Research fills void in our understanding of mental effort for those with ADHD

Chia Fen Hsu

Chia Fen Hsu

A ground-breaking study led by York University Postdoctoral Fellow Chia-Fen Hsu considers the experience of mental effort and discomfort in young adults at risk for Attention-Deficit/Hyperactivity Disorder (ADHD). Working with Faculty of Health Professors John Eastwood and Maggie Toplak, Hsu discovered evidence that could provide a new and productive line of investigation to advance our understanding in this area.

“The results of this research could have wide and interdisciplinary application. For example, helping people find better strategy to engage in tasks requiring mental effort in clinical and educational settings,” Hsu says.

The study, published in Frontiers in Psychology (March 2017), focused on differences in perceived mental effort and discomfort in those at risk and not at risk for ADHD. This work was supported the Natural Sciences and Engineering Research Council of Canada (NSERC) and Social Sciences and Humanities Research Council (SSHRC).

Most commonly diagnosed mental disorder in children

ADHD is the most commonly diagnosed and studied mental disorder in children. It affects between one and seven per cent of kids, and it is diagnosed approximately three times more often in boys than in girls, according to the American Psychiatric Association (APA). It is estimated to affect over 50 million people globally (2015, The Lancet). The disorder is often inherited from one’s parents with genetics determining about 75 per cent of cases, according to the National Collaborating Centre for Mental Health.

ADHD is diagnosed three times more often in boys than in girls, according to the American Psychiatric Association

Children with ADHD are hyperactive and they struggle for focus and control over their impulses. ADHD can continue into adulthood, where individuals have trouble managing time, setting goals and maintaining a job. It has also been linked to addictive behaviour. Current treatments include counselling, lifestyle changes and medications.

Study fills an important research gap

The avoidance of mental effort is a symptom of ADHD, but the experience of mental effort has received relatively little attention in the research world. To fill this research gap and add to the literature of ADHD, Hsu’s research studied individuals at risk for ADHD.

“We explored a novel method to assess the experience of effort and discomfort during a working memory task in a sample of young adults at risk and not at risk for ADHD,” Hsu explains.

Undergrad York students participate in study

The researchers started with 235 undergraduate York students whose average age was 21. The experimental protocol was approved by the Human Participants Review Committee of York’s Office of Research Ethics. Written, informed consent was obtained from all participants at the very beginning of the research protocol before any data was collected.

Based on the researchers’ screening methods, 136 (87 females, 49 males) participants met the criteria for the ADHD-risk group, while 99 (62 females, 37 males) were in the non-ADHD risk group.

The researchers used various tools to assess both groups in terms of mental effort and task difficulty. For example, they used an adapted version of the Paced Auditory Serial Addition Test where numbers were visually presented on a computer screen, one at a time, in a continuous stream. Participants were asked to continuously add the numbers. The easy trials involved adding two single digits that equaled nine or less. The medium trials involved adding two single digits that added up to more than nine. The hard trials involved adding one single and one double digit.

After each set of trials, participants were required to:

  • Rate their current level of mental effort (1 = none; 7 = a lot); and
  • Rate their current level of discomfort or distress (1 = none; 7 = a lot).

After completing this task, participants completed a six-minute demographic and self-report questionnaire. Next, they evaluated their experience with the task, answering the following four questions:

  1. How much mental effort was required to complete this task? (1 = none; 7 = a lot)
  2. On this task, what was your total amount of discomfort or distress? (1 = none; 7 = a lot)
  3. How well did you perform on the task? (1 = significantly below average; 7 = significantly above average)
  4. How willing would you be to do another such task right now? (1 = not at all willing; 7 = definitely willing)
Study participants were asked a series of questions mental effort and discomfort while doing certain tasks

Study participants were asked a series of questions mental effort and discomfort while doing certain tasks

Results: In-the-moment experience needs further research

The researchers discovered three main things:

  • At-risk individuals experienced higher mental effort and discomfort compared to those not at risk.
  • Individuals at risk displayed a stronger correlation between mental effort required and actual accuracy, compared to those not at risk.
  • The most intense and final moments of effort predicted how uncomfortable at-risk individuals remembered the task to be after it was finished. This was not the case for those not at risk.

This led the researchers to conclude that, for those at risk, the subjective experience of in-the-moment mental effort is very important and it should be more carefully defined and measured. “Our study showed that the experience of effort required (or how taxing a task is) was different for individuals at risk for ADHD compared to those not at risk,” Hsu explains.

This points the way for future research. “The experience of being mentally taxed might provide a productive line of investigation that could be used to advance our understanding of the cognitive and affective mechanisms underlying individuals at risk of ADHD,” Hsu concludes.

The article, “Differences in Perceived Mental Effort Required and Discomfort during a Working Memory Task between Individuals At-risk And Not At-risk for ADHD,” was published in Frontiers in Psychology (March 2017).

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By Megan Mueller, manager, research communications, Office of the Vice-President Research & Innovation, York University,

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