Randomized Controlled Trial Shows the Role of Mindful Acceptance in Lowering Stress Reactivity

 


Research published in the journal Psychoneuroendocrinology has shown accepting present-moment experience, over and above simply monitoring it, to be an essential component of stress reduction.  The experiment used a smartphone app to deliver three different types of training to groups of participants.  Results showed reductions in cortisol and systolic blood pressure after monitoring with acceptance training (MA), relative to monitoring only training (MO) or coping control  training (C).  This evidence demonstrates the link between acceptance and reductions in biological markers of stress, and that stress reduction training can be cost-effectively delivered using brief smartphone interventions.

The experiment drew on Unified Mindfulness, a meditation system which defines three distinct attentional training skills well suited to testing the effect of acceptance on stress.  Unified Mindfulness defines concentration as the ability to focus on what you choose, sensory clarity as the ability to track and explore  present moment experience, and equanimity as the ability to allow sensory experience to come and go naturally, without interference.  The monitoring component in both MA and MO consisted of concentration and sensory clarity training, whereas equanimity (acceptance), was only taught in the MA condition.  The coping control condition trained participants to reduce stress by letting their minds drift, reframing past and future events, and analyzing personal problems, strategies which contrast to concentration, clarity and equanimity respectively.  Training in all conditions was matched on attentional demand, length, structure and delivery tone.

The preregistered hypothesis was that MA would reduce cortisol, blood pressure and subjective stress reactivity over and above the active control conditions (MO and C).  Participants aged between 18-70 (M = 32, SD = 14) from the Pittsburgh area, who scored highly on the Perceived Stress Scale, were randomly allocated to conditions, with 144 completing the study (MA=55, MO=54, C=35).  Throughout most of the procedure, both participants and experimenters were blind to the condition under test.  In the training phase, participants used a smartphone at home to complete 20 minute audio lessons, and 3-10 minute homework practice once daily, for 14 days.  After completing all 14 lessons, participants undertook a social stress test under laboratory conditions.  This consisted of a 20-minute booster lesson on how to apply their previous training to the stress test.  The two-part test required participants to deliver a 5-minute defence against a false shoplifting charge, followed by a 5-minute performance of mental arithmetic.  Throughout the tasks, experimenters gave critical feedback to elevate stress levels.  Salivary cortisol was measured at the start of the testing appointment and 25, 35, and 60 minutes after the start of the stress test.  Average systolic and diastolic blood pressure (BP) was calculated over 5 epochs starting 5 minutes before and ending 5 minutes after the stress test.  Subjective stress was measured during the test with a visual analogue scale.

Significant Increases in cortisol and blood pressure relative to baseline indicated that all participants showed a neuroendocrine response to the social stressor.  At 25 and 35 minutes, cortisol reactivity was significantly lower in the MA group than in MO and C groups.  There were no significant differences between MO and C.  Systolic blood pressure was significantly lower in MA than in MO and C groups, both during the stress test, and in the recovery period immediately afterwards.  However, there were no significant differences between groups for diastolic blood pressure, or for subjective stress.  Taken together, the hypothesis that MA would differentially affect outcomes relative to MO and C was supported for reduced cortisol reactivity, partially supported for blood pressure, but not supported for subjective stress reactivity.

Although mindfulness interventions such as eight-week training courses have been shown to reduce stress, this study is the first to demonstrate a mechanism underlying these outcomes.  Furthermore, it demonstrates that positive clinical outcomes are possible using relatively brief, mindfulness-based therapy delivered by smartphones.

References

Lindsay, E. K., Young, S., Smyth, J. M., Brown, K. W., & Creswell, J. D. (2018). Acceptance lowers stress reactivity: Dismantling mindfulness training in a randomized controlled trial. Psychoneuroendocrinology, 87, 63–73.

Link to Original:  https://doi.org/10.1016/j.psyneuen.2017.09.015