Cognitive issues in ADHD and learning difficulties appear to have different roots

A new study reports that the widespread cognitive difficulties in children with learning problems appear to be a core feature of their condition, independent of their attentional behaviors. In contrast, the more limited cognitive challenges found in children with Attention Deficit Hyperactivity Disorder (ADHD) who do not have learning difficulties may be consequences of their inattention and hyperactivity. The research was published in the Journal of Attention Disorders.

Children with ADHD and those with specific learning difficulties often exhibit overlapping challenges with attention and certain thinking skills. This has led researchers to question the nature of this relationship: Are the difficulties with memory and processing simply a side effect of being inattentive or hyperactive? A team of researchers sought to disentangle these factors to better understand the underlying cognitive profiles of these distinct but frequently co-occurring conditions.

“While there have been previous studies that examined the link between ADHD symptoms and learning or cognitive skills in groups of children with ADHD or learning difficulties, there has been no study that examined how ADHD symptoms influence cognitive skills that are key to learning in these neurodivergent groups,” said study author Yufei Cai, a PhD researcher in the Department of Psychiatry at the University of Cambridge.

“Understanding how ADHD attentional behaviors influence these cognitive skills that are essential for successful learning in these neurodivergent populations can offer suggestions for designing interventions that might improve cognitive or learning functioning in these neurodivergent groups.”

To investigate, the researchers performed a detailed analysis of existing data from the Centre for Attention, Learning, and Memory, a large cohort of children referred for concerns related to attention, memory, or learning. They selected data from 770 children, aged 5 to 18, and organized them into four distinct groups. These groups included children with a diagnosis of ADHD only, children with learning difficulties only, children with both ADHD and learning difficulties, and a comparison group of children with no known neurodevelopmental conditions.

Each child had completed a broad range of standardized tests. These assessments measured fundamental cognitive skills such as verbal and visuospatial short-term memory, working memory (the ability to hold and manipulate information temporarily), processing speed, and sustained attention. Higher-level executive functions, like the ability to flexibly shift between different tasks or rules, were also evaluated. Alongside these direct assessments, parents provided ratings of their child’s daily behaviors related to inattention and hyperactivity or impulsivity.

“Our study is the first to date that has (1) a relatively large neurodivergent sample size, (2) a comprehensive battery of cognitive and learning measures, and (3) the inclusion of a co-occurring condition group of those with both ADHD and learning difficulties to examine the extent to which elevated scores of ADHD symptoms can account for the group differences in cognitive skills that are key to learning between these neurodivergent and comparison groups,” Cai told PsyPost.

“The study aims to characterize the cognitive profiles of these three neurodivergent groups, as well as examine the associations between ADHD symptoms (i.e., inattentive and hyperactive/impulsive behaviors) and cognitive skills that are key to learning in children with ADHD, learning difficulties, and those with both conditions.”

The core of the analysis involved a two-step comparison. First, the researchers compared the performance of the four groups across all the cognitive tests to identify where differences existed. Next, they applied a statistical approach to see what would happen to these differences if they mathematically adjusted for each child’s level of parent-rated inattention and hyperactivity. If a group’s cognitive weakness disappeared after this adjustment, it would suggest the cognitive issue might be a consequence of attentional behaviors. If the weakness remained, it would point to a more fundamental cognitive deficit.

The results revealed a clear divergence between the groups. Children with learning difficulties, both with and without a co-occurring ADHD diagnosis, displayed a broad pattern of lower performance across many cognitive domains. They showed weaknesses in short-term memory, working memory, processing speed, sustained attention, and the ability to sequence information.

When the researchers statistically accounted for levels of inattention and hyperactivity, these cognitive deficits largely persisted. This outcome suggests that for children with learning difficulties, these cognitive challenges are likely foundational to their condition, not just a byproduct of attentional issues.

The profile for children with ADHD only was quite different. This group performed at age-appropriate levels on many of the cognitive tasks, including verbal short-term memory, working memory, processing speed, and sustained attention. They did show some specific difficulties, particularly in visuospatial short-term memory and the ability to quickly sequence numbers or letters.

However, these particular challenges were no longer apparent after the statistical analysis adjusted for their levels of inattention and hyperactivity. This finding indicates that for these children, their attentional behaviors may directly interfere with performance on certain cognitive tasks.

One specific challenge did appear to be independent of attentional behaviors for the ADHD only group. Their difficulty with set shifting, or mentally switching between different task rules, remained even after accounting for inattention and hyperactivity. This points to a more specific executive function challenge in ADHD that may not be fully explained by its primary behavioral symptoms.

Overall, the findings paint a picture of two different neurodevelopmental pathways. For children with learning difficulties, core cognitive weaknesses appear to drive their academic struggles. For many children with ADHD alone, their primary attentional challenges may be what creates more limited and specific hurdles in their cognitive performance.

“Children with learning difficulties, either with or without ADHD, had lower levels of cognitive skills than children with ADHD without co-occurring learning difficulties and those in the comparison group,” Cai explained. “Elevated levels of inattention and hyperactive/impulsive behaviors did not influence the low cognitive performance observed in these children. Instead, this lower cognitive performance may be more closely associated with their learning ability, which is central to their neurodevelopmental characteristics.”

“However, these attentional behaviors are closely linked to the more limited cognitive challenges observed in children with ADHD without co-occurring learning difficulties. Understanding whether neurodivergent children with ADHD, learning difficulties, or both experience cognitive or learning-related challenges provides a valuable framework for designing targeted intervention and support strategies.”

But as with all research, the study includes some limitations. The group with learning difficulties was identified based on low scores on academic tests rather than formal clinical diagnoses of conditions like dyslexia or dyscalculia, which might not be perfectly equivalent. The study’s design provides a snapshot at a single point in time, so it cannot capture how these relationships might evolve as children develop.

Future research could build on these findings by following children over several years to observe these developmental trajectories directly. Incorporating a wider array of cognitive measures and gathering behavioral information from multiple sources, including teachers, could also help create an even more detailed understanding. Such work could help refine support strategies, ensuring that interventions are targeted to a child’s specific profile of cognitive and behavioral needs.

The study, “Associations Between ADHD Symptom Dimensions and Cognition in Children With ADHD and Learning Difficulties,” was authored by Yufei Cai, Joni Holmes, and Susan E. Gathercole.