Psychosis and schizophrenia

The main remit of the Psychosis Research Group within the Centre for Academic Mental Health (Lead: Stan Zammit) is to increase understanding of the aetiology of schizophrenia and other psychotic disorders, and improve treatment outcomes for people with such disorders.  There are a number of strands of research conducted within our group:

1)    Lifecourse epidemiology: We are interested in understanding the development of psychotic experiences, persistence of symptoms, symptom trajectories, and transition to psychotic disorder from childhood through older adulthood. We aim to apply rigorous methodology to examine the role of aetiological factors, operating prenatally through to adulthood, on development of specific symptoms of psychosis, and to understand the pathways mediating causal relationships. The aetiological factors we are examining include genetic variation, prenatal nutrient deficiency and exposure to infection, neurocognitive development, social cognition, social relationships, substance use, trauma and adversity, and the wider social environment.

2)    Biomarkers and cognitive markers for psychosis: We are studying the use of genetic, epigenetic, proteomic, neuroimaging and cognitive data to help inform prediction for incident psychotic experiences and transition to clinical disorder to inform early intervention approaches. Work on the use of such data on predicting response to treatment can also help inform a personalised or stratified medicine approach. We are particularly interested in the predictive role of cognitive processes such as reasoning biases and errors in predictive processing that can help bridge the gap between biological abnormalities observed in psychosis and experiences of psychotic phenomena.

3)    Translation from clinical samples into the general population: We are interested in studying the likely population impact of key findings from clinical samples, for example, how genetic risk for schizophrenia, as determined by cutting-edge findings from collaborative GWA studies, is manifest phenotypically during childhood in the population, and whether this changes during adolescence and adulthood. We are also studying the overlap in genetic and non-genetic factors between psychosis and other disorders, particularly autism spectrum disorders, depression and anxiety.

4)    Psychosis and trauma: We are very interested in the overlap between psychosis, post-traumatic stress disorder and borderline personality disorder, and the common role of trauma in these disorders. We are examining the role of potentially modifiable cognitive processes mediating the impact of trauma on psychotic and quasi-psychotic experiences. Ultimately, our aim is to develop interventions to reduce trauma-related symptoms in people with psychotic disorders and related psychopathology.

5)    Improving care-pathways: Effective care-pathways are key to recovery-based care, reducing unmet need and achieving parity with physical health care. We are currently quantifying and investigating the whole care-pathway (including primary and secondary-care) for people with psychosis, to identify areas for improvement and evaluate possible solutions to problems identified.

The expertise within our group includes the application of robust methodology to longitudinal data, and the application of causal analysis methodology such as use of negative controls and Mendelian Randomisation approaches. We are experienced in using epidemiological data from a number of population-based cohort studies, particularly the Avon Longitudinal study of Parents and Children (ALSPAC) and Swedish record-linkage datasets, but also work with other datasets including CPRD, NCMH, and the Pattern Study.

We are part of a Bristol Health Partners Health Integration Team (HIT) Psychosis team and have strong links with the NIHR CLAHRC West. We have strong national and international collaborations, particularly with colleagues at the Karolinska Institute in Sweden, Cardiff University, UCL, Royal College of Surgeons in Ireland, University of Warwick, and Cambridge University.

Researchers

The Researchers working in this area include Sarah Sullivan, Jonathan Evans, David Gunnell, Matt Hickman, Paul Moran, Hannah Jones, Evie Stergiakouli, Dheeraj Rai, Jon Heron, Anna Guyatt, Stan Zammit, Professor of Psychiatric Epidemiology

Selected grants

  • Pathways to psychosis: Investigating epidemiological, cognitive and genetic mechanisms underlying development of psychotic experiences in young adults: S.Zammit, M. Cannon, A. David, P. Fletcher, J. Heron, P. Holmans, P.B. Jones, G. Lewis, D. Linden, J. Macleod, M. O’Donovan, M. Owen, A. Thompson, D. Wolke.Research Grant MR/M006727/1, MRC (£1,328,163) 2015 – 2019

Selected publications

  • Zammit, S., et al., A population-based study of genetic variation and psychotic experiences in adolescents. Schizophr Bull, 2014. 40(6): p. 1254-62.
  • Kounali, D., et al., Common versus psychopathology-specific risk factors for psychotic experiences and depression during adolescence. Psychol Med, 2014. 44(12):2557-66.
  • Khandaker, G.M., et al., Association of Serum Interleukin 6 and C-Reactive Protein in Childhood With Depression and Psychosis in Young Adult Life: A Population-Based Longitudinal Study. JAMA Psychiatry, 2014. 71(10):   1121-8
  • Gage, S.H., et al., Associations of cannabis and cigarette use with psychotic experiences at age 18: findings from the Avon Longitudinal Study of Parents and Children. Psychol Med, 2014: 44(16):3435-44.                  
  • Zammit, S., et al., Psychotic experiences and psychotic disorders at age 18 in relation to psychotic experiences at age 12 in a longitudinal population-based cohort study. Am J Psychiatry, 2013. 170(7): p. 742-50.
  • Fisher, H.L., et al., Pathways Between Childhood Victimization and Psychosis-like Symptoms in the ALSPAC Birth Cohort. Schizophr Bull, 2013. 39(5): p. 1045-55.
  • Fowler, T., et al., A population-based study of shared genetic variation between premorbid IQ and psychosis among male twin pairs and sibling pairs from Sweden. Arch Gen Psychiatry, 2012. 69(5): p. 460-6.
  • Zammit, S., et al., Cannabis, COMT and psychotic experiences. Br J Psychiatry, 2011. 199(5): p. 380-5.
  • Gunawardana, L., et al., Pre-conception inter-pregnancy interval and risk of schizophrenia. Br J Psychiatry, 2011. 199(4): p. 338-9.
  •  Zammit, S., et al., Individuals, schools, and neighborhood: a multilevel longitudinal study of variation in incidence of psychotic disorders. Arch Gen Psychiatry, 2010. 67(9): p. 914-22.
  •  Moore, T.H., et al., Cannabis use and risk of psychotic or affective mental health outcomes: a systematic review. Lancet, 2007. 370(9584): p. 319-28.
  •  Zammit, S., et al., Self-reported cannabis use as a risk factor for schizophrenia: further analysis of the 1969 Swedish conscript cohort. BMJ, 2002. 325: p. 1199-1201.
psychosis
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