July 2, 2012 -- Childhood punishments such as spanking, slapping, and hitting – even in the absence of full-scale maltreatment – are associated with an increased risk of mental disorders in adulthood, researchers reported.

Adults who reported such punishments in their childhood had a greater risk of mood disorders, anxiety disorders, alcohol and drug abuse dependence, and several personality disorders, according to Tracie Afifi, PhD, of the University of Manitoba in Winnipeg, and colleagues.

Up to 7 percent of some adult disorders can be attributed to "harsh physical punishment" in childhood, Afifi and colleagues reported online in Pediatrics.

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The link between child abuse – both physical and sexual – and mental disorders in adulthood has long been established, the researchers noted.

But studies of milder forms of punishment that had similar findings have been disputed as having "weaknesses in design, measurement, and analysis," they added, including the lack of adjustment for confounding factors such as full-scale abuse.

To try to overcome those limitations, Afifi and colleagues turned to the National Epidemiologic Survey on Alcohol and Related Conditions, which included a representative sample of civilian, non-institutionalized adults in the U.S.

The second wave of the survey, conducted between 2004 and 2005, included 34,653 adults, 20 or older, and asked about current mental conditions, as well as the past incidence of physical punishments.

In interviews, participants were asked: "As a child how often were you ever pushed, grabbed, shoved, slapped or hit by your parents or any adult living in your house?"

Answers, on a five-point Likert scale, could be never, almost never, sometimes, fairly often, and very often. Participants who answered sometimes or higher were defined to have experienced harsh physical punishment.

For this analysis, participants who also reported severe physical abuse, sexual abuse, emotional abuse, physical neglect, emotional neglect, or exposure to intimate partner violence were excluded. The final analytic sample included 20,607 participants.

Overall, Afifi and colleagues reported, 1,258 participants reported physical punishment, or 5.9 percent of the total. They were more likely to be male, black, and to have a family history of dysfunction.

After adjustment for sociodemographic factors and family dysfunction, harsh physical punishment was associated with an increased risk of most lifetime Axis I mental disorders. Specifically:

The risk of major depression was 41 percent higher;

The risk of mania was 93 percent higher;

The risk of any mood disorder was 49 percent higher;

The risk of any anxiety disorder was 36 percent higher;

The risk of any alcohol abuse or dependence was 59 percent higher;

The risk of any drug abuse or dependence was 53 percent higher.

The findings "provide evidence that harsh physical punishment independent of child maltreatment is related to mental disorders," Afifi and colleagues concluded.

They cautioned that the study was cross-sectional, which precludes drawing any causal inferences. Moreover, they noted, the data was retrospective, which could introduce recall and reporting biases.