July 6, 2021
An international team of researchers sets out to measure the association between ADHD symptoms and self-evaluations of happiness among adults in the general population of the U.K. A nationally representative sample of 7,274 adults was asked to rate their happiness on a three-point scale. They also used the Adult ADHD Self-Report Scale (ASRS) Screener to assess ADHD symptom levels.
Higher ADHD symptom levels were found to be inversely associated with self-assessments of happiness. Adults with the lowest ADHD symptoms (0-9 on theaters) were roughly twice as likely to report being happy as those scoring10-13, five times as happy as those scoring 14-17, and ten times as happy as those with the highest ADHD symptom scores (18-24). These results were highly significant.
That did not mean that most adults with high ADHD symptom scores were unhappy. Even among those with the highest ADHD symptom scores (18-24), a majority (58 percent) reported being either "fairly happy" or "very happy." Butonly11 a percent of that group reported being "very happy," as opposed to 44 percent of those scoring the lowest on ADHD symptoms.
While the association is clear and strong, establishing causation is trickier. As the authors acknowledge, "as the symptoms associated with ADHD are similar to, and sometimes overlap, with those that are commonly observed in individuals with other psychiatric disorders ... a screening instrument to identify ADHD symptoms may have had limited power to distinguish 'pure' ADHD and cases with ADHD symptoms related to other psychiatric disorders." Emotional instability and anxiety disorder each mediated more than a third of the association between ADHD and unhappiness, and depression almost a third. These could have been brought about by ADHD and could also have been produced by other psychiatric disorders. Because the ASRS is not a diagnostic instrument, the authors concluded that "the results of this study should be considered provisional, until if, and when, they are replicated in those with a clinical diagnosis of ADHD with and without comorbid disorders."
Andrew Stickley, AiKoyanagi, Hidetoshi Takahashi, VladislavRuchkin, Yosuke Inoue, Aki Yazawa, Yoko Kamio, "Attention-deficit/hyperactivity disorder symptoms and happiness among adults in the general population," PsychiatryResearch (2018), DOI: 10.1016/j.psychres.2018.05.004.
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:
Ineligible Patients Face Unique Challenges:
Higher Risk of Adverse Outcomes:
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.
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.
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.
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.
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.
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