ADHD, or attention deficit hyperactivity disorder, is a neurodevelopmental disorder affecting millions worldwide. While the exact causes of ADHD are still not fully understood, research has shown that differences in brain chemistry may play a role in the disorder. One of the critical neurotransmitters implicated in ADHD is dopamine.
Dopamine is a neurotransmitter that plays a crucial role in motivation, reward processing, and attention. In people with ADHD, research has shown that dopamine levels may be lower than in those without the disorder (1). This can lead to difficulties with attention focus and impulse control, which are hallmark symptoms of ADHD.
One study that examined dopamine levels in people with ADHD found that they had lower dopamine levels in some areas of the brain than those without the disorder (2). This suggests that dopamine dysregulation may be critical in developing ADHD symptoms.
In addition to dopamine levels, research has also shown that dopamine receptor function may differ in people with ADHD compared to those without the disorder. Dopamine receptors are proteins on the surface of cells that allow dopamine to bind and exert its effects. One study found that people with ADHD had fewer dopamine receptors in specific brain regions than those without the disorder (3). This suggests that dopamine signalling may be less efficient in people with ADHD, which could contribute to their symptoms.
While the exact role of dopamine in ADHD is still being studied, medications that increase dopamine levels, such as stimulants, are often used to treat the disorder. These medications have improved attention, focus, and impulse control in people with ADHD (4). However, the exact mechanisms by which these medications work are not fully understood.
Dopamine dysregulation may play a vital role in the development of ADHD symptoms. Research has shown that people with ADHD may have lower dopamine levels and fewer dopamine receptors than those without the disorder. While medications that increase dopamine levels are often used to treat ADHD, more research is needed to understand dopamine's role in the disorder fully.
References:
Volkow ND, Wang GJ, Kollins SH, et al. "Evaluating dopamine reward pathway in ADHD: clinical implications." JAMA. 2009;302(10):1084-1091.
Del Campo N, Chamberlain SR, Sahakian BJ, and Robbins TW The roles of dopamine and noradrenaline in the pathophysiology and treatment of attention-deficit/hyperactivity disorder Biol Psychiatry. 2011;69(12):e145–e157.
Volkow ND, Fowler JS, Wang GJ, et al. Decreased dopamine D2 receptor availability is associated with reduced frontal metabolism in cocaine abusers. Synapse. 1993;14(2):169-177.
Spencer T.J., Brown A., Seidman L.J., et al. Effect of psychostimulants on brain structure and function in ADHD: a systematic review and meta-analysis Biol Psychiatry. 2013;74(8):611-618.