Study: Drug May Treat Symptoms of Sluggish Thinking In Adults With ADHD

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Key Takeaways

  • There's an ongoing debate between scientists about whether sluggish cognitive tempo (SCT) is a subset of symptoms of ADHD or whether it's a different disorder.
  • However, researchers have recently found that a brain-stimulating drug called lisdexamfetamine can tackle symptoms present in both SCT and ADHD.
  • This is the first time researchers can prove that treatments like this work in adults and not just children.

In a new study, researchers found that a common brain-stimulating drug has shown some early success in reducing a key set of symptoms of attention deficit hyperactivity disorder (ADHD) in adults.

The latest research on the brain-stimulating drug called lisdexamfetamine (LDX)—commercially sold as Vyvanse—finds that it reduced symptoms such as brain sluggishness, fatigue, and persistent daydreaming, which are also known as sluggish cognitive tempo (SCT).

Although the debate is still open among researchers about whether sluggish cognitive tempo is a different attention-deficit condition from ADHD altogether, or a result and subset of the disorder, finding a medication that can treat symptoms like these can have a positive long-term effect for patients regardless.

In fact, the scientists behind these lisdexamfetamine tests explain that this is the first time treatments like this have been shown to work in adults and not just children. This could pave the way for more research on how to treat adults with ADHD using brain stimulants.

“There is some disagreement in the medical community about whether sluggish cognitive tempo should be considered separate from ADHD, and SCT is still not recognized as a formal diagnosis,” Matthew Edelstein, PsyD, BCBA-D, a Maryland-based psychologist who was not involved in the study, tells Verywell. “But ultimately, the study’s importance is more practical than taxonomical: It suggests that lisdexamfetamine can be an effective pharmacological tool to improve the functional impact of ADHD.”

This June study was published in The Journal of Clinical Psychiatry.

The Difference Between ADHD and Sluggish Cognitive Tempo

ADHD is a mental health disorder that can lead to high levels of hyperactive behaviors and low levels of attention. This can result in issues with finding focus, trouble concentrating on a single task or staying put, difficulty following instructions or listening to conversations, and more.

Although it is a disorder that persists throughout a person’s lifetime, less is known about ADHD in adults. Scientists have called for more research in this field.  

SCT is thought to have similar symptoms to ADHD. It could possibly be a sub-set of symptoms of the latter. According to the researcher Russell Barkley, PhD, who developed the Barkley SCT Scale, symptoms of sluggish cognitive tempo include:

  • Being prone to daydreaming
  • Having trouble staying alert
  • Being easily confused
  • Being easily bored
  • Feeling spacey
  • Often feeling lethargic
  • Having less energy than others
  • Being slow-moving
  • Not processing information quickly and or accurately.

People affected by the sluggish cognitive tempo cluster of symptoms tend to manifest a slightly different kind of inattention disorder: more spacey and passive. 

According to Barkley’s school of thought, sluggish cognitive tempo may be present in a large subgroup of adults with ADHD but it is not necessary to have ADHD to have SCT.

Wanting to understand whether both can be treated at the same time was at the core of testing lisdexamfetamine, although more research is needed to discover whether stimulant medications such as this can improve SCT in patients without ADHD.

What This Means For You

If you've been diagnosed with ADHD, a psychologist may recommend you take Vyvanse as a form of treatment. You can learn more about the drug here.

Finding a Drug That Can Treat Both ADHD and SCT

The research looked at how 38 adult men and women with ADHD reacted to four weeks of treatment with 30–70 milligrams of lisdexamfetamine daily or with a placebo.

The psychiatric health and brain functions of the participants were then tracked with tests and surveys and participants’ overall functional impairment was measured via two different professional rating scales to understand the impact of the treatment.

Overall, the results of the study suggest that lisdexamfetamine is an effective medication to treat a variety of symptoms associated with ADHD. Researchers found:

  • There was a 30% improvement in sluggish cognitive tempo symptoms (boredom, trouble staying alert, and signs of confusion).
  • There was a 40% improvement in other ADHD symptoms such as decreased procrastination and improvement in focusing and prioritizing.

While the sample size of the study is relatively small, the improvement noted by the authors suggested a moderate effect of the medication, according to Edelstein.

"The effect noted in the study suggests that the treatment is efficacious in reducing the symptoms targeted," Edelstein says. While this is a great start, more research is needed to understand whether it is an effective treatment and its impact on real-world functional impairment.

He suggests looking into reports from family members or friends to determine whether the treatment significantly improved participants' lives.

According to Edelstein, these conclusions are consistent with other studies in this area of research, and future investigations should build on the work of this preliminary study by including a larger sample of adults from diverse backgrounds to continue creating solid research in this field.

The research paper also points out some side-effects of LDX treatment, such as decreased appetite, headache, trouble sleeping, and anxiety, so further research could better define these side-effects too. Scientists can also take a closer look at how medication like this can be combined with therapy to bolster treatment.

"While medications are often an important component to treatment for ADHD, there are limits to their effectiveness overall," Edelstein adds. "Medication does not teach skills; in other words, behavioral therapy in combination with medication is often cited as best practice in order to ensure that individuals with ADHD develop effective strategies to support areas of relative weakness."

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Adler LA, Leon TL, Sardoff TM, et al. A placebo-controlled trial of lisdexamfetamine in the treatment of comorbid sluggish cognitive tempo and adult ADHD. J Clin Psychiatry. 2021;82(4). doi:10.4088/JCP.20m13687

  2. Barkley RA. Distinguishing sluggish cognitive tempo from attention-deficit/hyperactivity disorder in adultsJ Abnorm Psychol. 2012;121(4):978–990. doi:10.1037/a0023961

By Sofia Quaglia
Sofia Quaglia is a science and health writer based between Italy, the United Kingdom, and the United States.