Modifying resilience mechanisms in at-risk individuals: a controlled study of mindfulness training in Marines preparing for deployment

Abstract

Objective: Military deployment can have profound effects on physical and mental health. Few studies have examined whether interventions prior to deployment can improve mechanisms underlying resilience. Mindfulness-based techniques have been shown to aid recovery from stress and may affect brain-behavior relationships prior to deployment. The authors examined the effect of mindfulness training on resilience mechanisms in active-duty Marines preparing for deployment.

Method: Eight Marine infantry platoons (N=281) were randomly selected. Four platoons were assigned to receive mindfulness training (N=147) and four were assigned to a training-as-usual control condition (N=134). Platoons were assessed at baseline, 8 weeks after baseline, and during and after a stressful combat training session approximately 9 weeks after baseline. The mindfulness training condition was delivered in the form of 8 weeks of Mindfulness-Based Mind Fitness Training (MMFT), a program comprising 20 hours of classroom instruction plus daily homework exercises. MMFT emphasizes interoceptive awareness, attentional control, and tolerance of present-moment experiences. The main outcome measures were heart rate, breathing rate, plasma neuropeptide Y concentration, score on the Response to Stressful Experiences Scale, and brain activation as measured by functional MRI.

Results: Marines who received MMFT showed greater reactivity (heart rate [d=0.43]) and enhanced recovery (heart rate [d=0.67], breathing rate [d=0.93]) after stressful training; lower plasma neuropeptide Y concentration after stressful training (d=0.38); and attenuated blood-oxygen-level-dependent signal in the right insula and anterior cingulate.

Conclusions: The results show that mechanisms related to stress recovery can be modified in healthy individuals prior to stress exposure, with important implications for evidence-based mental health research and treatment.

Conflict of interest statement

The other authors report no financial relationships with commercial interests.

Figures

FIGURE 1

Heart and Breathing Rates Before, During, and After a Stressful Immersive Training Session in Marines Receiving Mindfulness Training (MT) or Training as Usual (Control)a aThe stressful immersive training session took place at the Infantry Immersion Trainer facility approximately 9 weeks after baseline. In panel A, heart rate during the 10-minute anticipatory period prior to immersive training was higher for the MT group. Although peak heart rate did not differ between groups during the training, the MT group also showed quicker heart rate recovery during the 10-minute period immediately following stressful training. In panel B, there were no differences between groups in breathing rate during the anticipatory or stress periods. During the 10-minute recovery period, the mean breathing rate for the control group did not significantly differ from peak response; however, the mean breathing rate for the MT group decreased significantly from peak during the stress period and was significantly lower than the rate for the control group during both the 10-minute recovery and the 45-minute rest period.

FIGURE 2

Mean Plasma Neuropeptide Y and Norepinephrine Concentrations in Marines Receiving Mindfulness Training (MT) or Training as Usual (Control)a aNeuropeptide Y and norepinephrine levels are shown for baseline, after 8 weeks, and after a stressful immersive training session at the Infantry Immersion Trainer facility approximately 9 weeks after baseline. For neuropeptide Y, there were no group differences at baseline or at 8 weeks. There was a significant interaction in response to stressful training (F=4.67, df=2, 350, p<0.01; d=0.33), with the control group showing significantly higher levels of neuropeptide Y 45 minutes after stressful training, whereas the MT group had recovered to near baseline levels.

FIGURE 3

Activation of the Right Insula and Anterior Cingulate Cortex During Emotion Recognition in Marines Receiving Mindfulness Training (MT) or Training as Usual (Control)a aFrom the original fMRI subsample of 20 Marines in each group, data from one Marine in the MT group and four in the control group were excluded from analyses because of excessive head-motion artifact at either the baseline or the follow-up assessment (at approximately 10 weeks). Analyses adjusted for baseline differences in sleep quality, combat exposure, and previous training at the Infantry Immersion Trainer facility. Compared with Marines in the control group, those in the MT group showed significantly decreased activation in the right insula and anterior cingulate cortex.

FIGURE 4

Relationship Between Change Score From Baseline to Follow-Up on the Response to Stressful Experiences Scale and Changes in Activation in the Right Anterior Insula (N=25)a afMRI scanning took place at baseline and again approximately 10 weeks later, within 2 weeks after a stressful immersive training session at the Infantry Immersion Trainer. As insula activation decreased from baseline to follow-up, resilience characteristics increased (r=−0.42). BOLD=blood-oxygen-level-dependent.