The concept of dissociation is a poorly understood one, and definitions have changed somewhat over time (1). An early (and possibly the first) usage of the term is attributed to the French psychiatrist Moreau De Tours in 1845, where it referred to an isolation of ideas and a splitting of different elements of the personality (2).
DSM-IV-tr defined dissociation as “a disruption in the usually integrated functions of consciousness, memory, identity, or perception, and where the disturbance may be sudden or gradual, transient, or chronic” (3).
DSM V defines dissociation as “the splitting off of clusters of mental contents from conscious awareness” and “the separation of an idea from its emotional significance and affect” (4).
According to the WHO diagnostic manual ICD-10, the common themes that are shared by dissociative disorders (of which dissociation is a central element) are a partial or complete loss of the normal integration between memories of the past, awareness of identity and immediate sensations, and control of bodily movements, which often result from traumatic experiences, intolerable problems or disturbed relationships (5).
Sources:
1. Dillon, J. M. (2008). “Defining Dissociation Based on the Factor Structures of Three Instruments“. Umi Dissertation Publishing
2. P. F. Dell, & J. A. O’Neil (Eds.) (2011). “Dissociation and the Dissociative Disorders: DSM-V and Beyond
3. American Psychiatric Association. (2000). Diagnostic and statistical
manual of mental disorders (4th ed., text rev.). 519
4. American Psychiatric Association (2013). The Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM–5;). 820
5.. World Health Organization. (1990). Dissociative [conversion] disorders. In International statistical classification of diseases and related health problems (10th ed.). Retrieved from: http://apps.who.int/classifications/icd10/browse/2010/en#/F44