ADHD & the Brain

What Parts of the Brain Are Involved?


Before explaining how ADHD affects the brain, we will briefly review the different areas and functions of each part of the brain.

The brain is responsible for all of the body’s activities, and divides tasks across its different areas. This is how the brain can manage sensory information and coordination as well as control movements and behaviour, amongst other things.  After being processed, information is shared amongst all the other areas of the brain, so the body can quickly and appropriately respond.  The ability to share information between the different parts of the brain is critical to healthy brain function.

How Does ADHD Affect the Brain?

Neurotransmitters are like chemical messengers between the different parts of the brain. Studies indicate that ADHD causes problems with the chemical messengers that connect two brain areas: the prefrontal cortex and the basal ganglia. These areas communicate through two neurotransmitters called dopamine and noradrenaline. It is believed that in people with ADHD, there is an alteration in the way noradrenaline and dopamine level are regulated, leading to reduction in their levels and abnormal functioning.

Many brain-imaging studies have shown that there are several brain regions broadly affected by inactivity and dysfunction as a result of neurotransmitter imbalance experienced by children with ADHD:

  • The Prefrontal Cortex is responsible for planning, initiating, and realising actions as well as correcting errors, avoiding distractions, and being flexible when things change.
  • The Basal Ganglia is responsible for impulse control. It coordinates information coming from other regions of the brain to prevent automatic responses to stimuli, such as loud noises.
  • The Corpus Callosum is responsible for communication between the two brain hemispheres to ensure coordinated, complementary work.
  • The Anterior Cingulate is responsible for management of emotions.

brain

If these areas of the prefrontal cortex (shown in green, blue, and brown) are not able to function and process their tasks, this can negatively impact attention, alertness, and working memory, resulting in the following:

  • Diminished focus:
    • The inability to start and continue activities
    • Reduced working memory (or short-term memory)
    • The inability to block inappropriate responses
  • Difficulty in planning complex activities:
    • A hampered ability to organise
    • Increased physical activity
    • Increased impulsivity