Child abuse affects nearly a third of Canadian adults, according to a new study that finds "robust associations" between exposure to physical and sexual abuse, and mental conditions.

Tuesday's research in the Canadian Medical Association Journal is the first nationally representative study on child abuse and mental disorders.

"Our findings indicate that 32 per cent of the adult population in Canada has experienced child abuse (i.e., physical abuse, sexual abuse and/or exposure to intimate partner violence) and that child abuse has robust associations with mental conditions," conclude Prof. Tracie Afifi of the departments of community health sciences, and psychiatry at the University of Manitoba and her co-authors.

"From a public health standpoint, these findings highlight the urgent need to make prevention of child abuse a priority in Canada."

In the study, physical abuse was the most common (26 per cent), followed by sexual abuse (10 per cent) and exposure to intimate partner violence (eight per cent).

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Sheldon Kennedy leaves his palm print for a display at child abuse centre in 2013. A new study offers the first national look at the prevalence of child abuse experienced by Canadian adults. (CBC)

Participants were interviewed 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.

Researchers also asked whether people were slapped on the face or head, spanked with a hard object, pushed, grabbed, shoved or had something thrown at them. If the respondent said it happened at least three times then it was counted as a "yes."

Assess patients for abuse

Men were more likely than women to have experienced physical abuse — 31 per cent compared with 21 per cent. Women were more likely to have experienced sexual abuse — at 14 per cent — versus six per cent among men.

Sexual abuse was classified as experiencing attempts or being forced into unwanted sexual activity by being threatened, held down or hurt in some way, or sexually touched, meaning unwanted touching or grabbing, kissing or fondling against the respondent’s will, one or more times.

The researchers suggested that clinicians working in the mental-health field should be skilled in assessing patients for exposure to abuse and should understand the implications for treatment.

Mental conditions included having suicidal thoughts and attempted suicide, and drug abuse or dependence.

Respondents also said whether they were diagnosed with a mental disorder, or a long-term health condition diagnosed by a health professional that had lasted or was expected to last six months or longer, including obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), or a phobia, eating disorder or learning disability.

The study can't prove cause and effect, the researchers noted. 

"It may be that for some people, a direct relation does exist between child abuse and mental disorders. It may also be the case that behavioural issues for some children could be associated with mental disorders and that behavioural problems could increase the likelihood of child abuse."

The researchers considered factors such as age, sex, education, household income, visible minority and province of residence in their analysis.

A 1990 study in Ontario suggested that 31 per cent of males and 21 per cent of females had experienced physical child abuse. Similarly, data collected in Quebec in 2006 suggested 23 per cent of men and 17 per cent of women had experienced physical child abuse.

The study was funded by the Canadian Institutes of Health Research and the Manitoba Health Research Council.