Attention Deficit Hyperactivity Disorder (ADHD) is a chronic developmental condition that is usually diagnosed in childhood. Approximately 1 out of every 10 children have some form of the disorder. ADHD is categorized into three main types that differ by the predominance of either inattentiveness or hyperactivity. While anyone can have moments of inattention or hyperactivity, these symptoms are more pronounced in people with ADHD and have a marked effect on their daily lives.
Inattentive ADHD is characterized by difficulty concentrating and staying organized. People with hyperactive ADHD experience restlessness and often talk or move incessantly. Combination type ADHD includes a mix of both main symptoms.
Researchers believe that the symptoms associated with all types of ADHD may be correlated with brain function. Neurotransmitters are substances that transmit information along the neurons or brain cells. Neurons produce these neurotransmitters and release them into the space between neurons, known as the synapse.
The neurotransmitters activate receptors on the end of the neuron, which causes that neuron to release more of the substance and send the message along. An imbalance of neurotransmitters can impact how the brain sends and receives messages to other parts of the body.
People with ADHD often have lower than normal levels of the neurotransmitter dopamine. Dopamine is essential to the brain’s reward system. When individuals encounter something exciting, the brain releases dopamine, which causes a pleasurable sensation.
In people without ADHD, dopamine motivates them to remain focused and complete a task, even if they are somewhat mundane. However, in people with ADHD, dopamine cannot stay in the system long enough to elicit a pleasurable response for most tasks. This contributes to symptoms such as distractibility and listlessness.
Dopamine imbalances also impact the function of other neurotransmitters. Norepinephrine is a neurotransmitter that is a byproduct of dopamine synthesis. This complex substance interacts with a part of the brain that is responsible for planning and suppressing impulsivity.
Norepinephrine imbalance may be why people with ADHD often have difficulty with “executive function” tasks, including cognitive skills such as emotional self-control and short-term memory.
Many types of ADHD medications directly interact with neurotransmitter processes to restore balance in the brain. Stimulants such as Adderall and Concerta trigger dopamine production, making it easier for the brain to remain focused and alert.
These medications also hinder the reuptake process, which happens when the neurons absorb the neurotransmitter. Allowing dopamine to stay in the system longer increases an individual’s attention span and ability to follow through on tasks.
There are also non-stimulant treatments that block norepinephrine reuptake but do not stimulate neurotransmitter production. Treatments like atomoxetine allow norepinephrine to remain in the neural synapse longer and ameliorates symptoms such as inattention and impulsivity.
In addition to medication, some dietary changes can also stimulate dopamine production. Foods that contain substances used in dopamine production, such as nuts, cheese, and fish, can increase dopamine levels. Protein-rich diets are also beneficial for people with ADHD. Exercise also stimulates dopamine and norepinephrine synthesis. A study of 135 adults found that 3 hours a week of exercise correlated with improving the brain's reward system.
