Addressing methodological issues in a study of impulsivity and vulnerability for transition to alcohol use disorder

Abstract

Although large numbers of people consume alcohol, relatively few are diagnosed with alcohol use disorder (AUD). Factors influencing why some individuals transition from alcohol use to AUD remain unclear. Alcohol misuse, especially in adolescence/young adulthood, has been linked to a range of negative outcomes, including increased risk of developing AUD. In addition, a rich literature suggests individuals with AUD have heightened impulsivity. Specifically, they demonstrate increased choice impulsivity and diminished response inhibition. As such, heightened impulsivity, especially in young at-risk drinkers, might be a marker for vulnerability to transition to AUD. Although a number of studies have investigated this proposition, results have been mixed. Various methodological reasons have been posited for these inconsistent findings. Problems related to how to describe/quantify at-risk consumption and/or a reliance on retrospective methods of assessing this intake might be confounding results. Also, such studies typically have relatively modest sample sizes. The overarching aim of research presented in this thesis was to address these methodological limitations. To that end, two studies examined smartphone app development, reliability, and validity. It was proposed use of an app might assist in overcoming difficulties pertaining to empirical definitions and/or measurement of alcohol intake, as well as facilitate data collection from a large, diverse sample. Two studies investigated psychometric properties of online protocols that assess cognition. It was anticipated use of online tools would also enable data collection from a large sample. Finally, two studies concentrated on examining the relationship between alcohol intake and outcomes. Utilising the smartphone app as well as online protocols, the first of these studies explored adverse alcohol use consequences among tertiary students, while the second investigated facets of behavioural impulsivity among individuals who engage in at-risk alcohol intake behaviour. The app-related studies yielded a large representative sample (N = 671). Findings showed i) participants were compliant and demonstrated minimal reactivity to app protocols; and ii) the app is a valid means of assessing alcohol intake behaviour when compared to Timeline Followback. Studies investigating the psychometric properties of online protocols found i) the web-based Stop-Signal Task, when undertaken outside the laboratory as compared to in the laboratory, is a reliable method of assessing response inhibition (N = 166; r = .48); and ii) untimed/timed web-based 12-item versions of the Advanced Progressive Matrices are reliable and, relative to the Wechsler Abbreviated Scale of Intelligence, valid measures of perceptual reasoning and full-scale IQ (Study 1, N = 608, r = .34-.50; Study 2, N = 479, r = .41-.56). Finally, studies examining the relationship between alcohol intake and outcomes showed i) real-time intake of alcohol, age of drinking onset, and drug use predicts severity of alcohol use consequences in tertiary students, as measured by the Brief Young Adult Alcohol Consequences Questionnaire (N = 893; 37.3% of variance); and ii) contrary to expectations, significantly greater impulsivity – that is, either increased choice impulsivity and/or reduced response inhibition – was not apparent in at-risk drinkers, as compared to controls, regardless of the criteria employed to categorise alcohol intake. While this result might be related to the online nature of this research, it is possible more sensitive measures of behavioural impulsivity are required when assessing non-dependent drinkers.