Effects of mindfulness and psychoeducation on working memory in adult ADHD: A randomised, controlled fMRI study

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Highlights

  • Psychoeducation and mindfulness exercises improve ADHD symptoms and working memory performance.

  • Psychotherapeutic interventions affect brain functioning in adults with ADHD.

  • Mindfulness exercise can be associated with a stronger activation in brain areas related to working memory and attention.

Abstract

Adult attention-deficit/hyperactivity disorder (ADHD) is a serious mental disorder associated with impaired neurocognitive performance related to working memory function. Recent clinical trials have suggested that mindfulness is a promising intervention in adults with ADHD. We performed a randomised controlled clinical trial to investigate working memory (WM) with an n-back task in adults with ADHD during fMRI before and after an 8-week mindfulness intervention (MAP) compared with psychoeducation (PE). ADHD symptoms were assessed using the self- and observer-rated Conners Adult ADHD Rating Scales (CAARS).

The complete pre–post data of 21 MAP and 19 PE participants were analysed. We found no group difference in ADHD symptoms or task performance at the pre-measurement, but there was a significant decrease in ADHD symptoms and significant improvement in task performance in both groups at the post-measurement. Furthermore, we found a significant increase in task-related activation in the right parietal lobe, with no difference between groups. Exploratory two-sample paired t-tests revealed significant increased brain activation after MAP in the bilateral inferior parietal lobule, right posterior insula and right precuneus. A decrease in self-rated ‘Inattention/Memory Problems’ after MAP compared to baseline was associated with stronger activation in parts of the left putamen, globus pallidus and thalamus.

Introduction

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects healthy psychological functioning (Volkow & Swanson, 2013), and it is associated with mental health problems, as well as impaired academic and social functioning (Asherson, Buitelaar, Faraone, & Rohde, 2016; NICE, 2013). The DSM characterises ADHD by its three cardinal symptoms: inattention, hyperactivity and impulsivity. Approximately 2.5% of the adult population meets the criteria for ADHD (APA, 2013; Volkow & Swanson, 2013).

Although methylphenidate hydrochloride is recommended as the first-line treatment for ADHD's core symptoms (NICE, 2013), psychopharmacological treatment with methylphenidate has limitations, such as nonresponse, contraindications, adverse events or patients' preference for a nonpsychopharmacological treatment. Therefore, nonpharmacological interventions are needed.

Impairments in working memory are a defining and persisting characteristic of ADHD in adulthood (Alderson, Kasper, Hudec, & Patros, 2013; Salavert et al., 2015). Working memory is a vital function for managing everyday life, for instance, in making decisions and plans or storing information (Owen, McMillan, Laird, & Bullmore, 2005). Difficulties with working memory function can be quite impairing, and they can distort everyday functioning. ADHD-related impairments in working memory have been associated with low academic achievement, inhibition control and social functioning (Fried et al., 2016; Kofler et al., 2017; Tseng & Gau, 2013).

The current research suggests that mindfulness can improve working memory capacity (Chambers, Lo, Chuen Yee, & Allen, 2008; Fabio & Towey, 2018; Jha, Stanley, Kiyonaga, Wong, & Gelfand, 2010; Zeidan, Johnson, Diamond, David, & Goolkasian, 2010). For example, a recent study assessed the effect of an intense, 8-week mindfulness programme on executive functioning in an adult ADHD sample. The post-treatment effects indicated a significant improvement in executive functioning, including working memory (Janssen, Vries, Hepark, & Speckens, 2017).

When applied as a clinical intervention, mindfulness is intended to increase one's awareness of internal and external experiences of the present moment (Kabat-Zinn, 1990). It teaches patients to respond more adaptively to the physiological and psychological processes involved in psychiatric disorders (Bishop et al., 2004). Research on the behavioural and psychological changes after mindfulness training has shown clear beneficial effects of mindfulness on ADHD symptoms, improving attention, emotion regulation and quality of life, thereby supporting the application of mindfulness interventions for ADHD (Bueno et al., 2015; Hoxhaj et al., 2018; Mitchell, Zylowska, & Kollins, 2015; Mitchell et al., 2017). For example, a recent meta-analytic review by Cairncross and Miller (2016) has provided preliminary evidence for the effectiveness of mindfulness in reducing core ADHD symptoms. The findings of this study demonstrated that mindfulness-based therapies significantly reduce the symptoms of inattention and hyperactivity/impulsivity in adults with ADHD.

Mindfulness applied as clinical intervention in ADHD is of great interests since it can be considered as a form of mental training that can improve neuropsychological deficits in ADHD, such as attention control, working memory, and emotion regulation, by strengthening the function of the brain regions thought to underlie these deficits, such as the frontal and parietal brain areas (Bachmann, Lam, & Philipsen, 2016). Research on ADHD psychopathology suggests that there are structural and functional abnormalities in multiple neuronal systems related to cognitive functions (Cortese et al., 2012; Francx et al., 2016; Frodl & Skokauskas, 2012; Sörös et al., 2017). Specifically, dysfunctions in the prefrontal cortex, parietal brain areas, and basal ganglia are associated with ADHD, and they have been related to impairments in executive functioning and working memory (Frank, Loughry, & O'Reilly, 2001; Norman et al., 2016; van Ewijk et al., 2015).

Earlier studies that used an n-back paradigm during functional magnetic resonance imaging (fMRI) to examine the neural correlates of working memory in ADHD found abnormal activation in brain regions associated with working memory. For example, Salavert et al. (2015) found less deactivation of the medial frontal cortex during n-back performance in ADHD patients compared with healthy controls. Another study demonstrated less activation of the left middle frontal gyrus, left frontal pole and paracingulate gyrus, as well as the right middle frontal gyrus, during the n-back task in adults with ADHD compared with healthy controls (Salavert et al., 2015).

Research on the neurobiological effects of mindfulness meditation suggests that mindfulness is associated with changes in brain areas associated with working memory. For example, functional changes in the frontoparietal networks, as well as structural and functional changes in the cingulate cortex and basal ganglia, have been reported after mindfulness training in nonclinical samples (Brewer et al., 2011; Tang, Hölzel, & Posner, 2015). These findings suggest that mindfulness may improve working memory function in adults with ADHD by altering the brain functioning in related brain areas.

In the current study the effects of a mindfulness treatment (MAP)1 were compared with the effects of an active control treatment. The experience of the active control group was closely matched to the training group in terms of effort (same amount of lessons and homework), duration of the treatment and equal amount of attention and interaction time with the therapist. The active control group received psychoeducation about ADHD. Psychoeducation (PE)2 is a psychological intervention that has demonstrated efficacy in reducing ADHD symptoms (Hoxhaj et al., 2018; Vidal et al., 2013). PE is an approach that aims at improving the patients' understanding and awareness of the disorder; it can offer insight into past difficulties and can improve the patient's general functioning (Vidal et al., 2013). PE's major objective is to provide patients with information about their disorder. These characteristics distinguish PE from other psychological interventions that focus more on cognitive and behavioural changes, such as cognitive behavioural therapy methods involving cognitive restructuring, behavioural change, or mindfulness meditation practice.

However, research on PE's neurobiological effects is scarce. We found one published fMRI study that investigated the effects of PE on emotional Stroop task performance in patients with euthymic bipolar disorder and healthy controls. The results revealed altered frontolimbic activity after PE in the patient group only (Favre et al., 2013). However, we did not find trials investigating PE's effects on working memory–related brain functioning. Furthermore, there have been no trials investigating the neurobiological effects of mindfulness or PE in adults with ADHD.

The current study aimed to close the identified gap in the literature by investigating the working memory–associated neurobiological effects of MAP compared with an active control group (PE) in an adult ADHD sample. Based on the research on ADHD pathophysiology and neural effects of mindfulness mentioned above, we predicted stronger brain activation in the frontoparietal regions and basal ganglia after MAP. We hypothesised that MAP would lead to increased brain activation compared with PE. Finally, we expected stronger improvement in working memory performance for MAP relative to PE.

Section snippets

Study design and participants

The current fMRI study was part of a randomised controlled clinical trial comparing the effects of MAP and PE on the symptomatology and neurobiological correlates of adult ADHD. The study was approved by the local ethics committee and registered in the Current Controlled Trials database (ISRCTN12722296).

The subjects were recruited in the adult ADHD outpatient clinic and inpatient units of the Department of Psychiatry and Psychotherapy Medical Center at the University Hospital Freiburg. In

Demographics

There were no significant differences between the MAP and PE group for any of the demographic variables of age, gender and education (see Table 1). Furthermore, no significant differences were found in terms of the ADHD symptoms, subtype, comorbidity or medication (see Table 1).

Behavioural data analyses

The task performance analysis revealed no ceiling effects on the one-back task (see Table 1). Before treatment, the MAP participants had 54.55% (mean: 61.29 [SD: 15.51]) and PE participants had 50.85% (57.13 [14.04])

Effect of intervention

A group x time ANOVA across all patients revealed a significant main effect of time, indicating significantly higher activation in the right parietal lobe (peak coordinates: x = 28 mm, y = −58 mm, z = 44 mm; max. Z-value: 3.61) for the contrast target-correct minus nontarget responses during the one-back task after compared with before the intervention. There was no main effect of therapy or a significant interaction effect. To explore whether the main effect of time was driven by one of the

Discussion

In our pioneer longitudinal fMRI study, we investigated the neurobiological effects of a highly structured, intense mindfulness programme compared with an active control group (PE) in an adult ADHD sample. Both groups received the same number of treatment sessions and attention. Working memory was assessed by means of a visual one-back memory task during fMRI. Against our hypothesis, MAP was not superior in improving working memory function compared with PE. We found a significant main effect

Declaration of interests

KB, PS, MK, EH, BF, HM, JÖ and CMT 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. APL declares that she received travel grants in the last year from MEDICE Arzneimittel Pütter GmbH and Co. KG. SM received a speaker's fee from Jansen-Cilag and was involved in clinical trials conducted by Janssen-Cilag and Lilly as a study physician in 2007–2009. AP declares that she served on

Authors’ contributions

KB, PS: Literature search, figures, data analysis, data interpretation, writing.

APL, HM, JÖ, CMT: Literature search, data interpretation.

MK, EH: Literature search, figures, data collection.

BF: Literature search, figures, data collection, data interpretation.

SM, AP: Literature search, figures, study design, data collection, data analysis, data interpretation, writing, supervision.

Funding

The project was partly funded by the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, BMBF, 01GV0606).

Trial registration

isrctn.org Identifier: ISRCTN12722296.

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