New research out of the American Psychological Association links persistent attention-deficit hyperactivity disorder (ADHD) to having critical parents, suggesting that parental behavior can have a significant impact on the mental disorder. In many cases, ADHD fades away towards the end of adolescence, and may completely disappear in adulthood. Among those whose symptoms persist as they age, harsh and critical parents may play a role, the research suggests.

“Why ADHD symptoms decline in some children as they reach adolescence and not for others is an important phenomenon to be better understood,” Erica Musser, assistant professor of psychology at Florida International University and lead author of the study, said in the press release. “The finding here is that children with ADHD whose parents regularly expressed high levels of criticism over time were less likely to experience this decline in symptoms.”

The researchers examined 388 children with ADHD, and 127 children who didn’t have the disorder, over the course of three years. Most of the children were white males from two-parent households. The researchers analyzed their ADHD symptoms over the three years, in addition to measuring their parents’ level of criticism and overprotective feelings. To do so, they recorded the parents as they talked about their relationship with their child for five minutes, then rated the levels of criticism (negative statements about the child) and levels of emotional over-involvement or overprotection.

They found that parents who ranked high as both critical and overprotective were more strongly associated with having kids with continuous ADHD. “The novel finding here is that children with ADHD whose families continued to express high levels of criticism over time failed to experience the usual decline in symptoms with age and instead maintained persistent, high levels of ADHD symptoms,” Musser said in the press release.

However, there are a huge amount of factors that go into ADHD; it can’t only be attributed to levels of parental criticism. Research has shown that kids with ADHD have certain neural networks that are weaker than normal; children in foster care are three times more likely to be diagnosed with ADHD; and kids with ADHD (as well as their mothers) have shorter telomeres than kids without the disorder. When it comes to parental factors, research has suggested that severely obese mothers — or teen parents — are more likely to have kids with ADHD. The list of ADHD factors goes on, however — from genetic to environmental, hundreds of things may contribute to the incidence and development of the mental disorder, including exposure to secondhand smoke.

However, it's still an interesting connection — and may perhaps offer new ways for parents to learn how to manage their children with ADHD better. “We cannot say, from our data, that criticism is the cause of the sustained symptoms,” Musser said in the press release. “Interventions to reduce parental criticism could lead to a reduction in ADHD symptoms, but other efforts to improve the severe symptoms of children with ADHD could also lead to a reduction in parental criticism, creating greater well-being in the family over time.”

Source: Musser E, et al. Attention-Deficit/Hyperactivity Disorder Developmental Trajectories Related to Parental Expressed Emotion.” Journal of Abnormal Psychology, 2016.