A new study published in Neuropsychology Review has revealed that children and adolescents diagnosed with attention-deficit hyperactivity disorder (ADHD) exhibit significantly poorer object recognition memory compared to their peers without ADHD. This meta-analysis of 28 studies sheds light on the cognitive challenges faced by this population.
ADHD is a neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with functioning or development. Children with ADHD often struggle with maintaining focus, following through on tasks, and controlling their impulses. These symptoms can significantly impact academic performance, social interactions, and daily activities. ADHD is one of the most commonly diagnosed mental health disorders in children, but it also affects adults.
Object recognition memory refers to the ability to recognize previously encountered objects and distinguish them from new ones. This type of memory is an important component of declarative memory, which encompasses facts and events that can be consciously recalled. Object recognition memory involves two primary processes: familiarity discrimination, which allows one to recognize something as familiar, and recollection, which involves retrieving details about the encounter.
While previous research has extensively explored verbal memory deficits in ADHD, object recognition memory has received less attention, and findings have been inconsistent. By conducting a meta-analysis of existing studies, the researchers aimed to clarify whether children with ADHD exhibit significant impairments in this type of memory.
“My interest in the topic derives from my doctoral thesis on the long-term effects of stimulant treatment on memory in people diagnosed with ADHD, especially in children and adolescents,” said study author Francisco José Lobato-Camacho, a PhD student at the University of Seville.
The researchers conducted a meta-analysis of 28 studies involving 1,619 participants diagnosed with ADHD and 1,567 control participants without ADHD. The participants were between the ages of 6 and 18, covering a critical developmental period for memory and learning.
To assess object recognition memory, the studies used tasks similar to the delayed matching-to-sample (DMS) task. This task involves an encoding phase, where participants are shown a target stimulus, followed by a recognition phase, where they must identify the previously seen stimulus among distractors after a delay. The DMS task can be divided into two types:
Type A: A single stimulus is shown, and after a short delay, participants choose the previously seen stimulus from several options.
Type B: Multiple target stimuli are shown sequentially, followed by a recognition phase where participants identify old and new stimuli.
The studies included in the meta-analysis used various versions of these tasks, presented on computer screens or as part of neuropsychological assessment batteries.
The results showed a moderate but consistent deficit in object recognition memory among the ADHD group, indicating that these children struggle more with recognizing previously seen objects.
One of the key insights from the study is the influence of task type on the extent of memory impairment. The researchers found that the deficits were more pronounced when children with ADHD were tested using Type A tasks. The need to distinguish the target stimulus from distractors may exacerbate the memory difficulties experienced by children with ADHD, possibly due to their known issues with inhibitory control and attention.
“People diagnosed with ADHD usually have learning problems,” Lobato-Camacho told PsyPost. “These are generally related to behavioral issues or attention problems. However, without excluding the above problems, a deficit in recognition memory can negatively influence your learning. Bearing in mind that recognition memory tests are an important part of the curriculum, it is logical to deduce that these people start at a disadvantage both in their learning and in their evaluation.”
Additionally, the study explored the impact of medication on memory performance. Both medicated and non-medicated children with ADHD showed poorer recognition memory compared to their control counterparts, but there was greater variability in performance among the medicated group. This suggests that while medication can help manage ADHD symptoms, its effects on memory might be influenced by factors such as the duration and consistency of treatment.
“I was surprised that there was greater intra-group variability in people on stimulant treatment compared to the group of people not receiving treatment,” Lobato-Camacho said. “This may be due to intragroup differences in times under treatment.”
This meta-analysis highlights that children and adolescents with ADHD face specific challenges in object recognition memory, adding to the broader understanding of memory deficits associated with the disorder. These findings underscore the importance of addressing memory difficulties in interventions for ADHD to improve educational and daily functioning outcomes for affected children.
“In the long term, it would be interesting to conduct a study that relates the deficit in object recognition memory and learning problems in this population,” Lobato-Camacho said said.
The study, “Object Recognition Memory Deficits in ADHD: A Meta‑analysis,” was authored by Francisco José Lobato‑Camacho and Luís Faísca.
