It's widely believed that individuals who were physically abused during childhood are more likely to abuse their own children than those who were not abused, but the studies examining this belief have not been systematically reviewed.
The aim of a study by Ilgi Ozturk Ertem and colleagues, detailed in this week's issue of the Lancet, was to evaluate systematically the design of studies investigating the intergenerational transmission of child physical abuse.
The investigators reviewed studies published between 1965 and 2000 that provided information about physical maltreatment in two generations and included a comparison group.
Two investigators independently assessed whether each study met eight specific methodological standards that would help ensure a well-designed study of this complex problem.
In ten studies identified, the relative risks of maltreatment in the children of parents who were abused during childhood were significantly increased in four studies, but in three other studies the relative risks were small.
Most study reports provided a clear description of abuse of parents during childhood and abuse of their children. However, five studies failed to avoid recall and detection bias; five did not ensure that controls were not themselves maltreated; eight did not provide adequate follow-up; and in six the report did not state whether the enrolled parent was responsible for the maltreatment.
Most studies did not control for intervening factors, such as sociodemographic characteristics during the time of abuse of the parent generation or at the time their children were abused.
Only one study met all eight criteria, and this study showed that mothers who were abused during childhood were 12.6 times more likely to abuse their own children than mothers who were not abused when growing up.
By contrast, the one study meeting six of eight criteria did not support the intergenerational hypothesis.
John Leventhal comments: "The transmission of parenting behaviours, such as child physical abuse, from one generation to the next is a complex process and difficult to study in a rigorous, scientific manner. Clinicians should be aware of the conflicting results of the empirical studies and the methodological limitations of previous work."
(Editor's Note: Quote by e-mail; does not appear in published paper).
[Contact: John M. Leventhal MD]