What is known about untreated trauma and violence in cities?

How common are trauma and PTSD in the studies we have?

In one Atlanta study, 1,600 adults were interviewed at an urban public hospital (Grady Memorial; primary care and obstetrics-gynecology clinics, 2005–2008; low-income patients), and 1,256 people — 87.8% of those who answered the trauma questions — reported significant lifetime trauma. Among 318 who volunteered for a clinical interview, 46.2% had lifetime post-traumatic stress disorder (PTSD). These are patients of one hospital, and the PTSD figure comes from 318 self-selected volunteers — not from all patients and not from a neighbourhood population sample (Gillespie et al. 2009).

Across the WHO World Mental Health Surveys (24 countries, 68,894 people), traumas involving interpersonal violence carried the highest PTSD risk, and prior trauma predicted both future trauma exposure and future PTSD. This is an association, not a cause, and cities were not analysed separately (Kessler et al. 2017).

In the same survey programme, lifetime PTSD prevalence was 3.9% across the whole sample and 5.6% among people exposed to trauma. This is a cross-national average and cannot be compared with the Atlanta figure: the samples and methods are different (Koenen et al. 2017).

Does experiencing violence lead to committing it?

Studies find a raised risk, not a rule: being abused or neglected as a child raised the risk of delinquency and of adult criminal and violent behaviour, but the majority of abused and neglected children did not become delinquent, criminal or violent (Widom 1989).

A meta-analysis of 37 studies with 253,719 adults found that people with four or more adverse childhood experiences had a higher risk of all outcomes studied; the associations were strongest for problematic drug use and for interpersonal and self-directed violence, with more than seven times the odds. Results varied widely between studies for almost half of the outcomes, the included studies were cross-sectional, case-control or cohort studies, many relying on recalled childhood, and an odds ratio is an association, not a cause (Hughes et al. 2017).

How many people with PTSD get any care?

In the WHO World Mental Health Surveys (26 surveys, 24 countries, 71,083 people), only about half of people with severe PTSD reported any treatment, and a minority received specialty mental health care. Among everyone with PTSD in the past 12 months, 48.8% sought any treatment. These are self-reports over 12 months; the survey asked whether people sought treatment, not how good it was (Koenen et al. 2017).

Among people with PTSD in the past 12 months, treatment seeking was 53.5% in high-income countries, 28.7% in upper-middle-income countries and 22.8% in low and lower-middle-income countries. These figures are by country income, not by city or neighbourhood (Koenen et al. 2017).

Do people injured by violence come back injured again?

Of 53,908 patients treated for a violent injury in Florida emergency departments in 2010, 11.1% returned with another violent injury by 2012, and 58.9% of them went to a different hospital the second time. The follow-up covers 2–3 years and Florida hospitals only, so the figure is likely an undercount (Kaufman et al. 2016).

Earlier studies report recurrence of violent injury from 0.8% to 44%. The range is wide because the studies use different definitions and follow-up periods (Kaufman et al. 2016).

What have violence-prevention programmes shown?

None of the programmes below tested treatment of post-traumatic stress disorder.

Becoming a Man in Chicago is a cognitive-behavioural school programme tested in two randomized trials with 4,804 boys in grades 7–10 in disadvantaged neighbourhoods, plus a third trial of a related programme in the Cook County juvenile detention centre. Participation reduced violent-crime arrests among participants by 45–50% and total arrests during the programme period by 28–35%; in the first study only, graduation rose by 6–9 percentage points (12–19% above the baseline). These are arrests, not all offending, and the effects were mostly during the programme (Heller et al. 2017).

In Monrovia, Liberia, 999 men aged 18–35 involved in crime received 8 weeks of cognitive behavioural therapy, a $200 grant, or both. Cash alone and therapy alone initially reduced crime and violence, but the effects faded; when cash followed therapy, crime and violence fell for at least a year — at 12–13 months an index of antisocial behaviour, including crime and violence, fell by 0.25 standard deviations, against 0.08 for therapy alone, which was not significant (NBER working paper figures). The data are self-reported and cover about one year (Blattman, Jamison, Sheridan 2017).

In a Baltimore randomized trial with 100 repeat victims of violence on parole or probation (1999–2001; 56 in the programme, 44 in the control group), there was no significant difference in total arrests; the control group was three times more likely to be arrested for a violent crime and four times more likely to be convicted for one. The sample was small and narrow (Cooper et al. 2006).

A review of 10 articles found insufficient evidence to recommend hospital-based violence intervention programmes for adults; the studies were limited by self-selection bias and small samples. A lack of evidence is not evidence of no effect (Affinati et al. 2016).

Cure Violence in Chicago is rated "Promising" by the US National Institute of Justice on the basis of one study in seven neighbourhoods. Reductions in shootings and killings appeared in only some of the seven neighbourhoods, and overall the results were mixed. This rests on one study, and the profile is no longer updated (CrimeSolutions 2011).