New research released Thursday by the Mayo Clinic suggests childhood attention deficit/hyperactivity disorder (ADHD) may be tied to the development of obesity, particularly in women.

The study, published in Mayo Clinic Proceedings, analyzed the medical records of 336 people diagnosed with childhood ADHD who were born from 1976 to 1982 and compared them to a similarly matched group of people without ADHD (665 participants in total). Women with ADHD were twice as likely to develop obesity during either childhood or adulthood than their controls following their initial diagnosis. The stark difference, however, wasn’t linked to stimulants, a popular ADHD treatment.

"Females with ADHD are at risk of developing obesity during adulthood, and stimulant medications used to treat ADHD do not appear to alter that risk," said lead author Dr. Seema Kumar, pediatrician and researcher at Mayo Clinic Children's Research Center in a statement.

Earlier research has hinted at the connection between the often misunderstood condition and obesity, particularly for those whose ADHD continues to progress into adulthood. A 2002 study, for instance, showed that a large proportion of people seeking weight loss treatment have a history of ADHD, while a 2009 study broadly looked at the prevalence of obesity in ADHD and non-ADHD populations and found it higher in the former group (29 percent vs 21 percent). Kumar and her colleagues decided to take a different approach, one that allowed them to trace the potential development of obesity from an early age onward.

"This is the first population-based longitudinal study to examine the association between ADHD and development of obesity using ADHD cases and controls of both sexes derived from the same birth cohort," said Kumar. The subjects were followed for an average of 26 years, up until 2010. Ultimately, 155 patients with ADHD and 232 control subjects became obese by the end of the study period.

Like all population studies, though, these latest findings can only tell us that a relationship between ADHD and obesity exists, not the reason(s) why. The 2009 study found that people with a history of ADHD were also more likely to suffer from other psychological conditions that might in turn increase obesity risk, such as binge-eating disorder, but that only partially explained the link. As the researchers note, the dysfunctional dopamine production often found in people with ADHD may also play a part, since dopamine helps regulate appetite, impulse control, and how we respond to rewards such as food.

While men with ADHD did appear to have an elevated risk of obesity as well, that risk wasn’t noticeably significant. Because of that, the researchers theorize the link may have to do with how each gender experiences ADHD. Women are more likely to develop an inattentive subtype of ADHD, while men are more often impulsive and hyperactive, they noted, before going on to add that “lower self-efficacy and poorer coping strategies as well as higher rates of depression, anxiety, and eating disorders in girls with ADHD may contribute to habits that predispose to excess weight gain.”

Reasons aside, the researchers hope their findings highlight the need to reach out to ADHD patients and discuss their lifestyle habits.

“There is a need for greater awareness of the association between ADHD and obesity in female patients among patients themselves, caregivers, and medical staff,” the researchers concluded. “Preventive measures targeting healthy eating and active lifestyle should be incorporated as part of routine care of all patients with ADHD.”

Source: Castaneda R, Kumar S, Voigt R, et al. Childhood Attention-Deficit/Hyperactivity Disorder, Sex, and Obesity: A Longitudinal Population-Based Study. Mayo Clinic Proceedings. 2016.