Why Some Generations Are More Violent Than Others

University of Pittsburgh Researchers Report Findings on Youth Violence

PITTSBURGH, July 18, 2006 — Violence cannot be blamed on individual circumstances alone, but rather on changing societal influences, according to the first study to assess age, era and group effects on youth violence while simultaneously tracking individual risk factors. The University of Pittsburgh School of Medicine study is published in the July 15 issue of the American Journal of Epidemiology. The article currently is available online at http://aje.oxfordjournals.org .

Rates of violent crime in the United States have increased over the years with a series of peaks in time spans such as the late 1980s and early 1990s. Although researchers have gained a better understanding of individual risk factors that contribute to violence, such as drug use and gang membership, there have been conflicting theories as to why violence rates vary over specific time periods. Some suggest that there is a cohort effect where specific generations have a higher percentage of high-risk children. Others suggest that there is a period effect where circumstances during the period in which a generation grows up increase the risk for that generation. The results of the Pitt study show that while individual factors are important, they do not explain completely the differences in rates of violence between generations. Period effect can account for the remaining difference.

The researchers, led by Anthony Fabio, Ph.D., M.P.H., assistant professor of the Center for Injury Research and Control, division of neurosurgery at the University of Pittsburgh School of Medicine, and colleagues used data from a previously conducted local youth study, which tracked delinquency and risk factors between two groups of males from 1987 to 2000. This involved interviewing male participants over a 14 year period and obtaining supplemental information from parents and teachers. For this analysis, two groups were examined, one who entered the study when they were in the first grade and one who entered the study when they were in the seventh grade, totaling 1,009 (503 from the younger group and 506 from the older group).

The authors of the current study assessed differences in self-reported violence between these two groups of males to better understand the role of period and cohort effects on violence trends. Yearly measures of violence were studied through statistical analysis based on survey questions regarding violence, which consisted of a positive response to gang fighting, strong arming, attacking someone with a weapon, an intent to seriously hurt or kill, and rape or forced sex. Other factors taken into account by the study included the participant’s socioeconomic status, whether or not the young man was held back in school, involved in drug dealing, heavy drug use and gun use. Additional information factored into the study was obtained from U.S. Census data for 1990 and 2000 and the Uniform Crime Reports.

In comparing the data between the younger and older groups over the different time spans, the researchers noticed that the older group consistently reported more incidents of violence. The study was conducted to try to understand why this difference occurred. “Our data showed that though part of this difference was due to individual factors such as gang participation or drug dealing, the individual factors could not explain the entire difference,” Dr. Fabio explained. “However, we found that period effects helped to explain the difference in violence rates between the two groups. We have not yet tested what exactly this period effect or effects might be, but plan to look at various societal processes such as the economy or changes in social norms.”

This study was supported by a training grant from the U.S. Centers for Disease Control and Prevention, the National Institute of Mental Health and the Office of Juvenile Justice and Delinquency Prevention.

Co-authors of this study include Rolf Loeber, Ph.D., Distinguished University Professor of Psychiatry, department of psychiatry and epidemiology, University of Pittsburgh School of Medicine and the University of Pittsburgh Graduate School of Public Health; G.K. Balasubramani, Ph.D., research associate, Epidemiology Data Center, University of Pittsburgh Graduate School of Public Health; Jeffrey Roth, Ph.D., associate director for research, Jerry Lee Center of Criminology, University of Pennsylvania; Wenjiang Fu, Ph.D., department of epidemiology, Michigan State University; and David P. Farrington, Ph.D., professor of psychological criminology, Institute of Criminology, Cambridge University, England.

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Maureen McGaffin

University of Pittsburgh

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