Neuropsychiatric outcomes of traumatic brain injury: incidence, nature and risk factors

Traumatic brain injury (TBI) is a global health problem and a leading cause of death and disability worldwide (Maas et al., 2022). It has been demonstrated that TBI impacts on cognition, behaviour and personality and is a known risk factor for the later development of psychiatric disorder (Maas et al., 2022). Despite this, many people experiencing mental health difficulties post-injury are currently not receiving appropriate care, as access to rehabilitation services and structured follow-up of patients is variable (Chan et al., 2022). There is an urgent need to improve the current research landscape, as the neuropsychiatric profiles of people who have experienced TBI are often heterogeneous and not well understood. One difficulty in this area is that the vast majority of existing studies are based on clinical data, which usually have small sample size and are biased towards inclusion of more severe cases (Tagliaferri et al., 2006). There is evidence that mild-moderate TBIs may also raise the longer-term risk for psychiatric disorder, although this has not been well-studied (Sariaslan et al., 2016). Furthermore, many of these existing studies are cross-sectional, meaning that it is unclear to what extent mental health problems may precede TBI and to what extent they develop as a consequence of the injury. It is also therefore unclear how symptoms develop over time, and which factors may predict poor psychological outcomes. This PhD project will take a data science approach to characterising the neuropsychiatric impact of brain injury by conducting epidemiological analysis of existing longitudinal cohort studies. This will allow the neuropsychiatric outcomes of brain injury to be studied at different stages of the lifespan, as well as over longer-term follow-up periods. By using population studies, rather than data from clinical follow-ups, this will allow for a broader understanding of how mild and moderate brain injuries impact on neuropsychiatric outcomes across thousands of participants. Study 1 uses data from the ongoing Adolescent Brain Cognitive Development (ABCD) study being conducted in the United States. It has recruited 11,000+ children from 9-10 years of age who are measured annually or biannually across a number of variables, including physical health, mental health, cognition, neuroimaging and social and family environment. This study looks at the association between mild TBI in childhood and multidimensional psychological outcomes (symptoms, diagnoses and service use) at baseline and two-year follow-up. It also analyses the contribution of pre-injury mental health on post-injury outcomes. Study 2 will use data from the TRACK-TBI study, which collected data on 2,700 TBI patients and 300 controls across 18 U.S. level 1 trauma centres. Information collected includes demographic and social data and outcome assessments at 2-weeks, 3-months, 6-months, and 12- months post-injury. This study explores the relationship between TBI characteristics in adulthood and psychiatric outcomes in the first 12 months following injury. Study 3 will use data from UK Biobank that has followed 500,000 volunteers in the UK enrolled at ages from 40-69 in 2006. It records a wide range of physical and mental outcomes, as well as data on social environments, cognition and neuroimaging. This study will explore the association between TBI, mental health and cognition in adults aged >40. This PhD will make an important contribution to our understanding of outcomes of traumatic brain injury using longitudinal population studies that can be controlled for a range of potential confounders and can examine the influence of pre- and post-injury factors.