Childhood ADHD medication is linked to slight changes in adult height and weight

Children who are diagnosed with attention-deficit/hyperactivity disorder, commonly known as ADHD, and treated with a common stimulant medication may be slightly more likely to experience a higher body weight and a fractionally shorter height by the time they reach adulthood. These physical changes remain small in scale, but the results suggest that doctors should regularly monitor the physical growth of children receiving this treatment. The research was published in the journal JAMA Network Open.

ADHD is a condition that affects how people behave, focus, and control their impulses. For many children, doctors prescribe a medication called methylphenidate to help manage these behavioral symptoms. Methylphenidate is a stimulant drug that works by changing the balance of certain chemicals in the brain.

The medication is widely recognized as a highly effective and safe treatment for helping young people succeed in daily activities. Despite its effectiveness, medical professionals have raised questions about how this medication might affect physical development over a long period. Some earlier reports suggested a potential link between stimulant medications and changes in childhood growth rates.

Researchers wanted to know if these physical changes simply fade away over time or if they last all the way into adulthood. Children with this behavioral condition often experience challenges that can independently affect their physical health. For example, they might have irregular eating habits, struggle with getting enough physical activity, or experience poor sleep quality.

Sleep is an especially important factor for growing children because the human body releases the majority of its growth hormones during deep sleep. If a child repeatedly fails to get restful sleep, this hormonal process can slow down their overall growth rate. Adding a stimulant medication like methylphenidate into the mix introduces additional variables for a growing child.

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The medication is well known to temporarily suppress a person’s appetite during the day. This suppression can cause children to skip meals, which might lead to overeating later in the evening when the medication wears off. A cycle of skipping meals and overeating can contribute to weight gain over several years.

At the same time, missing out on consistent calories during the day could potentially restrict the raw energy a child needs to grow taller. The physical stress of living with a behavioral condition can also disrupt a child’s natural circadian rhythms over time. This ongoing stress affects how the body manages energy and balances basic metabolic functions.

Over several years, these tiny disruptions to the internal clock could heavily influence how a child gains weight. The researchers noted that the medication also works by increasing levels of a brain chemical called dopamine. Beyond its role in behavior and attention, dopamine interacts with the brain structures that control growth hormones.

Repeated fluctuations in dopamine levels during childhood might create unstable conditions for optimal physical growth. To better understand these possibilities, a team of researchers from the Republic of Korea decided to look at long-term health records. The research team was led by Jihun Song, a biomedical researcher based at the Korea University College of Medicine.

Song and his colleagues aimed to see if a childhood diagnosis of ADHD, along with the use of methylphenidate, changed a person’s body mass index in their early twenties. Body mass index, or BMI, is a standard medical calculation that uses a person’s height and weight to estimate their total body fat. To conduct the study, the research team gathered anonymized records from the national health insurance system in South Korea.

They focused on two main groups of young people who were newly diagnosed with the behavioral condition between 2008 and 2013. The primary group included 12,866 prepubescent children who were between the ages of six and eleven. A second group included 21,984 adolescents who were between the ages of twelve and nineteen.

The researchers matched each of these individuals with a control subject of the exact same age, sex, and household income level who did not have the condition. This matching process helped ensure that the comparisons between the groups were as fair and accurate as possible. The team then looked at the medical records to see which individuals were prescribed methylphenidate.

They calculated exactly how many days each patient took the medication over a four-year period following their initial diagnosis. Next, the researchers waited for the data to catch up to the patients’ adulthood. Between the years of 2018 and 2022, when the participants were between the ages of 20 and 25, the researchers examined the results of their national health checkups.

They recorded the final adult height and BMI for each person in the study. The results showed a clear difference in body weight between the different groups of young adults. Children who were diagnosed with the condition had a higher average BMI in adulthood compared to the matched control group.

This weight difference was even more pronounced among the children who specifically took methylphenidate. When looking at the rates of clinical obesity, the trends followed a similar path. In the control group without the condition, exactly 35 percent of the adults were classified as overweight or obese.

For the adults who had a childhood diagnosis but did not take the medication, the overweight and obesity rate climbed to just over 43 percent. For those who were diagnosed and actively treated with the stimulant medication, the rate reached 46.5 percent. The researchers also noticed a connection between the amount of medication taken and the final adult weight.

Children who took the medication for more than a year showed higher BMI scores than those who took it for less than a year. The total dosage over time directly corresponded with the likelihood of having a higher body weight in adulthood. When it came to height, the results were slightly different.

For children who had ADHD but did not take the medication, the difference in final adult height was not statistically significant when compared to the control group. In other words, simply having the condition did not appear to stunt a person’s final adult height. However, the children who actively took methylphenidate did show a measurable reduction in their final adult height.

Much like the weight results, the height reduction was tied to the duration of the treatment. Those who took the medication for longer periods experienced a slightly greater reduction in their final height. While these height reductions were measurable in the data, they were incredibly small in a practical sense.

For example, women who took the medication for more than a year during childhood were only about 0.6 centimeters shorter on average than women in the control group. This difference is a fraction of an inch, which falls well below the standard threshold that doctors would consider physically alarming. The research team also looked at the group of older adolescents who were diagnosed between the ages of twelve and nineteen.

Because these teenagers had already completed a large portion of their physical growth, the medication had a much smaller effect on their final adult height and weight. The physical changes were most apparent in the children who started taking the medication before they hit puberty. The researchers noted several limitations to their work.

Because this was an observational study based on existing medical records, the researchers cannot definitively prove that the medication directly caused the changes in weight and height. The study design only allows them to show a correlation between the treatment and the physical outcomes. The health records also lacked certain pieces of information that could influence a child’s growth.

For instance, the researchers did not have access to the heights and weights of the participants’ parents, which is a massive factor in determining a person’s adult size. They also lacked detailed information about the participants’ daily diets, exercise routines, and exact sleep schedules over the years. The research team stressed that parents and patients should not abandon this effective medication based on these findings.

The behavioral and academic benefits of managing the condition are well established and generally outweigh a fraction of a centimeter in height. Instead, the authors recommend that pediatricians simply keep a close eye on their patients’ physical development. If a child on this medication begins to show signs of slowed growth or excessive weight gain, doctors can intervene with lifestyle advice.

Counseling families on balanced nutrition, regular exercise, and healthy sleep habits might be enough to offset these mild physical effects. For children who are already at a high risk for growth delays, doctors might consider adjusting the medication dosage. Future studies will likely focus on tracking patients’ daily habits to see exactly how lifestyle choices interact with the medication.

Researchers hope to develop more specific medical guidelines for monitoring the metabolic health of children on long-term stimulant therapy. Until then, basic awareness and regular pediatrician checkups remain the best tools for keeping growing children healthy.

The study, “ADHD and Methylphenidate Use in Prepubertal Children and BMI and Height at Adulthood,” was authored by Jihun Song, Sun Jae Park, Jiwon Yu, Jina Chung, Seogsong Jeong, and Sang Min Park.