Study co-author Mireille Cyr, a psychology professor at the University of Montreal, and colleagues surveyed 800 Quebec men and women and found 25 percent of respondents who were sexually abused as children had not previously disclosed it.
Sixteen percent of women remained quiet about abuse, while 34 percent of men never shared their secret, Cyr said.
The data suggest victims are more likely to report an abuser when he or she is a stranger. However, in most cases -- more than 80 percent -- serious abuse such as rape is committed by friends or family members.
The psychological distress of victims includes anxiety, depression, troubles concentrating and irritability. Certain victims suffer from post-traumatic stress disorder, some relive the abuse psychologically while others have dulled emotions or become hyper-vigilant, the researchers said.
The finding was published in The Canadian Journal of Psychiatry.