dissociation

Meaning: Dissociation is a detachment among functions that are normally integrated: memory, identity, awareness, and perception of surroundings. It is often linked to trauma or severe stress. The dissociative disorders are dissociative amnesia (loss of important personal memories beyond ordinary forgetting; a fugue adds sudden travel or wandering), dissociative identity disorder (two or more distinct identities that alternate in control, formerly called multiple personality disorder), and depersonalization/derealization disorder (feeling detached from oneself or from surroundings). In chemistry, dissociation instead means a compound separating into ions.

On the MCAT: A vignette describes a person who cannot recall their identity or past after a stressful event, turns up in another city with no memory of traveling, or shows alternating identities. You name the disorder or tell it apart from other categories, such as psychotic, anxiety, or mood disorders.

Common confusion: Dissociative identity disorder is not schizophrenia. Schizophrenia is a psychotic disorder marked by hallucinations, delusions, and disorganized thinking, not by multiple identities. Also, in depersonalization/derealization the person recognizes the feeling as unreal, so reality testing is intact, unlike in psychosis.