Migraine and depersonalization disorder.

In a recent study of 204 patients with depersonaliza-tion disorder attending a specialist psychiatric clinic, Baker et al. (1) reported that 31% had a self-reported history of migraine and, of these, one third believed that their headaches and depersonalization were connected. Depersonalization disorder is classified as a dissociative disorder in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV), and is defined as 'persistent or recurrent experiences of feeling detached from, and as if one is an outside observer of, one's mental processes or body' (2). Other criteria necessary for diagnosis include that reality testing remain intact, and that the experience cause 'significant distress or impairment in social, occupational, or other important areas of functioning'. Depersonalization is often accompanied by derealization, which is defined as an 'alteration in perception or experience of the world so that it seems unreal'. It is currently unclear whether derealization represents a distinct disorder or is a subtype of Depersonalization. Depersonalization and/or derealization may occur in the context of organic disorders such as head injury, epilepsy or migraine (3). In such circumstances, a DSM-IV diagnosis of Depersonalization disorder is not permissible. Other exclusions to diagnosis include symptoms occurring exclusively during the course of another mental disorder, or secondary to the effects of a substance (drug of abuse or medication). The precise nature of the association between migraine and depersonalization/derealization is currently unknown. Such symptoms may occur as a component of migraine aura. A particularly dramatic example occurs in the so-called Alice in Won-derland syndrome, most common in children, where the aura is characterized by a variety of paroxysmal body schema disturbances, which may co-occur with depersonalization, derealization, visual illusions and disorders in the perception of time (4). In addition, Blau (5) has reported that migraineurs commonly experience a feeling of being 'unusually removed from reality' in the interval between termination of aura and the onset of headache, although patients do not often spontaneously volunteer this information. Observation by Baker et al. (1) that patients who described sudden onset of depersonal-ization/derealization (i.e. 38%) were significantly more likely to experience seeing flashes of light, may represent onset in association with visual aspects of migraine aura. Although 31% of their patients reported episodic symptomatology, the majority (64%) reported a pattern of chronic depersonaliza-tion with little or no fluctuation. A chronic pattern may not, however, completely exclude migraine as a possible aetiological factor in this subgroup …