Up to 11 percent of school-age children and 4 percent of adults are estimated to have attention-deficit/hyperactivity disorder. About 70 percent of those kids (and an unknown but growing number of adults) take medication for it. Scientists don’t know exactly what ADHD is — or why certain drugs improve its symptoms — but most research suggests that it causes signaling problems in the brain. ADHD medications are thought to improve those brain signals.
Fronto-striatal network Deciding to focus This lets us switch smoothly between tasks, filter out distractions and pick out relevant information from our environment. The network is thought to be underactive in people with ADHD and may contribute to hyperactivity, impulsivity and distractibility.
Executive function network Making a game plan After you choose what to do, this network figures out how to do it. Executive function includes planning, organization and working memory. About half of people with ADHD have executive dysfunction tion; no medication effectively treats it.
Attentional network Staying on task Once you’ve decided to pay attention to something, this network sustains that attention. Not all ADHD kids are hyperactive. Some are inattentive: more easily distracted, forgetful, disorganized and unfocused than their peers.
Fronto-cerebellar network Moving and thinking efficiently The cerebellum increases coordination, precision and efficiency in movement and thought processes. It may also function as an internal timekeeper, so signal disruption in this network may contribute to time management problems.
Reward network Choosing what’s important Signals in this network tell us, “Wow, this deserves our attention!" - The reward center may be understimulated and late to develop in children with ADHD, making it hard for them to choose among competing things. Hyperactivity, impulsivity and inattention are also related to this network.
Brain signals affected by ADHD
Supplementary motor cortex
Supplementary motor cortex
The decision zone Networks flow through the prefrontal cortex, and ADHD drugs operate in this area.
Networks that can be treated with medicines
Medications and their targets ADHD drugs increase the brain’s available supply of two important neurotransmitters, or signal carriers, dopamine and norepinephrine. Norepinephrine makes appropriate signals stronger, and dopamine weakens extraneous “noise.” Cell sending signal
Cell receiving signal
Direction of signal
Other drugs block the recycling process so signal carriers circulate longer and have a better chance of being received. Increasing neurotransmitters
ADHD DRUGS BOOST SIGNALS BY . . .
How a brain signal is sent
A cell releases a signal-carrying chemical, and a nearby cell receives it. The first cell then takes it back to reuse. ADHD brains often don’t have enough signal carriers in circulation.
Some drugs prompt cells to push extra signal carriers into circulation.
STIMULANTS – Work for 75-85 percent of people with ADHD It’s counterintuitive, but low doses of stimulants calm people with ADHD, decrease impulsivity and help them stay on task, probably by stimulating the brain’s under - active reward and decision centers so that they receive a normal range of signals. Common side effects: Reduced appetite, sleep problems, irritability, tics. Methylphenidate (Ritalin, Focalin, Concerta) Blocks reuptake of dopamine and norepinephrine, much like plugging a drain. Amphetamine (Adderall, Dexedrine) Causes brain cells to release more dopamine, like turning on a faucet. Blocks some reuptake of dopamine and norepinephrine as well. Lisdexamfetamine (Vyvanse) This version of amphetamine doesn’t work until the body metabolizes it, which reduces its desirability as a drug of abuse.
EXPERTS Glen Elliott , chief psychiatrist at the Children’s Health Council and author of “Medicating Young Minds: How to Know if Psychiatric Drugs Will Help or Hurt Your Child” Timothy Wilens , chief of child and adolescent psychiatry at Massachusetts General Hospital and author of “Straight Talk About Psychiatric Medications for Kids”
NON-STIMULANTS – Work for 45-60 percent Some people don’t respond well to stimulants or need a drug that will also treat another problem, such as anxiety or depression. Unlike stimulants, which act in minutes, these often take weeks to get fully into (and out of) a person’s system. Atomoxetine (Strattera) Blocks norepinephrine reuptake. Often prescribed to treat anxiety with ADHD. Common side effects: Sleep problems, fatigue, upset stomach. Guanfacine and clonidine (Intuniv, Kapvay) Modulates release of norepinephrine, which increases or decreases its activity in various brain regions. Exactly how is not well understood. Some doctors say these work better for hyperactivity, impulse control and tics than for core cognitive problems; some think they may help executive function. Common side effects: Fatigue, dizziness, irritability, low blood pressure and heart rate. Off-label medications Drugs that are not FDA-approved for ADHD may nonetheless be prescribed for it. For instance, the antidepressant Wellbutrin (buproprion) boosts mood in addition to easing ADHD symptoms, particularly in kids who are not hyperactive.
Note: Neither Elliott nor Wilens has received personal funding from a pharmaceutical company since 2006 and 2009, respectively.
SOURCE: National Resource Center on AD/HD; “ADHD Parents Medication Guide,” published by the American Academy of Child & Adolescent Psychiatry and American Psychiatric Association; FDA.