A Canadian team has published a systematic review examining the effectiveness of Mindfulness-Based Interventions (MBIs) for treating adults with ADHD. MBIs usually involve three forms of meditation – body scan, sitting meditation, and mindful yoga – that are intended to cultivate nonjudgmental awareness of present-moment experience. The team reviewed thirteen studies.

Three were single-group studies with no control group. One used dialectical behavior therapy (DBT). It reported mild to moderate improvements in ADHD symptoms, and substantial improvements in neurocognitive function (with standardized mean difference effect sizes from .99 to 2.22). A second enrolled both adults and adolescents in a mindful awareness program (MAP) which included a psychoeducational component. It found improvements in self-reported ADHD symptoms with standardized mean difference (SMD) effect sizes running from .50 to.93. Following training, it also reported improvement in attentional conflict (.93) set-shifting (.43). The third study also used DBT, focused on acceptance, mindfulness, functional behavioral analysis, and psychoeducation. ADHD symptoms showed mild improvement (.22), and functional impairment was slightly reduced (.15) and remained stable at 3-month follow-up.

The other ten studies used control groups. One used MAP and carefully stratified participants based on their ADHD medication status, then randomly assigned them to mindfulness treatment or waitlist. It reported large effect sizes in improvement of self-reported and clinician ratings of ADHD symptoms (1.35 to 3.14), executive functioning (1.45 to 2.67), and self-reported emotion regulation (1.27 to 1.63). Another study nonrandomly assigned adults to either mindfulness-based training (MBT) or skills training. Effect sizes were small to medium (.06 to .49), with 31% of MBT participants showing some improvement, versus only 11% of skills training participants.

Another study involved a controlled trial of college students with ADHD, randomized to receive either MBT or skills treatments. Treatment response rates were higher for MBT (59-65%, vs. 19-25%). At follow-up, the effect size for MBT on ADHD symptoms was large (.84), and similarly large on executive functioning (.81).

Another study tried a year’s worth of mindfulness training on poor responders to medication. Participants who received the treatment were compared to others who were waitlisted. The study reported a medium effect size (.63) in reducing the severity of ADHD.
Another looked at the impact of MAP on affective problems and impaired attention. It compared adults with ADHD and healthy controls who participated in MAP sessions with similar patients and controls who did not. The authors reported that MAP improved sustained attention and mood with medium to large effect sizes (.50 to .80).

A recent study explored the impact of MAP on neurocognitive performance with a randomized controlled trial. Following an 8-week mindfulness training, researchers “found a significant decrease in ADHD symptoms and significant improvement in task performance in both the MAP and the psychoeducation comparison group post- versus preintervention but did not find evidence for a significant main effect of treatment or a significant interaction effect on any ADHD symptoms (self- and observer-rated) nor on task performance (WM).”

Another study randomly assigned adults with ADHD either to a waitlist or to mindfulness-based cognitive therapy (MBCT). It found that MBCT led to a medium-to-large reduction in self-reported ADHD symptoms (.64) and a large reduction in investigator-reported symptoms (.78). It also found large (.93) improvements in executive functioning.

An 11th study looked at the effects of MBCT on neurophysiological correlates (event-related potentials (ERPs)) of performance monitoring in adults with ADHD. Half the patients were randomly assigned to MBCT, the other half to waitlist. MBCT produced reduced inattention, hyperactivity/impulsivity, and global ADHD index symptoms with medium to large effect sizes (.49 to .93).

A 12th study randomly assigned college students to MBCT or waitlist. At follow-up, participants who had received MBCT exhibited large (1.26) reductions in ADHD symptoms as well as greater treatment response rates (57%-71% vs. 23%-31%) versus waitlist. They also registered greater improvement on most neuropsychological performance and attentional scores.

Finally, another study compared the efficacy of MBCT plus treatment as usual (TAU) versus TAU only in reducing core symptoms in adults with ADHD. Participants were randomly assigned to an 8-weekly group therapy including meditation exercises, psychoeducation, and group discussions, or to TAU only, including pharmacotherapy and/or psychoeducation. At 6-month follow-up, MBCT+TAU patients reported large (SMD = .79) improvements in ADHD symptoms relative to TAU patients.

Overall, these are promising results for mindfulness-based interventions, and all the more so for those who do not respond well to drug therapy. Nevertheless, they must be seen as tentative. The sum total of participants over all thirteen studies was just 753, or an average of only 58 per study. There was too much variation in the studies to perform a meta-analysis. Only one of the studies included a healthy (non-ADHD) control group. And only one study received a perfect score by Cochrane Collaboration standards. Most studies did not use a suitable control group, i.e., in which there was an expectation of benefit from participating. As the authors noted, “Attrition bias was found to have high or unclear risk in more than a half of the studies. The reason for dropout of participants was not always clearly specified in those studies, so it is difficult to decide if it might be related to adverse effects or to some discomfort with treatment or instead to some incidental reasons.”

REFERENCES
Hélène Poissant, Adrianna Mendrek, Nadine Talbot, Bassam Khoury, and Jennifer Nolan, “Behavioral and Cognitive Impacts of Mindfulness-Based Interventions on Adults with Attention-Deficit Hyperactivity Disorder: A Systematic Review,” Behavioural Neurology, Vol. 2019, Article ID 5682050, 16 pages, https://doi.org/10.1155/2019/5682050.

Joseph Biederman AIA rX8AEq
This blog addresses the relationship between executive function deficits in general and working memory (WM) deficits in particular and attention-deficit/hyperactivity disorder (ADHD). 

Although some neuropsychological models of ADHD have proposed that ADHD arises from deficits in executive functions, accumulating clinical evidence show that it afflicts some but not all individuals with ADHD and suggests that ADHD and executive function deficits represent separate clinical conditions.

Because executive functions refer to a wide and diverse group of high order mental functions, one approach to evaluate this important issue is to focus on one prominent facet of executive functions, mainly working memory. Working memory (WM) refers to a key brain system that provides temporary storage and manipulation of information essential for adequate cognitive functioning.  It focuses attention, inhibits irrelevant stimuli, recognizes priority patterns and hierarchies and selects the goals that are best suited to solving a problem.

Since these cognitive processes are critical for learning, their impairment can lead to deficits in functioning including social and educational dysfunction, low educational achievement and can have a serious impact on educational success. 

To address this issue we examined referred youth with and without ADHD, and with and without WM deficits in functional, social and academic outcomes. We used Resting State FMRI imaging to examine whether the neural circuits subserving WM deficits overlap with those of ADHD.  We investigated this issue in preclinical studies where we examined spatial WM and dopamine receptor activity in rodents.  Our preclinical findings demonstrate that the magnitude of improvement in WM produced by the D4 receptor agonist is significantly greater than that produced by methylphenidate.

CBT treats Executive Dysfunction Free ADHD CME WyUaeE
In human studies, we examined whether the most standard treatment for ADHD has a different effect on measures of WM and ADHD. This body of research provides evidence for a clinical, pharmacological and neurobiological dissociation between ADHD and WM deficits.  Our human treatment study with methylphenidate provided evidence for very different effects for ADHD and WM deficits Our clinical studies show that significantly more youth with ADHD had WM deficits than controls (31.9% vs. 13.7%) and their presence is significantly and specifically associated with academic failure.

In our imaging study, we found that brain activations to a WM test were different in subjects with ADHD with associated WM deficits compared to controls and ADHD subjects without WM deficits.

This body of work indicates that WM deficits afflict a minority of subjects with ADHD and when present they significantly and selectively increase the risk for academic dysfunction in subjects with ADHD, they have separate neural underpinning, and respond differently to treatments for ADHD.

Screening for WM deficits may help identify individuals with ADHD at high risk for academic dysfunction.

 

References

P. LEE, N. PINEDA, T. BRUNE, K. PATEL, A. GANNON, T. J. SPENCER, J. BIEDERMAN, P. G. BHIDE, J. ZHU. Hyperactivity and working memory deficits induced by prenatal nicotine exposure are associated with dopamine D1 and D4 receptor dysfunction. Society for Neuroscience Annual Meeting, Washington, DC, November, 2014

Fried R, Chan J, Feinberg L, Pope A, Woodworth KY, Faraone SV, et al. Clinical correlates of working memory deficits in youth with and without ADHD: A controlled study. Journal of clinical and experimental neuropsychology. 2016;38(5):487-96.

Mattfeld AT, Whitfield-Gabrieli S, Biederman J, Spencer T, Brown A, Fried R, et al. Dissociation of working memory impairments and attention-deficit/hyperactivity disorder in the brain. NeuroImage Clinical. 2016;10:274-82.

Biederman J, Chan J, Spencer TJ, Woodworth KY, Kenworthy T, Fried R, Bhide P, Faraone SV. Evidence of a pharmacological dissociation between the robust effects of methylphenidate on ADHD symptoms and weaker effects on working memory. Journal of Brain Sciences. 2015; 1(2): 43-53.