Apache gangsters fight police in Paris, 1904. (Photo: Public Domain)

Gangs are a favorite topic among social scientists and criminologists. Research has consistently shown that, when kids join gangs, they immediately increase the risks that they will commit crimes and be incarcerated, become addicted to drugs, drop out of school, and be on either the giving or receiving end of violence. None of these findings are particularly surprising. But what about the long-term impact? Most gang stints are relatively short, with kids joining in their early teens and getting out a few years later. Then what? Amanda Gilman, a doctoral candidate in the University of Washington School of Social Work, saw a gap in this field.

“We think of gang membership as being an adolescent phenomenon, but what happens when they grow up and have their own families, and become adults?” asked Gilman, who is the lead author of a new paper out in the American Journal of Public Health. “Our theory was that we would see some of these negative outcomes in adulthood, but to some extent we were surprised to see how pervasive this sort of risky lifestyle of being in a gang could be in transitioning to adulthood.”

"It's not just the corrections systems and the police that need to be concerned about it, because it has broader public health impact."

Gilman found that the impact of those risks and stress were very pervasive indeed. Most people in the study who said that they had been in gangs said their memberships lasted for only three years or less. Even so, they felt the impact of this set of choices for years. Compared to those people who had never been members of a gang, former gang members reported much worse overall health—both mental health and physical health. Former gang members were more likely to suffer from depression, anxiety, alcoholism, and “poor general health” physically when they were 27, 30, and 33. They were also three times as likely to be addicted to drugs.

The results stayed the same “even after controlling for individual, family, peer, school, and neighborhood characteristics.” It was gang membership that made the difference. And these negative effects of the gang life are so significant, the authors explained, that they go beyond the realm of mere community crime and disorder, and can actually impact the level of the overall health of a community.

“Gang membership has always been under the discussion of criminologists; it's been like a juvenile justice issue, or a criminological issue,” says Karl Hill, a research associate professor and co-author on the paper. “What Amanda's showing here is that it's a bigger issue than that; it's a public health issue. It's not just the corrections systems and the police that need to be concerned about it, because it has broader public health impact.”

Aside from these particular findings, the source of Gilman’s data is also pretty remarkable. She and her colleagues conducted this research as part of the Seattle Social Development Project at the School of Social Work at the University of Washington. The Seattle Social Development Project is like a more controlled and extensive (and much less public) version of the fascinating British documentary Up Series, which interviewed 14 children every seven years, age seven in 1964 to age 56 in 2012. The Seattle project, on the other hand, started in 1985 with about 800 fifth-grade students from elementary schools in the Seattle area. The study was skewed to include the more high-crime, high-risk, and low-income areas of Seattle.

While the Up series explored (among other things) the persistent influence of class and economic situations on the development of the subjects’ life choices and levels of happiness, the Seattle program focuses particularly on how to best intervene in high-risk kids’ lives so as to improve their education and health. Researchers asked the kids all types of question about their lives, and from the answers they got, have published findings that focus on topics like health, crime, education, and sexuality.

They returned to interview the same children every year throughout adolescence, and then every three years in adulthood. The study kept an impressive retention rate; about 92 percent of the original fifth-graders are still participating, almost 30 years later. And of course, because of the project’s extended timeline, they can now learn from a new generation of children, too.

“These people who have been in this study since they were in elementary school, they're almost 40 years old now, and we have another study that's following their children,” says Hill of the Seattle program’s spinoff project, The Intergenerational Project. “It’s an intergenerational study that's looking to see how [the original participants] are functioning as parents, how their children are turning out, and then what the mechanisms are that are connecting the two generations.”