Understanding ADHD
Andy Shapira
Andy Shapira
Medical Director, Psychiatry – Medical Affairs

Attention-deficit/hyperactivity disorder (ADHD) is a chronic condition that includes attention difficulty, hyperactivity, and impulsiveness. Although most people associate it with children, it can also affect adults.

In recognition of ADHD Awareness Month, PRA Medical Directors Stephen Zukin and Andy Shapira discuss some of the nuances of this disorder:

What are some common misconceptions about ADHD?

SZ: On misconception is that ADHD is a disorder a person will “outgrow.” ADHD is a lifespan disorder, persisting from childhood to adulthood in around 65% of cases, with the remaining 35% showing remission. There is, however, some question around these figures. A recent analysis suggests that rate of persistence into adulthood may be significantly lower if the full diagnostic criteria are applied. But it may be accurate if considering persistence of clinically important criteria, for example, issues with retaining focus.

AS: There are also some very general misconceptions – for example, that girls rarely have ADHD compared to boys; that hyperactivity is a component of all kids with ADHD; that ADHD behaviors are completely volitional; or that ADHD is caused by non-attentive/”bad” parenting. Social factors can of course influence ADHD and coexisting conditions, but research suggests genetic and neurological factors (for example developmental issues) are the main cause of ADHD. ADHD has a complex etiology involving both genetic and environmental factors.

Are there differences between adult and pediatric ADHD?

AS: Symptoms of ADHD in children manifest themselves differently than in adults. Inattention, hyperactivity, and impulsive behavior remain hallmark symptoms, but these will impact differently in pediatric versus adult cases. For example, hyperactivity in children may manifest as excessive movement, fidgeting, and noisiness. While in adults, this can present as restlessness, boredom, and thrill seeking.

SZ: Research has shown differences in brain imaging between adults who recovered from pediatric ADHD and adults in whom the condition has continued. ADHD was more likely to continue into adulthood in those whose brain developed with a thinner cortex, while those whose cortical thickness developed within a normal range were more likely to enter remission. However, there is still much research to be done before we can predict the outcome of pediatric ADHD.

How is it treated?

SZ: With a combination of medication and behavioral therapy. Medications involve stimulants to improve focus which work for around 75% of sufferers, whether pediatric or adult cases. Where stimulants are ineffective or contraindicated, a physician may prescribe a non-stimulant such as atomoxetine. Clonidine hydrochloride, or guanfacine for pediatric cases, can be used as single agents or in combination with a stimulant.

AS: If stimulants/non-stimulants cause unpleasant side effects or simply do not work, some antidepressants such as tricyclic antidepressants, bupropion, or even other potential attention-focusing pharmacologic agents may also be considered by the treatment provider although it is important to highlight that none of these are specifically FDA-approved for the treatment of ADHD.

What are some of the challenges in treatment?

AS: As with many psychiatric indications, non-adherence is an issue. Even with patients who have had a good response to medication, having ADHD can make it difficult for a patient or caregiver to develop a consistent regimen to take the medication(s). Caregivers or patients may also choose to stop issuing a medication due to side effects. Research into less -nvestigated populations is also necessary.

SZ: The condition is heterogeneous in many respects. ADHD is also highly comorbid, meaning personalized treatments may assist us in improved clinical outcomes in years to come.

What is new in the ADHD research field?

SZ: Neuroimaging is aiding researchers in learning more about ADHD. Several regions of the brain have been linked to ADHD, including the pallidum, thalamus, caudate nucleus, putamen, nucleus accumbens, amygdala, hippocampus, and ventrolateral prefrontal cortex. Structural magnetic resonance imaging has demonstrated that caudate nucleus, putamen, nucleus accumbens, amygdala, and hippocampus were smaller in volume in subjects with ADHD. These areas are hypothesized to associate with regulation of emotion, motivation, and reward.

AS: Researchers have seen several pointers toward childhood psychiatric disorders increasing the risk of developing addictions in later life. These correlations indicate the importance of early detection and treatment of these childhood psychiatric disorders.

What is on the horizon for possible new treatment options?

AS: As we learn more about the etiology and neurobiology of ADHD, we can make advances in treating the condition. But there are still some knowledge gaps that we seek to fill in as researchers. As the mechanisms behind ADHD symptomology are identified, new therapeutic targets as well as the best timing and way to administer these treatments will continue to arise.

SZ: New stimulant medications for ADHD have been approved by the FDA this year, including a drug which can improve symptoms for up to 18 hours post-dose, avoiding a downturn in patient adherence of a second daily dose of stimulant medication. A second new drug which can dissolve in the mouth, making the medication easier for pediatric patients to swallow, was also recently approved.