Diphenhydramine-induced psychosis with therapeutic doses". American Journal of Emergency Medicine 15 (5): 548-549. PubMed. Retrieved on 2006-09-29.</ref><ref name=diphenhydramine_trip_supratherapeutic>Lang, K., H. Sigusch, and S. Muller (December 8, 1995). "[An anticholinergic syndrome with hallucinatory psychosis after diphenhydramine poisoning]". Deutsche medizinische Wochenschrift 120 (49): 1695-1698. PubMed.</ref><ref name=diphenhydramine_poisoning_psychosis>Schreiber, W., A. M. Pauls and J. C. Kreig (February 5, 1988). "[Toxic psychosis as an acute manifestation of diphenhydramine poisoning]". Deutsche medizinische Wochenschrift 113 (5): 180-183. PubMed.</ref><ref name=Promethazine>Timnak, Charles, Ondria Gleason (January-February 2004). "Promethazine-Induced Psychosis in a 16-Year-Old Girl". Psychosomatics 45 (1): 89-90. PubMed. Retrieved on 2006-09-29.</ref>

Intoxication with drugs that have general depressant effects on the central nervous system (especially alcohol and barbiturates) tend not to cause psychosis during use, and can actually decrease or lessen the impact of symptoms in some people. Withdrawal from barbiturates and alcohol can be particularly dangerous, however, leading to psychosis or delirium and other, potentially lethal, withdrawal effects.

Sleep deprivation has been linked to psychosis,<ref name=sleep_dep1>Sharma, Verinder, Dwight Mazmanian (April 2003). "Sleep loss and postpartum psychosis". Bipolar Disorders 5 (2): 98-105. DOI:10.1034/j.1399-5618.2003.00015.x. PubMed. Retrieved on 2006-09-27.</ref><ref name=sleep_dep2>Chan-Ob, T., V. Boonyanaruthee (September 1999). "Meditation in association with psychosis". Journal of the Medical Association of Thailand 82 (9): 925-930. PubMed.</ref><ref name=sleep_dep3>Devillieres, P., M. Opitz, P. Clervoy, and J. Stephany (May-June 1996). "[Delusion and sleep deprivation]". L'Encéphale 22 (3): 229-231. PubMed.</ref> although there is little evidence to suggest that it is a major risk factor in the majority of people. Some people experience hypnagogic or hypnopompic hallucinations, where unusual sensory experiences or thoughts appear during waking or drifting off to sleep. These are normal sleep phenomena, however, and are not considered signs of psychosis.<ref name=Ohayon_et_al_1996>Ohayon, M. M., R. G. Priest, M. Caulet, and C. Guilleminault (October 1996). "Hypnagogic and hypnopompic hallucinations: pathological phenomena?". British Journal of Psychiatry 169 (4): 459-467. PubMed. Retrieved on 2006-10-21.</ref>

[edit] Signs and symptoms

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A psychotic episode can be significantly affected by mood. For example, people experiencing a psychotic episode in the context of depression may experience persecutory or self-blaming delusions or hallucinations, while 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.

[edit] Hallucinations

Hallucinations are defined as sensory perception in the absence of external stimuli. They are different from illusions, which are the misperception of external stimuli.<ref>Harper, Douglas (November 2001). hallucinate. Online Etymology Dictionary. Retrieved on October 15, 2006.</ref> Hallucinations may occur in any of the five senses and take on almost any form, which may include simple sensations (such as lights, colors, 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, are 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. However, the experience of hearing voices need not always be a negative one. Research has shown that the majority of people who hear voices are not in need of psychiatric help.<ref> Honig, A; Romme MA, Ensink BJ, Escher SD, Pennings MH, deVries MW (1998). Auditory hallucinations: a comparison between patients and nonpatients. Journal of Nervous and Mental Disease. Retrieved on 2006-08-19.</ref> The Hearing Voices Movement has subsequently been created to support voice hearers, regardless of whether they are considered to have a mental illness or not.

[edit] 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 (i.e. ethnic or sexual descrimination, religious, superstitious belief).<ref name=Jaspers>Jaspers, Karl [1963] (1997-11-27). Allgemeine Psychopathologie (General Psychopathology), Translated by J. Hoenig & M.W. Hamilton from German, Reprint edtion (in English), Baltimore, Maryland: Johns Hopkins University Press. ISBN 0-8018-5775-9.</ref>

[edit] Thought disorder

Formal 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, and rhyming or punning.

[edit] 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.<ref name=Carpenter_et_al_1973>Carpenter, William T., Jr., John S. Strauss, and John J. Bartko (December 21, 1973). "Flexible system for the diagnosis of schizophrenia: Report from the WHO international pilot study of schizophrenia" (PDF). Science 182 (4118): 1275-1278. DOI:10.1126/science.182.4118.1275. PubMed. Retrieved on 2006-10-21.</ref> Even in the case of an acute psychosis, sufferers may be 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.

It was previously believed that lack of insight was related to general cognitive dysfunction<ref name=Lysaker_et_al_1994>Lysaker, Paul H., Morris D. Bell (November 1994). "Insight and cognitive impairment in schizophrenia. Performance on repeated administrations of the Wisconsin Card Sorting Test". Journal of Nervous and Mental Disease 182 (11): 656-660. PubMed.</ref> or to avoidant coping style.<ref name=Lysaker_et_al_2003>Lysaker, Paul H., Gary J. Bryson, Rebecca S. Lancaster, Jovier D. Evans and Morris D. Bell (January 1, 2003). "Insight in schizophrenia: associations with executive function and coping style". Schizophrenia Research 59 (1): 41-47. DOI:10.1016/S0920-9964(01)00383-8. PubMed. Retrieved on 2006-10-22.</ref> Later studies have found no statistical relationship between insight and cognitive function, either in groups of people who only have schizophrenia,<ref name=>Freudenreich, Oliver, Thilo Deckersbach and Donald C. Goff (July 2004). "Insight into current symptoms of schizophrenia. Association with frontal cortical function and affect". Acta Psychiatrica Scandinavica 110 (1): 14-20. DOI:10.1111/j.1600-0447.2004.00319.x. PubMed. Retrieved on 2006-10-22.</ref> or in groups of psychotic people from various diagnostic categories.<ref name=Cuesta_et_al_2006>Cuesta, Manuel J., Victor Peralta, Amalia Zarzuela, and Maria Zandio (May 31, 2006). "Insight dimensions and cognitive function in psychosis: a longitudinal study". BMC Psychiatry 6: 26-35. DOI:10.1186/1471-244X-6-26. PubMed. Retrieved on 2006-10-22.</ref>

In some cases, particularly with auditory and visual hallucinations, the patient has good insight, which makes the psychotic experience even more terrifying because the patient realizes that he or she should not be hearing voices, but is.

[edit] Pathophysiology

It has also been argued that psychosis exists on a continuum as everybody may have some unusual 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 experiences.<ref name=Johns_2001>Johns, Louise C., Jim van Os (2001). "The continuity of psychotic experiences in the general population.". Clinical Psychology Review 21 (8): 1125-41. DOI:10.1016/S0272-7358(01)00103-9. PubMed. Retrieved on 2006-08-19.</ref> 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 (see schizotypy).

[edit] Brain function

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

The first brain image of a person with psychosis was completed as far back as 1935 using a technique called pneumoencephalography<ref> Moore, M T, Nathan D, Elliot AR, Laubach C (1935). "Encephalographic studies in mental disease.". American Journal of Psychiatry 92 (1): 43-67.</ref> (a painful and now obsolete 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).

More recently, 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 psychotic.<ref> 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. PMID 12559861. Retrieved on 2006-08-19.</ref> 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 case<ref> Ho, BC, Alicata D, Ward J, Moser DJ, O'Leary DS, Arndt S, Andreasen NC (2003). "Untreated initial psychosis: relation to cognitive deficits and brain morphology in first-episode schizophrenia.". American Journal of Psychiatry 160 (1): 142-148. PMID 12505813. Retrieved on 2006-08-19.</ref> although further investigation is still ongoing.

Functional brain scans have revealed that the areas of the brain that react 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.<ref> Copolov DL, Seal ML, Maruff P, Ulusoy R, Wong MT, Tochon-Danguy HJ, Egan GF. (2003) Cortical activation associated with the experience of auditory hallucinations and perception of human speech in schizophrenia: a PET correlation study. Psychiatry Res, 122 (3), 139-52. PMID 12694889. </ref>

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 of brain activation patterns with the presence of delusional beliefs.<ref>Bell, V., Halligan, P.W. & Ellis, H.D. (2006) A Cognitive Neuroscience of Belief. In P.W. Halligan & M. Aylward (eds) The Power of Belief. Oxford: Oxford University Press.</ref>

One clear finding is that persons with a tendency to have psychotic experiences seem to show increased activation in the right hemisphere of the brain.<ref> Lohr, 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. PMID 9416648. Retrieved on 2006-08-19.</ref> This increased level of right hemisphere activation has also been found in healthy people who have high levels of paranormal beliefs<ref> Pizaagalli, D, Lehmann D, Gianotti L, Koenig T, Tanaka H, Wackermann J, Brugger P. (2000). "Brain electric correlates of strong belief in paranormal phenomena: intracerebral EEG source and regional Omega complexity analyses.". Psychiatry Research 100 (3): 139-154. PMID 11120441. Retrieved on 2006-08-19.</ref> and in people who report mystical experiences.<ref> Makarec, K, Persinger, MA (1985). "Temporal lobe signs: electroencephalographic validity and enhanced scores in special populations.". Perceptual and Motor Skills 60 (3): 831-842. PMID 3927256. Retrieved on 2006-08-19.</ref> It also seems to be the case that people who are more creative are also more likely to show a similar pattern of brain activation.<ref>Weinstein, S, Graves RE (2002). "Are creativity and schizotypy products of a right hemisphere bias?". Brain and Cognition 49 (1): 138-151. PMID 12027399. Retrieved on 2006-08-19.</ref> Some researchers have been quick to point out that this in no way suggests that paranormal, mystical or creative experiences are in any way by themselves a symptom of mental illness, as it is still not clear what makes some such experiences beneficial whilst others lead to the impairment or distress of diagnosable mental pathology. However, people who have profoundly different experiences of reality or hold unusual views or opinions have traditionally held a complex role in society, with some being viewed as kooks, whilst others are lauded as prophets or visionaries.

Psychosis has been traditionally linked to the neurotransmitter dopamine. In particular, the dopamine hypothesis of psychosis has been influential and states that psychosis results from an overactivity of dopamine function in the brain, particularly in the mesolimbic pathway. The two major sources of evidence given to support this theory are that dopamine-blocking drugs (i.e. antipsychotics) tend to reduce the intensity of psychotic symptoms, and that drugs which boost dopamine activity (such as amphetamine and cocaine) can trigger psychosis in some people (see amphetamine psychosis).<ref> Kapur S, Mizrahi R, Li M. (2005) From dopamine to salience to psychosis - linking biology, pharmacology and phenomenology of psychosis. Schizophr Res, 79 (1), 59-68. PMID 16005191</ref>

The connection between dopamine and psychosis is generally believed to be complex. First of all, while antipsychotic drugs immediately block dopamine receptors, they usually take a week or two to reduce the symptoms of psychosis. Moreover, newer and equally effective antipsychotic drugs actually block slightly less dopamine in the brain than older drugs whilst also affecting serotonin function, suggesting the 'dopamine hypothesis' is vastly oversimplified.<ref> Jones, H. M., & Pilowsky, L. S. (2002) Dopamine and antipsychotic drug action revisited. British Journal of Psychiatry, 181, 271-275. PMID 12356650 </ref> Also, Soyka and colleagues found no evidence of dopaminergic dysfunction people with alcohol-induced psychosis<ref name=>Soyka, Michael, Thomas Zetzsche, Stefan Dresel, and Klaus Tatsch (May 2000). "FDG-PET and IBZM-SPECT Suggest Reduced Thalamic Activity but No Dopaminergic Dysfunction in Chronic Alcohol Hallucinosis". Journal of Neuropsychiatry & Clinical Neurosciences 12 (2): 287-288. PubMed. Retrieved on 2006-10-15.</ref> and Zoldan et al reported on the use of ondansetron, a 5-HT3 receptor antagonist, in the treatment of levodopa psychosis in Parkinson's disease patients (they were moderately successful).<ref name=Zoldan_et_al_1995>Zoldan, J., G. Friedberg, M. Livneh, and E. Melamed. (July 1995). "Psychosis in advanced Parkinson's disease: treatment with ondansetron, a 5-HT3 receptor antagonist". Neurology 45 (7): 1305-1308. PubMed.</ref>

Psychiatrist David Healy has criticised pharmaceutical companies for promoting simplified biological theories of mental illness that seem to imply the primacy of pharmaceutical treatments while ignoring social and developmental factors which are known to be important influences in the aetiology of psychosis.<ref>Healy, David (2002). The Creation of Psychopharmacology. Cambridge: Harvard University Press. ISBN 0-674-00619-4.</ref>

Some theories regard many psychotic symptoms to be a problem with the perception of ownership of internally generated thoughts and experiences.<ref> Blakemore, 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. PMID 12027049. Retrieved on 2006-08-19.</ref> For example, the experience of hearing voices may arise from internally generated speech that is mislabeled by the psychotic person as coming from an external source.

[edit] Cannabis

There is growing evidence for a small but significant link between cannabis use and vulnerability to psychosis.<ref name = Deg> Degenhardt, L, Smith J, Steel R, Johnstone CE, Frith CD (2003). "Editorial: The link between cannabis use and psychosis: furthering the debate.". Psychological Medicine 33: 3-6. PMID 12537030. Retrieved on 2006-08-19.</ref> Some studies indicate that cannabis use correlates with a slight increase in psychotic experience, which may help trigger full-blown psychosis in some people.<ref name = Deg> Degenhardt, L, Smith J, Steel R, Johnstone CE, Frith CD (2003). "Editorial: The link between cannabis use and psychosis: furthering the debate.". Psychological Medicine 33: 3-6. PMID 12537030. Retrieved on 2006-08-19.</ref> Early studies have been criticized for failing to consider other drugs (such as LSD) that the participants 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 controls have still found a small increase in risk for psychosis in cannabis users. It is 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. Additionally, people with developing psychosis possibly make greater use of the drug to provide temporary relief to their mental discomfort. The fact that cannabis use has increased over the past few decades, whereas the rate of psychosis has not,<ref> Degenhardt L, Hall W, Lynskey M (2001). "Comorbidity between cannabis use and psychosis: Modelling some possible relationships." (PDF). Technical Report No. 121.. Sydney: National Drug and Alcohol Research Centre.. Retrieved on 2006-08-19.</ref> suggests that a direct causal link is unlikely for all users.

[edit] Treatment

The treatment of psychosis often depends on what associated diagnosis (such as schizophrenia or bipolar disorder) is thought to be present. However, the first line treatment for psychotic symptoms is usually antipsychotic medication, and in some cases hospitalisation. There is growing evidence that cognitive behavior therapy<ref> Birchwood, M, Trower P (2006). "The future of cognitive-behavioural therapy for psychosis: not a quasi-neuroleptic.". British Journal of Psychiatry 188: 108-108. PMID 16449695. Retrieved on 2006-08-19.</ref> and family therapy<ref> Haddock, G, Lewis S (2005). "Psychological interventions in early psychosis.". Schizophrenia Bulletin 31 (3): 697-704. PMID 16006594. Retrieved on 2006-08-19.</ref> can be effective in managing psychotic symptoms. When other treatments for psychosis are ineffective, electroconvulsive therapy (ECT) (aka shock treatment) is sometimes utilized to relieve the underlying symptoms of psychosis, such as depression or schizophrenia.

[edit] History

The word psychosis was first used by Ernst von Feuchtersleben in 1845 <ref> Beer, M D (1995). "Psychosis: from mental disorder to disease concept.". Hist Psychiatry 6 (22(II)): 177-200. PMID 11639691. Retrieved on 2006-08-19.</ref> as an alternative to insanity and mania and stems from the Greek psyche (mind) and -osis (diseased or abnormal condition).<ref>Online Etymology Dictionary. Douglas Harper (2001). Retrieved on 2006-08-19.</ref> The word was used to distinguish disorders which were thought to be disorders of the mind, as opposed to neurosis, which was thought to stem from a disorder of the nervous system.

The division of the major psychoses into manic depressive insanity (now called bipolar disorder) and dementia praecox (now called 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. Kraepelin used the term 'manic depressive insanity' to describe the whole spectrum of mood disorders, in a far wider sense than it is usually used today. In Kraepelin's classification this would include 'unipolar' clinical depression, as well as bipolar disorder and other mood disorders such as cyclothymia. These are 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.

During the 1960s and 1970s, psychosis was of particular interest to counterculture critics of mainstream psychiatric practice, who argued that it may simply be another way of constructing reality and is not necessarily a sign of illness. For example, R. D. Laing argued that psychosis is a symbolic way of expressing concerns in situations where such views may be unwelcome or uncomfortable to the recipients. He went on to say that psychosis could be also seen as a transcendental experience with healing and spiritual aspects. Thomas Szasz focused on the social implications of labelling people as psychotic; a label he argues unjustly medicalises different views of reality so such unorthodox people can be controlled by society.

Generally, however, advances in both diagnosis and the scientific study of psychosis have led to theories drawing on biology, cognitive psychology and neuropsychology being accepted as mainstream explanations. In the United States and Europe, few reputable practitioners since the 1990s have approached psychosis outside this scientific frame of reference.

[edit] Social impact

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[edit] Notable cases

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[edit] See also

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[edit] References

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[edit] Further reading

  • Sims, A. (2002) Symptoms in the mind: An introduction to descriptive psychopathology (3rd edition). Edinburgh: Elsevier Science Ltd. ISBN 0-7020-2627-1

[edit] Personal accounts

[edit] External links

cs:Psychóza da:Psykose de:Psychose es:Psicosis (enfermedad) fr:Psychose it:Psicosi he:פסיכוזה nl:Psychose ja:精神病 no:Psykose pl:Psychoza pt:Psicose ru:Психоз simple:Psychosis sk:Psychóza sr:Психоза fi:Psykoosi sv:Psykos tr:Psikoz zh:思覺失調

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