October 29, 2024

Updated Analysis of ADHD Prevalence in the United States: 2018-2021

Attention-Deficit/Hyperactivity Disorder (ADHD) remains a prevalent condition among children and adolescents in the United States. A recent analysis based on the National Health Interview Survey (NHIS), conducted by the National Center for Health Statistics at the CDC, provides an updated look at ADHD prevalence from 2018 to 2021. Here’s a closer look at what the data reveals.

How the Survey Works

The NHIS is an annual survey primarily conducted through face-to-face interviews in respondents’ homes. Telephone interviews are used as a substitute in cases where travel is impractical. For each family interviewed, one child aged 3-17 is randomly selected for the survey through a computer program. Over the four years studied (2018-2021), a total of 26,422 households with children or adolescents participated.

Overall ADHD Prevalence and Age-Related Trends

The analysis found that 9.5% of children and adolescents in the United States had been diagnosed with ADHD, based on reports from family members. However, the prevalence varied significantly with age:

  • Ages 3-5: 1.5%
  • Ages 6-11: 9.6%
  • Ages 12-17: 13.4%

The increase in ADHD diagnosis with age underscores the importance of monitoring children’s developmental needs as they progress through school and adolescence.

Gender Differences: Higher Rates Among Males

The survey revealed a notable difference in ADHD prevalence between genders, with 12.4% of males diagnosed compared to 6.6% of females—nearly a two-to-one gap. This aligns with previous research indicating that ADHD is more frequently diagnosed in boys than girls, though awareness of how ADHD presents differently across genders is growing.

Family Income and ADHD Rates

Family income played a significant role in ADHD prevalence, particularly among lower-income groups:

  • Below the poverty line: 12.7%
  • Above the poverty line but less than twice that level: 10.3%
  • Above twice the poverty level: 8.5%

This pattern suggests that socioeconomic factors might influence the diagnosis and management of ADHD, with lower-income families possibly experiencing greater barriers to early diagnosis or consistent treatment.

Regional Differences Across the U.S.

Geographic location also impacted ADHD rates. Prevalence was highest in the South (11.3%), followed by the Midwest (10%), the Northeast (9.1%), and significantly lower in the West (6.9%). These variations could reflect regional differences in healthcare access, diagnostic practices, or cultural attitudes towards ADHD.

Stability Over Time

Despite these variations in demographics, the overall prevalence of ADHD remained relatively stable across the study period from 2018 to 2021, showing no significant changes by year.

What This Means for Families and Healthcare Providers

The findings from this updated analysis provide a clearer picture of ADHD’s prevalence across different demographic groups in the United States. They highlight the need for tailored approaches to diagnosis and care, taking into account factors like age, gender, income, and geographic location. With ADHD being a common condition affecting nearly 1 in 10 children, ongoing research and support for families are crucial to ensure that those with ADHD receive the care and resources they need.

Conclusion: 

This study reinforces the importance of awareness and early intervention, especially for families in underserved regions or those facing economic challenges. As clinicians and educators continue to support children with ADHD, understanding these demographic trends can help in creating more equitable access to diagnosis and treatment.

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Qian Li, Yanmei Li, Juan Zheng, Xiaofang Yan, Jitian Huang, Yingxia Xu, Xia Zeng, Tianran Shen, Xiaohui Xing, Qingsong Chen, and Wenhan Yang, “Prevalence and trends of developmental disabilities among US children and adolescents aged 3 to 17 years, 2018–2021,” Scientific Reports (2023) 13: 17254, https://doi.org/10.1038/s41598-023-44472-1. 

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Inequities in ADHD diagnosis in the United States

Inequities in ADHD diagnosis in the United States

A transcontinental study team (California, Texas, Florida) used a nationally representative sample – the 2018 National Survey of Children’s Health – to query 26,205 caregivers of youth aged 3 to 17 years old to explore inequities in ADHD diagnosis.  

With increasing accessibility of the internet in the U.S., more than 80% of adults now search for health information online. Recognizing that search engine data could help clarify patterns of inequity, the team also consulted Google Trends.

The team noted at the outset that “[d]ocumenting the true prevalence of ADHD remains challenging in light of problems of overdiagnosis (e.g., following quick screening rather than full evaluation incorporating multi-informant and multi-method data given limited resources) and underdiagnosis (e.g., reflecting inequities in healthcare and education systems).” Underdiagnosis is known to be influenced by lack or inadequacy of health insurance, inadequate public health funding, stigma, sociocultural expectations in some ethnic groups, and structural racism, among other factors.

After controlling for poverty status, highest education in household, child’s sex, and child’s age, the team reported that Black youth were a quarter (22%) less likely to receive ADHD diagnoses than their white peers. Latino/Hispanic youth were a third (32%) less likely and Asian youth three-quarters (73%) less likely to receive ADHD diagnoses than their white peers.

The team also found that state-level online search interest in ADHD was positively associated with ADHD diagnoses, after controlling for race/ethnicity, poverty status, highest education in household, child’s sex, and child’s age. However, the odds ratio was low (1.01), “suggesting the need for additional evaluation.” Furthermore, “There was no interaction between individual-level racial/ethnic background and state-level information-seeking patterns. … the state-level online information-seeking variation did not affect the odds that youth of color would have a current ADHD diagnosis over and above other included characteristics.” 

That could be due in part to the gap in high-speed broadband access between Black and Hispanic in contrast to white populations, but that would not explain the even larger gaps in diagnosis for Asian youth, who tend to come from more prosperous backgrounds.

The team concluded, “Persistent racial/ethnic inequities warrant systematic changes in policy and clinical care that can attend to the needs of underserved communities. The digital divide adds complexity to persistent racial/ethnic and socioeconomic inequities in ADHD diagnosis …”

Variations in Diagnosis

Variations in Diagnosis

A cohort study looked at over five million adults, and over 850,000 children between the ages of five and eleven, who received care at Kaiser Permanente Northern California during the ten-year period from the beginning of 2007 through the end of 2016. At any given time, KPNC serves roughly four million persons. It is representative of the population of the region, except for the highest and lowest income strata.

Among adults rates of ADHD diagnosis rose from 0.43% to 0.96%. Among children the diagnosis rates rose from 2.96% to 3.74%, ending up almost four times as high as for adults.

Non-Hispanic whites had the highest adult rates throughout, increasing from 0.67% in 2007 to 1.42% in 2016. American Indian or Alaska Native (AIAN) had the second highest rates, rising from 0.56% to 1.14%. Blacks and Hispanics had roughly comparable rates of diagnosis, the former rising from 0.22% to 0.69%, the latter from 0.25% to 0.65%. The lowest rates were among Asians (rising from 0.11% to 0.35%) and Native Hawaiian or other Pacific Islanders (increasing from 0.11% to 0.39%).

Odds of diagnosis dropped steeply with age among adults. Relative to 18-24-year-olds, 25-34-year-olds were 1/6th less likely to be diagnosed with ADHD, 35-44-year-olds 1/3rd less likely, 45-54-year-olds less than half as likely, 55-64-year-olds less than a quarter as likely, and those over 65 about a twentieth as likely. This is consistent with other studies reporting and age dependent decline in the diagnosis.

Adults with the highest levels of education were twice as likely to be diagnosed as those with the lowest levels. But variations in median household income had almost no effect. Women were marginally less likely to be diagnosed than men.

ADHD is associated with some other psychiatric disorders. Compared with normally developing adults, and adjusted for confounders, those with ADHD were five times as likely to have an eating disorder, over four times as likely to be diagnosed with bipolar disorder or depression, more than twice as likely to suffer from anxiety, but only slightly more likely to abuse drugs or alcohol.

The authors speculate that rising rates of diagnosis could reflect increasing recognition of ADHD in adults by physicians and other clinicians as well as growing public awareness of ADHD during the decade under study. Turning to the strong differences among ethnicities, they note, Racial/ethnic differences could also reflect differential rates of treatment seeking or access to care. Racial/ethnic background is known to play an important role in opinions on mental health services, health care utilization, and physician preferences. In addition, rates of diagnosis- seeking to obtain stimulant medication for nonmedical use may be more common among white vs nonwhite patients. They conclude, greater consideration must be placed on cultural influences on health care seeking and delivery, along with an increased understanding of the various social, psychological, and biological differences among races/ethnicities as well as culturally sensitive approaches to identify and treat ADHD in the total population.

But the main take home message of this work is that most cases of ADHD in adults are not being diagnosed by clinicians. We know from population studies, worldwide, that about three percent of adults suffer from the disorder. This study found that less than 1 percent are diagnosed by their doctors. Clearly, more education is needed to teach clinicians how to identify, diagnose and treat ADHD in adults.

December 18, 2023

Addressing the challenge of under-diagnosed adult ADHD

Addressing the challenge of under-diagnosed adult ADHD

There is a well-documented gap between the known prevalence of adult ADHD and rates of diagnosis and treatment. In Germany, epidemiological studies of nationally representative community samples have found prevalence rates ranging from 3.1% to 4.7%. Yet, studies of publicly insured individuals aged 18 to 69 years old report rates of diagnosed ADHD between 0.04% and 0.4%. So, even in a country with universal health insurance, more than nine out of ten adults with ADHD go undiagnosed.

Many factors contribute to under-diagnosis: stigma, culturally influenced perceptions, and lack of motivation by those affected. Another crucial factor is the lack of recognition of ADHD symptoms by clinicians.

A research team surveyed 144 psychologists, 32 physicians, and two occupational therapists. Almost three in five participants were psychotherapists, a quarter were neuropsychologists, and one in seven were psychiatrists.

Four out of five clinicians stated they had received only a few hours of ADHD-specific training. One in four stated they had not examined guidelines for diagnosing ADHD. A lack of formal training among the vast majority, and unfamiliarity with current diagnostic guidelines in a significant minority, were surprising findings among clinicians who regularly work with adults with ADHD.

Many clinicians had difficulty identifying core features of adult ADHD as defined by the DSM-5 and International Classification of Diseases, Tenth Revision (ICD-10). Roughly one in five stated that hyperactivity had little relevance to adult ADHD. The only core feature correctly identified by more than half the respondents was having difficulties concentrating. Impairments in social behavior or aggression and memory impairment were not identified as being clearly relevant or irrelevant to adult ADHD.

The authors concluded that these findings appear to indicate some uncertainty or at least a lack of consensus among clinicians about what symptoms are relevant to ADHD in adulthood, and it is likely that this uncertainty contributes to diagnostic inaccuracy.

Most respondents reported using self-report scales of ADHD symptoms and using unstructured interviews. While slightly more than half agreed that collateral reports are important to diagnosis, only about a third reported regularly using them. This is a problem given the limited accuracy of self-reported childhood symptoms for documenting the childhood-onset of the disorder. Semi-structured interviews are also known to improve the accuracy of diagnosis, but are rarely used in clinical practice.

Over half of psychologists and a quarter of physicians reported using cognitive or neuropsychological testing, even though this is at variance with German (and other) guidelines, which specify that such testing is suitable for clarifying strengths and weaknesses, but not for ruling out or confirming a diagnosis of ADHD. The European Consensus Statement also states that cognitive/neuropsychological testing should only be used as a secondary or supplementary assessment tool.

While three out of four clinicians recommended stimulant drug treatment, psychologists tended to be more hesitant to do so. This is likely because German psychologists receive little training in pharmacotherapy, and do not have prescription privileges. Given the demonstrated efficacy of stimulant treatment, this points to a need to better educate psychologists in this regard.

Almost three in four respondents cited a lack of clinician knowledge and experience as a barrier to ADHD diagnosis. Most clinicians also stated they were either uncertain or only somewhat certain of their ability to diagnose ADHD. That suggests that more extensive ADHD-specific training is needed.

A limitation of the survey was the relatively low participation by physicians. It is also likely that the findings are not reflective of practices in ADHD specialty clinics.

The authors concluded, Further training is needed to improve clinicians' understanding of ADHD in adulthood and to align diagnostic practices with guideline recommendations. Whereas discrepancies between respondents regarding the relative importance of peripheral symptoms (e.g., memory problems) were most common, a lack of consensus was found even for core symptoms listed by diagnostic criteria. Particularly among psychologists improved awareness regarding the benefits of stimulant medications is needed to bring their treatment recommendations in line with evidence-based guidelines.

September 22, 2023

What Metabolites Tell Us About ADHD — And What This Means for Diet and Treatment

New research has uncovered important links between certain blood metabolites and ADHD by using a genetic method called Mendelian randomization. This approach leverages natural genetic differences to help identify which metabolites might actually cause changes in ADHD risk, offering stronger clues than traditional observational studies.

Key Metabolic Pathways Involved:

The study found 42 plasma metabolites with a causal relationship to ADHD. Most fall into two major groups:

  • Amino acid metabolites from protein metabolism, including those related to tyrosine, methionine, cysteine, and taurine.

  • Fatty acids, especially long-chain polyunsaturated fatty acids (PUFAs) like DHA and EPA, important for brain function.

What Does This Mean for Diet and ADHD?

Since many metabolites come from dietary sources like proteins and fats this supports the idea that diet could influence metabolic pathways involved in ADHD. However, because the study focused on genetic influences on metabolite levels, it doesn’t directly prove that dietary changes will have the same effects.

Notable Metabolites:

  • 3-Methoxytyramine sulfate (MTS): linked to dopamine metabolism, higher genetic levels of MTS were associated with a lower risk of ADHD. Dopamine plays a crucial role in attention and behavior.

  • DHA and EPA: Omega-3 fatty acids abundant in the brain; higher levels were linked to reduced ADHD risk, supporting existing research on omega-3 supplements.

  • N-acetylneuraminate: Involved in brain development and immune function, with higher levels linked to increased ADHD risk, though more research is needed to understand this.

Five metabolites showed bidirectional links with ADHD, meaning genetic risk for ADHD also affects their levels which suggests a complex interaction between brain function and metabolism.

Twelve ADHD-related metabolites are targets of existing drugs or supplements, including:

  • Acetylcysteine: an antioxidant used in various treatments.

  • DHA supplements: widely used to support brain and heart health.

What This Study Doesn’t Show

While these findings highlight biological pathways, they don’t prove that changing diet will directly alter ADHD symptoms. Metabolite levels are shaped by genetics plus environment, lifestyle, and health factors, which require further study.

Conclusion: 

This research provides stronger evidence of metabolic pathways involved in ADHD and points to new possibilities for diagnosis and treatment. Future work could explore how diet or drugs might safely adjust these metabolites to help manage ADHD.

While this study strengthens the link between amino acid and fatty acid metabolism and ADHD risk, suggesting that diet could play a role, ultimately more research is still needed before experts could use this research to give specific nutritional advice.

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July 21, 2025

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.

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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. 

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July 14, 2025

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