April 7, 2021

Adult Onset ADHD: Does it Exist? Is it Distinct from Youth Onset ADHD?

There is a growing interest (and controversy) in 'adult-onset ADHD. No current diagnostic system allows for the diagnosis of ADHD in adulthood, yet clinicians sometimes face adults who meet all criteria for ADHD, except for age at onset. Although many of these clinically referred adult-onset cases may reflect poor recall, several recent longitudinal population studies have claimed to detect cases of adult-onset ADHD that showed no signs of ADHD as a youth (Agnew-Blais, Polanczyk et al. 2016, Caye, Rocha, et al. 2016). They conclude, not only that ADHD can onset in adulthood, but that childhood-onset and adult-onset ADHD may be distinct syndromes(Moffitt, Houts, et al. 2015)

In each study, the prevalence of adult-onset ADHD was much larger than the prevalence of childhood-onset adult ADHD). These estimates should be viewed with caution.  The adults in two of the studies were 18-19 years old.  That is too small a slice of adulthood to draw firm conclusions. As discussed elsewhere (Faraone and Biederman 2016), the claims for adult-onset ADHD are all based on population as opposed to clinical studies.
Population studies are plagued by the "false positive paradox", which states that, even when false positive rates are low, many or even most diagnoses in a population study can be false.  

Another problem is that the false positive rate is sensitive to the method of diagnosis. The child diagnoses in the studies claiming the existence of adult-onset ADHDused reports from parents and/or teachers but the adult diagnoses were based on self-report. Self-reports of ADHD in adults are less reliable than informant reports, which raises concerns about measurement error.   Another longitudinal study found that current symptoms of ADHD were under-reported by adults who had had ADHD in childhood and over-reported by adults who did not have ADHD in childhood(Sibley, Pelham, et al. 2012).   These issues strongly suggest that the studies claiming the existence of adult-onset ADHD underestimated the prevalence of persistent ADHD and overestimated the prevalence of adult-onset ADHD.  Thus, we cannot yet accept the conclusion that most adults referred to clinicians with ADHD symptoms will not have a history of ADHD in youth.

The new papers conclude that child and adult ADHD are "distinct syndromes", "that adult ADHD is more complex than a straightforward continuation of the childhood disorder" and that adult ADHD is "not a neurodevelopmental disorder". These conclusions are provocative, suggesting a paradigm shift in how we view adulthood and childhood ADHD.   Yet they seem premature.  In these studies, people were categorized as adult-onset ADHD if full-threshold add had not been diagnosed in childhood.  Yet, in all of these population studies, there was substantial evidence that the adult-onset cases were not neurotypical in adulthood (Faraone and Biederman 2016).  Notably, in a study of referred cases, one-third of late adolescent and adult-onset cases had childhood histories of ODD, CD, and school failure(Chandra, Biederman, et al. 2016).   Thus, many of the "adult onsets" of ADHD appear to have had neurodevelopmental roots. 

Looking through a more parsimonious lens, Faraone and Biederman(2016)proposed that the putative cases of adult-onset ADHD reflect the existence of subthreshold childhood ADHD that emerges with full threshold diagnostic criteria in adulthood.   Other work shows that subthreshold ADHD in childhood predicts onsets of full-threshold ADHD in adolescence(Lecendreux, Konofal, et al. 2015).   Why is onset delayed in subthreshold cases? One possibility is that intellectual and social supports help subthreshold ADHD youth compensate in early life, with decompensation occurring when supports are removed in adulthood or the challenges of life increase.  A related possibility is that the subthreshold cases are at the lower end of a dimensional liability spectrum that indexes risk for onset of ADHD symptoms and impairments.  This is consistent with the idea that ADHD is an extreme form of a dimensional trait, which is supported by twin and molecular genetic studies(Larsson, Anckarsater, et al. 2012, Lee, Ripke, et al. 2013).  These data suggest that disorders emerge when risk factors accumulate over time to exceed a threshold.  Those with lower levels of risk at birth will take longer to accumulate sufficient risk factors and longer to onset.

In conclusion, it is premature to accept the idea that there exists an adult-onset form of ADHD that does not have its roots in neurodevelopment and is not expressed in childhood.   It is, however, the right time to carefully study apparent cases of adult-onset ADHD to test the idea that they are late manifestations of a subthreshold childhood condition.

Agnew-Blais, J. C., G.V. Polanczyk, A. Danese, J. Wertz, T. E. Moffitt and L. Arseneault (2016)."Persistence, Remission and Emergence of ADHD in Young Adulthood:Resultsfrom a Longitudinal, Prospective Population-Based Cohort." JAMA.Caye, A., T. B.-M. Rocha, L. Luciana Anselmi, J. Murray, A. M.B. Menezes, F. C. Barros, H. Gonçalves, F. Wehrmeister, C. M. Jensen, H.-C.Steinhausen, J. M. Swanson, C. Kieling and L. A. Rohde (2016). "ADHD doesnot always begin in childhood: E 1 vidence from a large birth cohort." JAMA.
Chandra, S., J. Biederman and S. V. Faraone (2016)."Assessing the Validity of  the Ageat Onset Criterion for Diagnosing ADHD in DSM-5." J Atten Disord.
Faraone, S. V. and J. Biederman (2016). "CanAttention-Deficit/Hyperactivity Disorder Onset Occur in Adulthood?" JAMAPsychiatry.
Larsson, H., H. Anckarsater, M. Rastam, Z. Chang and P.Lichtenstein (2012). "Childhood attention-deficit hyperactivity disorderas an extreme of a continuous trait: a quantitative genetic study of 8,500 twinpairs." J Child Psychol Psychiatry53(1): 73-80.
Lecendreux, M., E. Konofal, S. Cortese and S. V. Faraone(2015). "A 4-year follow-up of attention-deficit/hyperactivity disorder ina population sample." J Clin Psychiatry76(6): 712-719.
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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