CATECHOLAMINES IN ATTENTION-DEFICIT HYPERACTIVITY DISORDER - CURRENT PERSPECTIVES

Objective: To provide an update on the ''catecholamine hypothesis'' of attention-deficit hyperactivity disorder (ADHD). Method: Recent work examining the measurement of the norepinephrine, epinephrine, and dopa mine systems in ADHD and normal subjects is reviewed and discussed in the context of recent neuroimaging and animal studies. Results: While data clearly indicate a role for all three of the above neurotransmitt ers in ADHD, a hypothesis suggesting ''too much'' or ''too little'' of a single neurotransmitter will no longer suffice. The central norepin ephrine system may be dysregulated in ADHD, such that this system does not efficiently ''prime'' the cortical posterior attention system to external stimuli. Effective mental processing of information involves an anterior ''executive'' attention system which may depend on dopamin ergic input. The peripheral epinephrine system may be a critical facto r in the response of individuals with ADHD to stimulant medication. Co nclusion: A multistage hypothesis is presented which emphasizes the in teraction of norepinephrine, epinephrine, and dopamine in modulation o f attention and impulse control.