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May 26, 2005

Juvenile violence study assesses risk factors

Take 1,500 boys in 1987, 1st, 4th and 7th graders from the Pittsburgh School District, and follow them through to the present day. What conclusions about the progression of violent and criminal behavior in their lives can be drawn?

That is the continuing challenge of the Pittsburgh Youth Study (PYS), a nationally praised longitudinal assessment study of risk factors and mitigating “promotive” factors in the progression of violent behavior led by principal investigator Rolf Loeber, Pitt distinguished professor of psychiatry.

A sobering snapshot of the PYS cohort sample shows that between 1987 and 2002 there were 33 study subjects convicted of homicide and another 25 other subjects accused of homicide; 28 study participants were homicide victims. (An additional 10 subjects have died from other causes.)

“This gives you an idea of the enormous scope among young men that is associated with violence. And it is not concentrated in one single environment,” Loeber pointed out.

PYS is funded by the Office of Juvenile Justice and Delinquency Prevention, the National Institute of Mental Health, the National Institute of Drug Abuse and the Pew Charitable Trusts.

Loeber spoke May 12 on “Juvenile Violence in the City and the Nation” in an inaugural lecture marking his installation by Provost James V. Maher as distinguished professor of psychiatry.

“When we look at violent juvenile behavior, we’re looking at how it happens and why, and can we actually prevent these kinds of problems from progressing to more serious violence and crime,” Loeber said.

“Why are these questions important?” he asked. “Because violence affects all of us. Some of us are victims or we know victims.

Victimization also takes many forms he continued, affecting home, neighborhood and workplace safety; inducing fear and avoidance; limiting choices of where to live and travel; discouraging business development; restricting economic growth, increasing taxes and insurance costs.

“More importantly, it affects individuals who do not have a choice, who are powerless to move away, who are, in effect, captured in a violent environment,” Loeber said.

Because of its goals, the Pittsburgh Youth Study over-sampled for anti-social behavior, with 30 percent of the study sample comprising boys with the most disruptive behavior based on information provided at the initial screening. The remaining 70 percent are a random sample of boys who demonstrated less disruptive behavior. The total sample group is approximately half Caucasians and half African Americans, he said.

Each boy and a primary caregiver were interviewed at six-month intervals for the study’s first five years. The assessments also incorporated teacher ratings of the student.

The middle sample (4th grade) was discontinued after seven assessments. The youngest sample (1st grade) and oldest sample (7th grade) continue to be interviewed annually. The total number of assessments, which average 2-3 hours apiece, is approaching 50,000, Loeber said.

“We have been highly successful in retaining participants, with a current retention rate of 82 percent, which is quite good for this type of study,” he said.

“One very important caution, I must warn you, is that causation is particularly difficult to establish,” Loeber said. “Instead, we are looking at predictors: risks and promotive, or positive, factors.”

A basic premise of the Pittsburgh Youth Study is that offenses by most juveniles are the result of forces broken out over four domains: the individual child, his family, his peers and his neighborhood, he said.

The forces are within an individual (IQ, personality) as well as forces in an individual’s social environment (parents, siblings, peers) and those in different contexts (family, school, neighborhood).

For Loeber, the key questions are:

• What are the predictive risk factors of violence and what are the shifts in those factors over time, as an adolescent becomes more influenced by factors outside himself, such as peers and neighborhood conditions? What are the corresponding protective factors and their shifts?

• Can researchers construct a model of progressive developmental and behavioral factors in order to inform interventions?

“We discovered there are stages of violence,” Loeber said, with minor aggressive social behavior leading to fighting which begets more serious violent behavior.

“Ninety-four percent of those who commit homicide were known to be violent already. Most violent behavior follows this orderly progression,” he pointed out. “But not everybody does progress to more violence, and the time between early behavioral problems and the progression to more violent behaviors also varies.”

For example, for the younger group, who at age 7 showed moderate or high levels of anti-social behavior, their first court appearance occurred on average when they were 14.5 years old.

“There’s about a seven and a-half year interval between emergence of troubled kids and their first court appearance, and that window of opportunity is enormously important for intervention,” Loeber said.

Gang membership for the younger cohort peaked at age 14, while for the older sample group gang membership peaked at 19 years of age. This observation coincides roughly with the high point of Pittsburgh’s violent crime rate in 1993, when each group reached its peak gang membership, Loeber said.

Most of the predictive risk factors, of the 50-plus identified by Loeber’s research team, apply to the individual domain, such as low IQ level, negative emotional development and certain anti-social personality traits.

The most important risk factors in the PYS’s predictive analysis are: low motivation in school, truancy, cruelty to others, aggressive personality, impulsive behavior/lack of guilt feelings, the family on welfare, depression, low socio-economic status and low IQ.

“There is also a cumulative effect of the risk factors. To have three of these risk factors present increases the predictability of later violence,” Loeber said. “If all nine risk factors are present, without any promotive factors, the probability of being involved in violence is 100 percent.”

However, the study also concluded that mitigating factors can counter-balance the risk factors, he said. Among those promotive factors are: no physical punishment in the home; agreement on discipline by the parents; good supervision by parents; a boy’s involvement in family activities; low parental stress, and parental reinforcement of pro-social behavior outside the home.

Risk and promotive factors appear to cancel each other out in determining long-term risk of serious delinquency, the study found.

Other general conclusions of PYS include:

• Low IQ was related to delinquency independently of socio-economic status, ethnicity, neighborhood and impulsivity.

• Of the family risk factors examined by the study, poor supervision was the most telling variable for delinquency, increasing the risk by a factor of 2.6 for the older sample but somewhat less for the younger sample.

Poor parent-son communication, and physical punishment by the mother, also increased the risk of delinquency.

• Of the socio-economic risk factors examined by the study, having the family receiving public assistance (welfare) was associated with the highest risk of delinquency, followed by low socio-economic status.

• The demographic variable most strongly related to delinquency was having a broken family. Living in a high-crime neighborhood also doubles the risk for delinquency, the study concluded.

But Loeber offered another caution: “Factors are processes; they are complex mechanisms, and are not equally distributed. Some kids are much more exposed to outside risk factors than other kids, for example. So this is not a simple matter,” he said.

Are there developmental pathways that can be studied to aid intervention strategies?

Yes, according to Loeber.

PYS identified three developmental pathways that display progressively more serious problem behaviors:

• Authority conflict pathway — Youth on this pathway exhibit stubbornness prior to age 12, then move on to defiance and avoidance of authority.

• Covert pathway — This pathway includes minor covert acts (e.g., lying) followed by property damage and moderately serious delinquency, then serious delinquency.

• Overt pathway — This pathway includes minor aggression followed by fighting and violence.

“Why is this relevant? Because the pathways suggest intervention points, when to intervene and what intervention is appropriate,” Loeber said. “We need to decrease the risk factors, especially the more serious predictive ones, as early as possible. And we need to decrease the proportion of delinquent youth who progress to more serious violence.”

—Peter Hart

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