A series of articles in the November issue of Acta Psychiatrica Scandinavica explores the link between trauma and schizophrenia.
One suggestion is that some people would not have developed schizophrenia if they hadn’t had an earlier traumatic experience. According to this argument, psychotic experiences (for example, hearing voices; having paranoid thoughts) are not necessarily pathological (e.g. see here), rather they only become problematic if a person finds them distressing. Earlier trauma plays a causal role in schizophrenia, it’s argued, because it can leave people prone to finding these psychotic symptoms distressing.
To test this idea, Maarten Bak (Maastricht University) and colleagues interviewed thousands of people from the general population who had never had a psychotic experience, to find out if they had been traumatised in any way as a child. Three years later, researchers interviewed the same people again to find out whether or not they had had a psychotic experience since the first interview, and secondly, to find out if they found their psychotic experience(s) distressing or just unusual.
Among the 16 people who reported having had one or more non-distressing psychotic experiences since the first interview, just one (six per cent) had been traumatised as a child (according to their statements in the first interview). In contrast, among the 21 people who reported having had one or more distressing psychotic experiences, nine (43 per cent) had been traumatised as a child. The people who said they’d been traumatised also tended to report having less control over their psychotic experience(s).
The authors said their findings suggest “exposure to early trauma, defined here as self-reported traumatic experiences in childhood, predisposes persons to suffer from more emotional distress associated with psychotic experiences and less perceived control over these experiences, compared with those without a traumatic history”.
Bak, M., Krabbendam, L., Janssen, I., de Graaf, R., Vollebergh, W. & van Os, J. (2005). Early trauma may increase the risk for psychotic experiences by impacting on emotional response and perception of control. Acta Psychiatrica Scandinavica, 112, 360-366.
Link to related essay in the Guardian