Do ADHD subtypes have differences in brain structure?

Research has consistently shown that ADHD, or Attention Deficit Hyperactivity Disorder, impacts the brain's structure and function. One way scientists study this is through functional Magnetic Resonance Imaging (fMRI), a tool that helps visualize brain activity. fMRI studies on ADHD reveal changes in brain activation, particularly in children and adults, by highlighting which areas of the brain are more or less active during tasks.

ADHD manifests in different forms, often categorized as subtypes. In adults, the most common subtype is the combined subtype, followed by inattentive, and finally, the least common, hyperactive/impulsive.

Further diving into the differences among ADHD subtypes, advanced imaging techniques like MRI have been instrumental. For instance, those with combined ADHD (ADHD-C) show unusual connectivity in their midline default network and insular cortex. In contrast, those with the inattentive subtype (ADHD-I) exhibit atypical connectivity in dorsolateral prefrontal regions and the cerebellum. These distinct neural connectivity patterns in ADHD subtypes are significant because they align with the behavioral characteristics observed in each group.

The brain's default network plays a pivotal role in our internal thought processes. It's most active when we're not focusing on the external world, like during daydreaming or reminiscing. This network is essential in understanding ADHD, especially the combined subtype, as it is responsible for a range of functions from planning to imagining.

The insular cortex, though a small part of the brain, is mighty in its functions. It helps in processing everything from taste and movement to risk assessment and pain perception. Differences in the insular cortex in those with combined ADHD are particularly noteworthy as they could explain the unique challenges faced by individuals with this subtype.

The dorsolateral prefrontal cortex (dlPFC) is key in executive functioning, which includes skills like focusing, decision-making, and working memory. Variations in this region in those with inattentive ADHD might be the underlying reason for their distinct challenges, such as difficulty in maintaining attention or organizing tasks.

These findings are consistent with other studies showing that your subtype of ADHD is linked with how you perceive the world and process information.