Introduction
Heavy alcohol use is highly prevalent in the United States with recent estimates of almost 15 million individuals meeting criteria for past-year alcohol use disorder (AUD) and over a quarter of adults reporting past month binge drinking (SAMHSA, 2019). Despite the prevalence of AUD and numerous available evidenced-based psychosocial and pharmacological interventions [
1], treatment rates for AUD remain low [
2]. Problematic alcohol use is highly heterogenous, with distinctions in type and severity of alcohol-related harms experienced. With this variability in mind, certain treatments may be better targeted for individuals who are higher or lower on the AUD severity spectrum [
1]. Brief intervention (BI) is supported as an effective behavioral strategy designed to address risky drinking in individuals with heavy alcohol use who have yet to transition to a more severe AUD profile [
3]. BI typically consists of a single session, ranging from 5 to 60 min, and is designed to increase one’s motivation for behavior change (i.e., drinking reductions) by encouraging self-awareness and monitoring of high-risk drinking situations and alcohol-related consequences. Across BIs, several core components are shared and include providing feedback on normative drinking levels and individualized risk, inquiring about desire to change drinking, and collaborating on a plan to change behavior. Research in this area has consistently demonstrated reductions in drinking after BI [
4‐
6].
Promoting motivation for behavior change by identifying reasons and need for change, is thought to be a core component of BI [
7‐
9]. Motivation to change is a fluid, multi-dimensional construct that indicates an individual’s openness to participate in a behavior change plan (i.e., a plan with specific action steps to reach a drinking goal; [
10]). It is thought to incorporate an individual’s understanding of the importance of behavior change, confidence in their ability to make a change, and readiness to make this change. Several studies have demonstrated positive associations between BI, one’s motivation, and drinking outcomes, such that enhancing motivation may serve as an important mechanism for behavior change [
11‐
14]. For example, among chronically homeless individuals, post-intervention motivation to change was associated with decreases in alcohol use 2 years later [
11]. In adolescents and young adults, greater readiness to change was positively related to clinical response to BI [
13]. While motivation may be a key mediator of behavioral change in BI, investigation on this topic often lack specificity [
15,
16]. For example, research is limited in regard to which indices of motivation to change (e.g., importance, confidence, and readiness) facilitate drinking reductions following BI and which individual patient factors moderate response to treatment. Valuable and clinically relevant information may be gained from examining which dimensions of change function as relevant mediators of clinical response as well as identifying patient factors that moderate this response.
Critically, these potential moderators of intervention-based behavior change have only recently begun to be elucidated. Findings have been mixed as to whether BI is appropriate and effective for more severe clinical populations, such as those with comorbid psychiatric conditions or higher alcohol problem severity [
17,
18]. Particularly, there is a paucity of research examining the efficacy of BI delivered in medical settings for individuals with very heavy alcohol use or dependence, as these individuals are commonly excluded from randomized trials [
18]. However, recent investigations have tested the association between alcohol problem severity and BI utility. For instance, in an emergency department setting, the effects of a therapist-led BI differed across the range of alcohol use severity, such that greater reductions in alcohol consumption were seen for individuals with more severe AUD compared with mild AUD [
19]. Additionally, intervention delivery methods, such as computer-based versus in-person counseling, may differentially benefit individuals with lower versus higher severity of alcohol use problems [
20]. Low rates of treatment-seeking among individuals with AUD necessitates further work assessing the effectiveness of BI for non-treatment seekers with a range of alcohol problem severity, as BI can be delivered in settings not specialized in substance use treatment [
21].
Our group recently conducted a study investigating the efficacy of a brief, single session, intervention for improving drinking outcomes in a non-treatment-seeking heavy drinking sample, which was immediately followed by a neuroimaging scan [
22]. Participants reported on their motivation to change drinking behaviors via standardized rulers at baseline and post-intervention timepoints, and 1 month later completed a follow-up visit to assess drinking outcomes. While there was no overall intervention effect on drinking or neural activation to alcohol cues, both the BI and attention-control groups displayed lower drinking rates following participation in the study [
22]. Moreover, one dimension of motivation, namely importance of change, was significantly related to neural alcohol cue-reactivity in those who received the BI, as compared to the control condition [
23]. These findings advanced our understanding of the neural mechanisms underlying motivation to change elicited by BI but did not account for intervention effects on behavior change in this sample.
The present study extends this work by exploring mechanisms and moderators of behavioral response to BI. In this exploratory analysis, we examined whether participants’ post-intervention motivation to change accounts for treatment response (i.e., drinking reductions) and further, if this response depends on an alcohol problem severity factor. As such, we predicted that intervention-related increases in motivation to change, would result in greater drinking reductions for those with higher alcohol problem severity factor scores. We conducted moderated mediation analyses and hypothesized that the conditional indirect effect of a brief alcohol intervention on drinking outcomes at follow-up through post-intervention motivation to change would be stronger with increasing levels of alcohol problem severity.
Discussion
This study explored both mechanisms and moderators of behavioral response to BI in a sample of non-treatment seeking heavy drinkers. Overall, our hypothesis regarding the indirect effect of intervention on drinking at follow-up was supported for only one dimension of motivation to change. Specifically, the effect of BI on drinks per day at follow-up through enhancing importance for behavior change was stronger for those with high alcohol problem severity factor scores. Our preliminary results indicate that for individuals with higher degree of problem severity, the BI significantly reduced alcohol use at follow-up through the mechanism of promoting participants’ importance to make a drinking behavior change. Thus, it appears that as severity increased in this sample, the therapeutic effect of importance on post-intervention alcohol use became stronger. These effects were significant while controlling for baseline covariates of drinks per day and importance of change rating. Findings suggest that severity may be a relevant factor to consider in regard to the efficacy of BI in non-treatment seeking populations. Yet, this preliminary finding should be interpreted with caution and replicated in larger samples of brief alcohol intervention. Results should also be considered in the context of this study’s sample, which included heavy drinkers not required to meet DSM-5 criteria for AUD. As such, it represents a low- to moderate-severity sample overall. Our results are in line with recent findings examining the role of problem severity in the context of brief alcohol interventions [
19,
20]. As reported previously by our group, this BI did not significantly reduce drinking more than the control condition [
23]. Although not assessed in the current study, BIs are thought to be well-suited as an initial treatment contact for non-treatment seeking individuals with risky alcohol use that may prepare them to engage in later specialty treatment. A secondary analysis of data from the National Survey on Drug Use and Health found that only around 16% of individuals who received information about alcohol treatment from their healthcare provider obtained it [
21], signaling the potential benefit of providing BI to these individuals, as it may increase one’s motivation to seek further alcohol treatment or serve as a limited opportunity for intervention [
43,
44].
Markedly, in the second stage of mediation models for all three indices of motivation to change (i.e., importance, readiness, and confidence), the interaction term between post-intervention motivation and alcohol problem severity factor was significant after holding treatment condition and other covariates constant. Both groups completed alcohol-specific assessments and interviews at the baseline visit and this likely increased participants’ awareness of their drinking levels and related consequences [
45], which in turn could have increased participants’ motivation for behavior change following the baseline visit across groups. In line with our results, one’s self-identified motivation to change drinking following a clinical contact may be a possible indicator of future drinking reductions for those with elevated problem severity, irrespective of intervention-specific effects. As such, even a general screening for problematic or heavy alcohol use in medical settings might provide small benefits to individuals with at least moderate severity levels. Alternatively, this finding could point to a potential mechanism of ‘natural recovery’ for individuals high in alcohol problem severity, in which life events and consequences result in an increase in their motivation to reduce alcohol use, which in turn leads to cutting back on drinking [
46,
47]. However, these interpretations are speculative and should be carefully tested in larger samples. Notably, the alcohol problem severity factor used in these analyses included measures of mental health symptoms (i.e., generalized anxiety and depression symptomatology) in addition to alcohol-specific measures, which is consistent with a previous report from our group [
40]. Prior work highlights the relevance of negative affectivity in clinical AUD samples, as it is positively correlated with severity, such that those with more severe AUD report higher levels of negative affectivity [
48,
49].
Findings from the first path of the importance mediation model suggested that participants receiving the BI reported significantly greater importance of change ratings compared to those in the control condition after accounting for pre-intervention importance levels. Accordingly, this dimension of motivation to change may serve as a mechanism of the BI implemented in this study. Importance of change can be considered the first tier or step towards increasing one’s motivation to change, akin to the contemplation stage of change (i.e., individual acknowledges risky drinking and may be open to change but remains ambivalent; [
7]). The role of this initial stage of motivational readiness in this BI effect may be especially salient for the study’s population of community-based heavy drinking individuals who are not considering treatment. It should also be noted that single-item ratings of importance to change correlate highly with a stage-based multi-item measure of motivational readiness [
50]. Hence, the current findings may actually speak more broadly about the role of stage of change as a mechanism of BI in non-treatment seekers. However, treatment mechanisms may vary across brief alcohol interventions, as clinician training and implementation of BIs can differ, and as a result may contain distinctive treatment components. Further research aimed at better understanding which components of BI promote one’s motivation to change is warranted.
Intervention-related alterations in readiness and confidence dimensions of motivation to change were not detected in this study. This modest sample size lacks statistical power to detect small effect sizes, and this may have contributed to our null findings. Results may also point to issues that may be particularly relevant to the delivery of BI to non-treatment seeking individuals. A single-session brief behavioral intervention may be an insufficient dose to yield measurable changes in confidence or readiness to change among individuals who are not already motivated to change their alcohol use. Extant research on BI with non-treatment seeking populations (e.g., patients in the emergency department and college students) has also not found consistent support for a mediating role of readiness to change [
51,
52]. Thus, our findings only support importance as a potential mechanism of behavior change in this sample, particularly for individuals with high severity. Future research might explore whether more time-intensive interventions (e.g., Motivational Enhancement Therapy) are necessary to engender changes in one’s feelings of readiness or confidence to make drinking-related changes and whether this might be specific to treatment-seeking populations. Alternatively, these indices of motivation may similarly function as mechanisms of behavioral change, but BIs may provoke smaller changes in readiness and confidence motivational indices than importance, thus requiring larger or higher severity samples to detect these effects.
The current study should be considered in light of its strengths and limitations. First, this conditional process analysis consisted of variables collected with temporal precedence, which provides partial supports, albeit not sufficient evidence, for these mechanisms as causal. Second, the advanced statistical methods applied (i.e., conditional process analysis) are well-suited for examining complex relationships between mechanisms and subgroups of responders for whom these mechanisms are operative. Third, participants were recruited from the community and displayed a range of alcohol problem severity allowing for examination of our multi-method severity factor construct as a moderator. In terms of limitations, the current analyses relied on self-report measures of alcohol consumption, which can be susceptible to bias and drink size misestimation, resulting in possible inaccuracies in intervention-related outcomes [
53]. Moreover, the sample size is modest, and this study is not powered to detect small effects in mediation pathways. As such, while our results provide initial support for certain moderation and mediation effects, the analyses were exploratory and should be interpreted with caution and replicated in larger trials of brief alcohol intervention. Neither participants nor study staff were blinded to treatment condition after randomization, which could have contributed to social desirability bias in the treatment effect [
54,
55]. Participants rated their motivation to change drinking behaviors immediately following the brief intervention; this limited timeframe could have failed to capture more long-term intervention-related changes in motivation, particularly in the confidence and readiness dimensions. Finally, while participants reduced their drinking levels from baseline to follow-up regardless of treatment condition, the intervention main effect was not detected in this study.
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