An investigation of mechanisms underpinning substance dependence and novel interventions

A number of theories have attempted to explicate mechanisms underpinning the transition from recreational drug use to substance dependence. A highly reliable correlate of dependence is the value ascribed to the drug. However, supernormal drug valuation may be insufficient to fully account for a subgroup of dependent individuals for whom the course of dependence is chronic and relapsing and who persist in drug use in the face of devastating costs. Three candidate secondary mechanisms for dependence are considered in this thesis: cue reactivity, cost discounting, and sensitivity to negative affect. Neither cue reactivity nor cost discounting were found to be significantly associated with severity of alcohol dependence in samples of young adult drinkers. By contrast, induced negative affect was found to be reliably associated with augmented alcohol motivation, and sensitivity to this effect was related to symptoms of depression and self-reported drinking to cope with negative affect: both risk factors for the development of dependence. These findings delineate a particular subset of dependent individuals for whom negative affect may represent a substantial trigger to continued drug use. There are a lack of brief interventions to abolish or limit negative affect driven drug motivation. This thesis trialled three potential interventions. A natural walk intervention in hazardous drinkers showed no evidence of limiting this effect in two experiments. Brief instruction in acceptance-based coping showed no evidence of limiting annoyance in response to an aversive noise induction procedure in an alcohol dependent population, and was therefore also eliminated as a potential intervention. However, engagement with pleasant environmental images, as a proxy for environmental enrichment, significantly reduced negative affect driven alcohol choice in student drinkers who reported a desire to visit the locations shown (high liking), compared to low-liking individuals and controls. This provides preliminary evidence for the efficacy of environmental enrichment type interventions, justifying further trials. In treatment of dependence more generally, interventions to increase access to healthy, non-drug sources of positive reinforcement may prove effective.ESR

Behavior Change Techniques to Promote Smoking Cessation During Pregnancy: A Theory-Based Meta-Analysis

Despite significant progress, smoking during pregnancy remains one of the leading preventable causes of adverse fetal and maternal health outcomes. Using the current best practice standard of psychosocial counseling, only about one out of every 20 pregnant women quits smoking, and relapse rates are very high. Developing more effective interventions to promote smoking cessation during pregnancy is a critical public health priority that requires a thorough understanding of behavior change and its complex pathways and determinants. As such, the purpose of this three-part study was to conduct the first systematic theory-based evidence synthesis of smoking cessation interventions during pregnancy, and to quantify the effectiveness of specific behavior change techniques and behavioral theories used in these interventions, with the long-term goal of informing the development of more effective interventions to reduce smoking during pregnancy. The first aim was to conduct a meta-analysis to produce quantitative estimates of intervention effect sizes and to identify factors that may explain the observed heterogeneity in intervention effectiveness. A search of six major bibliographic databases for prenatal smoking cessation interventions published between 1995 and 2015 yielded 1,223 unique articles, of which 38 met criteria for inclusion and 34 were randomized controlled trials where the primary outcome was late-pregnancy biochemically-validated smoking cessation and the unit of randomization was the individual. The results of a random effects meta-analysis of the 34 randomized controlled trials of prenatal smoking cessation interventions yielded a significant risk ratio for the primary outcome of late-pregnancy smoking cessation, such that women in the treatment groups were 1.53 times as likely to achieve smoking cessation before giving birth than women in the respective control groups (RR = 1.53; 95% CI: 1.30-1.79). Several study-level variables emerged as potential moderators of intervention effectiveness. Treatment-group participants in contingent rewards interventions were 2.82 times as likely to achieve late-pregnancy smoking abstinence than control group participants. In comparison, treatment-group participants in counseling interventions were 1.3 times as likely to achieve late pregnancy smoking abstinence than their control group counterparts. Intensity level was not associated with effectiveness in this sample. Interventions in this review also yielded promising (significant) results for many secondary outcomes of interest, including additional measures of smoking behavior as well as perinatal outcomes. Specifically, treatment group participants were 1.44 times as likely as control group participants to significantly reduce (by at least 50%) their cigarette consumption, 1.54 times as likely to be smoke free in the early postpartum period, and 1.99 times as likely to be smoke free in the late postpartum period. The results also revealed that smoking cessation interventions reduced the risk of two very common adverse perinatal health outcomes: low birthweight and preterm birth. Specifically, treatment group participants had 73% less risk of delivering a low birthweight or very low birthweight infant and 67% less risk of preterm birth compared to control group participants. The second aim was to evaluate the use of the health behavior theory in intervention design, implementation, and evaluation, and to assess whether the use of theory was associated with intervention effectiveness. Of the 26 published trials that explicitly mentioned theory in the introduction or methods, only nine were based on a single theoretical framework. Five of these studies utilized the learning-based theory of operant conditioning, two studies utilized the transtheoretical/stages of change model, one study used social cognitive theory, and one study used social learning theory. Even among these nine trials, theory was used primarily in a descriptive manner, as opposed to an explanatory or predictive manner. The results of the subgroup analyses and meta-regression models were counter to the hypothesis that use of theory would be positively associated with intervention effectiveness. Scores on two categories of the theory coding scheme (“Was theory tested?” and “Was theory used to tailor or select participants?”) were significantly associated with the primary outcome of late-pregnancy smoking abstinence, but both of the associations were negative, indicating that greater use of theory was associated with a lower likelihood of smoking abstinence during the late-pregnancy period. However, this may reflect the limited use of theory in intervention planning and design among trials included in this meta-analysis, rather than the contribution of theory when it is used optimally. The third aim was to isolate the “active” ingredients in prenatal smoking cessation programs by applying a standardized taxonomy of behavior change techniques to identify the techniques, and then quantifying the effectiveness of each individual technique. We first used Abraham and Michie’s (2008) 26-item taxonomy to identify theory-derived behavior change techniques in published descriptions of intervention content, then performed a meta-regression analysis to determine whether interventions utilizing more techniques were more likely to be effective, and then used subgroup and moderator analyses in order to quantify the effectiveness of each technique. The results revealed that the total number of behavior change techniques used was not associated with late pregnancy smoking abstinence, indicating that more is not necessarily better. Effect sizes were significantly larger for the treatment group than the control group for subsets of interventions that 1) provided information about the link between smoking and health (RR = 1.68; 95% CI: 1.26-2.12); 2) provided information about the negative consequences of smoking (RR = 1.38; 95% CI: 1.08-1.77); 3) prompted the formation of intentions to quit smoking (RR = 1.24; 95% CI: 1.00-1.53); 4) provided instructions (RR = 1.51; 95% CI: 1.21-1.89); 5) prompted specific goal setting (RR = 1.48; 95% CI: 1.17-1.88); 6) provided contingent rewards (RR = 2.82; 95% CI: 2.05-3.88); 7) taught participants to use prompts and/or cues (RR = 1.63; 95% CI: 1.03-2.59); and/or 8) had participants agree to a behavioral contract (RR = 2.14; 95% CI: 1.29-3.56). Several key findings emerged from this study. First, behavior change theory is not being utilized to its full capacity in the development and evaluation of prenatal smoking cessation interventions, with only half of the studies in this review (n = 19) reporting an explicit link between at least one behavior change technique and at least one targeted predictor of behavior change. Secondly, many of the most common behavior change techniques used in prenatal smoking cessation interventions were not associated with better intervention outcomes, nor was the quantity of techniques used associated with effectiveness. Third, the current review identified contingent rewards as the most effective behavior change technique for promoting smoking cessation during pregnancy and into the postpartum period when tangible rewards were no longer offered. While previous meta-analyses have assessed whether or not prenatal smoking cessation interventions were effective, this review expanded on existing findings by using a recently developed taxonomy to identify, isolate, and quantify the effectiveness of individual behavior change techniques used in interventions, as well as applying a coding scheme to evaluate how theory is being used in the literature and whether the use of theory is associated with the effectiveness of interventions. The results provide a framework for evaluating not only if an intervention worked, but also why, how, and under what conditions, marking an important step towards a new set of standards in evidence synthesis and theory-testing in smoking cessation research and beyond

Saliva continine levels of babies and mothers living with smoking fathers under different housing types in Hong Kong: a cross-sectional study

Paper Session 15 - The Challenge of Second-Hand Smoke: PA15-3BACKGROUND: After the Smoking Ordinance enacted in HK since 1/2007, shifting of smoking from outdoor to home was found, home becomes a major source of secondhand smoke (SHS) exposure of nonsmokers. OBJECTIVES: It aimed to assess the SHS exposure of babies and mothers living with smoking fathers of two housing types by using a biomarker. METHODS: Trios of smoking father, non-smoking mother and a baby under 18-months were recruited from Maternal and Child Health Centres (MCHCs) from 6/2008 to 10/2009. Consented couples completed the baseline survey including demographic data, fathers’ household smoking behaviors and mothers’ actions in protecting babies from household SHS exposure. Saliva samples from baby and mother were collected and then sent to the National University of Singapore for cotinine analyses. Log-transformations were used for the saliva cotinine due to skewed data. There were 2 housing types (public/private) and father was asked if they smoked at home (yes/no). MANOVA was used to compare the babies’ and mothers’ cotinine levels when fathers smoked at home under the 2 housing types. RESULTS: 1,158 trios were consented. 1,142 mothers’ and 1,058 babies’ samples were assayed. The mean age of the fathers and mothers was 35.5(±7.0) and 31.2(±4.9). The mean mothers’ cotinine level was 12.15ng/ml (±61.20) while babies’ was 2.38ng/ml (±6.01). 606 and 501 trios were living in public and private housing. Fathers’ smoked at home led to higher mothers’ and babies’ saliva cotininary (mean log of mothers’ cotininary: 0.14±0.62 vs. 0.05±0.55, p=0.06; babies: 0.16±0.38 vs. 0.07±0.34, p=0.003). Housing types influenced babies’ cotinine level (public: 0.17±0.37; private: 0.10±0.36, p=0.01). MANOVA showed that fathers smoked at home (Λ=0.99, p=0.01) and housing types (Λ=0.99, p=0.01) were positively related to the saliva cotinine levels. CONCLUSIONS: Father smoked at home and the housing types have greater impact on babies’ saliva cotininary, showing that they were highly exposed at home and in public housing environment. HK government should promote smoke-free homes and to provide more smoking cessation services to minimize the household SHS exposure to babiespublished_or_final_versio

Optimizing Making Every Contact Count (MECC) Interventions:A Strategic Behavioral Analysis

Objective: This Strategic Behavioural Analysis aimed to: identify barriers and facilitators to healthcare professionals’ implementation of MECC; code behavioural components of nationally delivered interventions to improve MECC implementation; assess the extent to which these components are theoretically congruent with identified theoretical domains representing barriers and facilitators. Comparing national interventions that aim to support implementation of behaviour change related activity to the barriers and facilitators for the target behaviour enables identification of opportunities being missed in practice thereby facilitating intervention optimisation.Methods: A mixed-methods study involving: a systematic review to identify barriers and facilitators to implementing MECC classified using the COM-B model and Theoretical Domains Framework (TDF); a content analysis of national interventions to improve MECC implementation in England using the Behaviour Change Wheel (BCW) and Behaviour Change Techniques Taxonomy (BCTTv1); linking intervention content to barriers identified in the systematic review.Results: Across 27 studies, the most frequently-reported barriers related to eight TDF domains: Environmental Context and Resources, Beliefs About Capabilities, Knowledge, Beliefs About Consequences, Intentions, Skills, Social Professional Role and Identity, Emotions. National interventions aimed at supporting MECC implementation included on average 5.1 BCW intervention functions (Education, Modelling, Persuasion, Training were used in all interventions) and 8.7 BCTs. Only 21 of BCTs potentially relevant to key domains were used across interventions. The majority of BCTs linked to seven of the eight most important domains were not used in any existing interventions.Conclusions: Intervention developers should seize missed opportunities by incorporating more theoretically relevant BCTs to target barriers to implementing MECC

The Behaviour Change Wheel approach

The Behaviour Change Wheel (BCW) approach is a set of interrelated tools and principles intended to guide decision-making and facilitate systematic development of behavioural interventions. This chapter presents the four behavioural science tools of the BCW and demonstrates how they interlink and can be applied as a system for understanding behaviour and designing behaviour change interventions. Implementing new practices and/or changing existing practices in organizations, services and systems requires changes in individual (for example, health care professional) and collective (for example, clinical team) human behaviour. The implementation research literature contains multiple examples of how the BCW approach has been applied in different ways for different purposes. These include exploring implementation problems, designing and refining implementation interventions, conducting process evaluation of implementation interventions and synthesising implementation research. The authors report on ways in which the various tools have predominantly been used, with accompanying examples to illustrate objectives, methods and high-level outcomes

Interactions between Cannabinoids and Tobacco: Implications for understanding and treating addictive disorders

Cannabis and tobacco are two of the most commonly used drugs in the world and their use often co-occurs. Cigarette smoking continues to be a global epidemic where novel drugs for smoking cessation are necessary. In chapter 1, I review the literature concerning cannabis, tobacco and co-used cannabis and tobacco, in relation to their prevalence and effects on cognition, addiction and psychosis. In chapter 2, I provide a ‘worldwide’ overview of routes of administration (ROA) of cannabis with and without tobacco (n=33, 687). Tobacco-based ROAs were most common in Europe (77.2–90.9%) and Australasia (20.7–51.6%) but uncommon in the Americas (4.4–16.0%). Tobacco-based ROAs were associated with reduced motivation to quit tobacco. In chapter 3, I describe the first investigation of the individual and interactive effects of cannabis and tobacco in a randomized, placebo-controlled, double-blind crossover design (n=24). I found tobacco may offset effects of cannabis on delayed recall, had no effect of cannabis-induced psychotomimetic or subjective effects and was more harmful for cardiovascular outcomes. In chapter 4, in the same sample, I found tobacco did not influence the rewarding effects of cannabis. In chapter 5, in the same sample, I developed an innovative “roll a joint” paradigm to assess quantity of both drugs. I found self-reported quantity was accurate for tobacco but overestimates cannabis exposure. In chapter 6 and 7, in a sample of overnight-abstinent dependent cigarette smokers (n=30), I investigated if cannabidiol (CBD) can reduce nicotine withdrawal. Results showed CBD reduced attentional bias and pleasantness ratings but increased errors on the go/no-go, compared to placebo. There were no effects on verbal episodic, working memory or delay discounting. Finally, in chapter 8, I summarise and integrate my findings into the literature, discuss implications, consider limitations and suggest future research on the interaction between cannabinoids and tobacco

INDIVIDUAL DIFFERENCES IN ESCALATION OF TOBACCO USE: IMPULSIVITY AND ALCOHOL USE

Like adolescents, young adults are at risk of initiating tobacco use and escalating to daily use and tobacco dependence. However, not every young adult who uses cigarettes intermittently becomes tobacco dependent, and the time-course of those who transition to daily use varies widely. Individual differences likely contribute to the variability observed in patterns of tobacco use. This dissertation uses a multi-modal research approach to examine dimensions of impulsivity and alcohol use that are associated with vulnerability for escalation of cigarette smoking, and whether alcohol’s effects on behavioral disinhibition impact cigarette consumption. Study 1 investigated the associations between dimensions of trait impulsivity, alcohol use, and smoking behavior in a cross-sectional sample of young adults who varied in frequency of cigarette smoking. Study 2 expanded on the results of Study 1 by examining the separate and combined effects of impulsivity and alcohol use on escalation of tobacco use in a longitudinal study of young adults in their first three years of college to determine whether alcohol use and dimensions of impulsivity influenced trajectories of smoking behavior, and whether alcohol use and behavioral impulsivity changed across time as a function of tobacco use trajectories. Study 3 utilized a randomized, within-subject, placebo controlled design to examine whether alcohol-induced impairments in behavioral inhibition mediated the relationship between acute alcohol administration and ad-libitum cigarette consumption. Results from studies 1 and 2 indicated that alcohol use was associated with smoking frequency, and that dimensions of impulsivity (i.e. sensation seeking, lack of premeditation, and urgency) differentiated smoking groups. Study 3 found that acute alcohol increased smoking behavior, but alcohol impairment of inhibitory control did not mediate the relationship between alcohol and smoking consumption. Taken together, the results of these studies demonstrate that alcohol use and impulsivity play a significant role in tobacco use escalation, though more research is needed to determine the mechanism(s) that drive alcohol-induced increases in cigarette consumption

Behaviour Change Update: Stage 1. BCT analysis of existing, cost-effective interventions

Seventy-nine cost-effective interventions across six different health behaviours (smoking cessation, diet, physical activity, alcohol, sexual health, multiple behaviour targets) were identified from 23 economic reports. Interventions were mainly of high intensity, set in primary care or the community, delivered by health professionals and aimed at individuals from the general population, involving pharmacological or other forms of support. Education, enablement, training and persuasion were the focus of the majority of interventions, clustering around BCTs concerning: shaping knowledge; goals and planning; social support; antecedents and natural consequences of behaviour; outcome comparison; and feedback and monitoring. Interventions included an average of ten BCTs with ‘instructions on how to perform a behaviour’, ‘unspecified social support’, ‘information about health consequences’ and ‘problem solving’ included in 81%, 67%, 57% and 53% of interventions, respectively. While the use of ‘choice architecture’ was common, being present in 71% of cost-effective interventions, prevalence was lower (29%) when stricter criteria to define ‘choice architecture’ were applied. Sexual health interventions were least cost-effective but no other characteristics or BCTs were related to cost-effectiveness estimates. However, these findings need to be interpreted cautiously given 1.) the limitations imposed by considering only cost-effective interventions in this report, 2.) the reliance on often incomplete information in published papers (possibly not accurately reflecting intervention content) and 3.) the lack of consensus for a definition of ‘choice architecture’