Alcohol use and response inhibition: Alcohol use in the United Kingdom has a rich and detailed history that is often reflected by changing societal and political contexts (see Nicholls, 2014; Vetter, 2012). Its use is often associated with social situations and there had been an observable trend of this increasing over the years, although current figures suggest there has since been a decline following a peak circa 2008 (PHE, 2016a). Despite a general decline in alcohol use, problematic, hazardous or dependent drinking behaviours are still thought to affect around 10 million people in England (Copeland, 2020). Harmful or addictive drinking is often associated with a multitude of potential risks including, but not limited to; sexual health risk, physical risk (e.g., accidents or injury, increased risk of heart disease, liver disease, stroke), psychological/mental health risk (e.g., depression, anxiety, insomnia), and neurological risk (e.g., Wernicke-Korsakoff Syndrome) (NHS, 2018; PHE, 2016b; Zubaran, Fernandes, & Rodnight, 1997). This can subsequently place a significant demand upon National Health Service (NHS) resources with regards to how professionals support and care for these individuals. Understanding what may influence or maintain alcohol misuse is therefore fundamental in recognising how to offer treatment interventions for this population and there have been multiple proposed theories that can arguably be grouped into three fields: neurobiological, psychosocial, and psychological. An example of neurobiological theorising includes the dopamine theory of addiction. This was considered within the 1970's in light of predominantly rat-based studies that looked at the role of dopamine on maintaining and ceasing addiction (Nutt, Lingford-Hughes, Erritzoe, & Stokes, 2015). Psychosocial explanations include the influence of family and peer relationships (Friedman, Terras, & Glassman, 2000; McDonough, Jose, & Stuart, 2016), attachment with caregivers (Patock- Peckham, Cheong, Balhorn, & Nagoshi, 2001) and socioeconomic status (Allen et al., 2018). Lastly, psychological theories include ideas such as the role of risk factors, including poor inhibitory control (Weafer, Phan, & de Wit, 2020). This denotes that either disinhibition contributes to the development of misusing alcohol, the misuse of alcohol leads to increased disinhibition, or that there is a combination of the two (De Wit, 2009; Zhao, Qian, Fu, & Maes, 2017). Various studies have explored this relationship between inhibitory control and the development and maintenance of substance dependence (De Wit, 2009; Verdejo-García, Lawrence, & Clark, 2008; Zeng et al., 2013; Zeng, Su, Jiang, Zhu, & Ye, 2016). A metaanalytic review of 97 studies conducted by Smith, Mattick, Jamadar, and Iredale (2014) found that between samples of heavy substance users or those with addiction-like behaviours, versus healthy controls, there was an observable increase in behavioural impulsivity and poorer response inhibition for the former clinical groups, which may represent a vulnerability to addiction. Comparatively, experimental research by Jones and Field (2015) explored response inhibition abilities amongst social drinkers when presented with alcohol-related images and they found increased disinhibition associated with alcohol-related content. These findings suggest that groups of individuals that are characterised by poorer response inhibition may be at increased risk of problematic alcohol use. An example of such a group is people who show a constellation of personality traits clinically referred to as psychopathy, or 'psychopathic personality' (Hare, 2003). Psychopathy, response inhibition and associations with alcohol use: In 1941, Hervey Cleckley formally outlined the classic concept of psychopathy in his book 'The Mask of Sanity' (Cleckley, 1941). Since then, it has been the subject of considerable empirical investigation (Coffey, Cox, & Kopkin, 2018). The term holds many negative connotations, perpetuated by the way it is defined as "a pathologic syndrome involving prominent behavioural deviancy in the presence of distinctive emotional and interpersonal features" (Patrick, Fowles, & Krueger, 2009, p. 913). This is coupled with a tendency in forensic and legal settings to label individuals as 'psychopathic' unfavourably. However, it can be a helpful construct in predicting and managing risk and tailoring treatment plans, specifically within secure clinical settings. Despite psychopathy being formerly viewed as a categorical constellation of traits (i.e. 'psychopathic' versus 'non-psychopathic'), there is now shared consensus that a continuous trait approach is more accurate than a categorical approach when considering psychopathy as a construct (Edens, Marcus, Lilienfeld, & Poythress Jr, 2006). Amongst other characteristics, psychopathy is widely considered to be associated with problems in response inhibition (Baskin-Sommers & Newman, 2014), and these problems may contribute to externalising proneness such as substance (mis)use. Previous research that explored the predictive relationship of elevated psychopathy traits and drug use found a positive effect (Ahn & Vassileva, 2016) as well as the Disinhibition facet of the Triarchic Psychopathy Measure (TriPM; Patrick et al., 2009) relating to increased selfreport of hazardous drinking (Satchell, Johnson, Hudson, & Harper, 2020). Consequently, further understanding the relationship between psychopathy, response inhibition and alcohol use has clinical importance when considering risk and possible means of assessment and treatment or intervention. The current studies: This research thesis aimed to address this area of interest. Consequently, chapter one details a systematic review of the research literature on the relationship between elevated personality traits associated with psychopathy (as determined by validated measures), and performance on response inhibition tasks. The review considered this relationship particularly in participants who are reported to have a history of offending or forensic psychiatric care. Eleven papers were identified and accepted for inclusion within this review. Synthesis of the findings indicated that the relationship between 'psychopathic tendencies' and response inhibition is complex, and given the potential individual, clinical and societal benefits of better understanding this relationship directions for future research were discussed. Chapter two details a research paper that aims to further the literature base in this area. It describes the results of an empirical study that tested the relationship between increased personality traits associated with psychopathy in the general population, and alcohol use. This relationship is explored after adjusting for the effects of internalising behaviours and behavioural response inhibition abilities. Whilst individuals in secure forensic settings often display heightened levels of 'psychopathic tendencies' and increased alcohol use, we found limited support for a relationship of 'psychopathic tendencies' with alcohol use in a general population sample of social drinkers. Furthermore, internalising features (i.e. anxiety) were the only significant predictor of increased alcohol use following hierarchical regression analysis. The need for extending research within forensic populations and the potential implications for clinical treatment interventions were discussed. The systematic review and empirical paper are intended to be submitted to the Clinical Psychology Review and the Journal of Abnormal Psychology for publication, respectively. It was determined that the aims and findings of each chapter aligned with the interests and objectives of these journals.