Thirty percent of adults with Attention Deficit Disorder or Attention Deficit Hyperactivity Disorder (ADD/ADHD) report they were physically abused before they turned 18.
This compares to seven per cent of those without ADD/ADHD who were physically abused before 18.
"This strong association between abuse and ADD/ADHD was not explained by differences in demographic characteristics or other early adversities experienced by those who had been abused," says lead author Esme Fuller-Thomson, professor and Sandra Rotman Chair at University of Toronto's Factor-Inwentash Faculty of Social Work.
"Even after adjusting for different factors, those who reported being physically abused before age 18 had seven times the odds of ADD/ADHD."
Investigators examined a representative sample of 13,054 adults aged 18 and over in the 2005 Canadian Community Health Survey including 1,020 respondents who reported childhood physical abuse and 64 respondents who reported that they had been diagnosed by a health professional with either ADHD or ADD.
The results were in a study published in this week's online Journal of Aggression, Maltreatment, and Trauma. (Read the study.)
"Our data do not allow us to know the direction of the association. It is possible that the behaviors of children with ADD/ADHD increase parental stress and the likelihood of abuse," says co-author Rukshan Mehta, a graduate of the University of Toronto's Masters of Social Work program.
"Alternatively, some new literature suggests early childhood abuse may result in and/or exacerbate the risk of ADD/ADHD."
The study underlines the importance of ADD/ADHD as a marker of abuse, said co-author Angela Valeo from Ryerson University.
"With 30 per cent of adults with ADD/ADHD reporting childhood abuse, it is important that health professionals working with children with these disorders screen them for physical abuse."
Michael Kennedy and Dominic Ali are writers with University Relations at the University of Toronto.