May 19, 2021

OTHER MYTHS ABOUT ADHD

Myth: ADHD is an American disorder.
Those who claim ADHD is an American disorder believe that ADHD is due to the pressures of living in a fast-paced, competitive American society.   Some argue that if we lived in a simpler world, ADHD would not exist.  

Fact:  ADHD occurs throughout the world.

Wherever scientists have searched for ADHD, they have found it.  They have done this by going to different countries, and speaking to people in the community to diagnose them with or without ADHD.   These studies show that ADHD occurs throughout the world and that the percentage of people having ADHD does not differ between the United States and the rest of the world.   Examples of where ADHD has been found include  Australia, Brazil, Canada, China, Colombia, Finland, Germany, Iceland, Israel, Italy, Japan, New Zealand, Spain, Sweden, Taiwan, The Netherlands, and Ukraine.   ADHD is not an American disorder.

Myth: A child who sits still to watch TV or play video games cannot have ADHD.
Many parents are puzzled that their child can sit still to watch TV or play video games for hours, but that same child cannot sit still for dinner or stay at their desk for long to do homework.  Are these children faking ADHD symptoms to get out of homework?

Fact:  ADHD does not necessarily interfere with playing video games or watching TV.

Because children cannot turn their ADHD on and off to suit their needs, it does seem odd that a child who is typically hyperactive and inattentive can sit for hours playing a video game.  But this ability of ADHD children fits in very well with scientific facts about ADHD. First, you probably understand the effects of rewards and punishment on behavior.  If your behavior is rewarded, you are likely to do it again.  If it is punished, you will avoid that behavior in the future.  Rewards that have the strongest effect on our behavior are large and will occur soon. For example, consider these two choices:
a)      if you listen to a boring one-hour lecture, I will pay you $100 immediately after the lecture
b)      if you listen to a boring one-hour lecture, I will pay you $110 one year after the lecture
Choice (a) is more appealing than choice (b).  Most people will not think it is worthwhile to wait one year for $10.  We say they have 'discounted' the $10 to $0.
Now consider the choices:
c)      if you listen to a boring one-hour lecture, I will pay you $100 immediately after the lecture
d)     if you listen to a boring one-hour lecture, I will pay you $2,000 one year after the lecture

Choice (d) is more appealing than choice (c).  Most people will wait one year for$2,000.   It is obvious here is that if I want the best chance of having you watch a lecture, I should offer you a large sum of money immediately after the lecture. What is not so obvious is that people vary a great deal in the degree to which they are affected by rewards that are either small or distant in the future.   For some people, getting $2,000in one year is almost like getting nothing at all.  We say that such people are not sensitive to distant rewards.

What does this have to do with ADHD and video games?  Well, people with ADHD are usually not very sensitive to weak or distant rewards.  To affect the behavior of a person with ADHD, the reward needs to be immediate and fairly large.  When a child with ADHD sits down to do homework, the potential reward is getting a good grade on their report card, but they won't receive that grade for weeks or months, so it is very distant.  Thus, it is not surprising that the possibility of that reward cannot control the child's behavior.  In contrast, video games are created so that players are rewarded very frequently by winning points or completing one of the many levels one must pass to finally complete the game.  Because playing well is also rewarded by friends, the video game rewards are strong and immediate, which makes it easy for people with ADHD to sit still and play for long periods.

 Myth: ADHD disappears in adulthood.
Until the 1990s, it was commonly believed that children grew out of ADHD.  The reason for this is not clear.  Some theories about ADHD suggested that ADHD children had a lag in brain development, and that they would make up for that lag during adolescence.  So ADHD was seen as a delay in brain development that could be overcome.   The idea that children routinely recovered from ADHD was so strong that many insurance companies would not pay for the ADHD treatment of adults.

Fact: In the majority of cases, ADHD persists into adulthood.
This myth about ADHD has been proven wrong by studies that diagnosed ADHD in children and then examined it many years later than in adults.  These studies showed that, although there was some recovery from ADHD, about two-thirds of cases persisted into adulthood. The studies also taught us that ADHD symptoms tend to change with age.  The extreme and disruptive hyperactivity of many ADHD children gets somewhat better by adulthood, as do some symptoms of impulsivity.   In contrast, inattentive symptoms do not decrease much with age.

 Myth: People with ADHD cannot do well in school or succeed in life.
This myth is based on several facts: 1) ADHD affects many aspects of life; 2) ADHD impairs thinking and behavior and 3) for most people, ADHD is a lifelong disorder.   Altogether, doesn't this mean that people with ADHD won't succeed in life?

Fact: People with ADHD can succeed and live productive lives.
There are two reasons why people with ADHD can succeed in life. The first is obvious.  Although treatments for ADHD are not perfect, they can eliminate many of the obstacles that would otherwise make it difficult for ADHD patients to do well in school or on the job.  But, more importantly, having ADHD is only one of many facts about a person's life.   Some ADHD people have other skills or traits that help them compensate for their ADHD.  For example, if you have a high level of intelligence, an engaging personality, or excellent athletic skills, you can do well despite having ADHD.   Consider Michael Phelps, who broke so many Olympic swimming records. He was diagnosed with ADHD at age 9 and took Ritalin to help his hyperactivity.   James Carville has ADHD, but he completed law school and helped Bill Clinton become President of the United States.  Cammi Granato's ADHD did not stop her from becoming captain of the United  States Olympic ice hockey team, and Ty Pennington's ADHD did not stop him from becoming a  star on TV.

 Myth: ADHD does not affect highly intelligent people
The mistake behind this myth is that it assumes that being very intelligent protects people from having ADHD.  It's true that if you are highly intelligent, you can use that intelligence to compensate for some ADHD' effects, but does high intelligence completely protect a person from ADHD?

Fact: People with ADHD can succeed and live productive lives.
When my colleagues and I studied this question, we found clear evidence that high intelligence does not completely protect people from ADHD. Like people who don't have ADHD, having high intelligence will help Alderpeople do better than ADHD people who are not smart.  But when we compared highly intelligent Alderpeople with highly intelligent non-ADHD people, we found that the highly intelligent ADHD people had many of the impairing problems that are known to be associated with ADHD.  For details about these problems, see Complications of ADHD.  In another study, we compared ADHD adults who had received straight A grades in high school, with non-ADHD people who had achieved the same grades.  Despite their good grades, these ADHD adults were not doing as well in their jobs and not earning as much income as the non-ADHD adults.  And ADHD also has an impact at every level of education.  As you can see from the figure, even for people with college degrees, having ADHD lowers your chances of being employed.

Faraone, S. V., Sergeant, J.,Gillberg, C. &Biederman, J. (2003). The Worldwide Prevalence of ADHD: Is it an American condition? World Psychiatry2, 104-113.Polanczyk, G., de Lima, M. S., Horta, B. L., Biederman, J. &Rohde, L. A. (2007). The Worldwide Prevalence of ADHD: a systematic Review and Meta-regression Analysis. Am J Psychiatry164,942-8.
Scheres, A., Lee, A. &Sumiya,M. (2008). Temporal reward discounting and ADHD: task and symptom-specific effects. J Neurol Transm115, 221-6.
Faraone, S., Biederman, J. &Mick, E. (2006). the Dependent Decline Of Attention-Deficit/Hyperactivity Disorder:  Aneta-Analysis Of Follow-Up Studies. Psychological Medicine36,159-165.

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NEW STUDY: Understanding the Gap Between ADHD Clinical Trials and Real-World Patients

Background 

ADHD (Attention-Deficit/Hyperactivity Disorder) is one of the most studied neurodevelopmental conditions, with many clinical trials evaluating the effectiveness and safety of various medications. These trials, known as randomized controlled trials (RCTs), are considered the gold standard for assessing treatments. However, strict eligibility criteria often exclude many real-world patients, raising questions about whether the findings from these trials apply to everyday clinical settings.

Our latest study sheds light on this issue, revealing just how many individuals with ADHD might be excluded from RCTs and the impact this exclusion has on their treatment outcomes. 

Method

Researchers used Swedish national registries to analyze data from 189,699 individuals diagnosed with ADHD who started medication between 2007 and 2019. They applied exclusion criteria from 164 international RCTs to identify who would have been considered ineligible for these trials in order to determine the proportion of individuals with ADHD who would not meet the eligibility criteria for RCTs.  

Key Findings

Many Patients Are Ineligible for Clinical Trials:

  • Over half (53%) of the study population would have been ineligible for ADHD medication trials.
  • Adults were most likely to be excluded (74%), followed by adolescents (35%) and children (21%).

Ineligible Patients Face Unique Challenges:

  • Treatment Switching: Ineligible individuals were more likely to switch medications within the first year (14% higher likelihood compared to eligible patients).
  • Medication Discontinuation: They were slightly less likely to stop taking their medication during the first year.

Higher Risk of Adverse Outcomes:

  • Ineligible patients experienced significantly higher rates of psychiatric hospitalizations and health issues such as depression, anxiety, and substance use disorders. For instance:some text
    • Psychiatric hospitalizations: Nearly 10 times more likely.
    • Specialist visits for substance use disorders: About 15 times more likely.
    • Anxiety-related visits: Over 11 times more likely.

What This Means

These findings highlight a major gap between the controlled environments of clinical trials and the realities faced by individuals with ADHD in everyday life. While RCTs provide valuable insights, their restrictive criteria often exclude patients with more complex health profiles or co-existing conditions. This limits the generalisability of trial results, meaning that treatment guidelines based solely on RCTs may not fully address the needs of all patients.

Conclusion

This study demonstrated that a significant proportion of individuals with ADHD, particularly adults, do not meet the eligibility criteria for standard RCTs. These results emphasize the importance of bridging the gap between research settings and real-world applications. By recognizing and addressing the limitations of RCTs, we can work towards more equitable and effective ADHD treatment strategies for everyone.

January 14, 2025

Where Does ADHD Fit in the Psychopathology Hierarchy? A Symptom-Focused Study

NEWS TUESDAY: Where Does ADHD Fit in the Psychopathology Hierarchy? A Symptom-Focused Study

Background:

Our understanding of Attention-deficit/hyperactivity disorder (ADHD) has grown and evolved considerably since it first appeared in the DSM-II as “Hyperkinetic Reaction of Childhood.”  This study aimed to find the disorder’s placement within the modern psychopathology classification systems like the Hierarchical Taxonomy Of Psychopathology (HiTOP). 

The HiTOP model aims to address limitations of traditional classification systems for mental illness, such as the DSM-5 and ICD-10, by organizing psychopathology according to evidence from research on observable patterns of mental health problems.. Is ADHD best categorized under externalizing conditions, neurodevelopmental disorders, or something else entirely? A recent study by Zheyue Peng, Kasey Stanton, Beatriz Dominguez-Alvarez, and Ashley L. Watts takes a closer look at this question using a symptom-focused approach.

The Study:

Traditionally, ADHD has been associated with externalizing behaviors, such as impulsivity and hyperactivity, or with neurodevelopmental traits, like cognitive delays. However, this study challenges the idea of placing ADHD into a single category. Instead, it maps ADHD symptoms across three major psychopathology spectra: externalizing, neurodevelopmental, and internalizing.

The findings reveal that ADHD symptoms don’t fit neatly into one box. For example, symptoms like impulsivity, poor school performance, and low perseverance were strongly associated with externalizing behaviors. On the other hand, cognitive disengagement (e.g., daydreaming, blank staring) and immaturity were closely linked to neurodevelopmental challenges. Interestingly, cognitive disengagement also showed ties to internalizing symptoms, such as anxiety or depression.

This research underscores the complexity of ADHD. Rather than treating ADHD as a single, unitary construct, the study advocates for a symptom-based approach to better understand and treat individuals. By acknowledging that ADHD symptoms relate to multiple psychopathology spectra, clinicians and researchers can move toward more nuanced classification systems and targeted interventions.

Conclusion: 

Ultimately, this study highlights the need for modern systems to move beyond rigid categories and adopt a more flexible, symptom-focused framework for understanding ADHD’s place in psychopathology.

January 6, 2025

Meta-analyses Find Dose-response Association Between Lead Exposure and Subsequent ADHD

Meta-analyses Find Dose-response Association Between Lead Exposure and Subsequent ADHD

Background:

Exposure to heavy metals like lead, arsenic, mercury, cadmium, and manganese is known to harm developing nervous systems. However, past studies on whether heavy metals specifically increase the risk of ADHD have shown mixed results.

A research team from China (Gu et al., 2024) reviewed medical studies and conducted meta-analyses to better understand this issue.

Methods:

The team included studies on children and teens, focusing on cohort studies, case-control studies, and cross-sectional studies. They only used articles written in English and required validated biomonitoring (like blood tests) to measure heavy metal exposure. ADHD diagnoses had to come from clinical evaluations.

To be included, studies had to report effect sizes such as odds ratios and relative risks with confidence intervals. The team focused on comparisons between groups with high, low, or no exposure, which made it harder to analyze dose-response relationships.

They also evaluated the quality of each study. All cohort studies were rated high-quality. Of the 15 case-control studies, 6 were high-quality, and 9 were moderate-quality. Among cross-sectional studies, only 2 were high-quality, and the rest were moderate-quality.

Key Findings:
  1. Lead Exposure and ADHD:some text
    • A meta-analysis of 22 studies with over 20,000 participants found that early exposure to lead was linked to about twice the odds of an ADHD diagnosis compared to unexposed children.
    • However, results varied widely among studies, and signs of publication bias were detected. After adjusting for this bias, the increased odds dropped to about 50%.
    • A dose-response relationship was found:some text
      • Blood lead levels of 2.5 µg/dL increased ADHD risk by 1.8 times.
      • Levels of 5 µg/dL increased the risk 2.5 times.
      • Levels of 7.5 µg/dL increased the risk 2.75 times.
      • Levels of 10 µg/dL tripled the risk.
  2. Other Metals:some text
    • No significant links were found between ADHD and exposure to arsenic, mercury, cadmium, or manganese. Fewer studies were available for these metals, and participant numbers were much smaller:some text
      • Arsenic exposure: 25% higher odds of ADHD (4 studies, 3,116 participants).
      • Mercury exposure: 25% higher odds (6 studies, 2,916 participants).
      • Cadmium exposure: 25% higher odds (5 studies, 2,419 participants).
      • Manganese exposure: 45% higher odds (6 studies, 1,664 participants).
  3. Austrian Study: An Austrian team (Rosenauer et al., 2024) also conducted a meta-analysis on lead exposure and ADHD. They included 14 studies with over 7,600 participants and found:some text
    • Lead exposure increased the odds of ADHD by about 25%.
    • Studies focusing on higher lead levels found a 43% increased risk, supporting a dose-response relationship.
    • Study results were consistent, with no signs of publication bias.
Conclusion:

There was no evidence linking ADHD to other heavy metals like arsenic, mercury, cadmium, or manganese.  Both meta-analyses suggest that lead exposure is associated with the risk for ADHD.  However, because these studies cannot rule out other explanations, one cannot conclude that lead exposure causes ADHD.  For example, other work shows that people with ADHD are likely to have lower incomes than those without ADHD.  

January 17, 2025