Depersonalization can consist of a detachment within the self, regarding one's mind or body, or being a detached observer of oneself. Subjects feel they have changed and that the world has become vague, dreamlike, less real, lacking in significance or being outside reality while looking in. It can be a disturbing experience. Chronic depersonalization refers to depersonalization-derealization disorder, which is classified by the DSM-5 as a dissociative disorder.
Though degrees of depersonalization and derealization can happen to anyone who is subject to temporary anxiety or stress, chronic depersonalization is more related to individuals who have experienced a severe trauma or prolonged stress/anxiety. Depersonalization-derealization is the single most important symptom in the spectrum of dissociative disorders, including dissociative identity disorder and "dissociative disorder not otherwise specified" (DD-NOS). It is also a prominent symptom in some other non-dissociative disorders, such as anxiety disorders, clinical depression, bipolar disorder, schizophrenia, schizoid personality disorder, hypothyroidism or endocrine disorders, schizotypal personality disorder, borderline personality disorder, obsessive-compulsive disorder, migraines, and sleep deprivation; it can also be a symptom of some types of neurological seizure and can indicate low levels of brain serotonin.
In social psychology, and in particular self-categorization theory, the term depersonalization has a different meaning and refers to "the stereotypical perception of the self as an example of some defining social category".
Individuals who experience depersonalization feel divorced from their own personal self by sensing their body sensations, feelings, emotions, behaviors etc. as not belonging to the same person or identity. Often a person who has experienced depersonalization claims that things seem unreal or hazy. Also, a recognition of a self breaks down (hence the name). Depersonalization can result in very high anxiety levels, which further increase these perceptions.
Depersonalization is a subjective experience of unreality in one's self, while derealization is unreality of the outside world. Although most authors currently regard depersonalization (self) and derealization (surroundings) as independent constructs, many do not want to separate derealization from depersonalization.
Depersonalization is the third most common psychological symptom, after feelings of anxiety and feelings of depression. Depersonalization is a symptom of anxiety disorders, such as panic disorder. It can also accompany sleep deprivation (often occurring when suffering from jet lag), migraine, epilepsy (especially temporal lobe epilepsy), obsessive-compulsive disorder, stress, anxiety, and some cases of low latent inhibition. Interoceptive exposure is a non-pharmacological method that can be used to induce depersonalization.
A similar and overlapping concept called ipseity disturbance (ipse is Latin for "self" or "itself") may be part of the core process of schizophrenia spectrum disorders. However, specific to the schizophrenia spectrum seems to be "a dislocation of first-person perspective such that self and other or self and world may seem to be non-distinguishable, or in which the individual self or field of consciousness takes on an inordinate significance in relation to the objective or intersubjective world" (emphasis in original).
For the purposes of evaluation and measurement depersonalisation can be conceived of as a construct and scales are now available to map its dimensions in time and space. A study of undergraduate students found that individuals high on the depersonalization/derealization subscale of the Dissociative Experiences Scale exhibited a more pronounced cortisol response. Individuals high on the absorption subscale, which measures a subject's experiences of concentration to the exclusion of awareness of other events, showed weaker cortisol responses.
Pharmacological and situational causes
Depersonalization has been described by some as a desirable state, particularly by those that have experienced it under the influence of mood-altering recreational drugs. It is an effect of dissociatives and psychedelics, as well as a possible side effect of caffeine, alcohol, amphetamine, and cannabis. It is a classic withdrawal symptom from many drugs.
Benzodiazepine dependence, which can occur with long-term use of benzodiazepines, can induce chronic depersonalization symptomatology and perceptual disturbances in some people, even in those who are taking a stable daily dosage, and it can also become a protracted feature of the benzodiazepine withdrawal syndrome.
Lieutenant Colonel Dave Grossman, in his book On Killing, suggests that military training artificially creates depersonalization in soldiers, suppressing empathy and making it easier for them to kill other human beings.
Depersonalization as a psychological mechanism
Psychologically depersonalization can, just like dissociation in general, be considered a type of coping mechanism. Depersonalization is in that case unconsciously used to decrease the intensity of unpleasant experience, whether that is something as mild as stress or something as severe as chronically high anxiety and post-traumatic stress disorder. Depersonalization is an overgeneralized reaction in that it doesn't diminish just the unpleasant experience, but more or less all experience - leading to a feeling of being detached from the world and experiencing it in a more bland way. An important distinction must be made between depersonalization as a mild, short term reaction to unpleasant experience and depersonalization as a chronic symptom stemming from a severe mental disorder such as PTSD or Dissociative Identity Disorder 
Infectious disease & differential diagnosis
Depersonalization is also a direct symptom of Lyme disease as well as other tick-borne diseases. If depersonalization is suspected a blood-test is required in search of anti-bodies.
Treatment is dependent on the underlying cause, whether it is organic or psychological in origin. If depersonalization is a symptom of neurological disease, then diagnosis and treatment of the specific disease is the first approach. Depersonalization can be a cognitive symptom of such diseases as amyotrophic lateral sclerosis, Alzheimer's, multiple sclerosis (MS), neuroborreliosis (Lyme disease), or any other neurological disease affecting the brain. For those suffering from depersonalization with migraine, tricyclic antidepressants are often prescribed.
If depersonalization is a symptom of psychological causes such as developmental trauma, treatment depends on the diagnosis. In case of dissociative identity disorder or DD-NOS as a developmental disorder, in which extreme developmental trauma interferes with formation of a single cohesive identity, treatment requires proper psychotherapy, and—in the case of additional (co-morbid) disorders such as eating disorders—a team of specialists treating such an individual. It can also be a symptom of borderline personality disorder, which can be treated in the long term with proper psychotherapy and psychopharmacology.
The treatment of chronic depersonalization is considered in depersonalization disorder.
A recently completed study at Columbia University in New York City has shown positive effects from transcranial magnetic stimulation (TMS) to treat depersonalization disorder. Currently, however, the FDA has not approved TMS to treat DP.
A 2001 Russian study showed that naloxone, a drug used to reverse the intoxicating effects of opioid drugs, can successfully treat depersonalization disorder. According to the study: "In three of 14 patients, depersonalization symptoms disappeared entirely and seven patients showed a marked improvement. The therapeutic effect of naloxone provides evidence for the role of the endogenous opioid system in the pathogenesis of depersonalization."
The Depersonalisation Research Unit at the Institute of Psychiatry in London conducts research into depersonalization disorder. Researchers there use the acronym DPAFU (Depersonalisation and Feelings of Unreality) as a shortened label for the disorder.
- Brain fog
- Catatonic state
- Compassion fatigue
- Dissociation (psychology)
- Ego death
- Falling (sensation)
- Hallucinogen persisting perception disorder
- Human spirit
- Nina Searl
- Out-of-body experience
- Post-traumatic stress disorder
- Psychedelic experience
- Psychological trauma
- Spiritual crisis
- Sierra M & Berrios GE (2001) The Phenomenological Stability of Depersonalization: comparing the old with the new. Journal of Nervous and Mental Disease 189: 629-636.
- American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders DSM-5. American Psychiatric Association. ISBN 9780890425541.
- Sass L, Pienkos E, Nelson B, Medford N (2013). "Anomalous self-experience in depersonalization and schizophrenia: A comparative investigation". Consciousness and Cognition. 22 (2): 430–41. doi:10.1016/j.concog.2013.01.009. PMID 23454432.
- Sharma, Kirti; Behera, Joshil Kumar; Sood, Sushma; Rajput, Rajesh; Satpal; Praveen, Prashant (2014). "Study of cognitive functions in newly diagnosed cases of subclinical and clinical hypothyroidism". Journal of Natural Science, Biology, and Medicine. 5 (1): 63–66. doi:10.4103/0976-9668.127290. ISSN 0976-9668. PMC 3961955. PMID 24678200.
- The Edge Effect, by Eric R. Braverman, M.D., 2004, pp. 142
- Turner, John; Oakes, Penny (1986). "The significance of the social identity concept for social psychology with reference to individualism, interactionism and social influence". British Journal of Social Psychology. 25 (3): 237–52. doi:10.1111/j.2044-8309.1986.tb00732.x.
- Depersonalization Disorder at Merck Manual of Diagnosis and Therapy Home Edition
- Hall-Flavin, Daniel. "Depersonalization disorder: A feeling of being 'outside' your body". Retrieved 2007-09-08.
- Radovic F.; Radovic S. (2002). "Feelings of Unreality: A Conceptual and Phenomenological Analysis of the Language of Depersonalization". Philosophy, Psychiatry, & Psychology. 9 (3): 271–9. doi:10.1353/ppp.2003.0048.
- Simeon D (2004). "Depersonalisation Disorder: A Contemporary Overview". CNS Drugs. 18 (6): 343–54. doi:10.2165/00023210-200418060-00002. PMID 15089102.
- Sierra-Siegert M, David AS (December 2007). "Depersonalization and individualism: the effect of culture on symptom profiles in panic disorder". J. Nerv. Ment. Dis. 195 (12): 989–95. doi:10.1097/NMD.0b013e31815c19f7. PMID 18091192.
- Michelle V. Lambert; Mauricio Sierra; Mary L. Phillips; Anthony S. David (May 2002). "The Spectrum of Organic Depersonalization: A Review Plus Four New Cases". J Neuropsychiatry Clin Neurosci. 14 (2): 141–54. doi:10.1176/appi.neuropsych.14.2.141. PMID 11983788.
- Lickel J; Nelson E; Lickel A H; Brett Deacon (2008). "Interoceptive Exposure Exercises for Evoking Depersonalization and Derealization: A Pilot Study". Journal of Cognitive Psychotherapy. 22 (4): 321–30. doi:10.1891/0889-83220.127.116.111.
- Louis A. Sass; Josef Parnas (2003). "Schizophrenia, Consciousness, and the Self". Schizophrenia Bulletin. 29 (3): 427–44. doi:10.1093/oxfordjournals.schbul.a007017. PMID 14609238.
- Sierra M & Berrios GE (2000) The Cambridge Depersonalization Scale. A New Instrument of the Measurement of Depersonalisation. Psychiatry Research 93: 153-164.
- Giesbrecht, T.; T. Smeets; H. Merckelbac; M. Jelicic (2007). "Depersonalization experiences in undergraduates are related to heightened stress cortisol responses". J. Nerv. Ment. Dis. 195 (4): 282–87. doi:10.1097/01.nmd.0000253822.60618.60. PMID 17435477.
- Stein, M. B.; Uhde, TW (July 1989). "Depersonalization Disorder: Effects of Caffeine and Response to Pharmacotherapy". Biological Psychiatry. 26 (3): 315–20. doi:10.1016/0006-3223(89)90044-9. PMID 2742946.
- Raimo, E. B.; R. A. Roemer; M. Moster; Y. Shan (June 1999). "Alcohol-Induced Depersonalization". Biological Psychiatry. 45 (11): 1523–6. doi:10.1016/S0006-3223(98)00257-1. PMID 10356638.
- Cohen, P. R. (2004). "Medication-associated depersonalization symptoms: report of transient depersonalization symptoms induced by minocycline". Southern Medical Journal. 97 (1): 70–73. doi:10.1097/01.SMJ.0000083857.98870.98. PMID 14746427.
- "Medication-Associated Depersonalization Symptoms". medscape.com.
- "Depersonalization Again Finds Psychiatric Spotlight". Psychiatric News. 2003-08-15. pp. 18–30.
- Marriott, S.; P. Tyrer (1993). "Benzodiazepine dependence: avoidance and withdrawal". Drug Safety. 9 (2): 93–103. doi:10.2165/00002018-199309020-00003. PMID 8104417.
- Shufman, E.; A. Lerner; E. Witztum (2005). "Depersonalization after withdrawal from cannabis usage". Harefuah (in Hebrew). 144 (4): 249–51 and 303. PMID 15889607.
- Djenderedjian, A.; R. Tashjian (1982). "Agoraphobia following amphetamine withdrawal". The Journal of Clinical Psychiatry. 43 (6): 248–49. PMID 7085580.
- Mourad, I.; M. Lejoyeux; J. Adès (1998). "[Prospective evaluation of antidepressant discontinuation]". L'Encéphale (in French). 24 (3): 215–22. PMID 9696914.
- Ashton H (1991). "Protracted withdrawal syndromes from benzodiazepines". J Subst Abuse Treat. benzo.org.uk. 8 (1–2): 19–28. doi:10.1016/0740-5472(91)90023-4. PMID 1675688.
- Terao T; Yoshimura R; Terao M; Abe K. (1992-01-15). "Depersonalization following nitrazepam withdrawal". Biol Psychiatry. 31 (2): 212–3. doi:10.1016/0006-3223(92)90209-I. PMID 1737083.
- Grossman, Dave (1996). On Killing: The Psychological Cost of Learning to Kill in War and Society. Back Bay Books. ISBN 0-316-33000-0.
- Reed, Graham. (1972). The Psychology of Anomalous Experience. Hutchinson & Co. pages = 127
- Cardeña, Etzel (1 January 1994). "The Domain of Dissociation". Researchgate.com. Retrieved 7 November 2018.
- http://www.biologicalpsychiatryjournal.com/article/S0006-3223(98)00277-7/fulltext. Missing or empty
- Sierra M, Baker D, Medford N, et al. (2006). "Lamotrigine as an add-on treatment for depersonalization disorder: a retrospective study of 32 cases". Clin Neuropharmacol. 29 (5): 253–8. doi:10.1097/01.WNF.0000228368.17970.DA. PMID 16960469.
- Nuller, Yuri L.; Morozova, Marina G.; Kushnir, Olga N.; Hamper, Nikita (2001). "Effect of naloxone therapy on depersonalization: a pilot study". Journal of Psychopharmacology. Bekhterev Psychoneurological Research Institute. St-Petersburg, Russia: Journal of Psychopharmacology. 15 (2): 93–95. doi:10.1177/026988110101500205. PMID 11448093.
- Depersonalisation Research Unit - Institute of Psychiatry, London