Fibromyalgia is an incapacitating syndrome of unknown etiology. Its main characteristic is chronic diffuse pain, mostly muscular. Other related symptoms are sensations of rigidity in the limbs, sleep problems, and fatigue (Rodero et al., 2009; Glattacker et al., 2010). Additionally, about 32.3% of fibromyalgia patients have an anxiety disorder, and 34.8% have a mood disorder, especially of a depressive type (Comeche et al., 2012; Parra et al., 2012). Likewise, anger toward oneself is high in these patients (Sayar et al., 2004). In addition, these negative emotions can increase or amplify pain (Sayar et al., 2004; van Middendorp et al., 2013). Thus, the way that people with fibromyalgia process and regulate their emotions may be relevant for adjustment to pain (Geenen et al., 2012).

The presence of anxiety and depressive symptoms is related to inadequate coping with stress. Fibromyalgia patients show a high amount of maladaptive coping strategies and a reduction of positive emotions (van Ittersum et al., 2009; Aparicio et al., 2011; van Middendorp et al., 2013), as well as a tendency to internalize and suppress anger. Moreover, some psychological variables related to the inability to cope, such as catastrophic thoughts, external locus of control, a low sense of self-efficacy, and feelings of helplessness are also present (Torres et al., 2009; Glattacker et al., 2010; Miró et al., 2012).

Different psychotherapeutic approaches have been used (medication, physical therapy, educational programs, behavior therapy, and cognitive-behavior therapy). Behavior therapy includes techniques such as thought-suppression, and cognitive-behavioral therapies use cognitive restructuring. Some research has found that, among patients scoring high on affect intensity, emotion expression was associated with less fibromyalgia impact (Geenen et al., 2012). However, other authors (Sayar et al., 2004) report that chronic angry emotional reactions are often maladaptive because they lead to pervasive interpersonal disruption and chronic sympathetic activation. Overall, the results obtained for reducing discomfort and other symptoms related to fibromyalgia are limited in the long-term (Rodero et al., 2009; Fjorback et al., 2012).

Difficulty in identifying and understanding feelings and emotions seems to be associated with fibromyalgia (Sayar et al., 2004). Consequently, awareness and acceptance of the sensations and feelings associated with chronic pain while remaining active may be another approach to the treatment of the symptomatology. Currently, one of the most promising techniques is mindfulness. Mindfulness can be described as non-judgmental attention to experiences in the present moment (Kabat-Zinn, 1990). It is both a practice and a way of being in the world (Carlson, 2012). Bishop et al. (2004) proposed a two-component model of mindfulness: self-regulation of attention and acceptance of one’s own experiences in a non-evaluative way (non-reactive awareness). In this sense, mindfulness is a valuable tool for learning new non-reactive models of responding to the emotional discomfort associated with different disorders, including fibromyalgia and to relate to pain without suffering.

Different researchers have shown the applicability of mindfulness techniques in education and health. Systematic reviews and meta-analyses (Chiesa and Serreti, 2009; Irwing et al., 2009; Carlson, 2012) reveal the effectiveness of these techniques, especially of mindfulness based stress reduction (MBSR; Kabat-Zinn, 1990) and mindfulness-based cognitive therapy (MBCT; Segal et al., 2002) in the reduction of stress-related symptoms (anxiety and depression, among others).

Given the decline in the quality of life that fibromyalgia patients are likely to face, it is especially important to undertake research studies proving the effectiveness of such programs. Hence, the main goal of this study was to verify the efficacy of a mindfulness program to reduce anger, anxiety, and depression levels in patients diagnosed with fibromyalgia.

First, means and SDs for all the variables were calculated in both groups (see Tables 1 and 2.

Man–Whitney’s U test for independent samples of pretest scores revealed that there were no statistically significant group differences in the mean scores of the target variables. However, significant differences between the means of posttest scores were revealed for many variables. Specifically, significant lower scores were observed in the experimental group on State Anger (Z = -3.57; p = 0.001), Angry Feelings (Z = -3.16; p = 0.005), Anger Expression-In (Z = -4.32; p = 0.000), State-Anxiety (Z = -5.43; p = 0.000), and Depression (Z = -3.26; p = 0.005), and higher scores in internal control of anger (Z = -3.41; p = 0.001) when compared to the control group. Likewise, mean group comparisons performed at the follow-up phase revealed similar significant differences when compared to the posttest phase, except for Angry Feelings. Bonferroni correction was also used in order to reduce the probability of finding statistical differences due to chance. A significance level of 0.0083 was applied (Table 3).

Next, Friedman test for related samples was also performed in the experimental group. In order to reduce the probability of finding statistical differences due to chance Bonferroni correction was applied, considering a significance level equal or lower to 0.017. Significant differences were found in State Anger (χ² = 15.18, p = 0.001), internal expression of anger (χ² = 16.12, p = 0.000), internal control of Anger (χ² = 8.29, p = 0.016), Trait Anxiety (χ² = 25.08, p = 0.000), and Depression (χ² = 14.78, p = 0.001; Table 4).

In addition, Wilcoxon’s test for related samples comparing the pretest and posttest mean scores of the experimental group revealed significant reductions in several dimensions of anger: State Anger (Z = -4.92; p = 0.000), internal expression of anger (Z = -4.43; p = 0.000), and internal control of anger (Z = 2.87; p = 0.013), as well as in State Anxiety (Z = -6.18; p = 0.000), and Depression (Z = -3.79; p = 0.001), whereas a significant increase in internal control of anger was found (Z = 2.87, p = 0.0013). Similarly, when comparing mean pretest scores with mean follow-up scores, significant differences were also obtained in the same variables and dimensions. However, no significant differences were found between mean posttest and follow-up scores for any of the target variables of the experimental group (Table 5).

Conversely, Friedman test for related samples in the control group revealed no significant differences (see Table 6).

Cohen’s d (Cohen, 1988) was used to evaluate the effect size at posttest, as well as at the follow-up assessment. Values above 1.5 indicate the presence of very important changes, values between 1.5 and 0.5 indicate moderate changes, values between 0.5 and 0.2 indicate a low change, and values below 0.2 indicate a very low change. In Table 7, Cohen’s d scores for posttest measures show important changes in internal Expression of Anger and State Anxiety; moderate changes in State Anger, Angry Feelings, Angry Temperament, internal control of anger, and Depression; low changes in Verbal Expression of Anger, Trait Anger, Anger Reaction, External Expression of Anger, Anger Expression Index, and Trait Anxiety; and very low changes in physical expression and external control of anger.

Regarding the amount of change in the mean scores at pretest and follow-up, we observed important changes in State Anxiety; moderate changes in Angry Feelings, internal expression and internal control of anger, and Depression; low changes in state and trait anger, Angry Temperament, Angry Reaction, External Control of Anger, and Trait Anxiety; and very low changes in physical expression, verbal expression, external expression of anger, and in the anger expression index (see Table 7).

Finally, percentages of change between pretest and posttest measures, and between pretest and follow-up were calculated. As shown in Table 7, change between pretest and posttest measures showed an increase of 13% in internal anger control, as well as reductions ranging between 13 and 27% in State Anger, including Angry Feelings, Depression, State Anxiety, and internal expression of anger. The percentage of change between pretest and follow-up measures showed a 10% increment in internal control of anger, and reductions ranging between 28 and 16% in State-Anxiety, Depression, Angry Feelings, and internal expression of anger.

Findings confirm that the mindfulness-based training program was effective. After 7 weeks, patients achieved significantly lower scores in the following variables: State Anger, internal anger expression, State Anxiety, and Depression. Significant improvements were also attained in the internal control of anger. In contrast, the control group did not obtain any significant result in these variables. Moreover, the experimental group maintained many of the benefits throughout the follow-up phase, especially for depression, state anxiety, and internal expression and control of anger. The improvement obtained in the internal control of anger had a medium effect size. Remarkably, important improvements were obtained for state anxiety, which increased after the 3-months follow-up period.

These findings are relevant if we take into account that, to date, treatments for this disease, especially pharmacological treatments, have proven unsatisfactory due to lack of adherence and to relapses (Fjorback et al., 2012). The improvements obtained in internal control and expression of anger are especially important when considering that fibromyalgia patients use maladaptive strategies, such as internalizing and suppressing anger. In contrast, research has found that emotional expression and control through adaptive coping strategies is associated with lower impact of fibromyalgia (Geenen et al., 2002; Sayar et al., 2004; van Ittersum et al., 2009). Also, the changes in anxiety and depression are consistent with previous investigations associating the practice of mindfulness with important reductions in these variables and an increase in the experience of positive emotions (Segal et al., 2002; Grossman et al., 2007; Amutio et al., 2013; Parra and Latorre, 2013).

By practicing mindfulness, individuals can learn to maintain a relaxed mind and concentrate on the present moment. An integral part of the practice is to cultivate an attitude of kindness, acceptance, generosity, and patience toward unpleasant emotions and thoughts that may arise. Concretely, and for depression, mindfulness practice helps patients to interrupt depressogenic reactions toward pain and other related symptoms. Patients learn to accept their pain-related automatic thoughts (including catastrophizing) with a non-judgmental attitude of openness, minimizing behavioral avoidance (Segal et al., 2002). Some studies have shown that the development of acceptance and self-compassion are important mediating variables in the positive effects of mindfulness on anxiety and depression (Kuyken et al., 2010; Schütze et al., 2010; Luciano et al., 2014). At the same time, the experience of positive emotional states associated with mindfulness can provoke a modification of helplessness-related beliefs (Amutio and Smith, 2008) and a higher motivation to continue with the treatment.

Unlike other therapies, mindfulness-based interventions provide techniques, abilities, and perspectives that patients are encouraged to practice and that, once learned, can be applied to everyday life. Furthermore, mindfulness training is not aimed at symptom reduction but more basically toward altering the way that mental processes and content are experienced. Development of acceptance may enhance well-being, even in the face of continued symptoms.

Nevertheless, our study presents the limitation of not having an alternative treatment for the control group. Taking into account the heterogeneity of this disorder and the variability among patients, studies with active control groups are clearly needed to compare the efficacy of mindfulness-based interventions with different treatments, such as cognitive-behavior therapy and physical training programs and to determine the typologies of patients who could benefit from a certain treatment.

The findings reveal the feasibility of mindfulness-based treatment intervention on anger, a variable on which few studies have been carried out to date. They also add to the growing body of literature documenting the effectiveness of mindfulness for the treatment of anxiety and depression. Finally, one of the main advantages of this program is that it can be taught in a group format, which reduces the costs for participants. It also optimizes the economic and social resources invested in health.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.