December 11, 2023
To what extent does sex matter in the expression of ADHD symptoms and associated cognitive deficits among youths with ADHD?
A recently published meta-analysis of 54 studies by a Canadian team of researchers at the University of Quebec at Montreal suggests it makes little to no difference. A meta-analysis of 26 studies with over 5,900 youths found no significant difference in inattention symptoms, and a meta-analysis of 24 studies with over 5,500 youths likewise found no difference in hyperactivity-impulsivity symptoms. Separating out hyperactivity and impulsivity made no difference.
Given these results, it's no surprise that a meta-analysis of 15 studies with over 3,500 youths again found no significant divergence between the sexes for total ADHD symptoms. Parents and teachers differed, however, in their ratings of symptoms. Whereas parents observed no differences, teachers reported boys had slightly more inattention and hyperactive-impulsive behaviors than girls. Turning to cognitive functions, a series of meta-analyses found no significant sex differences for interference control, working memory, and planning scores. But boys performed slightly worse on inhibition and motor response inhibition. While the raw data also showed boys slightly under-performing girls on cognitive flexibility, strong evidence of publication bias made this unreliable.
The team also compared youths with ADHD and youths without ADHD. Both for females and for males, those differences in ADHD symptoms were - as would be expected - extremely large, whether for total symptoms, inattention, or hyperactivity-impulsivity. All cognitive function scores were moderately better for normally developing boys compared with boys with ADHD, and for normally developing girls compared with girls with ADHD. Yet once again, when comparing these effect sizes between girls and boys, there were no significant differences for any of the symptom and cognitive function effects.
"In other words," the authors wrote, "boys and girls with ADHD presented significantly more primary symptoms and executive and attention deficits than did their peers without ADHD, and effect sizes were not significantly different between the sexes." They concluded, "girls with ADHD do not differ from boys with ADHD in many domains of cognitive functioning, and they have significantly more severe difficulties across the executive and attentional functions measured relative to girls without ADHD. This meta-analysis is the first to examine sex differences in cognitive flexibility, working memory, and planning."
Maryanne LoyerCarbonneau, Martin Demers, Marc Bigras, and Marie-Claude Guay, "Meta-Analysis of Sex Differences in ADHD Symptoms and Associated Cognitive Deficits," Journal of Attention Disorders (2020), https://doi.org/10.1177/1087054720923736.
A recent U.S. study challenges assumptions about the link between prescription stimulant use for ADHD and later substance abuse. Adolescents who used prescription stimulants under a physician’s supervision did not exhibit increased rates of non-medical stimulant use or cocaine use as they transitioned into young adulthood. However, other factors, like binge drinking and cannabis use, showed significant associations with later substance misuse, suggesting that the landscape of risk is more complex than previously understood.
Prescription stimulants are considered one of the most effective treatments for ADHD. While these medications can significantly improve focus and behavior, concerns have persisted that using stimulants during adolescence might predispose individuals to substance use disorder (SUD). Some theories suggest that early exposure to stimulants could increase the likelihood of cocaine use, as both substances affect the brain's dopamine pathways similarly.
Yet, previous research often lacked large, longitudinal studies focusing on adolescents with ADHD who had never been treated with stimulants. To fill this gap, a research team followed a nationally representative cohort of 11,905 high school seniors (12th graders, mostly aged 18) for six years, tracking their substance use behaviors.
At the start of the study, participants completed surveys regarding their ADHD treatment history—whether they had used stimulant therapy, non-stimulant therapy, or no medication at all. This formed three groups:
Participants then completed follow-up surveys every two years, reporting on their use of substances like prescription stimulants and cocaine, as well as their engagement in behaviors like binge drinking and cannabis use.
The study found no significant differences in the rates of non-medical stimulant use or cocaine use among the three groups. Adolescents who had been prescribed stimulant medications were not more likely to misuse prescription stimulants or cocaine as young adults than those who had not received such medications.
However, other behaviors at age 18 showed strong associations with later substance use:
The study’s findings have important implications for both clinicians and families managing ADHD. Although ADHD is associated with an increased risk of SUD, the researchers observed no higher risk of nonmedical stimulant use among adolescents who had taken stimulant therapy compared to those who hadn’t. Additionally, there was no evidence that stimulant medications posed a greater risk than non-stimulant medications for subsequent misuse.
The findings also highlight the need for more robust screening for alcohol and other drug use among adolescents. As the study notes, current guidelines do not recommend routine screening for substance misuse in adolescents due to limited evidence. However, given the associations found between binge drinking, cannabis use, and later substance misuse, such preventive measures could play a key role in reducing risks during this vulnerable period of development.
Ultimately, the study sheds light on the multifaceted nature of substance use risks in adolescents and young adults, suggesting that while prescription stimulant use for ADHD under medical supervision may not directly contribute to substance abuse, the broader context of an adolescent’s behaviors and environment is crucial in shaping future outcomes.
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The report "Attention-Deficit/Hyperactivity Disorder Diagnosis, Treatment, and Telehealth Use in Adults" published in the CDC's Morbidity and Mortality Weekly Report provides a detailed examination of the prevalence and treatment of ADHD among U.S. adults based on data collected by the National Center for Health Statistics Rapid Surveys System during October–November 2023. This data is crucial as it offers updated estimates on the prevalence of ADHD in adults, a condition often regarded as primarily affecting children, and highlights the ongoing challenges in accessing ADHD-related treatments, including telehealth services and medication availability.
The methods used in this study involved the National Center for Health Statistics (NCHS) Rapid Surveys System (RSS), which gathers data to approximate the national representation of U.S. adults through two commercial survey panels: the AmeriSpeak Panel from NORC at the University of Chicago and Ipsos’s KnowledgePanel. The data were collected via online and telephone interviews from 7,046 adults. The responses were weighted to reflect the total U.S. adult population, ensuring that the results approximate national estimates. In identifying adults with current ADHD, respondents were asked if they had ever been diagnosed with ADHD and, if so, whether they currently had the condition. The study also collected data on treatment types (including stimulant and nonstimulant medications), telehealth use, and demographic variables such as age, education, race, and household income.
The results showed that approximately 6.0% of U.S. adults, or an estimated 15.5 million people, had a current ADHD diagnosis. Notably, more than half of the adults with ADHD reported receiving their diagnosis during adulthood (age ≥18 years), indicating that diagnosis can occur well beyond childhood. Analysis of demographics showed significant differences between adults with ADHD and those without; adults with ADHD were more likely to be younger, with 84.5% under the age of 50. Adults with ADHD were also less likely to have completed a bachelor's degree and more likely to have a household income below the federal poverty level compared to those without ADHD. Regarding treatment, the report found that approximately one-third of adults with ADHD were untreated, and around one-third received both medication and behavioral treatment. Among those receiving pharmacological treatment, 33.4% used stimulant medications, and 71.5% of these individuals reported difficulties in getting their prescriptions filled due to medication unavailability, reflecting recent stimulant shortages in the United States. Additionally, nearly half of adults with ADHD had used telehealth services for ADHD-related care, including obtaining prescriptions and receiving counseling or therapy.
The discussion emphasizes the public health implications of these findings. ADHD is often diagnosed late, with many individuals not receiving a diagnosis until adulthood, which underscores the need for improved awareness and early identification of ADHD symptoms across the life course. Moreover, the high prevalence of untreated ADHD and the barriers to accessing stimulant medications reveal significant gaps in the healthcare system's ability to support adults with ADHD. These gaps can contribute to poorer outcomes, such as increased risk of injury, substance use, and social impairment. The report also highlights the role of telehealth, which became more prominent during the COVID-19 pandemic. Telehealth appears to provide a viable solution for expanding access to ADHD diagnosis and treatment, though challenges remain regarding the quality of care and potential for misuse. The authors suggest that improved clinical care guidelines for adults with ADHD could help reduce delays in diagnosis and treatment access, thus improving long-term outcomes for affected individuals.
In conclusion, the study provides a comprehensive view of the prevalence, treatment, and telehealth use for ADHD among adults in the U.S. These data are crucial for guiding clinical care and shaping policies related to medication access and telehealth services. The findings underscore the importance of ensuring an adequate supply of stimulant medications and reducing barriers to ADHD care, ultimately enhancing the quality of life for adults with this condition. The good news is that many adults with ADHD are being diagnosed and treated. It is, however, concerning that many are not treated and that many of those treated with stimulants were impacted by the stimulant shortage.
For more details, see: https://www.cdc.gov/mmwr/volumes/73/wr/mm7340a1.htm
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60% to 90% of youth with ADHD continue to have symptoms as adults. In older adults, about 2.5% are believed to have ADHD, but it often goes unnoticed because research is limited and current diagnosis methods are based mostly on studies of young people.
Our commentary discusses key points about ADHD in older adults. Although 2 to 3 percent of older adults have ADHD when using proper diagnostic tools, only 0.23% are diagnosed in medical records. This shows that ADHD is greatly underdiagnosed in older adults. Even worse, less than 40% of those who are diagnosed receive any treatment, which highlights the need for doctors to be better educated about ADHD in this age group. Current ways of diagnosing ADHD need to be improved for people over 50. Also, there isn’t much research on ADHD medications for people over 60, with most studies excluding them, which raises concerns about how safe and effective these treatments are for older adults, especially since stimulant medications can affect the heart.
There are also biases among doctors that make it harder to diagnose and treat ADHD in older adults. Many doctors aren’t trained to recognize ADHD in this age group and still see it as a condition that only affects young people. Some think that if a person hasn’t been treated for ADHD by this stage in life, they don’t need treatment now. But this ignores the fact that untreated ADHD can cause lifelong struggles and reduce the person’s quality of life. Some doctors are also worried about the risks of ADHD medications for older patients, even though research shows that these medications are usually safe when properly monitored.
Diagnosing ADHD in older adults can be tricky because its symptoms can look similar to other conditions, like mild cognitive impairment or dementia. This makes it important for doctors to do a thorough assessment that looks at medical, psychiatric, and psychological factors. Since older adults often have other health issues, it’s crucial for doctors to tell the difference between ADHD symptoms and those caused by other conditions.
In the end, we need more awareness, training, and research on ADHD in older adults. Doctors need to push past biases and consider the benefits of treating ADHD in this age group, carefully weighing the risks and rewards. As the population of older adults grows, so does the need for studies and guidelines to provide better care for older people with ADHD. Filling these gaps will ensure that older adults with ADHD get the attention and treatment they need.
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