Researchers say this is the first study to show the psychological result of physical punishment in the absence of abuse or heightened family dysfunction.
The study appearing in Pediatrics finds that "harsh physical punishment was associated with increased odds of mood disorders, anxiety disorders, alcohol and drug abuse/dependence, and several personality disorders after adjusting for sociodemographic variables and family history of dysfunction..."
In other words, no matter what other strikes are already against kids in life, beating them only makes things worse.
Respondents 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?” Those who answered "sometimes" or more often were considered. (The mere occasional spanking didn't qualify subjects.)
Those who endured more severe treatment, e.g. sexual abuse, were excluded; adjustments were made for those whose home life had a heightened dysfunction (e.g., parent on drugs or in prison).
"To our knowledge," say the authors, "there have been no examinations of the link between physical punishment and a broad range of mental health disorders in a nationally representative sample controlling for several types of child maltreatment" prior to theirs.
By this standard, about 6% of subjects qualified as physically punished without complicating factors -- much lower than the presumed range in the general population, probably because of the strict exclusions.
Corporal punishment didn't seem to factor into Axis II psychological disorders in adulthood. For example, while subjects from a dysfunctional family who experienced harsh physical punishment showed a tendency toward schizoid and obsessive-compulsive personality as adults, those who were not from such families showed no such tendency.
But for Axis I disorders, such as "major depression, dysthymia, mania, any mood disorder, specific phobia, any anxiety disorder, and any alcohol and drug abuse or dependence disorders," the physically punished showed higher rates than those who received lighter punishments.
"From a public health perspective," the authors conclude, "reducing physical punishment may help to decrease the prevalence of mental disorders in the general population."