Adult ADHD
Visual Abstract
Executive functioning in adult ADHD: a meta-analytic review
A Marije Boonstra, Jaap Oosterlaan, Joseph A Sergeant, Jan K Buitelaar
Summarized by:
April 22, 2023
study source
Psychological Medicine
Aug 2005
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What they studied
This study wanted to confirm the effects of ADHD on executive function to see whether other cognitive deficits were linked with ADHD.
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What they found
Researchers found strong links between ADHD and cognitive deficits in executive function. They also found evidence of non-executive function cognitive deficits.
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What this means
This study confirms the link between ADHD and executive function. It also provides data suggesting other potential cognitive deficits, but we will need more research to know for sure.
Executive functioning in adult ADHD: a meta-analytic review
Objectives
Executive function is believed to play a key role in ADHD.
It encompasses functions such as staying attentive and impulse control. These are areas where those with ADHD can struggle.
What is executive function?
However, ADHD is a broad condition linked with many symptoms. As a result, the researchers in the study wanted to see how strong the link between ADHD and executive function was.
Study Quote
Several theoretical explanations of ADHD in children have focused on executive functioning as the main explanatory neuropsychological domain for the disorder. In order to establish if these theoretical accounts are supported by research data for adults with ADHD, we compared neuropsychol...
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Methods
The researchers conducted a meta-analysis covering 13 studies that compared adults with ADHD and adults without ADHD.
Study Quote
We compared 13 studies that (1) included at least one executive functioning measure, (2) compared the performance of an adult ADHD group with that of an adult normal control group, (3) provided sufficient information for calculation of effect sizes, and (4) used DSM-III-R or DSM-IV crit...
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Results
As expected, researchers found that those with ADHD had more trouble with tasks involving executive function. These included tasks involving verbal fluency, inhibition, and set-shifting.
Each area involved a specific test designed to differentiate strengths and weaknesses. For example, set shifting was tested with the trail-making test, a standardized test detailed below:
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The Trail Making Test is one of the most commonly used pencil-and-paper instruments in neuropsychology practice... Part B (TMT-B) involves the patient connecting numbered and lettered circles in alternating alphanumeric sequencing (i.e., 1-A-2-B-3-C, and so-on through L-13)
The results showed that those with ADHD also struggled with tests outside of executive function. This suggests that cognitive deficits in ADHD may extend further than previously thought.
Study Quote
We found medium effect sizes both in executive functioning areas [verbal fluency (d= 0-62), inhibition (d = 0-64 and d = 0.89), and set shifting (d = 0.65)] and in non-executive functioning domains [consistency of response (d = 0.57), word reading (d = 0.60) and color naming (d = 0.62)].
Conclusions
Based on the study's results, the researchers concluded that cognitive issues in ADHD may be broader than we previously thought.
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In light of the current emphasis on EF in ADHD research, we feel that the most striking outcome of this review is the similarity in ES between the EF domain and the non-EF domain.
One ambiguity in the results is that some of the tests for non-executive functions may still involve some level of executive function. For example, the color naming and word reading tasks require a fair amount of focus and sustained attention, which are executive functions.
At this point, it’s hard to tell whether the results of non-executive function tests truly reflect deficits outside of executive function. The authors state in the conclusion that these results highlight the need for more research and for better tests of executive function.
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We do not believe that our similar results in the EF and non-EF domains indicate that we should discard the possible EF explanation for ADHD altogether, but it seems high time for some changes in the field. For one thing, it seems, now more than ever, necessary to develop reliable and valid measures of EF.
Study Quote
Neuropsychological difficulties in adult ADHD may not be confined to executive functioning. The field is in urgent need of better-designed executive functioning tests, methodological improvements, and direct comparisons with multiple clinical groups to answer questions of specificity.