ADHD, part 2

By Alan Koenigsberg, M.D.

So just what is going on in our brain that helps us understand Attention Deficit Hyperactivity Disorder (ADHD) as well as how the treatments work? Here is what we understand and what I teach my medical students.

There are neurotransmitters, chemicals, which help with nerve communications throughout our brain. Nerve circuitry is what makes the brain function.

Electrical impulses, which we can detect with electroencephalogram (EEG) machines, travel along a nerve cell. Between nerve cells, there are microscopic spaces, called synapses, across which these neurotransmitters travel. They leave tiny vesicles in the presynaptic nerve, cross the synapse and attach to the post-synaptic receptors and the nerve impulse continues onward.

The chemical that is relevant for understanding ADHD is called dopamine and is present throughout the body. In the peripheral part of the body, dopamine can help raise blood pressure in cases of traumatic shock.

In the middle part of the brain, called the substantial nigra, dopamine helps coordinate movement. In the autoimmune disease of Parkinson disease, these nerve fibers are destroyed, dopamine is not produced or released and movement disorders occur.

In the prefrontal cortex, which is the frontmost part of the brain right behind our forehead, dopamine has several functions: It helps form a filtering mechanism which filters out repetitive stimuli. When there is a deficiency in release of dopamine in this area of the brain, there is an inability to filter out repetitive stimuli. In other words, tags on shirts, eyeglasses, collars, neckties, peanut butter in the teeth, don’t fade away, but continue to annoy and irritate people with ADHD.

They are easily distracted by external noises, lights and other stimuli and can’t maintain focus and concentration on less exciting work.

So an optimal level of dopamine helps us stay focused and on-task, filter out extraneous stimuli, remember what we need to and avoid distractions.

Dopamine is also known as the “pleasure chemical,” in that it is a main neurotransmitter involved in our experiencing pleasure. This is in part why some of the medications and drugs that help the release of dopamine can be addicting in vulnerable people.

So, treatment for people with ADHD is often a combination of medications and some form of therapy.

The medications typically used are those that release dopamine from these presynaptic vesicles, allowing an optimal amount to be transmitted.

The amphetamine-based medications have been around for about 100 years and are well understood. The commonly known ones are Adderall, both immediate release and extended release; Vyvanse; and Mydayis.

The methylphenidate medications, most often known as Ritalin, Metadata, Concerta and others, are not exactly the same but similar.

After a thorough evaluation, the treating physician usually picks a medication based on family history, potential for abuse and addiction, age and general medical health.

We tend to start with low doses and increase gradually, until the person says they don’t notice any additional improvement, has side effects or says they feel well.

Given that most of the medications we use are Schedule II medications, meaning they have a strong affinity for addiction in people with that genetic vulnerability, we need to monitor our patients closely and see them regularly.

Also, we cannot provide refills for these medications. A new prescription must be written every time and must be submitted electronically to the pharmacy.

I’ll go into more details about treatment in the next article.

Alan Koenigsberg, M.D., is a practicing psychiatrist and clinical professor of psychiatry at UTSW Medical School in Dallas.

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