Introduction
Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neuropsychiatric disorders in childhood, and often persists into adulthood (Barkley
1998; Wender
2000). Deficits in ADHD can be described on a behavioral, neuropsychological and brain level. On a behavioral level, ADHD is characterized by age-inappropriate symptoms of attention, hyperactivity and impulsive behavior (American Psychiatric Association
2000). On a neuropsychological level, ADHD is associated with poorer performance on tasks tapping into executive functions (EF), such as response inhibition, attention and working memory (Rubia
2010; Rubia et al.
2001; Seidman
2006). On a brain level, children with ADHD have been found to have reduced size and function of fronto-parietal and fronto-striatal neural networks (Cubillo et al.
2011; Krain and Castellanos
2006; Rubia
2010), during performance on inhibition and attention tasks (Rubia et al.
2005). Children with ADHD often experience impairments in academic as well as social domains. Since ADHD is highly heritable, parents of children with ADHD may also show ADHD symptoms (Thapar et al.
2007). Recent studies on the interaction between genes and the environment indicate that inconsistent parenting increases the susceptibility to ADHD in children who are genetically at risk for ADHD (Martel et al.
2010). Moreover, parenting has been shown to be more inconsistent in parents of children with ADHD (Harvey et al.
2001) and in parents with ADHD (symptoms) (Harvey et al.
2003; Murray and Johnston
2006).
Behavioral treatments and medication have been shown to be effective in the treatment of ADHD, but have several limitations (Van der Oord et al.
2008). First, although behavioral parent management training has been shown to be effective, a diagnosis of ADHD in parents predicts non-response to this treatment (Sonuga-Barke et al.
2002; Van den Hoofdakker et al.
2010). Moreover, parent management training has been investigated predominantly in pre-adolescent children, and effects for adolescents seem lower (Barkley
2004; Chronis et al.
2004). Second, cognitive behavioral therapy (CBT) for children with ADHD has only limited long term effects, and generalization of the learned skills is often low (Chambles and Ollendick
2001; Pelham and Fabiano
2008). Consistent with these findings, no effects of CBT were found in a study of adolescents with ADHD (Morris
1993). Third, medication (mostly stimulants) works only short-term, is often accompanied by side-effects, and treatment fidelity is often low (Schachter et al.
2001). Moreover, medication adherence decreases during adolescence (Wolraich et al.
2005). The annual societal costs of illness (COI) for ADHD in children and adolescents in the USA are roughly estimated to be around 42.5 billion dollars (Pelham et al.
2007) which is enormous, compared to for instance the annual costs for a somatic disorder like asthma of around 4 billion dollars (Stock et al.
2005). Further, the risk for suicide in youngsters with ADHD is nearly three times higher than in controls (James et al.
2004). These findings indicate there is a need to develop and investigate new and effective treatments for adolescents with ADHD. Therefore, we examined the effectiveness of a novel treatment approach, mindfulness training, for adolescents with ADHD and their parents.
Mindfulness is a form of attention or meditation training, based on Buddhist tradition and Western knowledge of psychology, in which awareness of the present moment and non-judgmental observation is increased, whereas automatic responding is reduced (Kabat-Zinn
2003). Mindfulness-based interventions have been shown to be effective in adults who suffer from depression, stress, pain and illness (Bear
2003; Hofmann et al.
2010). Two recent reviews show that there is a growing body of evidence on the effectiveness of mindfulness training for children and adolescents (Black et al.
2009; Burke
2009). However, effect sizes are smaller than in adult samples, and studies are often conducted with clinically diverse populations (Black et al.
2009; Burke
2009). The answer to why mindfulness training may be an effective treatment for ADHD, lies in the three levels of functioning mentioned earlier with regard to ADHD. On a behavioral level, mindfulness meditation focuses on increasing the ability to control attention, and on reducing automatic responses (Teasdale et al.
1995). On a neuropsychological level, research shows that mindfulness meditation enhances performance on tasks measuring EF, such as attention, working memory and cognitive control (Heeren and Philippot
2011; Semple
2010). And at brain level, evidence is found for changes in activity in the fronto-striatal circuits after mindfulness or meditation training (Chiesa and Serretti
2010; Kilpatrick et al.
2011; Tang et al.
2010). These results suggest that mindfulness training may be relevant as an attention training for adolescents with ADHD.
To our knowledge, there are only few studies investigating the effects of mindfulness or meditation training in children or adolescents with ADHD (Grosswald et al.
2008; Zylowksa et al.
2008). Grosswald et al. (
2008) for example found reduced attention and total problems after transcendental meditation in 11–14 year old children with ADHD, using a non-controlled pre-post design. Zylowksa et al. (
2008) also found that self-reported ADHD symptoms and performance on several neurocognitive attention tasks improved after mindfulness training in a mixed group of adults and adolescents. However, this study also used a non-controlled pre-post design and results for the seven participating adolescents were not reported separately.
The abovementioned studies only included children and adolescents in the treatment. However, including parents in treatment may be beneficial, because parents (of children) with ADHD (Harvey et al.
2001; Murray and Johnston
2006) may show less consistent parenting, and inconsistent parenting increases the susceptibility to ADHD in children who are genetically at risk for ADHD (Martel et al.
2010). That is, parents of children with ADHD are likely to experience more stress (Deault
2010), which may lead to becoming less patient, paying more attention to disruptive behavior and acting more reactive (Bögels et al.
2010; Dumas
2005). This ‘parental overreactivity’ is predictive of externalizing behavior of the child (Johnston et al.
2002). In addition, generalization of the learned skills outside the treatment setting may be enhanced by including parents (Bögels et al.
2008). In Mindful Parenting (MP) training, parents learn to pay attention to their children and their parenting in a non-judgmental way, to increase their awareness of the present moment with their child, and to reduce automatic (negative) reactions to their child (Bögels et al.
2010; Kabat-Zinn and Kabat-Zinn
1997). Also, participants learn to take care of themselves and bring calm into their family. A few studies have investigated the effects of mindfulness or meditation training for children and adolescents with ADHD and mindfulness or meditation training for parents and show promising results (Bögels et al.
2008; Harrison et al.
2004; Singh et al.
2010; van der Oord et al.
2011). Bögels et al. (
2008) found strong improvements on externalizing problems and sustained attention after mindfulness training for adolescents with behavior disorders (ADHD, Oppositional Defiant Disorders [ODD], and Autism Spectrum Disorders [ASD]) paralleled by MP for their parents. However, due to the heterogeneity in DSM-IV diagnoses in this group of adolescents, the training was not specifically aimed at improving ADHD symptoms, and it is not clear how adolescents with ADHD specifically benefited from this training. A recent pilot study of our research group on mindfulness training for 8–12 year old children with ADHD (
N = 18) and MP for their parents showed promising results using a waitlist-pre-post-follow-up design (van der Oord et al.
2011). ADHD symptoms of children as well as parents reduced significantly, as reported by parents. Effect sizes (ES) were medium to large for children’s improvements and small for parents improvement, and effects were maintained at 8-week follow-up. Also, parenting stress (medium ES) and parental overreactivity (large ES) showed significant reductions. Harrison et al. (
2004) investigated the effects of a 6-week Sahaja yoga meditation training for 4–12 year old children and their parents in a pre-post design. Parent-reported ADHD symptoms, anxiety and self-esteem of the children improved significantly, as well as child-reported self-esteem. Also, parent–child relationships improved, mainly due to a reduction in conflict. Singh et al. (
2010) found compliance to increase in two children with ADHD, after mindfulness training for their mothers, and consecutive mindfulness training for the children. These findings indicate that including parents in the treatment may increase the effects of mindfulness training for children and adolescents with ADHD.
Summarized, previous studies have shown preliminary but promising results. However, study samples were small, were often conducted with pre-adolescent children, were mostly lacking teacher reports, did not include objective neuropsychological measures of attention, and/or did not examine long term effects of mindfulness training. Therefore, in our study, we investigated the effectiveness of mindfulness training for adolescents with ADHD and MP for their parents, using a non-controlled pre-post-follow-up design. Adolescent functioning was assessed using adolescent, parent and tutor reports of attention and behavioral problems, as well as neurocognitive computerized tasks measuring attention and impulsivity. We expected symptoms and behavioral problems to reduce after mindfulness training, and task performance to improve.
Discussion
This study evaluated the direct, middle-term and longer-term effects of mindfulness training for adolescents with ADHD and Minful Parenting for their parents, using self-report questionnaires with multiple informants as well as objective neurocognitive measures of attentional functioning.
Directly after training, adolescents’ externalizing, internalizing and attention problems reduced, and executive functioning improved on self-report measures. Reported improvements were confirmed by enhanced performance on the computerized attention tests. Effect sizes ranged from small to large. At 8-week follow-up, reductions in problem behaviors and improvements in executive functioning were maintained and became stronger. Again, improvements were confirmed by enhanced performance on computerized attention tests. Most effects were of medium to large size. At 16-week follow-up, reductions in problems behaviors diminished, as did the improved performance on computerized attention tests. Self-reported mindful awareness of adolescents and parents did not change at any time, and neither did adolescent’s fatigue or feelings of happiness. A direct as well as a longer-term reduction of parenting stress was found in fathers. A reduction in parental overreactivity was found in mothers, whereas fathers reported an increase.
The vast majority of results point to improvement, although there are some noticeable findings that need further consideration. First, all informants reported improvements in adolescent functioning at some point, except for mothers. This is especially striking since mothers reported no improvement on any of these measures while fathers reported improvement on every measure. Although discrepant ratings are common between informants (Langberg et al.
2010), informants from the same setting (e.g., fathers and mothers) rate children more similar than informants from different setting (e.g. fathers and teachers), which stresses the importance of independent reports from parents and teachers on ADHD symptoms in the home and school setting respectively (de Nijs et al.
2004). In a meta-analysis (Duhig et al.
2000), a moderate level of mother-father agreement on ratings of child behavioral problems was found (
r = .61). In our study, agreement between parents on behavioral problems ranged from
r = .47 to .78. One possible explanation for this difference between fathers and mothers in report of adolescent’s behaviors may be found in the stress levels of parents. Parental stress has been shown to moderate parent’s ratings of child disruptive behavior. That is, when parental stress is low, fathers rate children’s ADHD and externalizing symptoms lower than mothers, but when stress levels are high, fathers rate children’s symptoms higher than mothers (Langberg et al.
2010). Perhaps the fact that fathers did report reduced parenting stress after mindfulness training, and not mothers, may have influenced their perception of improvement in the adolescents’ behaviors. Or, alternatively or in addition, fathers’ perceived reduction in adolescents’ externalizing behavior may have affected their parental stress. Inspection of the correlations between difference scores in parenting stress and difference scores in adolescent symptoms revealed that pre- to posttest reductions in parental stress level were only significantly related to improvement in adolescent’s attention problems (
r = .68, 2-sided
p < .05) for fathers, but significantly related to improvement in attention problems (
r = .64,
p < . 05), as well as behavioral regulation (
r = .75,
p < .05) and metacognition (
r = .83,
p < .01) reported by mothers. Reductions in parental stress from pretest to 8-week follow-up was related to improved attention (
r = .70,
p < .10), internalizing (
r = .77,
p < .05), behavioral regulation (
r = .75,
p < .05) and metacognition (
r = .75,
p < .05) as reported by mothers, but not by fathers. These results suggest that improvement reported by fathers was not merely a subjective effect, as a result of the reduction of stress after the mindfulness training. In addition, the objective findings from the computerized tests and the tutor-reported improvements indicate that reduced stress cannot account for all effects.
In addition, an interesting result is that all fathers reported a significant reduction in stress levels after treatment, participating fathers (posttest t(6) = 3.57, p < .01; follow-up t(6) = 4.86, p < .01) as well as non-participating fathers (posttest t(6) = 2.95, p < .05; follow-up t(6) = 2.81, p < .05), indicating that the mindfulness training has indirect additional benefits, at least for fathers.
A second explanation for the differences in change reported by fathers and mothers may be that fathers report higher stress levels or adolescent problems than mothers at pretest, leaving more room for improvement. However, paired sample
t tests revealed that, at pretest, fathers and mothers did not differ significantly in reports of parenting stress, or any of the adolescent symptoms or problem behaviors. Similar parenting stress for fathers and mothers had also been found in earlier studies of children with ADHD (Baker
1994) and children without ADHD (Deater-Deckard and Scarr
1996).
Another factor that could be related to the differential findings for mothers and fathers may be found in the father-mother ratio of the parent-group. Compared to the normal ratio of fathers versus mothers in child therapy, ranging between 1:2 and 1:3 (Lamb
2010), the proportion of fathers participating in our training was high (1:1). It is possible that fathers were particularly motivated to participate. In fact, most participating fathers indicated during the intake interview before training that they recognized ADHD symptoms in themselves. This may have raised motivation, not only for the adolescent’s improvement but also for their own, and may have enhanced the effects of the training for fathers on stress levels, and indirectly on ratings of adolescent’s behavior as well, at least partly. The finding that mothers reported no significant improvement may also be the result of the small sample size of our study.
Striking is the finding that fathers reported an increase in parental overreactivity after training, whereas mothers reported the expected reduction. This is in contrast to the findings of Van der Oord et al. (
2011), who found a reduction in parental overreactivity. However, their study included mostly mothers (95%), and therefore results were not analyzed for mothers and fathers separately. A possible explanation is that fathers became more aware of their parental overreactivity during the MP training but were not able to change this, whereas mothers were able to. In fact, fathers reported lower parental overreactivity at pretest than mothers, although the difference was not significant.
With regard to the computerized attention measures, the finding that adolescents showed inconsistencies in their improvements on attention, impulsivity and reaction speed measures of the visual and auditory sustained attention tasks, could be explained by the different types of information processing the tasks tap into (Jonkman et al.
1997). We also found inconsistencies between different measurement occasions, with some effects appearing directly after training, and others appearing at follow-up. Little is known about the duration and time of appearance of treatment effects on different symptoms of ADHD, but perhaps results in larger samples will be more stable, and future studies should investigate this in more detail.
The finding that none of the respondents reported improvement in mindful attention and awareness might be explained by the fact that the MAAS was designed to assess one’s general tendency to be mindful over time, or what might be referred to as ‘trait’ mindfulness (an example item is:
“I rush through activities without being really attentive to them”) (Schmertz et al.
2008). In the adolescent group the focus was more on an applied form, that is, the ability to deploy attention and awareness when needed, and could be referred to as ‘state’ mindfulness. This also applied to the parent-group, for whom the emphasis of the training was on learning to be more mindful in their parenting practices, specifically. However, these findings were in contrast with other studies in which improvements on the adolescent version of the MAAS were shown after participation in mindfulness training (i.e., Brown et al.
2011).
Another notable finding is that some effects on report-measures became stronger at 8-weeks follow-up, but seemed to wane at 16-week follow-up. Unfortunately, since we do not have follow-up measurement for all informant groups (e.g. tutors were not included after posttest, parents dropped out after 8-week follow-up), we do not know if these findings are confirmed across informant groups. Also, the failure to reach significance at 16-week follow-up is probably the result of our sample size becoming smaller with each measurement, since effect sizes stayed the same or became larger. The results, however, may suggest that more booster sessions are necessary to sustain or enhance treatment effects.
Alongside the strong points of our pilot-study (multiple informants, objective neuropsychological attention measures, two follow-up measurements, and the combination of mindfulness training and MP training for adolescents and parents respectively), our study has several limitations that should be mentioned. First, the sample size was small and therefore generalization of the findings is limited. Studies using larger sample sizes are needed to replicate these findings. Second, this study was based on a quasi-experimental design rather than a randomized controlled clinical trial (RCT). Participants were not assigned randomly to treatment and no-treatment or different treatment groups. In future studies, a RCT should be used to compare mindfulness training and MP to no or different treatment. Of particular interest here would be to make the comparison between the previously mentioned parent management training, medication and MP and/or mindfulness training for the adolescents. Third, the effect of the mindfulness training on attention was only objectively investigated in sustained attention, and as a result we cannot draw conclusions about the effects on other aspects of attention (e.g., focused or divided attention). Fourth, the relative contribution of parent and adolescent training to the improvements reported is unknown due to parallel training, and therefore it is unknown which aspects are (most) effective. Although our clinical judgment is that the effectiveness of the mindfulness training lays in the parallel training for an important part, the comparison of the combination of MP plus mindfulness training for the adolescents, versus MP or mindfulness training for the adolescents alone might disentangle these effects.