Dysfunctional modulation of default mode network activity in attention-deficit/hyperactivity disorder

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Attention-deficit/hyperactivity disorder (ADHD) is linked to difficulties in state regulation and effective mental effort application.
• Individuals with ADHD exhibit diminished suppression of the default mode network (DMN), impacting performance on effortful tasks.
• The state regulation deficit model suggests challenges arise under suboptimal conditions, like extreme event rates (ERs).

Purpose of the Study:

• To investigate if DMN activity modulation in ADHD is particularly disrupted at extreme event rates (fast and slow).
• To test the hypothesis that altered DMN activity in ADHD is exacerbated under suboptimal task conditions.

Main Methods:

• Nineteen adults with ADHD and 20 controls performed a target detection task under three ER conditions (2-, 4-, 8-s ISIs) while undergoing fMRI.
• Task-related DMN deactivations were compared between the ADHD and control groups across different ERs.

Main Results:

• A differential effect of ER on DMN activity was observed between groups.
• Individuals with ADHD showed excessive DMN activity at fast and slow ERs, but not at moderate ERs.
• This suggests DMN attenuation is disrupted in ADHD under conditions requiring increased effort.

Conclusions:

• DMN dysregulation in ADHD is pronounced during suboptimal energetic states that demand greater effort for task engagement.
• Altered DMN activity may underlie state regulation deficits observed in attention-deficit/hyperactivity disorder.
• These findings contribute to understanding the neurobiological basis of ADHD-related challenges in effortful cognitive control.