February 4, 2021

New insights into the brains of people living with ADHD and those with ADHD symptoms.

The ENIGMA-ADHD Working Group published their second large study on the brains of people with ADHD in the American Journal of Psychiatry this month. In this second study, the focus was on the cerebral cortex, which is the outer layer of the brain.

ADHD symptoms include inattention and/or hyperactivity and acting impulsively. The disorder affects more than one in 20 (5.3%) children, and two-thirds of those diagnosed continue to experience symptoms as adults.

In this study, researchers found subtle differences in the brain’s outer layer - the cortex - when they combined brain imaging data on almost 4,000 participants from 37 research groups worldwide. The differences were only significant for children and did not hold for adolescents or adults. The childhood effects were most prominent and widespread for the surface area of the cortex. More focal changes were found in the thickness of the cortex. All differences were subtle and detected only at a group level, and thus these brain images cannot be used to diagnose ADHD or guide its treatment.

These subtle differences in the brain’s cortex were not limited to people with the clinical diagnosis of ADHD: they were also present - in a less marked form - in youth with some ADHD symptoms. This second finding results from a collaboration between the ENIGMA-ADHD Working Group and the Generation-R study from Rotterdam, which has brain images on 2700 children aged 9-11 years from the general population. The researchers found more symptoms of inattention to be associated with a decrease in cortical surface area. Furthermore, siblings of those with ADHD showed changes to their cortical surface area that resembled their affected sibling. This suggests that familial factors such as genetics or shared environment may play a role in brain cortical characteristics.

This is the largest study to date to look at the cortex of people with ADHD. It included 2246 people with a diagnosis of ADHD and 1713 people without, aged between four and 63 years old. This is the second study published by the ENIGMA-ADHD Working Group; the first examined structures that are deep in the brain. The ADHD Working Group is one of over 50 working groups of the ENIGMA Consortium, in which international researchers pull together to understand the brain alterations associated with different disorders and the role of genetic and environmental factors in those alterations.

The authors say the findings could help improve understanding of the disorder. ‘We identify cortical differences that are consistently associated with ADHD by combining data from many different research groups internationally. We find that the differences extend beyond narrowly-defined clinical diagnoses and are seen, in a less marked manner, in those with some ADHD symptoms and in unaffected siblings of people with ADHD. This finding supports the idea that the symptoms underlying ADHD may be a continuous trait in the population, which has already been reported by other behavioral and genetic studies.’. In the future, the ADHD Working Group hopes to look at additional key features in the brain- such as the structural connections between brain areas – and to increase the representation of adults affected by ADHD, in whom limited research has been performed to date. 

See: https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2019.18091033

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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

Swedish nationwide population study identifies top predictors of ADHD diagnoses among preschoolers

Most preschool-aged children diagnosed with ADHD also exhibit comorbid mental or developmental conditions. Long-term studies following these children into adulthood have demonstrated that higher severity of ADHD symptoms in early childhood is associated with a more persistent course of ADHD. 

The Study: 

Sweden has a single-payer national health insurance system that covers virtually all residents, facilitating nationwide population studies. An international study team (US, Brazil, Sweden) searched national registers for predictors of ADHD diagnoses among all 631,695 surviving and non-emigrating preschoolers born from 2001 through 2007.  

Preschool ADHD was defined by diagnosis or prescription of ADHD medications issued to toddlers aged three through five years old.  

Predictors were conditions diagnosed prior to the ADHD diagnosis. 

A total of 1,686 (2.7%) preschoolers were diagnosed with ADHD, with the mean age at diagnosis being 4.6 years. 

The Numbers:

Adjusting for sex and birth year, the team reported the following predictors, in order of magnitude: 

  • Previous diagnosis of autism spectrum disorder increased subsequent likelihood of ADHD diagnosis twentyfold. 
  • Previous diagnosis of intellectual disability increased subsequent likelihood of ADHD diagnosis fifteenfold. 
  • Previous diagnosis of speech/language developmental disorders and learning disorders, as well as motor and tic disorders, increased subsequent likelihood of ADHD diagnosis thirteen-fold. 
  • Previous diagnosis of sleep disorders increased subsequent likelihood of ADHD diagnosis fivefold. 
  • Previous diagnosis of feeding and eating disorders increased subsequent likelihood of ADHD diagnosis almost fourfold. 
  • Previous diagnosis of gastroesophageal reflux disease (GERD) increased subsequent likelihood of ADHD diagnosis 3.5-fold. 
  • Previous diagnosis of asthma increased subsequent likelihood of ADHD diagnosis 2.4-fold. 
  • Previous diagnosis of allergic rhinitis increased subsequent likelihood of ADHD diagnosis by 70%. 
  • Previous diagnosis of atopic dermatitis or unintentional injuries increased subsequent likelihood of ADHD diagnosis by 50%. 

The Conclusion: 

This large population study underscores that many conditions present in early childhood can help predict an ADHD diagnosis in preschoolers. Recognizing these risk factors early may aid in identifying and addressing ADHD sooner, hopefully improving outcomes for children as they grow

July 2, 2025