Table 1.

Summary of the main findings of the analyzed studies (in alphabetic order).

References Study type	Participants	Pain	MBI	Communication research team/participants	Participants expectations	Analysis of placebo effects	Outcomes
Case et al. (2021) Study type: secondary analysis of previous work	Population: 78 (39 ♂/39 ♀) Mean age: 27 ± 7 Experimental groups: Meditation + naloxone Control + naloxone Meditation + saline Control + saline Previous experience in MBI: Not referred	Duration: Acute Modality/type: Noxious heat (35–49°C)	Type: Mindfulness-based mental training Duration: 4 sessions of 20 min Instructors: - Formation/experience: not referred - Conflicts of interest/Disclosure of Instructors/Authors: Referred: none	Referred: - Participants were told that: “the study would assess whether meditation was associated with the release of naturally occurring opiates” - They would receive intravenous administration of saline or naloxone, a relatively safe drug that blocks the transmission of opioid activity	Evaluated: Yes Remarks: In a scale of 0–10 how much do you expect that meditation will be effective in reducing your pain?	Placebo of the MBI intervention: Placebo saline for naloxone	- MBI lowered pain during saline and naloxone infusion - Higher expected pain- relief from MBI predicted lower pain intensity - Relation between meditation- related expectations and reduction of pain intensity during naloxone infusion, but not saline - Expectations for book- listening based analgesia did not significantly predict pain changes during saline or naloxone infusion in the control group.
Davies et al. (2021) Study type: RCT	Population: 93 (34 ♂/59 ♀) Mean age: 21 ± 9 Experimental groups: - Mindfulness - Sham mindfulness - No treatment Inclusion criteria: Fluent in English Pain-free (< 3/10) - Meditation naïve Not pregnant/breastfeeding - Not under analgesic or psychotropic medication. Previous experience in MBI/meditation: Meditation naïve	Duration: Acute Modality/type: Heat	Type: “Mindfulness of Breath and Body” (MBCT adaptation for chronic pain) Duration: Four sessions of 20-min training in home practice of an audio recording Instructors: Formation/experience: not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred: None	Referred: Informed consent: Yes; No details provided	Evaluated: Yes Remarks: At the beginning of the project “no suggestion was made regarding mindfulness being effective for pain in any study materials or procedures, including the meditation training” and “How effective do you think mindfulness is for reducing pain?” At the end of the project “Do you think you were practicing a guided mindfulness meditation?”	Placebo of the MBI intervention: Sham- intervention group delivered as MBI	- Sham MBI produced equivalent credibility ratings and expectations of improvement as MBI, but did not influence mindfulness- related processes. - MBI increased “observing” (but none of the other four mindfulness facets) relative to no treatment, but not sham. - MBI and sham moderately increased pain tolerance relative to no treatment, with no difference between mindfulness and sham. - No effects in pain threshold. - Neither MBI nor sham reduced pain intensity or unpleasantness relative to no treatment, although MBI reduced pain unpleasantness relative to sham.
Davies et al. (2022) Study type: RCT	Population: 153 (42 ♂/111 ♀) Mean age: 22 ± 93 Experimental groups: - Mindfulness with expectancy (mindfulness treatment and told mindfulness); - Mindfulness without expectancy (mindfulness treatment and told sham); - SHAM+(sham treatment and told mindfulness) - SHAM- (sham treatment and told sham), with an additional comparison against a no treatment control group. Inclusion criteria: - Fluent in English - Pain free - Not pregnant, breastfeeding - Not taking analgesic or psychotropic medications. Previous experience in MBI/Meditation: Mindfulness naïve	Duration: Acute Modality/type: Noxious heat	Type: Focused attention mindfulness (breath and body) Duration/place: Six daily sessions lasting 20-min of audio guided training; first and last session in the lab and the remaining home Instructors: - Formation/experience: Not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred: none	Referred: - Several moments of communication with the participants to determine expectations. - Instructions displayed on the computer screen (and reiterated in a short audio introduction) revealed the group allocation to the participant (i.e., mindfulness, sham mindfulness, or no treatment, as per cover story) without the researcher's knowledge (to maintain blinding). Informed consent: Yes; Details provided	Evaluated: Yes The study evaluates expectancy so that it can be manipulated to test the effect of intervention. Remarks: Participants were asked in several moments questions like “How effective do you think mindfulness meditation is for reducing pain?” and “How effective do you think your training will be for reducing pain?”	Placebo of the MBI intervention: Balanced placebo designs allowing for manipulation of both treatment and instruction (expectation)	- MBI improved pain outcomes (unpleasantness, intensity, and tolerance) in comparison to control. - The instruction manipulation increased expectation for pain relief in those told mindfulness relative to those told sham. - There were no main effects or interactions of treatment or instruction on pain outcomes. - Irrespective of actual intervention received, the belief of receiving mindfulness predicted increased pain threshold and tolerance, with expectancy fully mediating the effect on pain tolerance.
Davies et al. (2023) Study type: RCT	Population: 169 (28 ♂/138 ♀) males; 3 other Mean age: 32 ± 8 Experimental groups: - Mindfulness of Breath/Body - Specific sham mindfulness - General sham mindfulness - Audiobook control Inclusion criteria: - 18 years of age or older, - Understand English, - Chronic or recurrent pain as clinical guidelines Previous experience in MBI/Meditation: Not referred	Duration: Chronic pain/recurrent pain Modality/type: Diverse (arthritis, muscle pain, headache, menstrual, neuropathic, other)	Type: Mindfulness of Breath and Body Duration: one 20-min session Instructors: - Formation/experience: experienced meditation instructor - Conflicts of interest/Disclosure of Instructors/Authors: Referred: “The authors have no conflicts of interest to declare.” After setup, the research team had no involvement in the running of the RCT, which was entirely automate (“the study was ostensibly double blind”).	Referred: Yes - Participants were asked to numerically rate the current intensity and unpleasantness of pain. - The analogy of listening to a song on the radio was used to help participants differentiate between intensity and unpleasantness. Informed consent: Yes	Evaluated: Yes Remarks: “We assessed pre-to-post changes in placebo-related (response expectancy and hope) processes to assess potential differential effects of mindfulness, specific sham, and general sham relative to audiobook control.” Expectancy was assessed at baseline by asking participants: “How effective do you think mindfulness meditation is for reducing pain?”	Placebo of the MBI intervention: - Specific sham mindfulness: condition developed and validated to explicitly control for non-specific factors present in the “Mindfulness of Breath and Body”; characterized by a facilitator voice, attention paid to the intervention, body posture and instructions designed to give the meditator the sense that they were practicing a guided meditation, except for instructions that explicitly or implicitly suggested training attention on present moment experience or brought mindfulness metacognitive qualities to attention General sham mindfulness: Did not include any mindfulness instructions.	- Mindfulness not superior to sham in reduction of pain intensity/unpleasantness. - Mindfulness and sham reduced pain unpleasantness (but not pain intensity) relative to audiobook control, with expectancy most strongly associated with this effect. - Treatment expectancy associated with decreases in pain intensity and unpleasantness after mindfulness and sham training. - Specific and general sham with equivalent expectancy and credibility ratings to each other and the mindfulness intervention (suggesting that all three interventions were likely to engage placebo-related processes equally) - Mindfulness and sham equally reduced pain catastrophizing relative to audiobook control - No differences in pain reappraisal between mindfulness, shams, and audiobook control.
Davoudi et al. (2021) Study type: RCT	Population: 225 (133 ♂/92♀) Mean age: 56 ± 25 Experimental groups: - Mindfulness and placebo - Placebo - Mindfulness - Vitamin D - Mindfulness + Vitamin D Inclusion criteria: Patients referred to the hospital. - Lack of major co-morbid disease - Age of 20–70 years Willingness to participate in studying - Vitamin D insufficiency or deficiency Previous experience in MBI: Not referred	Duration: Chronic Modality/type: Diabetic neuropathy	Type: modified mindfulness manual based on pain relief protocols Duration: 12 weeks (90 min per session) Instructors: - Formation/experience: trained psychotherapist - Conflicts of interest/Disclosure of Instructors/Authors: Referred: none	Referred: They were blinded about study aims and other groups' existence (VDs and other mindfulness groups). Informed consent: Not referred	Evaluated: No Remarks: Not referred	Placebo of the MBI intervention: similar drops in shape (without any VD) and duration.	- Improvement of QOL in all groups except the “placebo only” group for outcome variables. - There was no difference between VD and MBI groups (within and not combined with placebo) in improvement of QOL - “VD + MBI” has a greater improvement in QOL rather than VD and mindfulness groups. - Reduction in pain disability and pain severity in all groups except “placebo.” No difference between MBI and VD groups to reduce pain disability and pain severity. Yet, the “vitamin D + mindfulness” group showed the higher improvement.
Esch et al. (2017) Study type: RCT	Population: 31 (8 ♂/24♀) Mean age: 27 ± 8 Experimental groups: - Passive control condition (no intervention) - Combined breathing/mindfulness meditation technique Inclusion criteria: - At least 18 years old Language proficient - No visual impairments Previous experience in MBI: Meditation naïve volunteers	Duration: Acute Modality/type: Ischemic arm pain (tourniquet test)	Type: combined breathing/mindfulness meditation technique (bodyscan, attention to breath (ATB), attention to senses (ATS), open awareness/attention to experience (ATE), and walking meditation—with focused breath awareness as a steady anchor) Duration: daily group sessions of 1.5 h each Instructors: - Formation/experience: The trainer (TE) had 20 years of meditation experience, and is a professional meditation/mindfulness teacher, and researcher in the field. - Conflicts of interest/disclosure of Instructors/Authors: none	The topic of pain (e.g., pain awareness or pain perception) was intentionally and carefully avoided in this course. Participants were informed about their individual group assignment—intervention or control—(to get to know whether they would be required to show-up for intervention training) after the completion of assessments on day 2 by a person otherwise not interacting with the participants. Informed consent: Yes	Evaluated: No Remarks: It was measured the self-attributed minfulness by the Freiburg Mindfulness Inventory	Placebo of the MBI intervention: Placebo saline for naloxone	- The MBI group meditation group produced fewer errors in ANT (Attention Network Test) - Increases in pain tolerance occurred in both groups (accentuated in control), and correlated with reported mindfulness - Naloxone showed a trend to decrease pain tolerance in both groups.
Grazzi et al. (2021) Study type: Open Label Study	Population: 37 (2 ♂/35 ♀) Mean age: 15 ± 2 Experimental groups: Participants completed 6 weekly group sessions of guided meditation, and one booster session 15 days later. Inclusion criteria: Adolescents (12–18) chronic or high-frequency migraine without aura. Previous experience in MBI: meditation naive	Duration: Chronic Modality/type: Migraine	Type: Adaptation of MBSR and MBCT programs, by shortening these programs Duration/place: 6 weeks group sessions with 1 h duration followed by one booster session 15 days after	Referred: Not explicitly mentioned. Informed consent: Yes: for adolescents and their parents; details not available	Evaluated: No	Placebo of the MBI intervention: Not performed but authors refer as a limitation intrinsic to an open-label study	- MBI decreases headache frequency MBI had effects on medication intake, disability, trait anxiety, symptoms of depression and catastrophizing
Khatib et al. (2024) Study type: RCT	Population: 59 (29 ♂/30 ♀) Mean age: 46 Experimental groups: - Mindfulness - Sham mindfulness-meditation Inclusion criteria: - Not positive for opioids - Not pregnant - Meditation naive - Responsive to the straight leg-raise test, - Not having back surgery within a year of the enrollment - Not concurrently enrolled in other experiments - Not initiating new pain therapies during the study period. Previous experience in MBI/meditation: Mindfulness naive	Duration: Chronic Modality/type: Low back pain	Type: Mindfulness based mental training Duration: Four 20-min sessions Instructors: - Formation/experience: certified meditation instructors. - Conflicts of interest/Disclosure of Instructors/Authors: Referred: Drug assignment blinded to patients, nurses, and experimenters. Only the physicians, pharmacist, and coordinator aware of drug assignment. Participants were compensated $400 for study completion.	Referred: Yes - In Straight leg-raise 1 (non-meditation rest), patients were instructed to “rest with your eyes closed” and after 7 min, pain ratings were collected. - In pre-intervention bolus control, patients were instructed to “continue resting with your eyes closed” (8 min). - In all 4 mindfulness sessions, instructions acknowledging arising thoughts, feelings, and/or emotions, that such sensations and emotions were “momentary” and “fleeting,” and to “return their attention back to the breath” whenever such discursive events occurred. During training day 4, participants were asked to practice while lying in the supine position and wearing a face mask to emulate the conditions in the post-intervention testing sessions. - During each sham mindfulness-meditation training session, the participants were told, approximately every 2–3 min, to “take deep breaths as we sit in meditation.”	Evaluated: No Remarks: Not referred	Placebo of the MBI intervention: Sham- mindfulness meditation (train individuals to “take slow, deep breaths” in a meditative posture but omits the mindfulness-specific instructions non-reactive attention to breath sensations—hypothesized to mediate pain relief); Placebo saline for naloxone	- After the interventions, mindfulness and sham mindfulness-meditation effectively attenuated induced pain. - Mindfulness-meditation with lower pain before and after the straight leg-raise test when resting and during meditation when compared to the sham mindfulness-meditation group. - Mindfulness and sham mindfulness-meditation associated with significant reductions in back pain during saline and naloxone infusion when compared to rest (non-meditation). - Meditation directly reduces evoked chronic pain through non-opioidergic processes - Mindfulness group with lower straight leg-raise induced pain than the sham mindfulness-meditation group during rest (non-meditation) and meditation. - Mindfulness and sham mindfulness-meditation training was also associated with significantly lower Brief Pain Inventory severity and interference scores - Mindfulness and sham mindfulness-meditation training associated with significant improvements in pain interference and pain catastrophizing after 80-min of mental training
May et al. (2018) Study type: RCT	Population: 32 (18 ♂/14 ♀) Mean age: 52 ± 52 Experimental groups: - Saline - Naloxone Inclusion criteria: - Pain-free adults with established meditation practice - From the local community Previous experience in MBI/meditation: Experienced meditators	Duration: Acute Modality/type: Electric current 5 Hz	Type: Open Monitoring/Awareness but the background of the experienced meditators was very diverse. Duration/place: 10 min prior to nociceptive stimulation Instructors: - Formation/experience: Not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred in detail	Referred: The researcher described the protocol taking into account the specificities of the sessions and participants gave their consent Informed consent: Yes; in two different moments; Details not available	Evaluated: Yes The authors referred that “the participants had a variety of expectations of the drug effect”. Remarks: - Participants were kept blind as to the naloxone or saline administration. - They were subsequently asked “in which session they believed they received naloxone” and “in your opinion what does naloxone do”	Placebo of the MBI: No; the placebo effect focuses on naloxone/saline administration	- MBI induced analgesia (lowered pain intensity and pain unpleasantness) - Naloxone increased meditation-induced analgesia (lower pain intensity and pain unpleasantness)
Namjoo et al. (2019) Study type: RCT	Population: 85 (29 ♂/56 ♀) Mean age: 36 ± 7 Experimental groups: - MBCT - Attention Placebo Control Inclusion criteria: - >19 years - Headache experience at least - 3 days/month and for > 3 months) due to a primary headache - Reading and writing skills to understand and complete worksheets Previous experience in MBI/meditation: Not referred (just “engaging in other psychotherapies for pain condition”)	Duration: Chronic Modality/type: Headache	Type: MBCT (the first half of the protocol focused on the preferment of awareness of patients about mind default mode; in the second half of treatment, enhanced awareness converted to automatic skills and patients learn to choose intentionally to respond to their experiences rather than to react. Duration 8-weekly 2 h group program Instructors: - Formation/experience: Superior in MBCT fibromyalgia patients. - Conflicts of interest/Disclosure of Instructors/Authors: Referred: none	Referred: No Informed consent: Yes	Evaluated: No Remarks: Not referred	Placebo of the MBI intervention: Attention Placebo Control −8 weekly 2 h sessions; participants received attention and therapist's empathy and participated in group discussion.	- Change of scores across the two groups over time (for pain severity and for pain interference (pleasing result for researchers who claim that MBI can affect pain perception) - MBI resulted in a higher rate of pain openness and a lower rate of pain focus compared to the APC group from baseline to follow-up. - MBI resulted in a higher rate of pain distancing compared to the APC group from baseline to post-test and the reappraisal scores decreased in the follow-up—MBI was ineffective and could not make any changes on pain diversion
Schmidt et al. (2011) Study type: RCT	Population: 177 (0 ♂/177 ♀) Mean age: 52 ± 5 Experimental groups: - MBSR - Active control procedure (o que é?) Wait list Inclusion criteria: - 18–70 years of age - Currently with fibromyalgia diagnosis (criteria of the American - College of Rheumatology) - Command of the German language - Motivation to participate Previous experience in MBI/meditation: Not referred	Duration: Chronic Modality/type: Fibromyalgia	Type: MBSR (mindfulness meditation and mindful yoga exercises) Duration: 8-week group program (one 2.5-h session every week, and an additional 7-h all-day session on a weekend day.) Instructors: - Formation/experience: at least 7 years of previous experience teaching MBSR - Conflicts of interest/Disclosure of Instructors/Authors: Referred: none	Referred: “Informational brochures were provided that briefly described the 2 interventions as alternative behavioral treatments potentially capable of enhancing the wellbeing in fibromyalgia patients. - No suggestion was made about the superiority of either treatment.” - “Patients in the intervention arms were told that 2 new innovative treatments were to be compared, one based on the concept of mindfulness (entailing meditation and yoga lessons, as well as homework), and the other based on health support techniques (entailing relaxation and stretching exercises, as well as homework). The active control group was referred to as the relaxation group. All patients participating in one of the 2 active treatment arms were also offered participation in their treatment of choice after completion of the trial.” Informed consent: Yes	Evaluated: Yes Remarks: “Pre- and post-intervention 1-h personal interviews were conducted by each instructor to establish rapport and to help patients formulate realistic individual goals for the intervention.”	Placebo of the MBI intervention: The active control is considered the placebo. 8-week group of size and weekly format similar to that of the MBSR program taught by a single instructor; Equivalent amounts of social support and weekly topical educational discussions; use of Jacobson Progressive Muscle Relaxation training (PMR), and fibromyalgia- specific gentle stretching exercises; homework assignments were similar in duration and intensity to those in the MBSR group; patients received compact discs (CDs) with instructions for daily exercises	- No significant differences between groups on primary outcome (health related quality of life), but patients overall improved in HRQoL at short-term follow-up. Only MBI manifested a significant pre-to-post- intervention improvement in HRQoL - Multivariate analysis of secondary measures (disorder-specific quality of life, depression, pain, anxiety, somatic complaints, and a proposed index of mindfulness) indicated modest benefits for MBSR patients. MBSR yielded significant pre- to-post-intervention improvements in 6 of 8 secondary outcome variables, the active control in 3, and the wait list in 2.
Seminowicz et al. (2020) Study type: RCT	Population: 98 (9 ♂/89 ♀) Mean age: 36 Experimental groups: MBSR Stress management for headache (o que é?) Inclusion criteria: - 18–65 years of age - Diagnosis of migraine (International Classification of Headache Disorders for migraine with/without aura) - ≥1 year history of a migraine diagnosis Previous experience in MBI/meditation: Meditation naive	Duration: Chronic Modality/type: Migraine	Type: MBSR vs. stress management (active control) Duration/Place: 12 group sessions over 4 months, including 8 weekly sessions followed by 4 biweekly sessions. Instructors: - Formation/experience: Two experienced, certified instructors (10 and 40 years of meditation experience) - Conflicts of interest/Disclosures of Instructors/Authors: Referred: none	Referred: Not explicitly mentioned. Informed consent: Yes; details not available	Evaluated: No Remarks: Authors state that the study accounts for the influence of expectations and non-specific effects of intervention but it is not mentioned how the expectations were evaluated	Placebo of the MBI intervention: The active control is considered the placebo. This intervention included 12 sessions over 4 months with on didactic content about the role of stress and other triggers in headaches in a similar format of the intervention group, minus the retreat.	- MBI decreased headache and migraine frequency and intensity - MBI decreased headache-related disability, as well as yielded a higher treatment response rate, in comparison to the active control
Sharon et al. (2016) Study type: RCT	Population: 14 Mean Age: not specified Experimental groups: - Intravenous naloxone (0.1 mg/kg) - Intravenous saline Inclusion criteria: Same meditation practice Previous experience in MBI/meditation: Experienced meditators	Duration: Acute Modality/type: Cold stimulus (2–4°C water)	Type: Sitting mindfulness meditation with Shamatha or Vipassana meditation Duration/place: The details of the mindfulness practice (duration, guidance, groups) during the intervention are unclear Instructors: - Formation/experience: Not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred: None	Referred: No details Informed consent: Not referred	Evaluated: No Remarks: Not referred	Placebo of the MBI intervention: No; the placebo effect focuses on naloxone/saline administration	- MBI and placebo reduced pain and unpleasantness scores - Naloxone did not reverse MBI-induced induced analgesia - Positive correlation between pain scores following naloxone vs. placebo and participants' mindfulness meditation experience (reduced response to placebo with increasing experience).
Vencatachellum et al. (2021) Study type: Mixed factorial design	Population: 62 (31 ♂/31 ♀) Mean age: 26 ± 85 Experimental groups: - Mindfulness-meditation - Suppression (o que é?) Inclusion criteria: - 18 years or older - Healthy - Acute and chronic pain free Previous experience in MBI/meditation: Not referred	Duration: Acute Modality/type: Noxious heat (43–49.5°C)	Type: Mindfulness meditation: open awareness to sensations, thoughts and emotions; Audio recording Suppression: Mentally blocking out any arising sensations, thoughts and emotions and concealing any external manifestation of current experiences Duration: 10 min Instructors: - Formation/experience: not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred: none	Referred: A research staff member provided instructions. Informed consent: Yes; details not available	Evaluated: No Remarks: The authors state that mindfulness leads to a prioritization of current sensory information over previous expectations, which were not evaluated	Placebo of the MBI intervention: Lack of MBI reduction of conditioned hyperalgesia is interpreted as absence of placebo effect	- Pain Intensity: reduced conditioned hypoalgesia in the MBI group compared to the suppression group - Pain Unpleasantness: smaller conditioned hypoalgesia magnitudes in the MBI group compared to the suppression group
Wells et al. (2020) Study type: RCT	Population: 60 (30 ♂/30 ♀) Mean age: 27 ± 7 years old Experimental groups: - Mindfulness-meditation (n = 19) - Sham-mindfulness meditation - Slow-paced breathing Inclusion criteria: - 18 years or older Healthy - Acute and chronic pain-free Previous experience in MBI/meditation: Meditation-naive	Duration: Acute Modality/type: Noxious heat (49°C)	Type: Mindfulness meditation: non-reactive attention to breath sensations Duration: 4 separate sessions, 20 min each Instructors: - Formation/experience: Certified Meditation Teachers - Conflicts of interest/Disclosures of Instructors/Authors: Referred in detail	Referred: Participants were informed of their experimental group. Participants of the sham group were lead to believe “they were practicing mindfulness meditation without instructions related to mindfully attending to the breath in a non-evaluative manner. Participants were first told they were randomly assigned to the mindfulness meditation group.” Informed consent: Yes; details not available	Evaluated: No Referred: The sham group was intentionally lead to belied that they were practicing mindfulness breathing	Placebo of the MBI intervention: Sham- mindfulness meditation; Slow Breathing; Saline	- MBI reduced pain unpleasantness, but not pain intensity, after naloxone or saline infusion sessions when compared to rest. - Slow-paced breathing reduced pain intensity and unpleasantness ratings during naloxone, but not saline infusion. - Sham-mindfulness meditation reduced pain unpleasantness during saline infusion which was reversed by naloxone. - Sham-mindfulness did not lower pain intensity. - Self-reported “focusing on the breath” is a feature associated with the mindfulness-meditation and slow paced- breathing, but not sham-mindfulness meditation.
Westenberg et al. (2018) Study type: RCT	Population: 125 (63 ♂/62 ♀) Mean age: 55 ± 15 Experimental groups: - Mindfulness-based video exercise - Education pamphlet Inclusion criteria: Attending an appointment with the orthopedic Previous experience in MBI/meditation: Meditation naive	Duration: Chronic Modality/type: Musculoskeletal pain	Type: Visualization practice of identifying stress full thoughts/feeling and releasing with the breath using a video support Duration/place: 60-second mindfulness; waiting room Instructors: - Formation/experience: Background of the instructors not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred: none	Referred: Not explicitly mentioned. Informed consent: Yes; details not available	Evaluated: No Remarks: Participants were kept blind to the intervention. They were told that a comparison of 2 pain and stress management interventions was being performed without specifying the intervention.	Placebo of the MBI intervention: Attention placebo control with an educational pamphlet about pain and stress with the same duration as MBI.	- MBI improved momentary pain, anxiety, depression, and anger patients in the waiting room (high levels of psychologic distress)
Zautra et al. (2008) Study type: RCT	Population: 144 (46 ♂/98 ♀) Mean age: 52 ± 12 Experimental groups: - Mindfulness-meditation - Cognitive Behavioral Therapy - Education only Inclusion criteria: - >or 18 years - Self/Clinical- Diagnosis of rheumatoid arthritis	Duration: Chronic Modality/type: Rheumatoid arthritis	Type: Adaptation of MBSR and MBCT to chronic pain; examining and promoting emotion regulation and adaptation in chronic pain. Duration: 8 weeks program (MBSR/MBCT format) but shorter (no retreat; 10 min sitting meditations). Instructors: Formation/experience: not referred (doctoral- level psychologist; student level)	Referred: Not explicitly mentioned. Informed consent: Yes; details not available.	Evaluated: No Remarks: The authors state that “a direct assessment of expectation of improvement and satisfaction with treatment would be import to assess equivalence between groups”	Placebo of the MBI intervention: Education group used as an attention placebo control	- MBI improved self- reported pain, dependent on depression history and pain assessment method - Patients with recurrent depression benefited most from MBI, in the affective dimension and along with physicians' ratings of joint tenderness
Zeidan et al. (2015) Study type: RCT	Population: 75 (38 ♂/37 ♀) Mean age: 27 ± 6 Experimental groups: - Mindfulness meditation Placebo conditioning - Sham mindfulness meditation - Book-listening control Inclusion criteria: - Healthy - Pain-free - Right-handed volunteers Without any prior meditative experience Previous experience in MBI/meditation: Meditation naïve	Duration: Acute Modality/type: Noxious heat (35–49°C)	4 days of Mindfulness intervention vs. 4 days of a placebo conditioning regimen. Type: Mindfulness-based mental training: training day 1: focus on the breath sensations occurring “at the tip of the nose.” Training day 2: expansion of the focus to the “full flow of the breath,” including bodily sensations training days 3 and 4: minimal meditation instructions. Duration: 4 sessions in 4 days; 20 min Instructors: - Formation/experience: not referred - Conflicts of interest/Disclosures of Instructors/Authors: Not Referred	Referred: Participants were told that they were participating in an “experimental trial of a new formulation of a topical, local anesthetic being tested for its pain reducing effects over time.” They were told that the drug's name is “lidocaine” and that it “has been proven effective at progressively reducing pain after multiple applications in preliminary studies at other universities.” Informed consent: Yes; Details provided	Evaluated: No Remarks: The sham group was intentionally lead to belied that they were practicing mindfulness breathing	Placebo of the MBI intervention: A placebo- conditioned regimen was designed and tested	- All cognitive manipulations (i.e., MBI, placebo conditioning, sham MBI) attenuated pain intensity and unpleasantness ratings when compared to rest and the control condition. - MBI produced greater pain relief than placebo and sham MBI by engaging different brain mechanisms from those of placebo and sham induced analgesia - The cognitive state of mindfulness meditation deactivated brain regions that facilitate low-level sensory and nociceptive processing including the thalamus and PAG compared with rest and the main effects of placebo and sham MBI. - Compared with placebo manipulation, MBI produced greater activation in brain regions that mediate the cognitive control of pain. Placebo produced greater activation in several brain areas in comparison to MBI. - Sham MBI induce overlapping activation of some brain areas with MBI, and deactivation of brain regions associated with the default mode network of the brain. - Some brain areas presented higher activation during sham MBI compared with MBI, whereas other had the opposite response
Zeidan et al. (2016) Study type: RCT	Population: 78 (39 ♂/39 ♀) Mean age: 27 ± 7 Experimental groups: - Meditation + naloxone - Control + naloxone - Meditation + saline - Control + saline Inclusion criteria: - Healthy - Pain-free Meditation-naive - Recruited from the local community Previous experience in MBI/Meditation: Meditation naïve volunteers	Pain duration: Acute Pain modality: Noxious heat (35–49°C)	Type: Mindfulness-based mental training: training day 1: focus on the breath sensations occurring “at the tip of the nose.” Training day 2: expansion of the focus to the “full flow of the breath,” including bodily sensations training days 3 and 4: minimal meditation instructions (no instructions for practice tice outside training sessions). Duration: 4 sessions of 20 min. Instructors: - Formation/experience: not referred - Conflicts of interest/Disclosures of Instructors/Authors: Referred in detail	Referred: Participants in the meditation group were instructed to “begin meditating until the end of the experiment.” Participants in the control group subjects were told to “close your eyes and relax until the end of the experiment”	Evaluated: No Remarks: Not referred	Placebo of the MBI intervention: Placebo saline for naloxone	- MBI during saline infusion significantly reduced pain intensity and unpleasantness ratings when compared to the control+saline group. - Naloxone infusion failed to reverse meditation-induced analgesia (pain intensity and unpleasantness ratings) - No significant differences in pain intensity or pain unpleasantness reductions between the meditation+naloxone and the meditation+saline groups. - MBI during naloxone produced significantly greater reductions in pain intensity and unpleasantness than the groups.

MBCT, Mindfulness based Cognitive Therapy; MBSR, Mindfulness-Based Stress Reduction; RCT, Randomized Controlled Trial.