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October 29, 2024
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.
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.
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:
The increase in ADHD diagnosis with age underscores the importance of monitoring children’s developmental needs as they progress through school and adolescence.
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 played a significant role in ADHD prevalence, particularly among lower-income groups:
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.
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.
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.
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.
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.
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.
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 …”
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.
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.
Background:
Recent progress in reproductive medicine has increased the number of children conceived via assisted reproductive techniques (ART). These include:
Although ART helps with infertility, there are concerns about its long-term effects on offspring, especially regarding neurodevelopment. Factors such as hormonal treatments, gamete manipulation, altered embryonic environments, as well as parental age and infertility, may influence brain development and raise the risk of neurodevelopmental and mental health disorders.
With previous studies finding conflicting results on a possible association between ART and increased risk of mental health disorders, an Indian research team has just published a new meta-analysis exploring this topic.
The Study:
Studies were eligible if they were observational (cohort, case-control, or cross-sectional), reported confounder-adjusted effect sizes for ADHD, and were published in English in peer-reviewed journals.
A meta-analysis of eight studies encompassing nearly twelve million individuals indicated a 7% higher prevalence of ADHD in offspring conceived via IVF/ICSI compared to those conceived naturally. The heterogeneity among studies was minimal, and no evidence of publication bias was observed.
The study’s 95% confidence interval ranged from 4% to 10%. Further analysis of five studies comprising almost nine million participants that distinguished outcomes by sex revealed that the increase in ADHD risk among female offspring was not statistically significant. In contrast, the elevated risk in male offspring persisted, though it was marginally significant, with the lower bound of the confidence limit at only 1%.
Results:
A meta-analysis of three studies (1.4 million participants) found a 13% higher rate of ADHD in children conceived via ovulation induction/intrauterine insemination (OI/IUI) compared to natural conception. The effect size, though doubled, remains small. Minimal heterogeneity and no publication bias were observed.
The team concluded, “The review found a small but statistically significant moderate certainty evidence of an increased risk of ADHD in those conceived through ART, compared to spontaneous conception. The magnitude of observed risk is small and is reassuring for parents and clinicians.”
Our Take-Away:
Overall, the meta-analysis points to a small, but measurable increase in ADHD diagnoses among children conceived through ART, but the effect sizes are modest and supported by moderate-certainty evidence. And we must always keep in mind that the researchers who wrote the original articles could not correct for all possible confounds. These findings suggest that while reproductive technologies may introduce slight variation in neurodevelopmental outcomes, the effects are small and uncertain. For families and clinicians, the results are generally reassuring: ART remains a safe and effective avenue to parenthood, and the results of this study should not be viewed as a prohibitive concern. Thoughtful developmental monitoring and open, evidence-based counseling can help ensure that ART-conceived children receive support that caters to their individual needs.
The Background:
Myopia is a growing global health concern linked to conditions like macular degeneration, glaucoma, and retinal detachment. Its prevalence has surged in recent decades; by 2050, an estimated 5 billion people will have myopia. The increase is especially marked in Asia – a survey in Taiwan reports that 84% of students aged 15 to 18 are myopic, with 24% severely affected.
Dopamine is an important neurotransmitter in the retina, involved in eye development, visual signaling, and refractive changes. The dopamine hypothesis, suggesting that retinal dopamine release helps prevent myopia, has emerged as a leading theory of myopia control.
Most studies show ADHD is highly heritable, often involving dopamine system genes. ADHD is strongly associated with dopaminergic abnormalities, especially in dopamine transporter function and release dynamics.
Medications for ADHD, like methylphenidate, atomoxetine, and clonidine, help regulate dopamine to reduce symptoms.
The Study:
Given dopamine’s critical involvement in both ADHD and myopia, a Taiwanese research team hypothesized that medications for ADHD that influence dopaminergic pathways may have a significant effect on myopia risk.
To evaluate this hypothesis, the team conducted a nationwide cohort study using data from Taiwan’s National Health Insurance (NHI) program, which covers 99% of the nation’s 23 million residents and provides access to comprehensive eye care and screenings. Taiwan requires visual acuity screenings beginning at age four, with annual examinations for school-aged children to promote the early detection of visual anomalies such as myopia.
Furthermore, ADHD medication and diagnosis are tracked through compulsory diagnostic codes. This permits an accurate assessment of the effects of dopaminergic medications on myopia risk.
Propensity score allocation using a multivariable logistic regression model was applied to reduce bias from confounding influences, pairing cohorts based on similar scores.
The Results:
Comparing 133,945 individuals with ADHD with an equal number without ADHD, untreated ADHD was associated with a 22% greater risk of myopia.
However, after adjusting for covariates (gender, age, insured premium, comorbidities, location, and urbanization level), the ADHD cohort receiving medication treatment showed a 39% decreased risk of myopia relative to the untreated ADHD cohort.
Narrowing this further to the ADHD cohort receiving dopaminergic medications reduced the risk of myopia by more than half (52%) relative to the untreated ADHD cohort.
Treatment with two dopaminergic medications reduced the risk by well over two-thirds (72%) relative to the untreated ADHD cohort.
There were no significant differences between methylphenidate, atomoxetine, and clonidine. Each reduced risk by about 50%.
The team did not directly compare the ADHD cohort receiving dopaminergic medications with the non-ADHD cohort. But if there were 122 cases of myopia in the ADHD cohort for every 100 cases in the non-ADHD cohort, and dopaminergic medications halved the cases in the ADHD cohort to about 60, that would represent a roughly 40% reduction in myopia risk relative to the non-ADHD cohort.
The team concluded, “our research indicates that pharmacologically treated ADHD children have a reduced risk of myopia. Conversely, untreated ADHD children are at a heightened risk relative to those without ADHD. Moreover, the cumulative effects of ADHD medications were found to notably decrease myopia incidence, emphasizing the protective influence of dopaminergic modulation in these interventions.”
The Take-Away:
Children with untreated ADHD are more likely to develop myopia, but those receiving dopaminergic medications had a substantially lower risk. The findings suggest that ADHD medications may help protect against myopia by boosting dopamine signaling. More research is needed before firmly drawing this conclusion, but this research could open the door to new approaches for preventing myopia in at-risk children.
Background:
ADHD treatment includes medication, behavioral therapy, dietary changes, and special education. Stimulants are usually the first choice but may cause side effects like appetite loss and stomach discomfort, leading some to stop using them. Cognitive behavioral therapy (CBT) is effective but not always sufficient on its own. Research is increasingly exploring non-drug options, such as transcranial direct current stimulation (tDCS), which may boost medication effectiveness and improve results.
What is tDCS?
tDCS delivers a weak electric current (1.0–2.0 mA) via scalp electrodes to modulate brain activity, with current flowing from anode to cathode. Anodal stimulation increases neuronal activity, while cathodal stimulation generally inhibits it, though effects vary by region and neural circuitry. The impact of tDCS depends on factors such as current intensity, duration, and electrode shape. It targets cortical areas, often stimulating the dorsolateral prefrontal cortex for ADHD due to its role in cognitive control. Stimulation of the inferior frontal gyrus has also been shown to improve response inhibition, making it another target for ADHD therapy.
There is an ongoing debate about how effective tDCS is for individuals with ADHD. One study found that applying tDCS to the left dorsolateral prefrontal cortex can help reduce impulsivity symptoms in ADHD, whereas another study reported that several sessions of anodic tDCS did not lead to improvements in ADHD symptoms or cognitive abilities.
New Research:
Two recent meta-analyses have searched for a resolution to these conflicting findings. Both included only randomized controlled trials (RCTs) using either sham stimulation or a waitlist for controls.
Each team included seven studies in their respective meta-analyses, three of which appeared in both.
Both Wang et al. (three RCTs totaling 97 participants) and Wen et al. (three RCTs combining 121 participants) reported very large effect size reductions in inattention symptoms from tDCS versus controls. There was only one RCT overlap between them. Wang et al. had moderate to high variation (heterogeneity) in individual study outcomes, whereas Wen et al. had virtually none. There was no indication of publication bias.
Whereas Wen et al.’s same three RCTs found no significant reduction in hyperactivity/impulsivity symptoms, Wang et al. combined five RCTs with 221 total participants and reported a medium effect size reduction in impulsivity symptoms. This time, there was an overlap of two RCTs between the studies. Wen et al. had no heterogeneity, while Wang et al. had moderate heterogeneity. Neither showed signs of publication bias.
Turning to performance-based tasks, Wang et al. reported a medium effect size improvement in attentional performance from tDCS over controls (three RCTs totaling 136 participants), but no improvement in inhibitory control (five RCTs combining 234 persons).
Wang et al. found no significant difference in adverse events (four RCTs combining 161 participants) between tDCS and controls, with no heterogeneity. Wen et al. found no significant difference in dropout rates (4 RCTs totaling 143 individuals), again with no heterogeneity.
Wang et al. concluded, “tDCS may improve impulsive symptoms and inattentive symptoms among ADHD patients without increasing adverse effects, which is critical for clinical practice, especially when considering noninvasive brain stimulation, where patient safety is a key concern.”
Wen et al. further concluded, “Our study supported the use of tDCS for improving the self-reported symptoms of inattention and objective attentional performance in adults diagnosed with ADHD. However, the limited number of available trials hindered a robust investigation into the parameters required for establishing a standard protocol, such as the optimal location of electrode placement and treatment frequency in this setting. Further large-scale double-blind sham-controlled clinical trials that include assessments of self-reported symptoms and performance-based tasks both immediately after interventions and during follow-up periods, as well as comparisons of the efficacy of tDCS targeting different brain locations, are warranted to address these issues.”
The Take-Away:
Previous studies have shown mixed results on the benefits of this therapy on ADHD. These new findings suggest that tDCS may hold some real promise for adults with ADHD. While the technique didn’t meaningfully shift hyperactivity or impulsivity, it was well-tolerated and showed benefit, especially in self-reported symptoms. However, with only a handful of trials to draw from, it would be a mistake to suggest tDCS as a standard treatment protocol. Larger, well-designed studies are the next essential step to clarify where, how, and how often tDCS works best.
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