Sharon Dawe

The role of impulsivity in the development of substance use and eating disorders

Impulsivity is now widely viewed as a multidimensional construct consisting of a number of related dimensions. Although many measures of impulsivity are correlated, most recent factor analyses support at least a two-factor model. In the current paper, these two factors have been labelled reward sensitivity, reflecting one of the primary dimensions of Grays personality theory, and rash-spontaneous impulsiveness. The evidence supporting the existence of two dimensions of impulsivity is reviewed in relation to substance misuse and binge eating.

The relationship between sociocultural pressure to be thin and body dissatisfaction in preadolescent girls

This study investigates the relationships among sociocultural pressures to be thin, internalisation of the thin ideal, social comparison, body mass index, and body dissatisfaction in young girls. One hundred and fifty-three 10-13 year old girls completed measures assessing sociocultural pressure to be thin, media exposure, body dissatisfaction, social comparison, and internalisation of the thin ideal. Although sociocultural factors, as a group, were significantly associated with internalisation of the thin ideal, perceived media pressure was the only sociocultural influence uniquely related to internalisation of the thin ideal. Perceived pressure to be thin delivered by the media was found to be associated with body dissatisfaction via internalisation of the thin ideal. The relationship between internalisation of the thin ideal and body dissatisfaction was also partially influenced by social comparison. Body mass was found to have a direct association with body dissatisfaction. A model incorporating the relationships among media pressure, internalisation of the thin ideal, social comparison, and body dissatisfaction is proposed.

Does the tendency to act impulsively underlie binge eating and alcohol use problems? An empirical investigation

The co-occurrence of problem drinking and binge eating and purging has been well documented. However, there has been relatively little investigation of etiological models that may influence the development of this co-occurrence. This study tests the hypotheses that impulsivity is heightened in eating disordered women compared with controls, and that women with comorbid bulimia and alcohol use disorders show higher impulsivity than bulimic-only women. The Impulsivity scale, BIS/BAS scales, State Anxiety Inventory, and a behavioural measure of reward responsiveness (CARROT) were administered to 22 women with bulimia, 23 women with comorbid bulimia and alcohol abuse/dependence, and 21 control women. As hypothesised, eating disordered women scored higher than controls on several self-report measures of impulsivity and sorted cards faster during a financially rewarded trial on the behavioural task. Also, as predicted, comorbid women scored higher than bulimic women on the Impulsivity scale. These findings suggest that individual differences in impulsiveness and a tendency to approach rewarding stimuli may contribute to developing these disorders.

Impulsivity and adolescent substance use: rashly dismissed as "all-bad"?

The initial use of illicit drugs and alcohol typically occurs during adolescence. Individual differences in impulsivity and related constructs are consistently identified as key factors in the initiation and later problematic use of substances. Consequently, impulsivity is generally regarded as a negative trait; one that conveys only risk. However, what is often overlooked in addiction science is the positive role facets of trait impulsivity can play in everyday life and adaptive functioning. The following review aims to summarize recent advances in the psychobiology of impulsivity, including current perspectives on how it can convey risk for substance misuse. The review will also consider the importance of adolescence as a phase of life characterized by substantial neurodevelopment and natural increases in impulsivity. Uniquely, the review aims to reframe thinking on adolescent impulsivity to include the positive with the negative, and discuss how such thinking can benefit efforts for early intervention and future research.

Dose-Related Psychotic Symptoms in Chronic Methamphetamine Users: Evidence From a Prospective Longitudinal Study

CONTEXT Methamphetamine is associated with psychotic phenomena, but it is not clear to what extent this relationship is due to premorbid psychosis among people who use the drug. OBJECTIVE To determine the change in the probability of psychotic symptoms occurring during periods of methamphetamine use. DESIGN Longitudinal prospective cohort study. A fixed-effects analysis of longitudinal panel data, consisting of 4 noncontiguous 1-month observation periods, was used to examine the relationship between changes in methamphetamine use and the risk of experiencing psychotic symptoms within individuals over time. SETTING Sydney and Brisbane, Australia. PARTICIPANTS A total of 278 participants 16 years of age or older who met DSM-IV criteria for methamphetamine dependence on entry to the study but who did not meet DSM-IV criteria for lifetime schizophrenia or mania. MAIN OUTCOME MEASURES Clinically significant psychotic symptoms in the past month, defined as a score of 4 or more on any of the Brief Psychiatric Rating Scale items of suspiciousness, hallucinations, or unusual thought content. The number of days of methamphetamine use in the past month was assessed using the Opiate Treatment Index. RESULTS There was a 5-fold increase in the likelihood of psychotic symptoms during periods of methamphetamine use relative to periods of no use (odds ratio [OR], 5.3 [95% CI, 3.4-8.3]; P < .001), this increase being strongly dose-dependent (1-15 days of methamphetamine use vs abstinence in the past month: OR, 4.0 [95% CI, 2.5-6.5]; ≥16 days of methamphetamine use vs abstinence in the past month: OR, 11.2 [95% CI, 5.9-21.1]). Frequent cannabis and/or alcohol use (≥16 days of use in the past month) further increased the odds of psychotic symptoms (cannabis: OR, 2.0 [95% CI, 1.1-3.5]; alcohol: OR, 2.1 [95% CI, 1.1-4.2]). CONCLUSIONS There was a large dose-dependent increase in the occurrence of psychotic symptoms during periods of methamphetamine use among users of the drug.

Should personality traits be considered when refining substance misuse treatment programs

The interplay between stable personality characteristics and environmental factors is emphasised in most contemporary approaches to individual differences. This interaction appears to be important in understanding the development of substance use and misuse. Impulsivity related personality traits such as sensation-seeking, novelty seeking, reward-sensitivity and behavioural disinhibition, are strongly linked to adolescent and adult substance use and misuse. The role of anxiety-related traits, in the development of substance misuse is less clear. Nonetheless, anxiety disorders are very common amongst adult substance misusers and almost certainly play a critical role in the maintenance of a substance use disorder and influence treatment effectiveness. The data suggest that personality influences treatment outcomes and yet these individual differences are generally not addressed in treatment. We argue in this review that interventions which are matched to these relevant personality traits may improve treatment outcomes for substance misusers.

Evaluating the impact of community-based treatment options on methamphetamine use: findings from the Methamphetamine Treatment Evaluation Study (MATES)

AIMS To evaluate the impact of community-based drug treatment on methamphetamine use using inverse probability of treatment-weighted (IPTW) estimators to derive treatment effects. DESIGN A longitudinal prospective cohort study with follow-ups at 3 months, 1 year and 3 years. Treatment effects were derived by comparing groups at follow-up. IPTW estimators were used to adjust for pre-treatment differences between groups. SETTING Sydney and Brisbane, Australia. PARTICIPANTS Participants were methamphetamine users entering community-based detoxification (n = 112) or residential rehabilitation (n = 248) services and a quasi-control group of methamphetamine users (n = 101) recruited from the community. MEASUREMENTS Frequency of methamphetamine use between interviews (no use, less than weekly, 1-2 days per week, 3+ days per week), continuous abstinence from methamphetamine use, past month methamphetamine use and methamphetamine dependence. FINDINGS Detoxification did not reduce methamphetamine use at any follow-up relative to the quasi-control group. Relative to quasi-control and detoxification groups combined, residential rehabilitation produced large reductions in the frequency of methamphetamine use at 3 months [odds ratio (OR) = 0.23, 95% confidence interval (CI) 0.15-0.36, P < 0.001), with a marked attenuation of this effect at 1 year (OR 0.62, 95% CI 0.40-0.97, P = 0.038) and 3 years (OR = 0.71, 95% CI 0.42-1.19, P = 0.189). The greatest impact was for abstinence: for every 100 residential rehabilitation clients there was a gain of 33 being continuously abstinent at 3 months, with this falling to 14 at 1 year and 6 at 3 years. CONCLUSIONS Community-based residential rehabilitation may produce a time-limited decrease in methamphetamine use, while detoxification alone does not appear to do so.

Improving family functioning and child outcome in methadone maintained families: the Parents Under Pressure programme

Twelve families responded to posters displayed in a methadone clinic for inclusion in a pilot study assessing the viability and potential utility of an intensive, multi-component family-focused intervention, the Parents Under Pressure programme. The programme was designed to improve child behaviour, decrease parental stress and improve family functioning in methadone-maintained families by targeting affect regulation, mood, views of self as a parent, drug use and parenting skills. Nine of the families completed the programme delivered in their homes; eight were recontacted at 3 months. Each family reported significant improvements in three domains: parental functioning, parent-child relationship and parental substance use and risk behaviour. In addition to the changes in family functioning, the majority of families reported a decrease in concurrent alcohol use, HIV risk-taking behaviour and maintenance dose of methadone. The families reported high levels of satisfaction with the programme. It is recommended that future studies include independent measures (e.g. behavioural observations) of child outcome and parental functioning. The results were optimistic and provided the impetus to evaluate the treatment programme using a randomized controlled trial.

Does methamphetamine use increase violent behaviour? Evidence from a prospective longitudinal study

AIMS To determine whether violent behaviour increases during periods of methamphetamine use and whether this is due to methamphetamine-induced psychotic symptoms. DESIGN A fixed-effects (within-subject) analysis of four non-contiguous 1-month observation periods from a longitudinal prospective cohort study. SETTING Sydney and Brisbane, Australia. PARTICIPANTS A total of 278 participants aged 16 years or older who met DSM-IV criteria for methamphetamine dependence on entry to the study but who did not meet DSM-IV criteria for life-time schizophrenia or mania. MEASUREMENTS Violent behaviour was defined as severe hostility in the past month on the Brief Psychiatric Rating Scale (BPRS) (corresponding to assault/damage to property). Days of methamphetamine and other substance use in the past month were assessed using the Opiate Treatment Index. Positive psychotic symptoms in the past month were identified using the BPRS. FINDINGS There was a dose-related increase in violent behaviour when an individual was using methamphetamine compared with when they were not after adjusting for other substance use and socio-demographics [cf. no use in the past month: 1-15 days of use odds ratio (OR) = 2.8, 95% confidence interval (CI) =1.6-4.9; 16+ days of use OR = 9.5, 95% CI = 4.8-19.1]. The odds of violent behaviour were further increased by psychotic symptoms (OR = 2.0, 95% CI = 1.1-3.6), which accounted for 22-30% of violent behaviour related to methamphetamine use. Heavy alcohol consumption also increased the risk of violent behaviour (OR = 3.1, 95% CI = 1.4-7.0) and accounted for 12-18% of the violence risk related to methamphetamine use. CONCLUSIONS There is a dose-related increase in violent behaviour during periods of methamphetamine use that is largely independent of the violence risk associated with psychotic symptoms.

Can Opiate Addicts Tell Us About Their Relapse Risk?: Subjective Predictors Of Clinical Prognosis

Given the high relapse rate of opiate addicts following detoxification, it is pertinent to identify whether any subjective variables mediate outcome, since these may then be targets of treatment. The present study assessed personality, cue-elicited craving, outcome expectancies for drug use, and self-efficacy for resisting drug use, in 43 opiate addicts receiving inpatient detoxification in either a specialist drug-dependence unit or a behavioral/general psychiatric ward, within the context of a randomised, controlled-treatment trial. Subjects were followed-up at between 1 and 3 months and again at 6 months after discharge. Frequency of drug use was not predicted by any of the subjective variables at the first follow-up; but at 6 months, subjects with lower self-efficacy and higher positive outcome expectancies were found to be using less often. Latency to first lapse was greater in subjects with higher anxiety and neuroticism scores. Precipitants to the first lapse were identified, but none of the predicted relationships between subjective variables and circumstances of lapse emerged. It is suggested that greater awareness of personal vulnerability may promote effective coping strategies.