This project is one of a number that are in competition for funding from the ‘GW4 BioMed MRC Doctoral Training Partnership’ which is offering up to 18 studentships for entry in September 2020.
The DTP brings together the Universities of Bath, Bristol, Cardiff and Exeter to develop the next generation of biomedical researchers. Students will have access to the combined research strengths, training expertise and resources of the four research-intensive universities.
Lead supervisor: Dr Gemma Taylor, Department of Psychology, Addiction and Mental Health Group (AIM), University of Bath
Co-supervisors: Prof George Davey Smith (Bristol), Dr Tom Freeman (Bath), Dr Robyn Wootton (Bristol) and Dr Hannah Sallis (Bristol)
Can we isolate the relationships between cannabis, tobacco and psychiatric disease through triangulation of data from countries that smoke cannabis with, and without tobacco?
- By the end of your training you will be an expert in the scientific impact of smoking cannabis and tobacco on psychiatric disease.
- You will learn to use exciting, novel and cutting-edge statistical and causal inference methods.
- You will learn how to analyse genetic data and apply methods such as Mendelian randomization and polygenic risk score analysis.
- The findings from this research will have international impact.
Smoking is the world’s leading cause of preventable illness and death. One in every two smokers will die because of their addiction unless they quit. In the UK, smoking prevalence has decreased from 46% during the 1970s to about 16% in recent years. However, smoking prevalence has not reduced in people with mental disorders, in 2015 it was 32%.
Cannabis is gaining increasing acceptance as a medicinal and recreational drug and prevalence of use is rising worldwide. There are concerns about the adverse associations of cannabis and tobacco with risk of psychiatric disease. The association between cannabis and psychiatric disease may be confounded by tobacco-use.
Here we propose an innovative approach to address this problem, by comparing estimates of the association between cannabis use and psychiatric disease in cohorts where cannabis is generally utilised without tobacco (North America) to cohorts where it is generally utilised with tobacco (Europe).
AIMS AND METHOD:
1. Conduct a systematic review and meta-analysis of longitudinal studies exploring the association between cannabis, tobacco use and later psychiatric disease, and compare estimates between countries with different cannabis/tobacco use profiles. The exposure will be tobacco/cannabis use administration profile and the primary outcome will be diagnosis of a new psychiatric disease. Estimates will be compared between countries with different cannabis and tobacco use profiles.
2. Conduct longitudinal analyses using pre-existing data from cohort studies with genetic information (Canadian Biobank, UK Biobank, HUNT, ALSPAC and others) to examine the association between cannabis/tobacco use and mental health, and whether this differs between North American and European countries, which have different cannabis/tobacco administration profiles. Exposure will have four levels: sole-administered tobacco, sole-administered cannabis, co-administered cannabis and tobacco, and the reference category will be never tobacco/cannabis-use. The primary outcome will be diagnosis of depression, and secondary outcomes will be anxiety, suicidality, and psychosis.
To address confounding, selection bias and reverse causation (i.e., people with psychiatric disease are more likely to use cannabis and tobacco), the student will triangulate evidence across three different analytical techniques: i) multivariable adjusted regressions, ii) propensity score matched regressions, and iii) Mendelian randomisation (MR) with polygenic risk scores. The student will use multivariable MR, to partition the effects of tobacco and cannabis smoking on psychiatric disease and estimate the unique contribution of cannabis and tobacco.
Applicants for a studentship must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK, in an area appropriate to the skills requirements of the project.
IMPORTANT: In order to apply for this project, you should apply using the DTP’s online application form: https://cardiff.onlinesurveys.ac.uk/gw4-biomed-mrc-doctoral-training-partnership-student-appl
You do NOT need to apply to the University of Bath at this stage – only those applicants who are successful in obtaining an offer of funding form the DTP will be required to submit an application to study at Bath.
More information on the application process may be found here: https://www.gw4biomed.ac.uk/doctoral-students/
APPLICATIONS CLOSE AT 17:00 ON 25 NOVEMBER 2019.