Understanding Associations Between Traumatic Brain Injury, Cognition, and Offending Behaviour

Abstract

Traumatic Brain Injury (TBI) is a major public health concern that is disproportionately prevalent in offending populations. TBI can have persistent disabling effects that impact greatly on the wellbeing of those affected. Despite this, TBI is often undiagnosed and under-treated. This thesis aims to better understand the potential effects of TBI on offending populations and whether TBI are leading to the sorts of deficits that may predispose someone to offending behaviour.

This thesis includes three studies intended to investigate the relationship between the effects of TBI and anti-social or criminal behaviours. The first is a systematic review of the existing studies that have assessed the cognitive effects of TBI in offending populations, for the purpose of determining which domains appear to be most affected, and what assessment tools are most appropriate with a TBI-affected offending population. Study two is a prospective longitudinal cohort study investigating whether domains of post-acute cognitive functioning are associated with long-term anti-social offending behaviour in a New Zealand population. Study three is a cross-sectional assessment of the cognitive profile of a New Zealand prison population by TBI status.

Study one identified a pool of literature that is deeply heterogenous in both methods and quality, indicating a field of study that is in its formative stages. Due to inconsistency in both tools of cognitive assessment and of TBI measures, meta-analysis of this literature was not appropriate. As with the general population, studies of TBI and cognition in offending populations are weakened by inconsistent or poor methodology. However, this review was effective in identifying several areas of cognitive functioning that could be focussed on in the later stages of the PhD. This review also indicated the need to better delineate self-reported TBI by factors such as childhood injury, repetitive injury, and injury severity.

Study two assessed cognition at the post-acute stage of TBI recovery in a general population sample to determine whether there were differences in cognitive profiles of those who went on to engage in antisocial behaviour 10 years later and those that did not. Despite finding differences in performance on assessments of processing speed, reaction time, and cognitive flexibility as expected, these differences did not remain significant following adjustment for other relevant confounders such as sex. This study suggests that broader demographic and social factors should be considered when assessing the relationship between TBI, cognition and behaviour.

Study three assessed a New Zealand men’s prison population with a bespoke battery of standardised cognitive assessments and investigated differences across TBI exposure characteristics, including TBI frequency, severity, and pervasiveness. Within this population, performance on the Delis-Kaplan Executive Function System (D-KEFS) Colour-Word Interference Test (CWIT) was significantly lower in participants who reported a history of pervasive or repetitive TBI exposure.

The findings across the three studies suggest that the links between TBI, cognition and behaviour are likely to be part of a complex network of factors where injury, social, and environmental factors intersect to influence a person’s life trajectory. The challenges of being able to accurately assess and quantify historical TBI in these populations who have experienced high TBI exposure adds to this complexity. Future research in this area will require adaptations and bespoke tools that are fit for purpose with populations with pervasive TBI exposure, such as offenders. Studies with large sample sizes are needed to enable more detailed explorations of how different injury, socio-cultural, environmental and lifestyle factors interact with each other to influence behaviour. Consideration of exposure to pervasive TBI needs to be considered when in future studies exploring links between TBI, cognition, and behaviour.