Background: Over the last decade, there has been a renewed interest in the role of environmental adversities in the development of psychotic experiences (1-3). It is becoming increasingly evident that such experiences should be understood as "endpoints of atypical developmental trajectories" (5, 6).

In our work at the University of Liverpool, we have also found that communication deviance seems to be especially prevalent in the mothers of psychotic offspring (4). In the same paper, we suggest that disruptions in the child's early development may explain the findings from large birth cohort studies that document subtle developmental asymmetries in children who are later diagnosed with Schizophrenia (10-12).

One risk factor that has been found to be associated with later development of psychosis in the offspring is the unwantedness of the pregnancy (7-9). Unfortunately, these findings have received little attention from the research community and consequently little or no attention has been devoted to explore the potential developmental pathways and mediators that could explain such relationship.

Overall aim: The current study has the primary aim to replicate Myhrman et al.'s findings (7) and secondarily to explore potential mediators of this previously reported association.

Project 1

Aims: To investigate the association between unwanted pregnancy and psychotic experiences in the ALSPAC dataset

Hypothesis: It is anticipated that unwanted pregnancy will be associate with increased likelihood of self-reported psychotic experiences in the offspring.

Exposure variable(s): Unwantedness of the pregnancy

Outcome variable(s): Psychotic experiences

Cofounding variable(s): Maternal history of psychosis, family history of psychosis, socio-economic variables.

Project 2

Aims: To investigate potential mediators of the relationship between unwanted pregnancy and psychotic experiences

Hypothesis: It is anticipated that unwanted pregnancy and paranoia in the offspring will be mediated by low self-esteem, poor self-concept and external locus of control

Exposure variable(s): Unwantedness of the pregnancy

Outcome variable(s): Psychotic experiences [e.g. 'delusions of being spied on' (D1) and 'delusions of persecution' (D2)].

Cofounding variable(s): Maternal history of psychosis, family history of psychosis, socio-economic variables.

Project 3

Aims: To investigate potential mediators of the relationship between unwanted pregnancy and psychotic experiences

Hypothesis: It is anticipated that unwanted pregnancy and self-reported psychotic experiences in the offspring will be mediated by neuro- and social-cognitive variables.

Exposure variable(s): Unwantedness of the pregnancy

Outcome variable(s): Social cognition, neuro-cognition and psychotic experiences

Cofounding variable(s): Maternal history of psychosis, family history of psychosis, socio-economic variables.

Planned analysis:

Paulo de Sousa (PhD student) will carry out the statistical analysis. Initially, basic association between symptoms of psychosis (PLIKSi) and unwanted pregnancy will be tested using binary logistic regression. In a second stage, several mediation models will be estimated using Mplus 6.1.

Bibliographic references

1. Bentall RP. Madness explained: Psychosis and human nature. London: Allen Lane; 2003.

2. Bentall RP. Doctoring the mind : is our current treatment of mental illness really any good? New York: New York University Press; 2009.

3. Varese F, Smeets F, Drukker M, et al. Childhood adversities increase the risk of psychosis: A meta-analysis of patient-control, prospective- and cross-sectional cohort studies. Schizophrenia Bull 2012;38(4):661-671.

4. De Sousa P, Varese F, Sellwood W, Bentall, RP. Parental Communication and Psychosis: A Meta-analysis. Schizophr Bull 2013: sbt088v1-sbt088.

5. Bentall RP, Fernyhough C, Morrison AP, Lewis S, Corcoran R. Prospects for a cognitive-developmental account of psychotic experiences. Brit J Clin Psychol 2007;46:155-173.

6. Bentall RP, Fernyhough C. Social predictors of psychotic experiences: Specificity and psychological mechanisms. Schizophrenia Bull 2008;34(6):1012-1020.

7. Myhrman A, Rantakallio P, Isohanni M, Jones P, Partanen U. Unwantedness of a pregnancy and schizophrenia in the child. Brit J Psychiat 1996;169(5):637-640.

8. Herman DB, Brown AS, Opler MG, et al. Does unwantedness of pregnancy predict schizophrenia in the offspring? Findings from a prospective birth cohort study. Soc Psych Psych Epid 2006;41(8):605-610.

9. McNeil TF, Schubert EW, Cantor-Graae E, et al. Unwanted pregnancy as a risk factor for off spring schizophrenia-spectrum and affective disorders in adulthood: a prospective high-risk study. Psychol Med 2009;39(6):957-965.

10. Cannon M, Caspi A, Moffitt TE, Harrington H, Taylor A, Murray RM, Poulton R. Evidence for early childhood, pan-developmental impairment specific to schizophreniform disorder: results from a longitudinal birth cohort. Archives of General Psychiatry 2002;59:449-456.

11. Jones P, Rodgers B, Murray R, Marmot M. Child development risk factors for adult schizophrenia in the British 1946 birth cohort. Lancet 1994;344:1398-1402.

12. Welham J, Isohanni M, Jones P, McGrath J. The antecedents of schizophrenia: a review of birth cohort studies. Schizophrenia Bull 2009;35(3):603-623.