23 December 2010. Children victimized by abuse subsequently carry a heavy psychological burden, but whether that includes susceptibility to psychosis has remained unproven. Two new studies sidestepped certain methodological pitfalls that often hinder efforts to answer this question. In a case-control study in the November Archives of General Psychiatry, researchers in Australia, including Paul Mullen of Monash University, Victoria, tied documented child abuse involving sexual penetration to increased risk of later developing schizophrenia or psychotic disorders in general. A study of twins in the United Kingdom found that children who were physically harmed by adults or bullied by other children were more likely than their peers to report psychotic symptoms at age 12. The study, led by Louise Arseneault, Institute of Psychiatry, London, appeared online in the American Journal of Psychiatry on October 15.
Assaults bundled with another burden
While some studies have linked traumatic experiences during childhood to the eventual development of psychotic disorders (see SRF related news story), many have used small samples, relied on retrospective reports, or inadequately controlled for confounders. The Australian team, with first author Margaret Cutajar, Monash University, Victoria, used police and forensic medicine records to identify children who had been sexually abused before age 16. This approach reduced the bias associated with relying on the memories of subjects who are mentally ill.
The study compared 2,759 abuse survivors with 2,677 children who had been randomly chosen from mandatory voter rolls except for the caveat that they match abused subjects’ gender and age group. The research team used a psychiatric case register to learn which subjects had been diagnosed with a psychotic disorder. They gleaned the nature and timing of the abuse from information supplied by the child or other informants and from the medical examination.
On average, abused children were 10 years old, give or take four years, when the medical exam took place, an admittedly inexact marker of when the abuse occurred. About two-thirds of the cases involved actual or attempted penetration of the child with an object, penis, or finger. Abused subjects were more likely than the comparison group to subsequently receive a diagnosis of psychosis or schizophrenia, an association seen only in those who experienced penetrative abuse. Schizophrenia emerged in 2.4 percent of the latter versus 0.7 percent of control subjects (odds ratio = 3.3, 95 percent confidence interval = 2.0 to 5.5), a pattern echoed for psychotic disorders as a whole.
In addition to penetrative abuse, being violated by more than one person upped the risk of schizophrenia (odds ratio = 2.92, 95 percent confidence interval = 1.13 to 7.34) in controlled analyses. While one might expect younger children to suffer the most harm from being abused, this study found that subjects who were older when molested were more likely than younger ones to receive a schizophrenia diagnosis (odds ratio = 1.11, 95 percent confidence interval 1.01 to 1.22). At greatest risk were children who had been penetrated between ages 12 and 16 by more than one offender; 17 percent of them developed psychosis (odds ratio = 14.9, 95 percent confidence interval = 8.4 to 26.3).
Beyond sexual trauma
Whereas Cutajar and colleagues focused on sexual abuse and diagnosed disorder, Arseneault and colleagues asked whether various kinds of childhood trauma predict the emergence of psychotic symptoms. To control for genetic influences, they studied a nationally representative sample of 2,232 twins, whom they identified from a registry of twin births in England and Wales. They gathered additional data by visiting the homes of subjects who were five, seven, 10, or 12 years old. There, they interviewed mothers to learn whether either twin had been physically hurt by an adult, bullied by other children, or frightened or harmed in an accident, such as a car crash or house fire. They also asked 12-year-old children whether they had experienced bullying by their peers and whether they had experienced any of seven psychotic symptoms.
Analyses suggested that children who had been mistreated by adults or child bullies were at heightened risk of developing psychotic symptoms, independently of their genetic risk, socioeconomic status, and other factors. Children hurt by adults were 3.16 times (95 percent confidence interval = 1.92 to 5.19) more likely to report psychotic symptoms than those who had been spared such abuse. Bullying predicted psychotic symptoms most strongly when children rather than the mother reported it (relative risk based on child self-reports = 4.36, 95 percent confidence interval = 3.05 to 6.23).
Some, but not all analyses, connected accidents to the development of psychotic symptoms. The researchers interpreted this weaker, less reliable relationship as evidence that children who suffer events in which someone intends to harm them are most vulnerable. “However, our findings do not indicate that we can completely ignore the risk carried by forms of trauma that do not involve such intention,” they write.
In contrast to the Australian findings, this study found no greater psychosis proneness in children who were traumatized at older ages. Whether the exposure occurred before age seven, and between ages seven and 12, made no difference for psychosis risk in the British sample.
Despite the harm that trauma and abuse inflict on children, neither study proves that they cause psychotic outcomes. Rather, such exposures could simply be standing in for some other correlated risk factor. Even so, both research groups stress that their findings point out a vulnerable group of children who might benefit from early detection and intervention. The Cutajar study found that an average of 15 years had passed between the authorities learning about the abuse and the child receiving a schizophrenia diagnosis. This presents a big opportunity to help children beleaguered by a cruel environment.—Victoria L. Wilcox.
Cutajar MC, Mullen PE, Ogloff JRP, Thomas SD, Wells DL, Spataro J. Schizophrenia and other psychotic disorders in a cohort of sexually abused children. Arch Gen Psychiatry. 2010 Nov;67(11):1114-9. Abstract
Arseneault L, Cannon M, Fisher HL, Polanczyk G, Moffitt TE, Caspi A. Childhood Trauma and Children's Emerging Psychotic Symptoms: A Genetically Sensitive Longitudinal Cohort Study. Am J Psychiatry. 2010 Oct 15. Abstract