TORONTO -- A new study says one in three adult Canadians suffered some form of child abuse in their past, adding this abuse is associated with a higher risk of mental health disorders later in life.

The lead author of the study says it provides the first national look at the prevalence of child abuse experienced by Canadian adults.

Tracie Afifi of the University of Manitoba says previous estimates were based on a nearly 25-year-old study from Ontario and more recent data from Quebec.

The study is published today in the Canadian Medical Association Journal.

The authors studied data collected from more than 23,000 adults 18 and older who took part in Statistic Canada's 2012 Canadian Community Health Survey.

Respondents were asked questions about whether they were hit or subjected to other forms of physical or sexual abuse in childhood, or whether they were exposed to violence between the adults in their homes.

Afifi says the questions didn't ask "Were you abused?" because studies have shown that some people who have been abused don't characterize their experiences as abuse.

Instead, the questions asked whether respondents were slapped on the face or head, spanked with a hard object, pushed, grabbed, shoved or had something thrown at them to hurt them. For both those questions, respondents were asked to say yes only if the behaviour had happened a minimum of three times.

Another question asked if respondents were kicked, bit, punched, choked, burned or physically attacked at least once.

Sexual abuse questions were designed to determine whether respondents were forced into unwanted sexual activity. And the questions related to having witnessed intimate partner violence asked whether as children they had seen their parents, step-parents or guardians hit each other or other adults in the home three or more times.

One in three adults reported experiences that met the criteria for at least one of the types of abuse, with physical abuse the most common of the three; 26 per cent of respondents said they had experienced physical abuse.

Ten per cent of respondents said they had experienced sexual abuse and nearly eight per cent witnessed intimate partner violence.

Men were more likely than women to have experienced physical abuse, 31 per cent versus 21 per cent. But women were more likely to have experienced sexual abuse, 14 per cent versus nearly six per cent.

The researchers went a step further, looking to see if rates of mental illness were higher among adults who had suffered abuse in childhood.

"We found strong associations between child abuse and mental conditions," they wrote.

This type of study cannot prove cause-and-effect; it can only point to possible links.