May 13, 2021

MYTHS ABOUT THE DIAGNOSIS OF ADHD

Myth: The ADHD diagnosis is very much "in the eye of the beholder."
This is one of many ways in which the ADHD diagnosis has been ridiculed in the popular media. The idea here is that because we cannot diagnose ADHD with an objective brain scan or a blood test, the diagnosis is "subjective" and subject to the whim and fancy of the doctor making the diagnosis.

Fact:  The ADHD diagnosis is reliable and valid.
The usefulness of a diagnosis does not depend on whether it came from a blood test, a brain test, or from talking to a patient. A test is useful if it is reliable, which means that two doctors can agree on who does and does not have the disorder, and if it is valid, which means that the diagnosis predicts something important to the doctor and patient, such as whether the patient will respond to a specific treatment. Many research studies show that doctors usually agree about who does and does not have ADHD. This is because we have very strict rules that one must use to make a diagnosis. Much work over many decades has also shown ADHD to be a valid diagnosis. For details see: Faraone, S. V. (2005). The scientific foundation for understanding attention-deficit/hyperactivity disorder as a valid psychiatric disorder. Eur Child Adolesc Psychiatry, 14, 1-10. The short story is that the diagnosis of ADHD is very useful for predicting what treatments will be effective and what types of problems ADHD patients are likely to experience in the future.

Myth: ADHD is not a medical disorder.  It's just the extreme of normal childhood energy
Mental health professionals use the term "disorder" to describe ADHD, but others argue that what we view as a disorder named ADHD is simply the extreme of normal childhood energy. After all, most healthy children run around and don't always listen to their parents. Doesn't the ADHD child or adult simply have a higher dose of normal behavior?

Fact: Doctors have good reasons to describe ADHD as a disorder
The idea that the extreme of normal behavior cannot be a disorder is naïve. Consider hypertension(high blood pressure). Everyone has blood pressure, but when blood pressure exceeds a certain value, doctors get worried because people with high values are at risk for serious problems, such as heart attacks. Consider depression. Everyone gets sad from time to time, but people who are diagnosed with depression cannot function in normal activities and, in the extreme, are at risk of killing themselves. ADHD is not much different from hypertension or depression. Many people will show some signs of ADHD at some times, but not all have a "disorder." We call ADHD a disorder not only because the patient has many symptoms, but also because that patient is impaired, which means that they cannot carry out normal life activities. For example, the ADHD child cannot attend to homework or the ADHD adult cannot hold a job, despite adequate levels of intelligence. Like hypertension, untreated ADHD can lead to serious problems such as failing in school, accidents, or an inability to maintain friendships. These problems are so severe that the center for Disease Control described ADHD as  "serious public health problem."

Myth: The ADHD diagnosis was developed to justify the use of drugs to subdue the behaviors of children.
This is one of the more bizarre myths about ADHD. The theory here is that to sell more drugs, pharmaceutical companies invented the diagnosis of ADHD to describe normal children who were causing some problems in the past.

Fact: ADHD was discovered by doctors long before ADHD medications were discovered.
People who believe this myth do not know the history of ADHD. In 1798, long before there were any drugs for ADHD, Alexander Crichton, a Scottish doctor, described a "disease of attention," which we would not call ADHD.ADHD symptoms were described by a German doctor, Heinrich Hoffman, in1845 and by a British doctor, George Still, in 1902. Each of these doctors found that inattentive and overactive behaviors could lead to a problem that should be of concern to doctors. If they had had medications to treat ADHD, they probably would have prescribed them to their patients. But a medication for ADHD was not discovered until 1937 and even then, it was discovered by accident. Dr. Charles Bradley from Providence, Rhode Island had been doing brain scanning studies of troubled children in a hospital school. The scans left the children with headaches that Dr. Bradley thought would be relieved by an amphetamine drug. When he gave this drug to the children after the scan, it did not help their headaches. However, the next day, their teachers reported that the children were attending and behaving much better in the classroom. Dr. Bradley had accidentally discovered that amphetamine was very helpful in reducing ADHD symptoms, and amphetamine drugs are commonly used to treat ADHD today. So, as you can see, the diagnosis of ADHD was not "invented" by anyone; it was discovered by doctors long before drugs for ADHD were known.

Myth: Brain scans or computerized tests of brain function can diagnose ADHD.
Someday, this myth may become fact, but for now, and shortly it is a solid myth. You may think this is strange. After all, we know that ADHD is a brain disorder and that neuroimaging studies have documented structural and functional abnormalities in the brains of patients with ADHD. If ADHD is a biological disorder, why don’t we have a biological test for the diagnosis?

Fact:  No brain test has been shown to accurately diagnose ADHD.
ADHD is a biologically based disorder, but there are many biological changes and each of these is so small that they are not useful as diagnostic tests. We also think that there are several biological pathways to ADHD. That means that not all ADHD patients will show the same underlying biological problems. So for now, the only officially approved method of diagnosing ADHD is by asking patients and/or their parents about ADHD symptoms as described in the American Psychological Association's Diagnostic and Statistical Manual

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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