Motivational interviewing: a pilot test of active ingredients and mechanisms of change
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This entry is our analysis of a study considered particularly relevant to improving outcomes from drug or alcohol interventions in the UK. The original study was not published by Findings; click Title to order a copy. Free reprints may be available from the authors – click prepared e-mail. The summary conveys the findings and views expressed in the study. Below is a commentary from Drug and Alcohol Findings.

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Motivational interviewing: a pilot test of active ingredients and mechanisms of change.

Morgenstern J., Kuerbis A., Amrhein P. et al.
Psychology of Addictive Behaviors: 2012, 26(4), p. 859–869.
Unable to obtain a copy by clicking title? Try asking the author for a reprint by adapting this prepared e-mail or by writing to Dr Morgenstern at You could also try this alternative source.

Motivational interviewing’s originator has stressed how unexpected findings can force fruitful rethinking. This study may prove an example; designed to forefront the approach’s distinct active ingredients, other than fleetingly and non-significantly, these did not seem active at all among the stable, moderately dependent drinkers recruited to the trial.

Summary Motivational interviewing is probably the most influential and widely implemented formal counselling style in the treatment of problem substance use. How it works has been investigated, but rarely in studies which deliberately vary the mix of supposedly active ingredients (key therapist strategies that facilitate positive change) to test whether they really do affect mechanisms of change in the client (such as developing skills and making commitments to change) and finally substance use itself. This US study was the first to do so among heavily drinking clients aiming to cut down rather than stop altogether, and who sought help rather than being identified through screening programmes. Among treatment-seeking problem drinkers, also a first was its comparison of a ‘self-change’ option with therapist-led interventions.

Theory behind the study

Issues addressed by the study

The study was based on the distinction made in motivational interviewing between ‘relational’ and ‘technical’ active ingredients. The former (the ‘spirit’ of the approach) refer to elements of non-directive counselling including empathic listening, avoiding negative therapeutic interactions, and monitoring and repairing ruptures to the therapeutic relationship. Technical elements are the directive strategies and techniques geared to moving the client in the desired direction (in this case, reduced substance use), including sharpening their perception that how they actually behave is not how they wish to, the resolution of ambivalence, and securing a commitment to a behaviour change goal.

Together these active ingredients are intended to elicit statements from the client in support of the desired change – so called ‘change talk’, the sincere emergence of the client’s own reasons for change, promoted by active shaping and reinforcement of their responses by the therapist. Change talk is hypothesised to be the mechanism which in turn leads to behaviour change.

The implication is that without these directive, technical elements, non-directive counselling (motivational interviewing stripped of its specific levers of change) would be less effective, but both would be better than leaving patients to ‘self-change’ without any counselling.

How the theory was tested

To test these expectations the study recruited 89 adult problem drinkers, all but nine of those assessed after responding to ads for treatment aimed at drinking less and which emphasised client choice. As assessed in interviews with research staff, they had to be on average drinking more than 210g alcohol a week for women or 336g for men and to meet criteria for alcohol abuse or dependence, but not so severely dependent as to have experienced withdrawal symptoms. Most were mildly or moderately dependent, averaging around 434g alcohol a week and 84g on each day they drank. They had to be aiming for moderation rather than abstinence, socially stable, and not severely mentally ill or seriously involved in regular use of other drugs. About evenly split between men and women, typically they were in their 30s and 40s, employed, well educated and had never been treated for drinking problems.

Throughout the therapy phase of the study, all patients were asked each day to report their drinking and issues and situations which may have prompted drinking. For the first week this was all they did. Then all were further assessed and results fed back to them indicating the seriousness of their drinking.

The interventions

After this they were allocated at random to one of two therapies or told to try to curb drinking on their own. Effectively these options delivered the full set of motivational interviewing’s active ingredients, only the non-directive set, or none. The three options were:
• Motivational interviewing spanning four one-hour sessions over seven weeks with both the non-directive ‘spirit’ elements (see below) and more directive techniques to lead the client to commit to curb their drinking, a combination expected to lead to the greatest drinking reductions.
• Just the non-directive or ‘Rogerian’ [after the therapist Carl Rogers – see this discussion] elements over the same phasing of sessions and delivered by the same (generally) experienced motivational therapists, featuring therapist warmth, genuineness, and egalitarianism, emphasis on the client’s responsibility for change, extensive reflective listening, and avoiding therapist behaviours contrary to motivational interviewing’s spirit. More directive techniques were explicitly proscribed, extending to the use of reflective listening to reinforce change talk. Instead reflections focused on echoing and exploring the patient’s emotions and experiences.
• A self-change option in which (after the assessment feedback given to all clients) participants were told to try to change on their own over the next eight weeks, after which they would be offered treatment. They were told some people could manage this without professional help, and that monitoring their drinking and being interviewed for research purposes might help. Clients met only technical research staff, not therapists.

Primarily at issue was whether over the last half of the eight weeks before self-change clients were offered treatment, these options would be associated with progressively less steep reductions in average weekly alcohol consumption, assessed by three research interviews each completed by at least 92% of clients in the study. Patients from the start allocated to the two forms of therapy were also followed up for a further four weeks.

If these options did differ in effectiveness, what might have helped cause this was assessed by rating session videos for how often and how strongly clients committed to change (or not to change) their drinking, and related comments on, for example, their ability or desire to change. The videos also showed that therapists stuck well to their ‘scripts’, as did feedback from clients.

Main findings

The anticipated findings did not materialise. All three sets of clients reduced their drinking over the eight weeks of the therapy period, but not by significantly different degrees. Unexpectedly, such minor differences as there were favoured the spirit-only option, though (as expected) least effective was self-change. Among the two groups offered therapy over this period, drinking fell from an average of about 456g alcohol a week to 298g by the last half of the period. Over the next four weeks it fell further to average 227g, about half the pre-treatment level, but again with no significant differences between full motivational interviewing and the stripped down version.

With no advantages for any of the options needing to be explained, there was no point in looking for mechanisms to explain them. Instead the researchers probed the data for results they had not planned to look for in advance, a procedure which limits confidence in the robustness of any which emerge. None did emerge when drinking intensity or consequences replaced weekly consumption as the outcome, and such differences as there were did not favour the full motivational option. Also not found was any indication that more severely dependent participants had reacted better to this option than to the supposedly less effective alternatives.

Fleeting concordance with theory

However, during one period of the study the drinking reduction pattern did look like that expected. This was over the first two weeks of the therapy period during and after the first two sessions, when all three groups made most of their reductions in drinking. The drop was steepest among those offered full motivational interviewing and least among those left to their own devices, the expected pattern. These differences were appreciable but not statistically significant. Later the non-directive group ‘caught up’ and by the end of the eight weeks the difference had reversed, but the early pattern offered the opportunity to test whether the expected change-talk mechanism had fleetingly been at work.

The comparison was between full motivational interviewing versus non-directive counselling. Though not all the links were statistically significant, by the end of the first session the motivational option had generated stronger commitments to curb drinking, which seemed enacted in the following week when these clients’ did make extra drinking reductions. Further analysis indicated that generating stronger change talk was at least part of the reason for this advantage. In the second session a week later the motivational option also generated stronger change talk, but this was not linked to further reductions in drinking. Only the first session showed signs of the expected links.

The authors’ conclusions

Since differences were small and not in the expected direction, it seems unlikely that failure to find extra benefits from the full motivational option was due to having too few participants. This surprising outcome seems to direct our attention beyond the specific elements included or not in each of the three options, to the features they share, and to drivers of change which are not unique to therapy, but active in the self-change process which proved equal to formal therapy.

The first two sessions of motivational interviewing did (non-significantly) accelerate drinking reductions, but by the end these advantages had narrowed or reversed. Acceleration after the first session seemed due in part to the generation of stronger change talk, a finding consistent with the expected mechanism but which should be interpreted cautiously.

A plausible explanation of the findings is that motivational interviewing is uniquely effective in mobilising rapid change in the context of a one- or two-session intervention. However, in a longer treatment well delivered Rogerian therapy can achieve equivalent effects for problem drinkers. Why self-change was almost as effective as motivational interviewing might be due to daily self-monitoring of alcohol consumption, a high level of contact with research staff, and a short follow-up.

In the only previous similar study, over the following six months frequent heavy drinking was significantly less common when motivational interviewing techniques had been added to non-directive listening, but other drinking outcomes were not significantly affected. Another study has shown that (with college students concerned about their drinking) therapists can deploy strategies which increase the frequency of change talk, a finding confirmed in the current study.

Together with the current study, this work means it remains an open question whether motivational interviewing’s directive strategies augment its effects, or whether the non-directive elements alone might be equally effective.

All these studies used random allocation to different types of therapy to investigate how therapy works. Others have instead observed links between outcomes and active ingredients and mechanisms as they emerge in studies primarily designed for other purposes. It means any links they find cannot securely be attributed to cause and effect, but may have been due to other factors. Generally motivational interviewing’s stance and techniques have been found associated with increased change talk, and these commitments to change associated with reductions in drinking.

The primary limitations of this study are its relatively small sample size and short-term follow-up. Also its findings are limited to problem drinkers seeking moderation who voluntarily attend treatment with minimal coercion from outside sources. Participants with more severe drinking problems and those coerced in to treatment might respond differently.

Findings logo commentary William Miller, motivational interviewing’s originator, has observed that in science, “Failure to confirm expectations is a particularly fruitful point [which] if taken seriously, lead[s] one back to the drawing board of discovery to develop a better theory for subsequent testing”. This study may prove an example, delivering a comprehensive reversal for the expectation that motivational interviewing would prove preferable to non-directive counselling, and even more unexpectedly, failing to find it significantly better than going it alone pending therapy. On no measure of drinking were these expectations fulfilled; frequently the slight advantage was with non-directive counselling.

Not too much should be made of one small study, especially one seemingly contradicted by a predecessor, but to date this is the most rigorous test we have of whether motivational interviewing’s theory stands up and with it the approach’s intended superiority to the bedrock of substance use (and other problems) counselling – non-directive listening. Instead it turned the spotlight among treatment-seeking, stable and not very dependent drinkers, on their own impetus to change, and suggests change talk is not active in itself, but a sign of that impetus drawn out by motivational techniques. Along the way the study also demonstrated the value of offering some kind of intervention to excessive drinkers which does not deter by insisting on abstinence, and added to the substantial accumulation of research showing that well structured therapies are equivalent in their effects. It also suggested in line with other research that motivational interviewing can accelerate change and/or achieve it in a shorter time than alternatives, and partially confirmed the role techniques and activities play in forging a deeper therapeutic relationship, supporting assertions that how the therapist acts with clients cannot entirely be divorced from the content of those acts – from what they and the client do together.

Unfold supplementary text for more detailed discussion of these points.

For more on the mechanisms and processes involved in motivational interviewing run this search of the Effectiveness Bank site.

Thanks for their comments on this entry in draft to research author Jon Morgenstern of the National Center on Addiction and Substance Abuse at Columbia University in the USA, and Tim Leighton of the Centre for Addiction Treatment Studies of Action on Addiction. Commentators bear no responsibility for the text including the interpretations and any remaining errors.

Last revised 14 April 2014. First uploaded 07 April 2014

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