ADHD in Children
Visual Abstract
Differential Effects of Methylphenidate on Working Memory in ADHD Children with and without Comorbid Anxiety
Anxiety disorders can change how ADHD responds to Ritalin
ROSEMARY TANNOCK, PH.D., ABEL ICKOWICZ, M.D., AND RUSSELL SCHACHAR, M.D.
Summarized by:
March 6, 2023
study source
J Am Acad Child Adolesc Psychiatry
Jul 1995
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What they studied
Researchers wanted to study the effects of methylphenidate on those with ADHD and anxiety compared to those with only ADHD.
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What they found
Ritalin only improved working memory in those without anxiety. However, under time pressure, the differences in performance for those with and without anxiety diminished.
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What this means
Anxiety changes how ADHD affects our brain and how we respond to ADHD treatment. Those with ADHD and anxiety may have different symptoms and treatment needs than those with only ADHD.
Differential Effects of Methylphenidate on Working Memory in ADHD Children with and without Comorbid Anxiety
Objective
Growing evidence shows that those with anxiety and ADHD have different symptoms and experiences than those with only ADHD.
For example, those with ADHD and anxiety can have more difficulty with working memory than those with only ADHD. Some experts theorize that this may be because worry gets in the way of memory processing.
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Worry is the cognitive component of anxiety and according to processing efficiency theory, its effect is to preempt some processing and storage resources of the working memory system (Eysenck and Calvo, 1992). As a consequence, worry tends to impair performance on tasks with high demands on working memory.
Eysenck and Calvo. 1992
But, there’s still a lot to be studied on the effects of medication on those with ADHD and anxiety. Medication is a key part of ADHD treatment.
Ritalin, generically known as methylphenidate, is a medication commonly used for ADHD.
It’s a stimulant medication shown to be highly effective in many with ADHD.
In this study, researchers examined the effects of Ritalin on working memory and behavior to see whether it works differently in those with ADHD.
Study Quote
To examine the effects of methylphenidate (MPH) on working memory and behavior in anxious and non-anxious children with attention-deficit hyperactivity disorder (ADHD).
Method
Researchers ran a small clinical trial on 40 children with ADHD. Eighteen of these participants also had anxiety. The other 22 only had ADHD. During part of the study, participants received Ritalin. They then switched to a placebo control to determine the specific effects of Ritalin.
During the trial, researchers conducted tests of working memory and observed behavior to assess the effects of the medication.
Study Quote
A total of 40 ADHD children (22 nonanxious, 18 anxious) completed a randomized, double-blind, placebo-controlled, crossover trial with three doses (0.3, 0.6, 0.9 mg/kg) of MPH. A serial addition task was used to assess working memory; direct observation of motor activity indexed behavior.
Results
The results showed that Ritalin effectively reduced hyperactivity in both groups, as expected.
Those without an anxiety disorder also saw improvements in working memory.
However, no improvement was seen in working memory for those with anxiety and ADHD.
Ritalin was only partially effective in those with ADHD and anxiety. It reduced hyperactivity but did not help with working memory.
As you can see in the chart below, as researchers increased the Ritalin dose, those with only ADHD showed improvements in a working memory test.
Meanwhile, those with anxiety and ADHD saw no significant changes in performance.
Children with ADHD and Anxiety did not improve as much as those with just ADHD when given Ritalin
A second analysis found that when experimenters asked participants to work quickly, the differences between those with ADHD and anxiety and those with only ADHD diminished.
When forced to work quickly, the differences between the Anxiety + ADHD and ADHD only groups diminished
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Post hoc comparisons of the two groups at each presentation rate revealed that the ADHD+ANX group performed significantly worse than the ADHD group on both 2.8-second trials (p < .01), but the two groups did not differ on either the 2.4-second or 2.0-second trials.
This suggests that the differences between those with and without anxiety diminish when those with ADHD have to work faster.
Study Quote
MPH improved working memory in the nonanxious ADHD group but not in the comorbidly anxious group. By contrast, MPH reduced activity level in both groups. The presence of concurrent learning disabilities did not influence stimulant response.
Conclusions
The results of this study show that the relationship between ADHD and anxiety may be quite complex.
Anxiety changes how ADHD affects us. It can make it harder for those with health disorders to perform cognitive tasks.
One potential explanation theorized by the authors is that anxiety may increase arousal and effort when faced with time pressure.
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One possibility is that the increased rate of presentation exerted positive effects on arousal and effort in the A D H D + A N X group and offset the expected negative effects of increasing the rate of stimulus presentation.
Study Quote
The presence of comorbid anxiety in children with ADHD predicts a less robust response to stimulant treatment and suggests that ADHD with anxiety may constitute a distinct and clinically meaningful subtype of ADHD.