Table 3.
Characteristics of studies.
| References | Population | MBI program | Controls | Study duration | Intention-to-treat | Cortisol assessments | Cortisol indicators | Other biomarkers | Results | St Q | Tx Q |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Klatt et al., 2009 | 45 university employees Mean age: 43.41 ± 2.17 years (MBSR), 46.50 ± 1.89 years (Control) Gender: male 24%, female 76% (total). | MBSR-id (low-dose), (N = 22), 6 weeks programme training of 6 h. Homework: individual sessions for 20′ during the remaining work days. Listen to the daily meditations on the CD four times per week. Adherence workbook and two CDs. | Wait-list control (PC) (N = 23). | N/A | No | 30 time points pre and post intervention each 2 consecutive days collected at ~7 a.m., at 1 p.m., and at 10 p.m. once per week during intervention collected at ~7 a.m., at 1 p.m., and at 10 p.m. | Average daily values. | None | Baseline salivary cortisol was higher in the control compared to MBSR-ld group. There were no changes in the average daily levels of salivary cortisol over time in both groups and there were no differences from pre to post intervention. | AS (?) AC (?) PK (?) IO (−) | Man (+) Trai (?) Inte (?) |
| Oken et al., 2010 | 31 caregivers. Mean age: 62.50 ± 11.60 years (Mindfulness), 67.09 ± 8.36 years (Education), 63.80 ± 7.92 years (Respite). Gender: male 19%, female 81% (total). | Mindfulness (based MBCT) (N = 10). 6 weeks + common first-week session (total 7 weeks) programme training: 10.5 h. Homework: not declared contents and lengths of time written material and recorded audio instructions. | Education (AC) (N = 11). 6 weeks + common first-week session (total 7 weeks) programme training: 10.5 h caregiver help book. Respite (PC) (N = 10) 7 weeks respite care: 3 h | N/A | No | 6 time points pre and post intervention single day collected at within 5′ after awakening, 30′ later before eating, and at bedtime (~10–11 p.m.). | Each measured value (including morning levels). | IL-6, TNF-α, HS-CRP | There were no significant changes among the three groups in the levels of salivary cortisol. | AS (−) AC (−) PK (−) IO (?) | Man (+) Trai (+) Inte (?) |
| Jensen et al., 2012 | 47 healthy (mainly university students). Mean age: 20–36 years (total). Gender: male 34%, female 66% (total). | MBSR (N = 16) 8 weeks + intensive retreat (7 h) programme training: 27 h. Homework: formal assignments (45 min) following CDs with guided meditation practices and informal assignments (15 min). | NMSR (AC) (N = 15) 8 weeks (not declared intensive retreat) structurally similar to MBSR but did not include meditation practices or training in a non-judgemental attitude. Inactive controls (PC) (N = 16). | N/A | No | 10 time points baseline and post intervention single day collected upon awakening, at 15, 30, 45, 60 min after awakening. | CAR: AUCG and AUCI. | None | The groups did not initially differ on any cortisol measures. At post intervention, MBSR group showed a tendency toward a lower AUCGthan did the inactive controls. MBSR group decreased near-significantly on AUCG, NMSR decreased, and the inactive controls increased within each group. Only MBSR decreased significantly on AUCI, NMSR decreased, and the inactive controls showed no changes. | AS (?) AC (?)PK (−)IO (−) | Man (+) Trai (+) Inte (?) |
| Flook et al., 2013 | 18 teachers. Mean age: 46.70 ± 6.95 years (MBSR-m), 38.50 ± 11.49 years (Control). Gender: male 11%, female 89% (total). | MBSR modified (N = 10) 8 weeks + one day-long immersion (6 h) programme training: 26 h. Homework: guided and unguided meditation practices that ranged in duration from 12 to 45 min guided practices following audio CDs. | Wait-list control (PC) (N = 8). | N/A | No | 18 time points pre and post intervention each 3 consecutive working days collected at 30′ after awakening, before lunch, and before bed. | Morning levels and average daily values. | None | Both groups showed a marginally significant flattening of diurnal cortisol profiles over time. Although MBSR-m group didn't change the levels of morning salivary cortisol, the control group showed a significant decrease in the levels of that cortisol. | AS (?)AC (?) PK (?) IO (?) | Man (+) Trai (+) Inte (?) |
| Rosenkranz et al., 2013 | 49 community volunteers. Mean age: 44.4 ± 12.37 years (MBSR), 48.9 ± 7.66 years (HEP), Gender: male 20%, female 80% (total). | MBSR (N = 28) 8 weeks + one full-day session programme training: 20 h + α. Homework: daily at-home practice that ranged in duration from 45 to 60 min (not declared contents). | Health Enhancement Programme: HEP (AC) (N = 21) 8 weeks + one full-day session structurally similar to MBSR consisted of four components: (1) physical activity (2) balance, agility, and core strength (3) nutritional education and (4) music therapy. | 4 months | Yes | 18 time points: TSST pre and post intervention, and 4 months follow-up, single day collected after 20′ rest period, immediately before TSST, immediately after TSST, and subsequent 10′ intervals for 30′ during TSST. 45 time points: at home pre and post intervention, and 4 months follow-up each 3 days collected upon awakening, at 30′ post-awakening, before lunch, at 3 p.m., and before bed. | Diurnal slope and daily output (AUCGacross the whole day). | blister fluid TNF-α, IL-8 | There was neither a significant effect of group, nor a group × time interaction for stress-evoked cortisol response. The slope of the decline in cortisol produced across the day did not differ between the two groups at pre intervention, whereas there was a non-significant trend for the slope to be steeper for MBSR group and less steep for HEP group at post intervention, that became significant at 4 months follow-up. Cortisol AUC showed a main effect of group, where MBSR had lower daily cortisol output across assessments, but no main effect of time or group × time. | AS (?) AC (?) PK (?) IO (?) | Man (+) Trai (+) Inte (?) |
AC, active controls; AUC, area under the curve; AUCG, area under the curve with respect to ground; AUCI, area under the curve with respect to increase from awakening; BMI, body mass index; CAR, cortisol awakening response; CD, compact disc; HS-CRP, high-sensitivity C-reactive protein; IL, interleukin; MBCT, mindfulness-based cognitive therapy; MBSR, mindfulness-based stress reduction; mMBSR, modified mindfulness-based stress reduction; N/A, not available; NMSR, non-mindfulness stress reduction; Non-RCTs, non-randomized controlled trials; PC, passive controls; RCTs, randomized controlled trials; TNF-α, tumor necrosis factor-alpha; TSST, the Trier Social Stress Test. ST-Q: study quality. AS, adequate generation of allocation sequence; AC, concealment of allocation to conditions; PK, prevention of knowledge of the allocated intervention; IO, dealing with incomplete outcome data; St Q, Risk of bias (Higgins et al., 2011); Tx Q, Intervention quality; Man, the study referred to the use of a treatment manual; Trai, the therapists who conducted the therapy were trained; Inte, treatment integrity was checked during the study; +, high; −, low; ?, unclear.