Kids diagnosed with ADHD often don't take medication regularly

February 3, 2020

Science Daily/Murdoch Childrens Research Institute

Children diagnosed with ADHD inconsistently take their prescribed medication, going without treatment 40 per cent of the time, a new study has found.

The research, led by the Murdoch Children's Research Institute (MCRI) and published in Archives of Disease in Childhood, shows the average medication coverage, the total time on drug between the first and the last redeemed prescription, was just 60 per cent.

Lead author and MCRI Associate Professor Daryl Efron said medication use was relatively high in the first few months, then progressively decreased, only increasing again after five or six years of treatment.

Additionally, children from socially disadvantaged families who were prescribed ADHD medication were less likely to consistently take it.

"We know low socio economic families can find it more difficult to attend medical appointments, with factors including appointment costs, transport difficulties and missed work all potentially contributing," he said.

The study showed the average medication coverage was 81 per cent in the first 90 days dropping to 54 per cent after 90 days.

Associate Professor Efron said little had been known about the longer term adherence to medication by children with ADHD until now.

"About 90 per cent of children with ADHD respond well to at least one of the stimulant ADHD medications," he said.

"ADHD is a chronic condition and so there is a strong argument that treatment should be provided consistently for several years in most cases. But adherence with ADHD medications is often inconsistent."

The study of 3,537 children looked at all redeemed ADHD prescriptions of the three frontline treatments, methylphenidate, dexamphetamine, and atomoxetine, by participants in the Longitudinal Study of Australian Children.

The study found that 166 children (3.6 per cent) had ever redeemed a prescription for an ADHD medication. Boys were four times more likely to be prescribed ADHD medication than girls.

Associate Professor Efron said the findings have important clinical implications.

About one in 20 children in Australia has ADHD, according to ADHD Australia.

"Effort should be made to continue to engage children who stop taking medications and their families to ensure they are able to access appropriate interventions, which may include medication alongside other interventions such as mental health and educational supports," Associate Professor Efron said.

https://www.sciencedaily.com/releases/2020/02/200203104447.htm

Rich rewards: Scientists reveal ADHD medication's effect on the brain

Researchers scan the brain to uncover how medication for ADHD affects the brain's reward system

January 17, 2020

Science Daily/Okinawa Institute of Science and Technology (OIST) Graduate University

Researchers have identified how certain areas of the human brain respond to methylphenidate -- a stimulant drug which is used to treat symptoms of ADHD. The work may help researchers understand the precise mechanism of the drug and ultimately develop more targeted medicines for the condition.

Attention-deficit hyperactivity disorder (ADHD) is a neurobiological disorder characterized by symptoms of hyperactivity, inattention and impulsivity. People with the condition are often prescribed a stimulant drug called methylphenidate, which treats these symptoms. However, scientists do not fully understand how the drug works.

Now, researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) have identified how certain areas of the human brain respond to methylphenidate. The work may help researchers understand the precise mechanism of the drug and ultimately develop more targeted medicines for the condition.

Previous research suggests that people with ADHD have different brain responses when anticipating and receiving rewards, compared to individuals without ADHD. Scientists at OIST have proposed that in those with ADHD, neurons in the brain release less dopamine -- a 'feel-good' neurotransmitter involved in reward-motivated behavior -- when a reward is expected, with dopamine neurons firing more when a reward is given.

"In practice, what this means is that children, or even young adults, with ADHD may have difficulty engaging in behavior that doesn't result in an immediate positive outcome. For example, children may struggle to focus on schoolwork, as it may not be rewarding at the time, even though it could ultimately lead to better grades. Instead, they get distracted by external stimuli that are novel and interesting, such as a classmate talking or traffic noises," said Dr Emi Furukawa, first author of the study and a researcher in the OIST Human Developmental Neurobiology Unit, led by Professor Gail Tripp.

Scientists believe that methylphenidate helps people with ADHD maintain focus by influencing dopamine availability in the brain. Therefore, Dr Furukawa and her colleagues set out to examine how the drug affects a brain region called the ventral striatum, which is a vital component of the reward system and where dopamine is predominantly released.

"We wanted to take a look at how methylphenidate affects the ventral striatum's responses to reward cues and delivery," said Furukawa.

The study, which was recently published in the journal Neuropharmacology, was jointly conducted with scientists at D'Or Institute for Research and Education (IDOR) in Rio de Janeiro, Brazil. The collaboration allowed the researchers to combine expertise across multiple disciplines and provided access to IDOR's functional magnetic resonance imaging (fMRI) facility.

Delving into the brain

The researchers used fMRI to measure brain activity in young adults with and without ADHD as they played a computer game that simulated a slot machine. The researchers scanned individuals in the ADHD group on two separate occasions -- once when they took methylphenidate and another time when they took a placebo pill. Each time the reels of the slot machine spun, the computer also showed one of two cues, either the Japanese character み (mi) or そ (so). While familiarizing themselves with the game before being scanned, the participants quickly learned that when the slot machine showed み, they often won money, but when the slot machine showed そ, they didn't. The symbol み therefore acted as a reward-predicting cue, whereas そ acted as a non-reward-predicting cue.

The researchers found that when individuals with ADHD took the placebo, neuronal activity in the ventral striatum was similar in response to both the reward predicting and non-reward predicting cue. However, when they took methylphenidate, activity in the ventral striatum increased only in response to the reward cue, showing that they were now able to more easily discriminate between the two cues.

The researchers also explored how neuronal activity in the striatum correlated with neuronal activity in the medial prefrontal cortex -- a brain region involved in decision-making that receives information from the outside world and communicates with many parts of the brain, including the striatum.

When the individuals with ADHD took placebo instead of methylphenidate, neuronal activity in the striatum correlated strongly with activity in the prefrontal cortex at the exact moment the reward was delivered, and the participants received money from the slot machine game. Therefore, the researchers believe that in people with ADHD, the striatum and the prefrontal cortex communicate more actively, which may underline their increased sensitivity to rewarding external stimuli. In participants who took methylphenidate, this correlation was low, as it was in people without ADHD.

The results implicate a second neurotransmitter, norepinephrine, in the therapeutic effects of methylphenidate. Norepinephrine is released by a subset of neurons common in the prefrontal cortex. Researchers speculate that methylphenidate might boost levels of norepinephrine in the prefrontal cortex, which in turn regulates dopamine firing in the striatum when rewards are delivered.

"It's becoming clear to us that the mechanism by which methylphenidate modulates the reward response is very complex," said Furukawa.

Tailoring New Therapies for ADHD

Despite the complexity, the scientists believe that further research could elucidate methylphenidate's mechanism of action, which could benefit millions of people worldwide.

Pinning down how methylphenidate works may help scientists develop better therapies for ADHD, said Furukawa. "Methylphenidate is effective but has some side effects, so some people are hesitant to take the medication or give it to their children," she explained. "If we can understand what part of the mechanism results in therapeutic effects, we could potentially develop drugs that are more targeted."

Furukawa also hopes that understanding how methylphenidate impacts the brain could help with behavioral interventions. For example, by keeping in mind the difference in brain responses when children with ADHD anticipate and receive rewards, parents and teachers could instead help children with ADHD stay focused by praising them frequently and reducing the amount of distracting stimuli in the environment.

https://www.sciencedaily.com/releases/2020/01/200117100257.htm