Affected brain regions in ADHD

• 1. Affected brain regions in ADHD
• 2. Volume changes in brain regions in ADHD

1. Affected brain regions in ADHD¶

ADHD is associated with changes in different brain regions:

• PFC
  • DlPFC
  • MPFC
  • OlPFC
• Basal Ganglia¹
  • Striatum
    • Nucleus caudates
    • Thalamus
• Cerebellum¹
• Corpus Callosum¹
• Largest reductions in gray matter in:²
• Frontal-parietal brain regions
• Corpus callosum
• Limbic system
  This includes:³
  • Corpus mamillare
    • Memory formation, in the context of the Papez neuron circuit
    • Sexual functions
  • Cingulate gyrus
    • Vegetative functions
    • Psycho- and locomotor drive
  • Parahippocampal gyrus
    • Primarily transmits information from the limbic system to the hippocampus
    • Memory formation
  • Hippocampus
    • Memory formation
    • Vegetative and emotional functions
  • Amygdala
    • Storage of emotionally moving memory content
    • Vegetative and sexual functions
• Significant hypoactivation in²
  • Several frontal-temporal brain regions
  • Right postcentral gyrus
  • Left insula
  • Corpus callosum.

2. Volume changes in brain regions in ADHD¶

In ADHD, the volume of different brain regions is altered.

In children with ADHD, MRI studies found, compared with unaffected individuals

• Total brain volume reduced
  • (by 4 %)⁴
• Caudates reduced⁴⁵
• Anterior PFC reduced in size⁴
• Orbital PFC reduced, predominantly on right side⁶
• Inferior dorsolateral frontal region⁶
• Basal Ganglia
  • Striatum reduced⁶
  • Globus pallidus reduced^{4 6}
• Cerebellum reduced ⁵
  • Central vermis area, predominantly reduced on right side⁴⁶
• ACC
  • Reduced, mostly underactivated⁶
• Corpus callosum
  • Splenium (beam bulge) reduced⁶
• Putamen changed⁵
• Thalamus changed⁵ or hypoactive⁷

The effects were stronger in boys than in girls, he said, correlating with the Polygenic Risk Score.⁵

Children with ADHD showed microstructural changes and alterations in the long-range white matter connections. Learning problems and hyperactivity/impulsivity correlated negatively with mean FA levels in the right forceps major, left IFOF, and left genu internal capsule.⁸

German Interestingly, the reductions in size of certain brain regions that are usually observed from the age of 60 seem to be less pronounced in ADHD. This is discussed as a neuroprotective factor of ADHD. It is open whether this is a consequence of ADHD itself or of stimulant treatment.
This was particularly significant in brain regions where a strong loss of volume correlates with cognitive impairment and Alzheimer’s disease, such as the hippocampus and amygdala.
⁹