July 26, 2024

Meta-analysis Finds Little-to-No Association Between Prenatal Cannabis Exposure and Offspring ADHD

Prevalence of cannabis use among pregnant women is on the rise with the spread of legalization. The most frequently reported reasons for use are to relieve stress or anxiety, nausea or vomiting, pain, and for recreation.

Given that the primary psychoactive ingredient of cannabis, ∆9-tetrahydrocannabinol (THC) is a small fat-soluble molecule that can easily cross the placenta, an Israeli-U.S. research team conducted a systematic search of the peer-reviewed medical literature for studies exploring possible neuropsychiatric effects on offspring.  

They included not only studies evaluating likelihood of ADHD, but also autism spectrum disorder, anxiety, depression, and psychotic symptoms. For each of these, adjustment was made for known confounding variables.

With that adjustment, meta-analysis of six studies with a total of over half a million (503,661) participants reported a 13% increase in the odds of ADHD in offspring of mothers using cannabis during pregnancy compared with offspring of mothers not using cannabis while pregnant.

That is generally considered a small effect size increase in risk. But there are multiple reasons to question even this minimal finding:

  • It barely achieved statistical significance.
  • A few studies used more reliable clinical diagnoses, while most just used ADHD symptom rating scales.
  • It is virtually impossible to eliminate all confounding variables. Twin studies come closest to fully accounting for otherwise unmeasured environmental and genetic confounders, but no such studies were included.
  • The team made no effort to evaluate publication bias.  
  • Almost all the participants (497,821) were in a single study, and that study – which relied on clinical diagnoses – did not find a significant association.

Meta-analysis of two studies with a total of 741 individuals reported a 20% increase in offspring use of cannabis among mothers who used cannabis during pregnancy, but once again this was subject to methodological shortcomings:

  • Two studies do not make for a robust meta-analysis, even more so with only 741 participants.
  • The result barely achieved statistical significance.
  • Publication bias was unaddressed.
  • Small effect sizes are questionable due to the virtual impossibility of eliminating all confounding variables, especially without twin studies.

Some studies have suggested a link between cannabis and psychotic symptoms. But meta-analysis of four studies combining over nineteen thousand persons found no significant association between maternal cannabis use during pregnancy and offspring psychotic symptoms.

Many studies have pointed to commonalities in the etiology of ADHD and autism spectrum disorder (ASD). Yet meta-analysis of five studies encompassing over half a million participants found absolutely no association between maternal prenatal cannabis use and ASD.  

The remaining meta-analyses also reported no association with depression or anxiety.

With the caution that absence of evidence is not the same as evidence of absence, it is by no means clear from what is presently known that prenatal cannabis exposure has any significant neuropsychiatric effects on offspring. And if further research finds any effects, they are likely to be minor.

Hely Bassalov, Noa Yakirevich-Amir, Inbal Reuveni, Catherine Monk, Sharon Florentin, Omer Bonne, and Ilan Matok, “Prenatal Cannabis Exposure and The Risk for Neuropsychiatric Anomalies in the Offspring: A Systematic Review and Meta-Analysis,” American Journal of Obstetrics and Gynecology (2024), https://doi.org/10.1016/j.ajog.2024.06.014.

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New Study Examines ADHD Stimulant Use and Substance Use Risks Among Adolescents

U.S. Study Finds No Increased Non-Medical Use Among Those Prescribed Stimulants as Adolescents, but Finds Other Links

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.

Stimulants and ADHD: Understanding the Risks

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.

Study Design: Following the Participants

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:

  • Adolescents treated with stimulant therapy for ADHD
  • Adolescents treated with non-stimulant therapy for ADHD (ADHD controls)
  • Adolescents with no history of ADHD treatment (non-ADHD controls)

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.

Key Findings: No Direct Link to Non-medical Stimulant or Cocaine 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:

  • Binge drinking during late adolescence was linked to an 80% increase in the likelihood of subsequent nonmedical prescription stimulant use and cocaine use.
  • Nonmedical use of prescription opioids at age 18 increased the odds of later nonmedical stimulant use by 50% and of cocaine use by two-thirds.
  • Cannabis use by age 18 more than tripled the likelihood of later non-medical stimulant use and increased the odds of subsequent cocaine use sixfold.

Clinical Implications

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.

October 17, 2024

CDC: ADHD Diagnosis, Treatment, and Telehealth Use in Adults

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.

Methods:

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.

Results:

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.

Conclusion:

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

October 14, 2024

News Tuesday Study! Understanding ADHD in Older Adults: An Overlooked Concern

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.

October 8, 2024