Meta‐analysis reveals a reduced surface area of the amygdala in individuals with attention deficit/hyperactivity disorder

• Published in: Psychophysiology Vol. 60; no. 9; pp. e14308 - n/a
• Main Authors: Chen, Meng‐Hsiang, Lin, Hsiu‐Man, Sue, Yu‐Ru, Yu, Yun‐Chen, Yeh, Pin‐Yang
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.09.2023
• Subjects: ADHD; Amygdala; Amygdala - diagnostic imaging; Attention Deficit Disorder with Hyperactivity - diagnostic imaging; Attention deficit hyperactivity disorder; Between-subjects design; Brain - pathology; Female; Hemispheric laterality; Humans; Image processing; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Meta-analysis; Motivation; Observational studies; Observational Studies as Topic; review; Segmentation; Statistical analysis; structural magnetic resonance imaging; Surface area; voxel‐based morphometry; structural magnetic resonance imaging; ADHD; voxel-based morphometry; Amygdala; review
• ISSN: 0048-5772; 1469-8986; 1469-8986; 1540-5958
• DOI: 10.1111/psyp.14308

Despite the reported lack of structural alterations in the amygdala of individuals with attention deficit/hyperactivity disorder (ADHD) in previous meta‐analyses, subsequent observational studies produced conflicting results. Through incorporating the updated data from observational studies on structural features of the amygdala in ADHD, the primary goal of this study was to examine the anatomical differences in amygdala between subjects with ADHD and their neurotypical controls. Using the appropriate keyword strings, we searched the PubMed, Embase, and Web of Science databases for English articles from inception to February 2022. Eligibility criteria included observational studies comparing the structure of the amygdala between ADHD subjects and their comparators using magnetic resonance imaging (MRI). Subgroup analyses were conducted focusing on the amygdala side, as well as the use of different scanners and approach to segmentation. The effects of other continuous variables, such as age, intelligence quotient, and male percentage, on amygdala size were also investigated. Of the 5703 participants in 16 eligible studies, 2928 were diagnosed with ADHD. Compared with neurotypical controls, subjects with ADHD had a smaller amygdala surface area (particularly in the left hemisphere) but without a significant difference in volume between the two groups. Subgroup analysis of MRI scanners and different approaches to segmentation showed no statistically significant difference. There was no significant correlation between continuous variables and amygdala size. Our results showed consistent surface morphological alterations of the amygdala, in particular on the left side, in subjects with ADHD. However, the preliminary findings based on the limited data available for analysis warrant future studies for verification. This meta‐analytic review finds a difference in amygdala size between individuals with attention‐deficit/hyperactivity disorder (ADHD) and neurotypical controls, by using different image analyses. Although volumetric image analysis revealed no significant differences in amygdala anatomy, we used its surface area to identify the structural alterations, particularly on the left side, in ADHD, shedding light on psychotherapy designed to improve their emotion dysregulation.