Meta-analysis Finds Limited Benefits from Computerized Cognitive Training

Computerized cognitive training (CCT) uses computers to try to strengthen cognitive skills and processes, reduce ADHD symptoms, and improve executive functioning. Executive functions are cognitive processes and mental skills that help individuals plan, monitor, and successfully execute their goals.

CCT programs target one or more cognitive processes such as motor inhibition, interference inhibition, sustained attention, and working memory. They ramp up task difficulty as performance improves. The goal is to harness the brain’s inherent adaptability (neuroplasticity) to boost performance. 

A European study team that previously probed the efficacy of CCT through meta-analysis had been unable to provide a robust estimate of effect size due to an insufficient number of high-quality trials with probably blinded outcomes. Noting that “there have been a considerable number of new RCTs [randomized controlled trials] published, many with larger samples, well-controlled designs and blinded outcomes,” the team performed an updated systematic review and meta-analysis.

They included RCTs with participants of any age who either had a clinical diagnosis of ADHD or were above cut-off on validated ADHD rating scales. RCTs had to have been peer-reviewed and published in an academic journal, and to have reported a validated outcome measure of ADHD symptoms, neuropsychological processes, and/or academic outcomes.

Fourteen RCTs with a combined total of 631 participants had probably blinded outcomes. Meta-analysis of these studies yielded no significant effect on either overall ADHD symptoms or hyperactivity/impulsivity symptoms. There was a marginally significant reduction in inattention symptoms, but the effect size was small. Between-study variation (heterogeneity) was negligible and there was no sign of publication bias.

Regarding academic outcomes, meta-analyses revealed no gain in arithmetic ability or reading fluency. There was a small but not statistically significant improvement in reading comprehension. Heterogeneity was minimal, with no indication of publication bias.

With two related exceptions, meta-analyses of RCTs measuring executive functions likewise reported no significant improvements in attention, interference inhibition (initial stage in controlling impulsive behavior), motor inhibition (follow-up stage in controlling impulsive behavior), non-verbal reasoning, processing speed, and set shifting (the ability to unconsciously shift attention between one task and another).

The exceptions were for working memory tasks. Meta-analysis of 15 RCTs with a combined 753 participants reported a highly significant small-to-medium effect size improvement in verbal working memory. A separate meta-analysis of nine RCTs with a total of 441 participants similarly reported a highly significant improvement in visuospatial working memory, this time with medium effect size.

The team concluded, “There was no empirical support for the use of CCT as a stand-alone intervention for ADHD symptoms based on the largest and most comprehensive meta-analysis of RCTs conducted to date. Small effects, of likely limited clinical importance, on inattention symptoms were found – but these were limited to the setting in which the intervention was delivered. Robust evidence of small- to-moderate improvements in visual-spatial and verbal STM/WM tasks did not transfer to other domains of executive functions or academic outcomes.”

Samuel J. Westwood, Valeria Parlatini, Katya Rubia, Samuele Cortese, Edmund J. S. Sonuga-Barke, and European ADHD Guidelines Group (EAGG), “Computerized cognitive training in attention-deficit/hyperactivity disorder (ADHD): a meta-analysis of randomized controlled trials with blinded and objective outcomes,” Molecular Psychiatry (2023), https://doi.org/10.1038/s41380-023-02000-7.

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Network Meta-analysis Explores Long-term Efficacy of Nonpharmacological Treatments for Improving Inhibitory Control in Children and Adolescents with ADHD

Background Info:

Executive functions include inhibitory control, working memory, and cognitive flexibility. Inhibitory control is the ability to suppress distractions and focus on goals, which is the main deficit in ADHD. 

Children and adolescents with ADHD often have off-task, unrelated thoughts and are easily distracted, limiting their sustained attention. This makes it difficult for them to focus on tasks and leads to impulsive behaviors that affect their daily life, academics, and social interactions. Improving inhibitory control in ADHD children and adolescents is essential. 

Stimulant medications are commonly used to treat ADHD. However, side effects like insomnia, loss of appetite, and headaches may make parents hesitant to use these medications for their children. 

Non-pharmacological treatments like cognitive training, behavior therapy, and physical exercise have gained attention for their lack of side effects. Research shows that some non-pharmacological methods can improve cognitive outcomes significantly, underscoring their potential in treating ADHD. 

Study:

A Chinese research team identified four key gaps in current research on non-pharmacological treatments for inhibitory control in children with ADHD: 

  • Existing meta-analyses seldom differentiate between short-term and long-term interventions.  
  • Most studies focus primarily on short-term effects and neglect evaluation of maintenance effects through follow-up assessments.  
  • New treatment methods, such as meditation and board games, have not been systematically assessed in meta-analyses for their impact on inhibitory control in children and adolescents with ADHD, leaving their effectiveness uncertain.  
  • Traditional meta-analysis does not tell us which intervention is most effective. Without this comparative analysis, it is difficult to rank efficacy. 

The team therefore performed a network meta-analysis of long-term randomized controlled trials (RCTs) to assess and rank the effectiveness of various non-pharmacological treatments on inhibitory control in children and adolescents with ADHD. 

The team included only RCTs relying on professional diagnoses of ADHD, excluding those based only on parent and teacher rating scales.  

The included studies measured inhibitory control using objective neurocognitive tasks, such as the Stroop test and the Go/No-Go test, to reduce potential subjective bias. Studies relying on parent- or teacher-reported questionnaires were excluded. 

Controls either received no intervention or placebo, such as watching running videos and attending history classes. 

Meta-analysis of 16 studies combining 546 participants found large short-term effect size improvements in inhibitory control from physical exercise. But the two studies with a total of 110 participants that performed a follow-up test reported only a small-to-medium effect size improvement. 

For cognitive training, a meta-analysis of fifteen studies totaling 674 participants reported a medium effect size of short-term improvement in inhibitory control. The ten studies with 563 participants that performed a follow-up test found only a small effect size improvement since treatment initiation. 

For behavioral therapy, meta-analysis of six studies encompassing 244 individuals likewise found a medium effect size short-term improvement in inhibitory control. In this case, however two studies combining 91 participants that performed a follow-up test reported that the medium effect size improvement was maintained. 

For neurofeedback, meta-analysis of seven studies encompassing 186 individuals found a small-to-medium effect size short-term improvement in inhibitory control. The only study that performed a follow-up test reported a small effect size improvement since treatment initiation. 

The two studies with a combined 44 individuals exploring board games found no significant improvement in inhibitory control. Likewise, the two studies combining 32 participants that explored meditation found no significant improvement in inhibitory control. 

There was no indication of publication bias. 

Conclusion:

The team concluded, “Existing evidence shows that physical exercise, behavior therapy, cognitive training, and neurofeedback can effectively improve the inhibitory control of children and adolescents with ADHD. However, meditation, EMG feedback, and board games did not significantly affect inhibitory control. Physical exercise has the best effect among all non-pharmacological treatments, but its impact will be weakened after intervention. Behavior therapy and cognitive training had a slightly lower effect, but they have a better maintenance effect.” 

Ultimately, the study results suggest that non-drug treatments can help children and teens with ADHD improve their ability to control their actions and stay focused. Some methods, like physical exercise, work well at first but may fade once the activity stops. Other methods, like behavioral therapy and cognitive training, may take a little longer to show results but can last longer and make a bigger difference over time. Ultimately, and most importantly, because this work did not study the symptoms of ADHD or its real-world impairments, it provides no reason to change current treatment practices for ADHD.

July 16, 2025

The Role of Serotonin in ADHD and Its Many Comorbidities

Serotonin is a key chemical in the body that helps regulate mood, behavior, and also many physical functions such as sleep and digestion. It has also been linked to how ADHD (attention-deficit/hyperactivity disorder) develops in the brain. This study looks at how serotonin may be involved in both the mental health and physical health conditions that often occur alongside ADHD.

It is well-established that ADHD is more than just trouble focusing or staying still. For many, it brings along a host of other physical and mental health challenges. It is very common for those with ADHD to also have other diagnosed disorders. For example, those with ADHD are often also diagnosed with depression, anxiety, or sleep disorders. When these issues overlap, they are called comorbidities. 

A new comprehensive review, led by Dr. Stephen V. Faraone and colleagues, delves into how serotonin (5-HT), a major brain chemical, may be at the heart of many of these common comorbidities.

Wait! I thought ADHD had to do with Dopamine–Why are we looking at Serotonin?

Serotonin is a neurotransmitter most often linked to mood, but its role in regulating the body has much broader implications. It regulates sleep, digestion, metabolism, hormonal balance, and even immune responses. Although ADHD has long been associated with dopamine and norepinephrine dysregulation, this review suggests that serotonin also plays a central role, especially when it comes to comorbid conditions.

The Study:

  • Objective: To systematically review which conditions commonly co-occur with ADHD and determine whether serotonin dysfunction might be a common thread linking them.

  • Method: The authors combed through existing literature up to March 2024, analyzing evidence for serotonin involvement in each comorbidity associated with ADHD.

  • Scope: 182 psychiatric and somatic conditions were found to frequently occur in people with ADHD.

Key Findings

  • 74% of Comorbidities Linked to Serotonin: Of the 182 comorbidities identified, 135 showed evidence of serotonergic involvement—91 psychiatric and 44 somatic (physical) conditions.

  • Psychiatric Comorbidities: These include anxiety disorders, depression, bipolar disorder, and obsessive-compulsive disorder—all of which have long-standing associations with serotoninergic dysfunction.

  • Somatic Comorbidities: Conditions like irritable bowel syndrome (IBS), migraines, and certain sleep disorders also showed a significant serotonergic link.

This research suggests that serotonin dysregulation could explain the diverse and sometimes puzzling range of symptoms seen in ADHD patients. It supports a more integrative model of ADHD—one that goes beyond the brain’s attention, reward and executive control circuits and considers broader physiological and psychological health.

future research into the role of serotonin could help develop more tailored interventions, especially for patients who don't respond well to stimulant medications. Future studies may focus on serotonin’s role in early ADHD development and how it interacts with environmental and genetic factors.

The Take-Away: 

This study is a strong reminder that ADHD is a complex, multifaceted condition. Differential diagnosis is crucial to properly diagnosing and treating ADHD. Clinicians' understanding of the underlying link between ADHD and its common comorbidities may help future ADHD patients receive the individualized care they need. By shedding light on serotonin’s wide-reaching influence, this study may provide a valuable roadmap for improving how we diagnose and treat those with complex comorbidities in the future. 

July 14, 2025

Undiagnosed ADHD May Be Undermining Diabetes Control in Adults with Type 1 Diabetes

Our recent study, published in the Journal of Clinical Medicine, aims to shed light on an under-recognized challenge faced by many adults with Type 1 diabetes (T1D): attention-deficit/hyperactivity disorder (ADHD) symptoms.

We surveyed over 2,000 adults with T1D using the Adult Self-Report Scale (ASRS) for ADHD and analyzed their medical records. Of those who responded, nearly one-third met the criteria for ADHD symptoms—far higher than the general population average. Notably, only about 15% had a formal diagnosis or were receiving treatment.

The findings are striking: individuals with higher ADHD symptom scores had significantly worse blood sugar control, as indicated by higher HbA1c levels. Those flagged as "ASRS positive" were more than twice as likely to have poor glycemic control (HbA1c ≥ 8.0%). They also reported higher levels of depressive symptoms.

As expected, ADHD symptoms decreased with age but remained more common than in the general public. No strong links were found between ADHD symptoms and other cardiometabolic issues.

This study highlights a previously overlooked yet highly significant factor in diabetes management. ADHD-related difficulties—such as forgetfulness, inattention, or impulsivity—can make managing a complex condition like T1D more difficult. The researchers call for more screening and awareness of ADHD in adults with diabetes, which could lead to better mental health and improved blood sugar outcomes.

Takeaway: If you or a loved one with T1D struggles with focus, organization, or consistent self-care, it may be worth exploring whether ADHD could be part of the picture. Early identification and support are crucial to managing this common comorbidity. 

July 10, 2025