MBCT: A Look at the Mechanisms of Action

Mindfulness-based cognitive therapy (MBCT) is a psychological therapy designed to help prevent the relapse of depression, especially for those individuals who have Major Depressive Disorder (the principal type of depressive disorder defined by the DSM-5). MBCT employs traditional CBT methods and adds in mindfulness and mindfulness meditation strategies. In this article, we explore the mechanisms behind MBCT’s effectiveness in helping prevent relapse of depression.

How does MBCT work?

When a person experiences a Major Depressive Episode, both pharmacotherapy (anti-depressant medication) and psychotherapy have been shown to work to alleviate the depression: one equally as well as the other in at least one study (Kuyken et al, 2008). The problem with depression is that, while several approaches are effective at treating the acute phase, the major burden of depression is borne by health care systems, their consumers, and society as a whole through the high rate of recurrence.

MBCT is beginning to demonstrate the capacity to live up to its promise as a therapy specifically targeting the post-treatment phase of depressive illness, where up to 80 percent of those treated are likely to relapse. While the literature on depression recurrence is still not compelling or clear, the aggregate of mounting evidence – including recent brain imaging studies (Farb, Anderson, Mayberg, Bean, McKeon, & Segal, 2010 and Farb, Segal, Mayberg, Bean, McKeon, Fatima, & Anderson, 2007) – points to a putative mechanism of action involving neural changes in the areas of the brain responsible for emotions upon the individual experiencing high emotional reactivity to dysphoric mood or sad thoughts. Let us tease out the various aspects of this chain of events which seems to occur differently for formerly depressed people than for those who have never been depressed.

Rumination: the heart of the issue

Rumination – the act of brooding on unpleasant aspects of one’s life, such as perceived past failures, rejections, or losses – has a strong tendency to engender depression and has a strong negative correlation with mindfulness (Mathew et al, 2010; Crane et al, 2012; Rimes & Wingrove, 2011). Similarly, catastrophic worries about the future are often associated with high anxiety (Sipe & Eisendrath, 2012). Either way, the problem with such patterns of cognition is that people experience their thoughts as if they were actually occurring. Such cognitions register in the brain and neural networks as immediate threats which demand response and the parts of the brain that deal with emotion and danger become activated. For start, the amygdala fires up. It is a register for threat and for determining how intense an emotional reaction is appropriate. Chronic catastrophic ruminations and attempts to avoid perceived threat, not surprisingly, are associated with limbic dysfunction.

Over time, continued reaction of the amygdala creates a higher baseline of activity and higher reactivity to emotional stimuli, with ensuing dysfunction between the limbic and cortical circuits that regulate affective states. In Mayberg’s (2003) model, depression is characterised by these changes. Let’s translate this neural activity into an actual life scenario in order to better understand why depression often has such a firm grip on our psyche, and how MBCT may be able to change this.

An example

Let’s imagine for a moment that you are unemployed: not only that, but you have been unemployed for some time. To be sure, you’ve been on interviews: heaps of them. But no one has yet chosen you as the best person for the job being offered. Sitting at home alone, you begin to stew over the situation. You had a period of six months of depression once, about three years ago, and dealing with it left a hole in your resume. So in your current rounds of interviews, you have been careful to be honest about the fact that you weren’t working for six months. Now, however, re-assessing things from your couch, you begin to brood, becoming more certain every moment that you should have never allowed your break from working to become apparent. You wonder whether you will ever get another job and you work yourself into a highly emotional state. You feel really unsafe.

Several days later, after another bruising interview, you are back on your couch, only now you notice that it doesn’t take much to get you going. Today you are in a panic just thinking back on the way you’re sure the interviewer looked at you when you gave one of the answers. Fast forward one month, and you are aware that you now live on your couch. You aren’t even going to interviews these days, and it takes almost nothing to set you off into fear and panic. You are – like three years ago – deeply depressed. You feel despairing and unable to think clearly. To your brain and neural networks, it is as if you have already had it confirmed: “You will never have another job.” You begin to act in the way most people without the prospect of ever having employment would act: with extreme emotional sensitivity to any stimulus (real or imagined) related to unemployment, lowered self-esteem, and highly anxious behaviours.

Two distinct modes of being

There is increasing functional magnetic resonance imagery support for the notion of two distinct modes of reacting to apparently stressful, threatening stimuli: a “doing” or “narrative self-reference” mode and a “being” or “experiential self-reference” mode (Farb et al, 2007; Sipe & Eisendrath, 2012).

Doing mode: narrative self-reference

Describing your hypothetical situation in neural terms, we can say that it is likely your constant brooding over lack of a job and anxiety over fears of never having one led your brain to register that you are now in danger. Your amygdala is likely to have decided that the lack of a job is a big threat to survival and activated alarms to put you into “fight, flight, or freeze” mode. If you really had been in life-or-death danger at the start of this period, the activations of these parts of your brain would have served you well to warn you to go get work (any work!) in order to survive. Taking such action would have thus reduced the discrepancy between what “is” (your state of unemployment) and what “ought to be” (a state of having a job).

This problem-solving mode is the doing mode of being, or alternatively a “narrative self-reference”. It is highly effective when a clear course of action is available. Beyond that, it provides people with a sense of continuity of their identity, because they are tuning into the self as experienced across time (for instance: in brooding, you are activating memories of how bad you felt the last time you were unemployed – and depressed). Narrative self-reference is involved with memory for self and other traits and is linked with the activation of the media pre-frontal cortex of the brain associated in a pattern which has been described as the default neural network. In other words, we seem to have an automatic tendency to revert to this sort of “stimulus independent thought” (Smallwood & Schooler, 2006, in Farb et al, 2007) when we are not required to immediately respond to an external stimulus. Such narrative processing is temporally extended, relying on visual or verbal memories. Narrative self-reference mode is not “in the moment”.

Being mode: experiential self-reference

If, conversely, you are in a situation such as the unemployment we posed above and there is no clear action you can take in the outer world to alleviate the problem (e.g., doing job search activities), then applying a doing or narrative self-reference approach leads to greater suffering and sense of dissatisfaction. “Being mode” is characterised by a focus of attention on noticing and accepting whatever is in the present moment. In being mode, a person does not feel the need to try to reduce the discrepancy between his/her perception of “what is” and “what should be”, between actual and desired states. In experiential self-reference, which refers to one’s momentary experience, a right lateralised network involved in somatic and visceral sensation is involved (Farb et al, 2007).

In acting from being mode in regard to your ongoing unemployment, you would still notice that thoughts had come to you that you would never be employed again, but – and here is the crucial difference between being and doing modes – you would acknowledge that these were just thoughts: not reality. You would watch them come and go without feeling the need to engage with them (if you deemed them troublesome). In seeing them for the thoughts that they are, you would probably not respond with as much activation of the emotional, protective parts of the brain.

By helping to cultivate nonjudgmental present-moment awareness of your experience – including sadness, guilt, regret, or anything else – mindfulness can interrupt a person’s cycle of rumination (about, say, past unemployment) or anxiety (about, say, future catastrophes related to unemployment/finances, etc) and enhance self-compassion. Mindfulness would be able to break the association you will have been forming there on your couch between cognitive reactivity (becoming upset with increasing ease as a result of thoughts) and escalating depressive symptoms.

Mindful brains are different. Farb et al (2010) provoked sadness in subjects to demonstrate empirically how people trained in mindfulness show a distinct neural response, compared with untrained controls; the mindfulness-trained subjects had greater activation of lateral networks associated with somatic and visceral sensation (the parts of their brains that were responding to immediate physiological cues: that is, being present-moment focused) and fewer depressive symptoms. This outcome obtained despite both experimental and control groups having equivalent subjective reports of sadness.

Thus we would expect that, if we managed to get you off your couch long enough to train you in mindfulness, you would be able to acknowledge the many thoughts coming and going related to your employment predicament, but, in communicating to your brain that these were just thoughts – not reality, not predictions bound to come true – the areas of your brain that activate to warn and protect you (as noted above, the amygdala and limbic systems) would not need to go into overdrive. Rather, by staying mindful – focused on your experience of the moment – your brain would react by activating parts that are related to bodily and gut cues (the networks associated with somatic and visceral sensation).

The mindfulness advantage: freed up bandwidth

Carrying our scenario a step further, let’s say you did get MBCT training in the middle of the job search dip. There would likely be further good news for you, over and above less suffering in each moment about the lack of a job. That is that, because MBCT seems to enhance a person’s ability to deploy attention intentionally, you would be able to respond – in terms of both your cognitive processes and your behaviour – with greater flexibility. Recall that, as you lay on your couch day after day, sinking ever more deeply into the pit of depression, your world became smaller and smaller. The amount of energy required to do even simple things seemed greater and greater, because your attention, mental resources, and behaviour were increasingly tied up with attempting to either resolve your unemployment problem or else avoid unwanted thoughts and feelings related to it – or to your self-perception.

Post-MBCT training, you might be able to look back on that period and understand why your partner often complained that you weren’t really available then because all you could think about was your job issues. You might reflect that, during that period, the overwhelming concern about your unemployment made you feel like you simply didn’t have the bandwidth to do your normal life; going to the gym, taking in a movie, or even getting together with friends were all activities which either reduced or disappeared. In neural terms, the ostinato message being pounded into your brain – “No work; you’ll never have work” – was a threatening stimulus that competed (quite successfully when you were at your lowest) for your perceptual attention. This intrusive, repeating refrain sucked further processing resources from you when your amygdala reacted to it as a threat, thus activating all your bodily alert systems.

As you progressed through your MBCT training, however, you may have begun to notice that life became less exhausting, because your increasing metacognitive awareness allowed you to label such thoughts, and the feelings of despair and sadness that went with them, as “mental events” only. Thus your neural networks began to perceive them as less threatening and came to stop demanding the mental and emotional resources they had formerly used to process the thoughts.

Going through this process experientially, you would have understood how, in an experiment in functional brain imaging, subjects performing an affect labelling task similar to the mental noting of mindfulness meditation, showed increased activation in their pre-frontal cortex (the part of the brain responsible for abstract thinking, thought analysis, and behavioural/emotional regulation) and decreased activation in their amygdala. Subjects with social anxiety disorder displayed, post-MBCT training, reduced amygdala activity and increased activity in brain regions involved in attentional deployment (Stein, Ives-Deliperi, & Thomas, 2008).

Finally, your ever-patient partner may have begun to express appreciation that you now seemed to be paying more attention, that you were controlling your emotions better (not too many depression-inspired emotional outbursts these days), and you even appeared to be remembering things better: all capacities increasingly available to you as a result of your enhanced mindful attention (Sipe & Eisendrath, 2012). Such a mental-emotional state is surely more attractive to employment offers!

The above scenario asking you to imagine being depressed is (we hope) entirely hypothetical. To understand MBCT more deeply, and gain insight into how it may work beyond the presumed mechanism of action, it is illuminating to examine the lived experience of people who have been depressed and undergone MBCT training in order to avoid relapse.

This article was adapted from the upcoming Mental Health Academy CPD course “Mindfulness-Based Cognitive Therapy: An Overview”.


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