Physical punishment that goes beyond spanking—such as hitting, slapping or shoving—may cause kids to develop depression, anxiety and personality disorders as adults, according to a University of Manitoba in Winnipeg, Canada, study published in Pediatrics and reported by Reuters.

For the study, researchers looked at U.S. census data from 2004 to 2005 of more than 35,000 adults. In census interviews, participants were asked about physical punishments they received as children. They were also asked about any past or present symptoms of mental illness they’d experienced. In addition, scientists questioned them about any other family problems they’d undergone, such as whether their parents used drugs or had spent time in prison. (Scientists didn’t include those who’d suffered physical, sexual or emotional abuse because they specifically were concerned with the effects of less severe punishment.)

Researchers found that of the participants who reported a history of physical punishment more severe than spanking, 43 percent had abused alcohol and 20 percent had suffered from depression. Meanwhile, 30 percent of those who didn’t have a history of physical punishment had abused alcohol, and 16 percent had been depressed.

These results held true even after researchers adjusted for variables such as parental mental illness—as susceptibility to many mental illnesses is hereditary—ethnicity, education level and income.

“People believe that as long as you don’t cross that line into child maltreatment, and the physical punishment is controlled and doesn’t cross the line into abuse, it won’t have any negative long-term consequences for the child,” said Tracie Afifi, PhD, an assistant professor in the Department of Community Health Sciences at the University of Manitoba, and lead study author. “The way we see it is along a continuum of having no violence to severe violence.”

But other scientists cautioned that these findings can’t prove physical punishment will cause kids to develop mood and personality disorders.

The bottom line is experts noted that physical punishments can lead to other negative behaviors in children, such as delinquency or aggression. This means parents already have good reason to avoid inflicting this kind of punishment on their kids.

Click here to read more about links between childhood mistreatment and mental disorders.