National Birth Cohort Finds Young Adults with ADHD Over-represented in Criminal Justice System

Using Statistics New Zealand’s Integrated Data Infrastructure (IDI), a large database of linked de-identified administrative and survey data about people and households, a local study team examined a three-year birth cohort (mid-1992 through mid-1995) totaling 149,076 persons.

The team assessed the presence of ADHD within this cohort through diagnosis codes and inference from medication dispensing, where there was at least one code relating to an ADHD diagnosis in the medication datasets. This subgroup consisted of 3,975 persons.

Next, they related this information to criminal justice system interactions of increasing severity, starting with police proceedings, and continuing with court charges, court convictions, and incarcerations. These interactions were tracked during an eight-year period from participants’ 17th birthday through their 25th birthday.

In this same period the team also tracked types of offenses: against people; against property; against organizations, government, and community; and violent offenses.

In all cases, the study team adjusted for gender, ethnicity, deprivation, and area of residence as potential confounders. 

With these adjustments, young adults with ADHD were over twice as likely as their typically developing peers to be proceeded against by police, to be charged with an offense, and to be convicted. They were almost five times as likely to be incarcerated. 

With the same adjustments, young adults with ADHD were over twice as likely as their typically developing peers to be convicted of offenses against organizations, government, and community. They were almost three times as likely to be convicted of crimes against persons, and over three and a half times more likely to be convicted of either violent offenses or offenses against property.

The authors noted, “The greater effect size for incarceration observed in our study may be due to the lack of control for comorbid conditions such as CD [conduct disorder], which are known criminogenic risk factors.” 

They also noted, “The sharp increase in the risk of incarceration observed may also signal differences in the NZ justice system’s approach to ADHD, which may be less responsive to the condition than other nations, particularly the steps in the justice system between conviction and sentence. This would suggest that the UNCRPD [United Nations Convention on the Rights of Persons with Disabilities] obligations of equal recognition before the law and the elimination of discrimination on the basis of disability are not being met for individuals with ADHD in NZ.”

They concluded, “Our findings revealed that not only were individuals with ADHD overrepresented at all stages of the CJS [criminal justice system] and offense types examined, there was also a pattern of increasing risk for CJS interactions as these individuals moved through the system. These results highlight the importance of early identification and responsivity to ADHD within the CJS and suggest that the NZ justice system may require changes to both of these areas to ensure that young individuals with ADHD receive equitable access to, and treatment within, the CJS.”

Francesca Anns, Stephanie D’Souza, Conrad MacCormick, Brigit Mirfin-Veitch, Betony Clasby, Nathan Hughes, Warren Forster, Eden Tuisaula, and Nicholas Bowden, “Risk of Criminal Justice System Interactions in Young Adults with Attention-Deficit/Hyperactivity Disorder: Findings From a National Birth Cohort,” Journal of Attention Disorders (2023), 1-11, https://doi.org/10.1177/10870547231177469.

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Nationwide population study in Denmark finds children and adolescents with ADHD more than twice as likely to suffer criminal violence

Denmark Population Study Finds Children and Adolescents with ADHD More than Likely to Suffer Criminal Violence

Children with disabilities are known to be at heightened risk of violence compared to their non-disabled peers. To what extent does this hold true for ADHD?

Denmark has a single-payer health insurance system through which health data about virtually the entire population can be cross-referenced with population, crime, welfare, and other registers through unique individual person numbers.

A Danish study team accessed national registers to examine the relationship between ADHD and criminal victimhood among nine yearly birth cohorts totaling more than 570,000 children and adolescents. 

Of these, 557,521, among them 12,040 with ADHD, were not reported as being exposed to violence, and 12,830, among which 1,179 with ADHD, were exposed to violence.

From the raw data, children and adolescents with ADHD were more than four times as likely to be exposed to violence than their typically developing peers.

The team then adjusted for other disabilities, family risk factors, gender, birth year, and ethnic background.

With these confounders out of the way, children and adolescents with ADHD remained more than twice as likely to be exposed to violence than their typically developing peers.

To place this outcome in further perspective:

  • Brain injuries increased the odds of being exposed to violence by over 75% relative to typically developing peers.
  • Physical and speech disabilities raised the odds by a bit over 35%.
  • Intellectual and sensory disabilities, dyslexia, and congenital malformations had no effect. 
  • Epilepsy reduced the odds of being exposed to violence by just under 20%, and autistic spectrum disorder by just over 25%.

Certain family risk factors further aggravated the odds:

  • Violence in the family by more than 2.5-fold.
  • Out-of-home care and breakup of parental relationship by more than 75%.

Perhaps surprisingly, substance abuse by family members had no effect whatsoever after adjusting for confounders.

January 24, 2024

Nationwide population study suggests ADHD medication may reduce child abuse

Nationwide Population Study Suggests ADHD Medication May Reduce Child Abuse

Child abuse includes any of the following inflicted on a minor under 18 years old: physical or emotional harm, sexual abuse, or neglect.

It is known to be associated with environmental factors such as poverty, parents or neighbors with a history of violence, and gender inequality.

Chronic mental disorders in minors are also associated with child abuse. To what extent, if any, might that be true of ADHD?

Taiwan has a single-payer national health insurance system that covers more than 99.6% of all residents, enabling nationwide population studies.

A local research team used data from almost two million Taiwanese in their country’s National Health Insurance Research Database (NHIRD) spanning 15 years (2000-2015) to carry out a matched-cohort study. 

All diagnoses of ADHD were made by board-certified specialists such as psychiatrists, pediatricians, neurologists, or physiatrists with a specialty in child and adolescent development.

3,540 children and adolescents between 6 and 18 years old with a diagnosis of ADHD were matched on a one-to-three basis with 10,620 peers from the NHIRD without an ADHD diagnosis.

The team adjusted for age, gender, location of residence (Northern, Central, Southern, and Eastern Taiwan), urbanization level of residence, level of hospitals as medical centers, and monthly insured premium. They further adjusted for comorbid conditions: intellectual disability, autistic disorder/pervasive developmental disorder, conduct disorder (CD)/oppositional defiant disorder (ODD), other developmental disorders, childhood emotional disorder, Tourette syndrome/tics disorders, and involuntary urination and defecation.

Overall, children and adolescents with an ADHD diagnosis were 1.8 times as likely to be abused as those without an ADHD diagnosis.

Unmedicated children and adolescents with an ADHD diagnosis were three times more likely to be abused. ADHD medication cut that risk in half.

That held true whether the medication used was methylphenidate or atomoxetine. Methylphenidate appeared to be slightly more effective than atomoxetine, and the combination of methylphenidate and atomoxetine slightly more effective yet, but these differences were not statistically significant.

The team concluded, “The results support that pharmacotherapy may attenuate the risk of child abuse in ADHD patients.”

March 5, 2024

Assessing Co-occuring Disorders in Relatives of Those With ADHD

Taiwan Population Study Assesses Comorbidity of Psychiatric Disorders among First-degree Relatives of Those with ADHD

Taiwan's National Health Insurance program is a single-payer system that covers 99.6% of the island's 23 million residents. It includes family relationships.

This enabled a Taiwanese study team to examine the comorbidity of psychiatric disorders among close relatives in the entire population over eleven years, beginning at the start of 2001 and concluding at the end of2011.

For greater certainty of diagnosis, only persons twice diagnosed with the same psychiatric disorder were included as index individuals. There were 431,887 index patients, 152,443 of whom were ADHD index patients.

These index patients were then compared with all of their first-degree relatives (FDRs): parents, children, siblings, and twins. This produced 1,017,430 patient-FDR pairs, of which 401,301 were ADHD patient-FDR pairs.

Next, four controls were matched by age, gender, and type relative to each case, resulting in 4,069,720 control pairs.

After adjusting for age, gender, urbanization, and income level, ADHD patients were seven times more likely than controls to have first-degree relatives with ADHD. They were also seven times more likely to have FDRs with major depressive disorder, four times more likely to have FDRs with autism spectrum disorder, twice as likely to have FDRs with bipolar disorder, and 80%more likely to have FDRs with schizophrenia.

February 3, 2023

U.S. Nationwide Study Finds Down Syndrome Associated with 70% Greater Odds of ADHD

The Background:

Down syndrome (DS) is a genetic disorder resulting from an extra copy of chromosome 21. It is associated with intellectual disability. 

Three to five thousand children are born with Down syndrome each year. They have higher risks for conditions like hypothyroidism, sleep apnea, epilepsy, sensory issues, infections, and autoimmune diseases. Research on ADHD in patients with Down syndrome has been inconclusive. 

The Study:

The National Health Interview Survey (NHIS) is a household survey conducted by the National Center for Health Statistics at the CDC. 

Due to the low prevalence of Down syndrome, a Chinese research team used NHIS records from 1997 to 2018 to analyze data from 214,300 children aged 3 to 17, to obtain a sufficiently large and nationally representative sample to investigate any potential association with ADHD. 

DS and ADHD were identified by asking, “Has a doctor or health professional ever diagnosed your child with Down syndrome, Attention Deficit Hyperactivity Disorder (ADHD), or Attention Deficit Disorder (ADD)?” 

After adjusting for age, sex, and race/ethnicity, plus family highest education level, family income-to-poverty ratio, and geographic region, children and adolescents with Down syndrome had 70% greater odds of also having ADHD than children and adolescents without Down syndrome. There were no significant differences between males and females. 

The Take-Away:

The team concluded, “in a nationwide population-based study of U.S. children, we found that a Down syndrome diagnosis was associated with a higher prevalence of ASD and ADHD. Our findings highlight the necessity of conducting early and routine screenings for ASD and ADHD in children with Down syndrome within clinical settings to improve the effectiveness of interventions.” 

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June 27, 2025

Meta-analysis Explores Link Between ADHD and Homelessness Among Children and Adolescents

An estimated 150 million children and adolescents live on the streets worldwide. In the U.S., roughly 1.5 million experience homelessness annually. Homelessness increases the risk of health issues, violence, early pregnancy, substance use, vaccine-preventable diseases, mental disorders, suicidal behavior, and early death. 

Rates of anxiety, major depression, conduct disorders, and post-traumatic stress disorder are higher among school-age homeless children compared to their housed peers.  

However, there has been limited attention to ADHD, leading a French research team to conduct a systematic review and meta-analysis of its prevalence among homeless children and adolescents.  

The inclusion criteria required that participants be homeless, under 19 years of age at baseline, and have ADHD identified through a screening tool, self-report, or clinical assessment. 

Results:

Meta-analysis of 13 studies with a combined total of 2,878 individuals found indications of ADHD in almost one in four homeless children and adolescents. There was no sign of publication bias, but considerable variation in estimates across studies. 

The team found a dose-response effect. Meta-analysis of six studies with 1,334 participants under 12 years old reported 13% with indications of ADHD. Meta-analysis of five studies encompassing 991 individuals, 12 through 18 years old, found an ADHD rate of 43%. The ADHD rate among adolescents was 3.3 times greater than among children. 

There were no significant differences among countries. 

Moreover, limiting the meta-analysis to the seven studies with 1,538 participants that relied on clinical ADHD diagnoses, the gold standard,  resulted in an ADHD prevalence of 23%. 

The team concluded, “The review of 13 studies revealed that ADHD is common in homeless children and adolescents, suggesting that homelessness may contribute to the development or exacerbation of ADHD symptoms. Conversely, ADHD with other comorbidities may increase the likelihood of homelessness. Reintegrating these children and adolescents into care systems and ensuring access to public health interventions tailored for homeless families and youth is imperative for breaking the cycle of homelessness and improving long-term trajectories.” 

In other words, this review not only confirmed a strong link between homelessness and ADHD in children and youth, but also suggested a complex, cyclical relationship. Providing tailored health care and support for these vulnerable groups is crucial to interrupt this cycle and help improve their future outcomes.

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June 23, 2025

Nationwide Population Study Reports Increased Risk of Hospitalization for Psychosis or Mania Following Initiation of ADHD Medication

Background:

In Iceland, treatment with ADHD medication can only be initiated by psychiatrists or pediatricians with experience in diagnosing neurodevelopmental disorders. The diagnostic evaluation is most often carried out by a psychologist or psychiatrist, and must be confirmed by a psychiatrist. 

Some previous studies have suggested a small but significant increased risk of psychosis or mania associated with ADHD medication, while others have not. 

Iceland has a single-payer national healthcare insurance system that tracks virtually its entire population. An Icelandic research team accessed two administrative databases with nationwide coverage – the Icelandic Prescription Medicines Register and the Icelandic Hospital Discharge Register – to explore this relationship among all adults from 2010 through 2022. 

They included three categories of ADHD medications prescribed in Iceland: amphetamines, including dexamphetamine and lisdexamphetamine; methylphenidate; and atomoxetine. In Iceland, methylphenidate or atomoxetine must be prescribed and tried first before switching to lisdexamphetamine or dexamphetamine. 

Method:

Diagnoses of mania or psychosis recorded in electronic health records were used to identify individuals who were admitted to a psychiatric ward within one year of starting treatment with a specific class of ADHD medication. First-onset psychosis or mania was defined as the emergence of these conditions in individuals with no prior history, diagnosis, or hospitalization for psychosis or mania. 

A total of 16,125 adults began using an ADHD medication for the first time during the 13-year study period. 

Methylphenidate was the most used ADHD medication among those admitted for psychosis or mania (25 out of 61; 41%), reflecting its status as the most frequently prescribed stimulant during the study period. It was followed by amphetamines (21 out of 61; 34.4%) and atomoxetine (15 out of 61; 24.6%). 

Half of those hospitalized had previously received a diagnosis of substance use disorder. One in nine (11%) of those hospitalized acknowledged misuse of the type of ADHD medication they had been prescribed. 

Within a year of discharge, 42 out of the 61 patients (68.9%) had been prescribed an ADHD medication again. Among those, one in four (11 out of 42; 26%) were readmitted for psychosis or mania within the following year.  

The team noted, “It is concerning that most patients (68.9%) in our study resumed ADHD drug treatment within a year of hospital discharge … However, some studies have reported that the use of psychostimulants or atomoxetine to treat ADHD in individuals with psychotic disorders did not increase the risk of hospitalisation for psychosis if used concurrently with antipsychotic medication or that such use might even reduce this risk.”  

Findings: 

By comparison with the general population, adults initiating ADHD medications had eight times the relative risk of being admitted for psychosis or mania within the first year.  

The absolute risk was low: 0.38% overall for those initiating ADHD medication.  Adjusting for the general population risk of hospitalization for first-onset psychosis or mania, more than 300 patients would need to be initiated to ADHD medication to generate one hospital admission for psychosis or mania. 

The team conceded, “Confounders of real-life clinical settings, such as non-disclosed ADHD drug abuse or misuse or some degree of substance abuse, may have influenced our findings.” 

A further, unmentioned, limitation is that the team did not perform any of the usual adjustments for confounding variables, critically including co-occurring (comorbid) psychiatric disorders known to be common with ADHD, and likely to have a major effect on the relative risk of hospitalization. 

Given the very small increase in risk along with the methodological flaws, the team’s suggestion of a “potential causal role of ADHD drugs in the development of first-onset psychosis or mania” is unsubstantiated and speculative.  This is especially so given other studies suggesting no increased risk for psychosis due to these medications.  

In any event, causation cannot be established through observational studies.

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June 19, 2025

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