What parts of the brain are affected in ADHD?

In studies of ADHD children, the structures that most often have been found to play a role are the frontal lobes, the striatum (particularly the caudate), and the connection between these structures, which is called the frontostriatal circuitry. More recently, the cerebellum has also been found to play a role in ADHD (Figure 1).

If you are not a neurologist, that explanation probably does not mean much, so here is a quick lesson in brain anatomy and function. Your brain is made up of four lobes: frontal, parietal, temporal, and occipital. By and large, the frontal lobes control executive functioning (e.g., planning, organizing, starting, persisting, shifting, and inhibiting impulsive behaviors). The parietal lobes control sensory functions and spatial skills (especially the right parietal lobe). The temporal lobes control language comprehension and memory, and the occipital lobes control vision. The left frontal lobe has the bigger effect on language-related executive functions, and the right frontal lobe has more of an influence on spatial executive function (Figure 2).

The striatum is made up of a number of structures deep within the brain, the caudate being the most active in ADHD. In healthy individuals, the striatum is rich in dopamine. Some structures in the striatum play a significant role in motor function. Parts of the striatum are low in dopamine in such movement disorders as Parkinson’s disease, leading to tremors and very slow movements. Parts of the striatum have also been found to be involved in tic disorders.

The frontostriatal circuitry forms the connection between the frontal lobes and parts of the striatum. Brain cells connect these structures, and the connection is maintained by information passed between the cells via neurotransmitters.

Finally, the cerebellum is part of the hindbrain and has been thought to primarily handle coordination. However, recent studies suggest it plays an important role in cognitive functions, such as language and attention, as well as motor planning. Cerebellar striatal frontal circuitry may also play a role in ADHD.