It isn't just people with a diagnosis of schizophrenia who claim to hear voices inside their heads. Many other people do too. However, a key difference between psychiatric and non-psychiatric voice hearers is that the latter usually claim not to be bothered by their unusual experiences. One explanation for this difference in the hearers' interpretation is that voice hearers who develop schizophrenia have been traumatised in their past, thus predisposing them to find the voices in their heads distressing.
A new study by Liz Andrew and colleagues explores this idea further. Andrew's team compared the traumatic history of 22 voice hearers who were in contact with psychiatric services, with the history of 21 psychics and mediums, who also claimed to hear voices, but who had never been in contact with psychiatric services.
Both groups actually reported having experienced similar rates of trauma in the past. However, the psychiatric group reported having experienced more childhood sexual abuse. And crucially, there were also differences in the lasting psychological impact of the traumatic experiences the two groups had lived through. The psychiatric group still experienced anguish related to their trauma, and the persistence of these difficulties was related to how they interpreted the voices they heard. Specifically, the more that trauma-related anguish persisted, the more likely a participant was to say that they found their heard voices malevolent. In turn, interpreting voices as malevolent was associated with mental distress, in terms of depression levels.
In other words, these findings suggest that a traumatic past can predispose people to hear voices, and that it is the long-term effects of that trauma, and whether or not it is resolved psychologically, that then determines whether or not those heard voices are experienced as distressing.
The findings have clinical implications, as the researchers explained: "The high prevalence of childhood sexual abuse in the psychiatric voice hearers suggests that this may be an important factor to consider in the assessment, formulation and intervention of individuals who hear voices."
A final note of caution. It's possible that the non-psychiatric group in this study don't really experience voices in their heads in the same way that the psychiatric group do. Other researchers have excluded mediums and the like from their studies on the basis that they may experience "pseudo-hallucinations" not directly comparable to the voices heard by people with psychosis.
E. M. Andrew, N. S. Gray, R. J. Snowden (2008). The relationship between trauma and beliefs about hearing voices: a study of psychiatric and non-psychiatric voice hearers Psychological Medicine, 38 (10) DOI: 10.1017/S003329170700253X
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