For bodily distress, ACT, MBCT, and MBSR can be beneficial therapeutic approaches in adults to improve comorbid psychopathology, perceived health status, and somatic symptom severity.

This meta-analysis was carried out to examine the effectiveness of "third-wave" psychotherapies, specifically acceptance and commitment therapy (ACT), mindfulness-based cognitive therapy (MBCT), and mindfulness-based stress reduction (MBSR) in adults experiencing bodily distress.

The study encompassed randomized controlled trials (RCTs) that treated adults suffering from bodily distress  (somatoform disorders and linked functional somatic syndromes) utilizing MBCT, MBSR, or ACT in comparison with inactive and non-specific control groups. A random effects model was employed for analysis.

The key focus was on the severity of somatic symptoms, while secondary outcomes encompassed levels of depression, anxiety, pain acceptance, health anxiety, perceived health status, mindfulness, and psychological inflexibility.

The analysis comprised 16 RCTs involving 1,288 participants (4 MBCT, 7 MBSR, 5 ACT). The trials covered various conditions, such as fibromyalgia (7 studies), irritable bowel syndrome (5 studies), chronic fatigue syndrome (1 study), bodily distress (2 studies), and medically unexplained symptoms (1 study). However, not all studies offered data for each outcome of interest. The findings indicated that "third wave" therapies were more efficient than control conditions in minimizing the severity of somatic symptoms (15 studies, 1,100 participants, effect size [g] = -0.51).

The level of heterogeneity was moderate (I2 = 52.8%). The impact on secondary endpoints was generally small to moderate, with varying levels of heterogeneity. There were no significant differences observed between mindfulness-based and acceptance-based therapies. Neither therapy doses nor the number of sessions was found to be significant moderators of effectiveness.

Mindfulness and acceptance-based therapies demonstrated greater effectiveness than control conditions in addressing bodily distress, thus offering promising treatment approaches. But, further investigations are needed to assess which patient groups may benefit the most from these psychological interventions.