The LEAP Project

GEL team members working on the project: Professor Angelica Ronald, Laura Havers

Collaborators include: Prof Daniel Freeman, Prof Robert Plomin, Professor Philip McGuire

Funded by: The Medical Research Council and Wellcome Trust ISSF award

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


Barkhuizen, W., Taylor, M. J., Freeman, D. and Ronald, A. (2019). A twin study on the association between psychotic experiences and tobacco use during adolescence. Journal of the American Academy of Child and Adolescent Psychiatry, 58, 267-276

Ronald, A. & Pain, O. (2018). A systematic review of genome-wide research on psychotic experiences and negative symptom traits: New revelations and their implications for psychiatry. Human Molecular Genetics, 1;27(R2), R136-R152

Shakoor, S., McGuire, P., Cardno, A. G., Freeman, D. & Ronald, A. (2018). A twin study exploring the association between childhood emotional and behaviour problems and specific psychotic experiences in a community sample of adolescents. Journal of Child Psychology & Psychiatry, 59, 565-573.

Pain, O., Dudbridge, F., Cardno, A.G., Freeman, D., Yi, L., Lundstrom, S., Lichtenstein, P. & Ronald, A. (2018). Genome-wide analysis of adolescent psychotic-like experiences shows genetic overlap with psychiatric disorders. Neuropsychiatric Genetics, 177, 416-425.

Cheesman, R., Selzam, S., Ronald, A., Dale, P. S., McAdams, T. A., Eley, T. C. & Plomin, R. (2017). Childhood behaviour problems show the greatest gap between DNA-based and twin heritability. Translational Psychiatry, 7(12):1284.

Hosang, G., Cardno, A.G., Freeman, D., & Ronald, A. (2017). Characterization and structure of hypomania in a British nonclinical adolescent sample. Journal of Affective Disorders, 207, 228-235.

Singham, T., Viding, E., Schoeler, T., Arseneault, L., Ronald, A., Cecil, C. M., McCrory, E., Rijsdijk, F., Pingault, J. (2017). Concurrent and longitudinal impact of peer victimisation on mental health: A tale of vulnerability and resilience. JAMA Psychiatry, 74, 1112-1119.

Shakoor, S., Zavos, H., Haworth, C. M. A., McGuire, P., Cardno, A. G., Freeman, D., & Ronald, A. (2016). Association between stressful life events and psychotic experiences in adolescence: evidence for gene-environment correlations. British Journal of Psychiatry, 208, 532-8.

Taylor, M. J., Freeman, D. & Ronald, A. (2016). Dimensional psychotic experiences in adolescence: Evidence from a taxometric study of a community-based sample. Psychiatry Research, 241, 35-42.

Zavos, H. M. S., Eley, T. C., McGuire, P., Plomin, R., Cardno, A. G., Freeman. D. & Ronald, A. (2016). Shared etiology of psychotic experiences and depressive symptoms in adolescence: A longitudinal twin study. Schizophrenia Bulletin, 42, 1197-206.

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.

Sieradzka, D., Power, R. A., Freeman, D., Cardno, A. G., Dudbridge, F., & Ronald, A. (2015). Heritability of individual psychotic experiences captured by common genetic variants in a community sample of adolescents. Behavior Genetics, 45, 493-502.

Taylor, M. J., Gregory, A. M., Freeman, D. & Ronald, A. (2015). Do sleep disturbances and psychotic-like experiences in adolescence share genetic and environmental influences? Journal of Abnormal Psychology, 124, 674-84.

Taylor, M.J., Robinson, E.B., Happé, F., Bolton, P., Freeman, D., & Ronald, A. (2015). A longitudinal twin study of the association between childhood autistic traits and psychotic experiences in adolescence. Molecular Autism, 6, 44

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, 868-77.

Sieradzka, D., Power, R.A., Freeman, D., Cardno, A.D., 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(4):e94398. doi: 10.1371/journal.pone.0094398.

Zavos, H.M.S., Freeman, D., Haworth, C.M.A., McGuire, P., Plomin, R., Cardno, A.G., & Ronald, A. (2014). Consistent etiology of severe, frequent psychotic experiences and milder, less frequent manifestations: A twin study of specific psychotic experiences in adolescence. JAMA Psychiatry, 71, 1049-1057.