March 4, 2021
A Canadian team has published a systematic review examining the effectiveness of Mindfulness-Based Interventions (MBIs)for treating adults with ADHD. MBIs usually involves three forms of meditation –body scan, sitting meditation, and mindful yoga – that are intended to cultivate non-judgmental awareness of the 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 a 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 the 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). In another study, non randomly 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 an8-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 pre-intervention 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 neuropsychological 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, psycho education, and group discussions, or to TAU only, including pharmacotherapy and/or psycho education. 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 thirten 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 sce by Cochrane Collaboration standards. Most studies did not use a suitable control group, i.e., on 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.”
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.
Background
ADHD (Attention-Deficit/Hyperactivity Disorder) is one of the most studied neurodevelopmental conditions, with many clinical trials evaluating the effectiveness and safety of various medications. These trials, known as randomized controlled trials (RCTs), are considered the gold standard for assessing treatments. However, strict eligibility criteria often exclude many real-world patients, raising questions about whether the findings from these trials apply to everyday clinical settings.
Our latest study sheds light on this issue, revealing just how many individuals with ADHD might be excluded from RCTs and the impact this exclusion has on their treatment outcomes.
Method
Researchers used Swedish national registries to analyze data from 189,699 individuals diagnosed with ADHD who started medication between 2007 and 2019. They applied exclusion criteria from 164 international RCTs to identify who would have been considered ineligible for these trials in order to determine the proportion of individuals with ADHD who would not meet the eligibility criteria for RCTs.
Key Findings
Many Patients Are Ineligible for Clinical Trials:
Ineligible Patients Face Unique Challenges:
Higher Risk of Adverse Outcomes:
What This Means
These findings highlight a major gap between the controlled environments of clinical trials and the realities faced by individuals with ADHD in everyday life. While RCTs provide valuable insights, their restrictive criteria often exclude patients with more complex health profiles or co-existing conditions. This limits the generalisability of trial results, meaning that treatment guidelines based solely on RCTs may not fully address the needs of all patients.
Conclusion
This study demonstrated that a significant proportion of individuals with ADHD, particularly adults, do not meet the eligibility criteria for standard RCTs. These results emphasize the importance of bridging the gap between research settings and real-world applications. By recognizing and addressing the limitations of RCTs, we can work towards more equitable and effective ADHD treatment strategies for everyone.
Background:
Our understanding of Attention-deficit/hyperactivity disorder (ADHD) has grown and evolved considerably since it first appeared in the DSM-II as “Hyperkinetic Reaction of Childhood.” This study aimed to find the disorder’s placement within the modern psychopathology classification systems like the Hierarchical Taxonomy Of Psychopathology (HiTOP).
The HiTOP model aims to address limitations of traditional classification systems for mental illness, such as the DSM-5 and ICD-10, by organizing psychopathology according to evidence from research on observable patterns of mental health problems.. Is ADHD best categorized under externalizing conditions, neurodevelopmental disorders, or something else entirely? A recent study by Zheyue Peng, Kasey Stanton, Beatriz Dominguez-Alvarez, and Ashley L. Watts takes a closer look at this question using a symptom-focused approach.
The Study:
Traditionally, ADHD has been associated with externalizing behaviors, such as impulsivity and hyperactivity, or with neurodevelopmental traits, like cognitive delays. However, this study challenges the idea of placing ADHD into a single category. Instead, it maps ADHD symptoms across three major psychopathology spectra: externalizing, neurodevelopmental, and internalizing.
The findings reveal that ADHD symptoms don’t fit neatly into one box. For example, symptoms like impulsivity, poor school performance, and low perseverance were strongly associated with externalizing behaviors. On the other hand, cognitive disengagement (e.g., daydreaming, blank staring) and immaturity were closely linked to neurodevelopmental challenges. Interestingly, cognitive disengagement also showed ties to internalizing symptoms, such as anxiety or depression.
This research underscores the complexity of ADHD. Rather than treating ADHD as a single, unitary construct, the study advocates for a symptom-based approach to better understand and treat individuals. By acknowledging that ADHD symptoms relate to multiple psychopathology spectra, clinicians and researchers can move toward more nuanced classification systems and targeted interventions.
Conclusion:
Ultimately, this study highlights the need for modern systems to move beyond rigid categories and adopt a more flexible, symptom-focused framework for understanding ADHD’s place in psychopathology.
Exposure to heavy metals like lead, arsenic, mercury, cadmium, and manganese is known to harm developing nervous systems. However, past studies on whether heavy metals specifically increase the risk of ADHD have shown mixed results.
A research team from China (Gu et al., 2024) reviewed medical studies and conducted meta-analyses to better understand this issue.
The team included studies on children and teens, focusing on cohort studies, case-control studies, and cross-sectional studies. They only used articles written in English and required validated biomonitoring (like blood tests) to measure heavy metal exposure. ADHD diagnoses had to come from clinical evaluations.
To be included, studies had to report effect sizes such as odds ratios and relative risks with confidence intervals. The team focused on comparisons between groups with high, low, or no exposure, which made it harder to analyze dose-response relationships.
They also evaluated the quality of each study. All cohort studies were rated high-quality. Of the 15 case-control studies, 6 were high-quality, and 9 were moderate-quality. Among cross-sectional studies, only 2 were high-quality, and the rest were moderate-quality.
There was no evidence linking ADHD to other heavy metals like arsenic, mercury, cadmium, or manganese. Both meta-analyses suggest that lead exposure is associated with the risk for ADHD. However, because these studies cannot rule out other explanations, one cannot conclude that lead exposure causes ADHD. For example, other work shows that people with ADHD are likely to have lower incomes than those without ADHD.
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