Tuesday July 3 2012
Does smacking kids make them mentally ill later in life?
“Adults smacked as children have higher risk of mental illness later on,” the Daily Mail boldly reports today.
The news is based on a study that investigated whether there was a link between children who were physically punished (for example, spanked) but not abused, and the development of a mental disorder such as depression or alcohol and drug abuse as an adult. This study was based on the results of a nationally representative US survey of 34,653 adults. It found that harsh physical punishment (which stopped short of child abuse) was associated with mood and anxiety disorders, substance abuse and personality disorders.
Although this is an interesting study, it provides no evidence of a causal link between physical punishment and development of a mental disorder later in life. This study also relies upon self-reported information, with adults asked to recall being punished as a child. Both of these facts limit our ability to conclude that smacking causes mental illness. As such, the headline in the Mail is misleading because it does not take into account the limitations of this study.
Where did the story come from?
The study was carried out by researchers from the University of Manitoba and McMaster University, Canada. It was funded by awards from the Canadian Manitoba Medical Services Foundation, the Winnipeg Foundation and the Manitoba Health Research Council among other institutions. The study was published in the US peer-reviewed journal Pediatrics.
The story was picked up by the Mail, which had a misleading headline and incorrectly reported that the study was of just 653 US adults. It actually included 34,653 adults.
What kind of research was this?
This was a retrospective study based on the results of a survey of 34,653 US adults investigating the possible link between harsh physical punishment and development of mental disorders. Data for the study came from part of a larger nationally representative US survey – the National Epidemiologic Survey on Alcohol and Related Conditions, which collected information on over 20s between 2004 and 2005.
According to the researchers, 32 nations around the world have banned corporal punishment of kids, however the US and Canada are not among them. In the UK, parents are allowed to smack their children without causing “reddening of the skin”.
The researchers say that while other studies have examined the link between physical punishment and a broad range of mental health disorders, none have done so in a nationally representative sample that controlled for several types of child maltreatment.
What did the research involve?
All 34,653 adults were interviewed face-to-face by a trained interviewer. Most of the questions asked were based on a five-point scale (never, almost never, sometimes, fairly often and very often). Childhood physical punishment included events occurring before the age of 18.
To assess physical punishment, the 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?”. Those who answered “sometimes”, “fairly often” or “very often” were considered to have experienced “harsh physical punishment” and were included in the analysis. Harsh physical punishment included acts of physical force beyond slapping, such as spanking.
The researchers wanted to ensure that physical punishment was investigated in the absence of more severe child maltreatment. To do this they excluded from their analysis participants who reported:
- severe physical abuse (being hit so hard it left marks, bruises or caused an injury)
- sexual abuse
- emotional abuse
- physical neglect
- emotional neglect
- exposure to intimate partner violence (having an abused mother)
Mental disorders over the course of the participant’s lifetime were assessed using valid methods and classified as ‘axis I’ or ‘axis II’ disorders. Axis I clinical disorders included:
- major depression
- dysthymia (subthreshold depression)
- any mood disorder
- panic disorder with or without agoraphobia
- social phobia
- post-traumatic stress disorder
- any anxiety disorder
- any alcohol or drug abuse or dependence
Axis II personality disorders were examined individually and classified in three groups:
- paranoid, schizoid, schizotypal
- antisocial, histrionic, borderline, narcissistic
- avoidant, dependent, obsessive-compulsive
The results were analysed using statistical methods, adjusting for sociodemographic variables and family history.
What were the basic results?
Overall, 1,258 (5.9%) of the participants reported harsh physical punishment, without experiencing more severe child maltreatment. The main findings were:
- After adjusting for sociodemographic variables and family history of dysfunction, participants who reported harsh physical punishment were associated with an increased likelihood of some axis I mental disorders (adjusted odds ratio range from 1.31 to 1.93).
- The relationships between harsh physical punishment and axis II personality disorders were found to be significant after adjusting for sociodemographic variables and family history of dysfunction.
- The researchers estimated that approximately 2-5% of axis I clinical disorders and 4-7% of axis II personality disorders could be attributed to harsh physical punishment. They say this means that if no one experienced any harsh physical punishment, the prevalence of axis 1 disorders in the population would be expected to be reduced by 2-5%, and axis II disorders would be expected to be reduced by 4-7%.
How did the researchers interpret the results?
The researchers conclude that harsh physical punishment (in the absence of child maltreatment) is associated with mood disorders, anxiety disorders, substance abuse or dependence and personality disorders in the general population. They go on to say that their findings “inform the ongoing debate around the use of physical punishment” and that the findings provide evidence that harsh physical punishment is “related to mental disorders”. While the researchers suggest that policymakers might consider making a statement that physical punishment “should not be used in children of any age”, they do not call for a definitive “smacking ban”.
This study provides some evidence of a link between harsh physical punishment and lifetime adult mental disorders. It does not provide any evidence that one causes the other. Importantly, there may be many other medical, personal, social or lifestyle factors that contribute to adults developing a mental disorder. There are other limitations to this study, which the authors freely admit:
- Although the researchers attempted to use validated questions to assess harsh physical punishment and child maltreatment, this was determined by self-reporting, which makes the results less reliable. It is possible that adults did not correctly report whether they were punished or not.
- Participants were asked to recall events that took place in their childhood. This also may affect the results as it relies purely on the memory of the adult.
- The participants were also asked to recall whether their parents or adult carers had problems with alcohol or drugs. Ideally, this would have been confirmed through clinical records or by collecting this information from the parents themselves. However, the researchers did not do this.
As a result, the headline that “adults smacked as children have higher risk of mental illness later on” is misleading because it does not take into account the limitations of this study.
Edited by Bazian. Analysis by NHS Choices. Follow Behind the Headlines on twitter.