Table 1.

Results of systematic review of literature on the effect of mindfulness-based interventions on alexithymia

Author	Study type	Population (N)	Age and sex	Intervention	Control	Measures	Time measurements taken	Results
Bornemann and Singer35	RCT	Volunteers from the general public in Germany in good health and with no prior meditation experience. People with TAS20 scores of >60 were excluded n=318	Mean=40.8 (9.3) 59% Female	Three mental training modules, each 3 months long, involving a 3-day silent retreat, 13 weeks of weekly 2-hour group sessions and 30 min of daily practice. The Presence module was about directing attention to the present moment, the Affect module about approaching difficult emotions with acceptance and the Perspective module about metacognition, observing thoughts and reframing experiences. There were three intervention groups: groups 1 and 2 did all three modules over 9 months but in a different order, group 3 did just the Affect module for 3 months	No training	TAS20 and subscales1 Heartbeat perception task and ECG	Before the intervention and at 3, 6 and 9 months (after each module)	Alexithymia decreased more in the intervention groups than the control group from T0 to T3 (p<0.001, d=−0.331) and T0 to T2 (p=0.026, d=−0.155) but not T0 to T1 (p=0.143, d=−0.166). The effect at T3 was significant for all TAS subscales. Post hoc tests showed that the decreases in TAS scores were caused by the Presence and Affect modules but not the Perspective module Heartbeat perception accuracy increased more in the intervention groups than the control group from T0 to T3 (p=0.017, d=0.273) and T0 to T2 (p=0.020, d=0.173) but not T0 to T1 (p=0.220, d=0.111) Change in heartbeat perception accuracy between T0 and T1 were negatively correlated with changes in TAS20 (p=0.002). The correlation was significant for those who had taken the Presence training but not for those who had taken the Affect training
de la Fuente Arias et al 36	RCT	Students from the University of Almeria with no experience of meditation or yoga n=46	M=23.47 (6.34) 85% F	10 weekly 1.5-hour mindfulness/meditation training sessions adapted from the MBSR programme,21 combined with individual practice	Wait-list	TAS20 and subscales1 Social skills scale51	Before and after the intervention	Pre/post tests show significant changes in TAS20 in the intervention group (DIF p<0.001, DDF, EOT and Total TAS p<0.01). The size of the change was 20% decrease in DIF (d=0.32) and DDF (d=0.39), 22.2% in EOT (d=0.55) and 20.60% in total TAS (d=0.47). The control group’s TAS20 did not change significantly. The difference in TAS20 scores between the groups was not significant at baseline (p=0.321) or post intervention (t=0.600, p=0.552) There were no significant differences in social skills in the experimental and control groups at baseline, but post intervention social skills were significantly higher (p≤0.001) in the experimental group and there was a significant pre/post increase in social skills in the experimental group (total social skills, p≤0.001)
Santarnecchi et al 37	RCT and MRI study	Right-handed members of the public in Italy, with no prior meditation or mindfulness experience and in good physical and mental health n=48	Intervention group: 31 (±4) Control group: 30 (±4) 52% F	8-week MBSR programme21 involving weekly 2.5-hour group sessions and daily individual practice	Wait-list	TAS201 Penn State Worry Questionnaire52 State-Trait Anxiety Inventory53 Beck Depression Inventory II54 Mindfulness Attention Awareness Scale39 MRI scans measured grey matter volume and cortical thickness	Before and after the intervention	There was a significant reduction in TAS20 in the intervention group (p=0.004) and no significant change in the control group. There was no significant change in MAAS in either group There was a significant negative correlation between alexithymia level and insula cluster thickness values (r=−0.712, p<0.01) in the intervention group post training There were significant reductions in the intervention group in worry (p=0.012), state anxiety (p=0.031) and depression (p=0.046) but not in the control group
Viding et al 38	RCT	Adult women attending any of 4 healthcare centres in Sweden with burnout/exhaustion symptoms, excluding individuals with drug or alcohol abuse or severe depression n=48	M=53.8 (8.15) 100% F	A package of six cultural activities, including mindfulness (focused on breathing, body awareness and awareness of thoughts and feelings), dance, theatre, film and drawing, each delivered in two 90 min sessions	Standard care involving physiotherapy	TAS20 and subscales1 Karolinska Exhaustion Disorder Scale55 Sense of Coherence56 Single item measure of self-rated health	Baseline, 3 months (the length of the programme) and 6 months (follow-up)	There was a significantly greater decrease in the intervention group compared with the control group in total TAS (p=0.007), DDF (p=0.004) and DIF (p=0.051) at 6 months relative to baseline There was a significant decrease in exhaustion and self-reported health (p≤0.001) in the intervention group compared with the control group, but not in sense of coherence

MAAS, Mindful Attention Awareness Scale; MBSR, Mindfulness-Based Stress Reduction; RCT, randomised controlled trial; TAS20, 20-item Toronto Alexithymia Scale; DIF, Difficulty Identifying Feelings subscale of the TAS20; DDF, Difficulty Describing Feelings subscale of the TAS20; EOT, Externally Orientated Thinking subscale of the TAS20.