ADHD and the Prefrontal Cortex

Summary & key facts

Research links ADHD — which shows up as inattention, impulsivity, and too much activity — to weaker structure and function in the brain’s prefrontal cortex (PFC), especially on the right side. The PFC helps control top-down attention, stop inappropriate actions, and regulate emotion, and it needs the right balance of the chemicals norepinephrine and dopamine to work well. Genetic studies and brain imaging support these PFC findings, and common ADHD medicines boost norepinephrine and dopamine signaling in the PFC; animal studies at therapeutic doses show these drugs raise norepinephrine (and to a lesser extent dopamine) in the PFC and improve attention and reduce hyperactivity. The PFC is als

Key facts:

• ADHD is described by symptoms of inattention, poor impulse control, and increased motor activity.
• Imaging studies have found that people with ADHD often have weaker PFC circuits and less PFC activation when trying to control attention and behavior, especially in the right hemisphere.
• The prefrontal cortex (PFC) controls "top-down" attention — the ability to focus on goals and ignore distractions — and helps inhibit inappropriate responses.
• The PFC needs proper levels of norepinephrine (NE) and dopamine (DA) to work well; NE acts at alpha-2A receptors and DA acts at D1 receptors for optimal PFC function.
• Genetic studies have consistently reported changes in genes involved in catecholamine (norepinephrine and dopamine) transmission in people with ADHD.
• All approved drug treatments for ADHD strengthen catecholamine signaling in the PFC, according to the review.
• Animal studies show that therapeutic doses of stimulant medications preferentially increase norepinephrine and, to a lesser extent, dopamine in the PFC; at these doses animals show reduced locomotor activity and improved PFC regulation of a
• The right inferior PFC is especially important for stopping or inhibiting actions, and imaging and stimulation studies show this area is underactive or its weakening impairs inhibition.
• The PFC is the last brain region to mature, with full maturation occurring only in late adolescence, which makes it vulnerable to genetic or environmental problems.
• The term "inattention" in the DSM does not distinguish between PFC-related (top-down) attention problems and problems arising from posterior sensory cortices (bottom-up), so current diagnostic criteria can miss important differences.

Topics

Attention Deficit Hyperactivity Disorder Functional Brain Connectivity Studies Neural and Behavioral Psychology Studies

Categories

Health Sciences Medicine Psychiatry and Mental health

Tags

Attention deficit hyperactivity disorder Clonidine Cognition Dopamine Dopaminergic Guanfacine Impulsivity Internal medicine Medicine Neurochemical Neuroscience Prefrontal cortex Psychiatry Psychology Stimulant Stimulation