February 11, 2022

Might methylphenidate have a protective effect on brain development?

Methylphenidate, a psychostimulant, is among the drugs most frequently prescribed to children with ADHD.

Using magnetic resonance imaging(MRI), studies have shown that as children mature, those with ADHD differ from controls in developing regionally thinner cortices (the folded outer layer of the cerebrum that is essential to rational thought) and smaller lower basal ganglia(structures linked to the thalamus in the base of the brain and involved in the coordination of movement). The cortical differences were found in the right medial frontal motor region, the left middle/inferior frontal gyrus, and the right posterior parieto-occipital region in children with ADHD who were not taking psychostimulants.

A Dutch/Norwegian team of researchers conducted a randomized, double-blind, placebo-controlled trial with 96 males recruited from Dutch clinical programs. 48 were boys aged 10-12 years, and 47 were men between the ages of 23 and 40. None had previously been on methylphenidate. There were no significant differences in baseline age, ADHD symptom severity, estimated intelligence quotient, the proportion of right-handedness, or region of interest brain characteristics between the placebo and medication groups.

The trial was carried out during the standard 17-week waiting list time for evaluation and treatment to begin so that those receiving a placebo during the trial would not ultimately be at a disadvantage. The same MRI scanner was used for all measurements, both before and after treatment.

Among the boys, the methylphenidate group showed increased thickness in the right medial cortex, while the placebo group showed cortical thinning. In adults, both groups showed cortical thinning. When converted into an estimated mean rate of change in cortical thickness for the right medial cortex, boys taking methylphenidate could expect to lose about 0.01 mm per year, versus about 0.14 mm for boys not on methylphenidate.

In the right posterior cortex, scans also showed reduced thinning in the methylphenidate treatment group, though to a lesser extent. But there was no reduced thinning in the left frontal cortex.

The authors noted several limitations. The sample size was small. Second, "because we did not detect significant relationships between changes in cortical [regions of interest] and changes in symptom severity, the functional significance remains uncertain." Third, the follow-up period was relatively short, not allowing any assessment of the longer-term effects of the medication. Fourth, the differences in effects on the three brain regions examined were uneven, contrary to what had been expected from previous studies. They recommended replication with larger groups and longer follow-ups.

K.B. Walhovd, I.Amlien, A. Schrantee,D.A. Rohani, I. Groote, A. Bjørnerud, A.M. Fjell, and L.Reneman, "Methylphenidate Effects on Cortical Thickness in Children and Adults with Attention-Deficit/Hyperactivity Disorder: A Randomized Clinical Trial," American journal of Neuroradiology(2020)41 (5) 758-765,http://dx.doi.org/10.3174/ajnr.A6560.

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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

Norwegian Population Study Finds ADHD Associated with Much Higher Odds of Contact with Child Welfare Services

Background:

This nationwide population study by a Norwegian team aimed to evaluate the relationship between ADHD and various types of child welfare services contacts over a long-term period of up to 18 years among children and adolescents aged 5 to 18 years diagnosed with ADHD, in comparison to the general population within the same age group. 

Norway has a single-payer national health insurance system that fully covers virtually the entirety of its population. In combination with a system of national population and health registers, this facilitates nationwide population studies, overcoming the limitations of relying on population sampling. 

Study:

The study population included all 8,051 children and adolescents aged 5 to 18 who were diagnosed with ADHD for the first time in the Norwegian Patient Registry between 2009 and 2011. 

The study also included a comparison sample of 75,184 children and adolescents aged 5–18 with no child welfare services contact during 2009–2011. 

The interventions delivered by child welfare services in Norway are largely divided into two primary categories: supportive intervention and out-of-home placement. 

Supportive interventions include improving parenting skills, promoting child development, providing supervision and control, facilitating cooperation with other services, assessments and treatments by other institutions, and offering housing support. 

Norway uses foster homes or child welfare institutions as a last resort. When supportive interventions fail to meet the child’s needs, the child welfare services can temporarily place the child in these facilities. If parents disagree, the county social welfare board decides based on a municipal request. 

The team adjusted for potential confounders: sex, age, parental socioeconomic status (father’s and mother’s education and income level), and marital status. 

Results:

With these adjustments, children and adolescents diagnosed with ADHD were over six times more likely to have any contact with child welfare services than their general population peers. This was equally true for males and females.  

Children and adolescents diagnosed with ADHD were also over six times more likely to receive supportive interventions from child welfare services. Again, there were no differences between males and females. 

Finally, children and adolescents diagnosed with ADHD were roughly seven times more likely to have an out-of-home placement than their general population peers. For males this rose to eight times more likely. 

Conclusion:

The team concluded, “This population-based study provides robust evidence of a higher rate and strong association between ADHD and contact with CWS [Child Welfare Service] compared to the general population in Norway.” 

July 8, 2025