Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are common neurodevelopmental disorders characterised by distinct behavioural symptoms. While the causes of these disorders remain under investigation, recent research suggests that alterations in brain structure and function may play a significant role.
A new study published in BMC Medicine sheds light on this topic by investigating cortical thicknessĀ in youth with Autism and ADHD. Cortical thickness refers to the thickness of the outermost layer of the brain, known as the cerebral cortex, which is involved in various critical functions, including sensory processing, movement, and higher-order cognitive abilities.
The study employed a meta-analysisĀ approach, which involves statistically combining data from multiple existing studies. This approach allows researchers to gain a more comprehensive understanding of a phenomenon by analysing a larger sample size and reducing the impact of individual study variations.
The researchers compared cortical thickness in youth with ASD or ADHD to typically developing controls (TDC). Their findings revealed that both ASD and ADHD are associated with cortical thickness alterationsĀ in specific brain regions. However, importantly, the patterns of alterations differed between the two conditions.
ASD and Increased Cortical Thickness in Specific Regions
The study found that youth with ASD exhibited increased cortical thicknessĀ in several brain regions, including the:
Superior frontal gyrus:Ā This region is involved in various higher-order cognitive functions, including social interaction, planning, and decision-making.
Left middle temporal gyrus:Ā This region plays a crucial role in language processing and comprehension.
Right superior parietal lobule:Ā This region is involved in visual attention, spatial processing, and navigation.
These findings suggest that increased cortical thickness in these brain regions may contribute to some of the core symptoms observed in ASD, such as social difficulties, language impairments, and sensory processing challenges.
ADHD and Decreased Cortical Thickness in Specific Regions
In contrast to ASD, youth with ADHD displayed decreased cortical thicknessĀ in several brain regions, including the:
Bilateral precentral gyri:Ā These regions are involved in motor control and planning.
Right postcentral gyrus:Ā This region is involved in sensory perception and processing.
Right temporoparietal junction (RTPJ):Ā This region is involved in integrating information from different senses and is also implicated in social cognition.
The Right Temporoparietal Junction: A Key Player in Both ASD and ADHD
Interestingly, the study identified the right temporoparietal junction (RTPJ)Ā as a brain region where both ASD and ADHD showed decreased cortical thickness. This finding aligns with previous research, such as the study by S. C. Krall et al. [2014], which suggests that the RTPJ plays a crucial role in social interaction and the ability to understand the mental states of others (theory of mind).
Decreased cortical thickness in the RTPJ in both ASD and ADHD may contribute to the social interaction challenges observed in these conditions. However, it's important to note that the specific waysĀ in which the RTPJ dysfunction manifests in each condition might differ. For instance, in ASD, the RTPJ dysfunction might be related to difficulties in interpreting social cues, while in ADHD, it might be linked to problems with maintaining attention during social interactions.
Shared and Distinct Neurobiological Features of ASD and ADHD
The identification of the RTPJ as a shared region of cortical thickness reduction in ASD and ADHD highlights the existence of some overlapping neurobiological featuresĀ underlying both conditions. However, the study also revealed distinct patterns of cortical thickness alterations in other brain regions, suggesting significant neurological heterogeneity within these conditions.
Significance of the Study
This study holds significant implications for our understanding of ASD and ADHD. By identifying distinct patterns of cortical thickness alterations in each condition, the study contributes to a more nuanced understanding of the neurobiological heterogeneityĀ within these conditions.
Furthermore, the findings may have important clinical implications. By providing insights into the brain regions potentially involved in ASD and ADHD, the study may pave the way for the development of more targeted diagnostic and treatment approachesĀ in the future.
It is important to note that this study is correlational and cannot establish causality. Future research is needed to investigate the causal relationships between cortical thickness alterations and the symptoms of ASD and ADHD. Additionally, the study focused on youth, and further research is necessary to determine whether these findings generalise to adults with these conditions.
Overall, this study provides valuable new insights into the brain basis of ASD and ADHD. The findings highlight the importance of considering the neurological heterogeneityĀ within these conditions and pave the way for future research aimed at developing more targeted diagnostic and treatment approaches.
Did any of this resonate with you? If you have ADHD, or suspect you might, share your experiences in the comments below. Your story could help someone else feel less alone.
š A Smile and a Thought š¤
"ADHD is when you're on your way to grab a snack and decide to change careers, learn the drums, and clean out your cabinets first.ā
āPeople with ADHD often have a special "feel" for life, a way of seeing right into the heart of matters, while others have to reason their way along methodically. ā Dr Ned Hallowell
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