In 10 seconds? Emotional instability is an often-overlooked feature of attention deficit hyperactive disorder (ADHD). However, a recent meta-analysis shows that ADHD drugs help patients with both their attention deficit and emotional instability.

I thought ADHD had to do with attention and activity, not moods. So did some physicians and scientists. Unsurprisingly given the name, inattention, hyperactivity, and impulsive decision-making are the defining symptoms of ADHD. However, dramatic mood changes, inability to cope with normal stressors and outbursts of explosive tempers have long been observed in adult ADHD patients.

If people have always known about these mood problems, why is this such a big deal? Researchers knew ADHD patients show emotional instability, but they weren’t certain that ADHD caused emotional instability. ADHD patients often present with an additional psychiatric disorder, many of which could explain mood swings, outbursts, and hypersensitivity to stress. This research is novel because it showed that medications that treat inattention, impulsivity, and hyperactivity in ADHD patients also reduce emotional lability, strengthening the hypothesis that ADHD and changes in mood are related.

How did they do it? They reviewed 9 previously published clinical trials of commonly prescribed ADHD drugs, stimulants, and atomoxetine, and compared the effects of the therapies on classical ADHD symptoms to their effects of emotional lability. The review showed that ADHD drugs reduced hyperactivity, inattention, and impulsivity by about 80% while mood symptoms were reduced by 41%. Additionally, stimulants were more effective than atomoxetine at reducing emotional dysregulation.

Will these impact standards of care for adult ADHD patients? They might. While the study showed that currently available ADHD treatments can reduce emotional instability, the effects were modest compared to those on core ADHD symptoms. This suggests that combinatorial treatment strategies might be beneficial. One previous study showed that group therapy for adults with ADHD that covered topics such as mindfulness and emotional regulation led to improvement in symptoms and patients’ self-reported abilities to cope. Additional studies are needed to determine if the combination of therapy and drugs has greater effects than either one alone.

And they’re confident about these conclusions based on just nine studies? Optimistically so. So-called meta-analyses of previously published studies are always difficult because each one uses different measures, participant demographics, and durations of treatment. In fact, the authors of another study went on to look at the effects of methylphenidate, a commonly prescribed ADHD drug, on a specific population of patients they felt were understudied and may have different responses to the drug than most others.

What population is that? Prisoners. It turns out that ADHD is far more common in incarcerated young adults (20-30%) than in the broader population (3-4%). But people in prisons have unique circumstances that could affect their response to treatments. For example, drug abuse is more common in incarcerated populations and previous research shows methylphenidate is less effective in treating adult ADHD in people struggling with substance abuse. It turns out that in this new clinical trial of methylphenidate in prisoners, no benefit was shown for ADHD symptoms.

Woah, why is ADHD so common in prison? Even though a high proportion of prisoners meet the diagnostic criteria for ADHD, very few are diagnosed in childhood. Lack of early intervention may explain the association of adult ADHD with incarceration and other negative outcomes like unemployment.

Testing (medicinal) drugs on inmates…

… is definitely a tricky area of bioethics. As we saw in the methylphenidate trial, incarcerated populations may not be represented by participants used in most clinical trials.

Therefore, including them in research may lead to better treatment outcomes in this group. However, there are obvious concerns about potential exploitation.

For this reason, studies involving prisoners require additional review processes in the United States.

Riley distilled 9 research papers, saving you 31.5 hours of reading time.

The Science Integrity Check of this 3-min Science Digest was performed by Dr. Ángel V. Jiménez.