The LEAP Project

The Longitudinal Experiences And Perceptions (LEAP) Project

GEL team members working on the project: Dr Angelica Ronald, Dr Sania Shakoor, Dr Mark TaylorDominika Sieradzka

Collaborators include Prof Daniel Freeman, Prof Robert Plomin

Funded by the Medical Research Council


Schizophrenia and bipolar disorder, the most common psychotic disorders, have a point prevalence of 0.45% and 0.74% respectively. Extensive research has been conducted on psychotic disorders once they have emerged in adulthood, but the causal pathways of psychotic experiences when they first emerge in adolescence are poorly understood. Research that informs prevention and early intervention strategies has potential translational benefits.

The Project

This Medical Research Council-funded project aims to characterise the aetiology of psychotic experiences in adolescence. It is hoped that by understanding the causes of psychotic experiences in 15- to 18-year-olds this knowledge can inform the development of early interventions.


Sieradzka, D., Power, R. A., Freeman, D., Cardno, A. G., Dudbridge, F., & Ronald, A. (in press). Heritability of individual psychotic experiences captured by common genetic variants in a community sample of adolescents. Behavior Genetics.
Taylor, M. J., Gregory, A. M., Freeman, D. & Ronald, A. (in press). Do sleep disturbances and psychotic-like experiences in adolescence share genetic and environmental influences? Journal of Abnormal Psychology.
Shakoor, S., McGuire, P., Cardno, A. G., Freeman, D., Plomin, R., & Ronald, A. (2015). A shared genetic propensity underlies experiences of bullying victimization in late childhood and self-rated paranoid thinking in adolescence. Schizophrenia Bulletin, 41, 754-63.
Shakoor, S., Zavos, H. M. S., McGuire, P., Cardno, A. G., Freeman, D., & Ronald, A. (2015). Psychotic experiences are linked to cannabis use in adolescents in the community because of common underlying environmental risk factors. Psychiatry Research, 227, 144-151.

Zavos, H.M.S., Freeman, D., Haworth, C.M.A., McGuire, P., Plomin, R., Cardno, A.G., & Ronald, A. (in press). Consistent etiology of severe, frequent psychotic experiences and milder, less frequent manifestations: A twin study of specific psychotic experiences in adolescence. JAMA Psychiatry.

Sieradzka, D., Power, R.A., Freeman, D., Cardno, A.G., McGuire, P., Plomin, R., Meaburn, E.L., Dudbridge, F., & Ronald, A. (2014). Are genetic risk factors for psychosis also associated with dimension-specific psychotic experiences in adolescence? PlosOne, 9, e94398.

Ronald, A., Sieradzka, D., Cardno, A.G., Haworth, C.M.A., McGuire, P., & Freeman, D. (2014). Characterization of psychotic experiences in adolescence using the Specific Psychotic Experiences Questionnaire (SPEQ): Findings from a study of 5000 16-year-old twins. Schizophrenia Bulletin, 40, 868-877.

Genes Environment Lifespan Laboratory