A notable drop in crime in the U.S. in the 1990s, particularly violent crime, appears to have been mirrored by the introduction of new and more effective drugs to treat mental illness. That’s the conclusion of an intriguing National Bureau of Economic Research working paper, which takes as its starting point the fact that many of the presumed social, economic, and policy determinants of crime actually had little impact on this change, and so other factors may be responsible. As the authors note,
“One factor that has so far been ignored in the attempt to explain this recent drop in crime is a period of dramatic technological advances in the treatment of mental illness. As we summarize below, mental illness is a clear risk factor both for criminal behavior and for victimization. The decline in crime rates occurred during a period when many new pharmaceutical therapies became available to treat mental illness, resulting in exceptionally large increases in medical treatment of mental illness. For example, during the last two decades the use of antidepressants and anti psychotics has become increasingly common following a series of drug innovations in the late 1980s and early 1990s. The new drugs were marked improvements over the previous therapies in terms of side effects and efficacy, and their use has subsequently become widespread. Anti-depressants and anti-psychotic medications are now the 6th and 7thlargest therapeutic classes of drugs sold globally (IMS Health 2006), and by 2005 there were enough newer anti-depressants sold in the U.S to treat every man, woman, and child with a daily dose for almost two months.”
As the authors point out, it has long been established that people likely to engage in criminal behavior respond to incentives, but any such assessment of the risks and benefits may be undercut by mental illness.
“Mental illness may cause the afflicted to substantially discount the future, thereby lowering the deterrent effect of established punishments. This possibility is substantially related to Becker and Mulligan’s (1997) formulation of impatience. They observe that many people recognize their high rate of time preference as a weakness, and allocate resources to overcome that weakness. One might think of mental health treatment as just such an allocation. The expansion of treatment for mental illness can then affect crime not by changing the certainty or severity of punishment, but by changing the behavioral response to established costs.”
Given that severe mental illness is associated with delusional thinking, poor impulse control, narcissism, and altered perceptions of risk, it is not surprising to find correlational studies showing that those with severe mental illness are much more likely to be incarcerated in the past six months than comparable people in the general population. A study that followed all the children born in Dunedin, New Zealand over the course of a year found that those with mental illness were twice as likely to be violent.
So how much of an effect has the psycho-pharmacological revolution had on crime? The authors note that their paper is only a first step in an area of limited data, but they did find that “prescriptions for stimulants and antipsychotics [were] associated with relatively large reductions in violent crimes: 0.129 percent and 0.085 percent for every 1 percent increase in stimulants and antipsychotics, respectively.” The findings were statistically significant.
They also tested their model with the increased use of statins for cholesterol, to see if there findings might be confounded by broader changes in health care. As the authors note, the growth of drugs such as Lipitor and Crestor “was likely shaped by some of the same social, economic and policy conditions that led to the rise in pharmaceutical treatment of mental illnesses.” The relationship between crime and statins was insignificant (and in some cases, positive).
Their conclusion of this long and fascinating paper are noteworthy:
“Our evidence suggests that, in particular, sales of new generation antidepressants and stimulants used to treat ADHD are associated with rates of violent crime, with weaker evidence that anti-psychotic medications played a role in declining crime rates. The magnitude of the elasticities estimated here are clearly small. We estimate that a one percent increase in the total prescription rate is associated with a 0.051 percent decrease in violent crimes. To put this in perspective, doubling the prescription rate would reduce violent crimes by 5 percent, or by about 27 crimes per 100,000, at the average rate of 518 crimes per 100,000 population. While doubling the prescription rate seems like a large change, it has been estimated that 28 percent of the U.S. adult population in any year has a diagnosable mental or
addictive disorder, yet only 8 percent seeks treatment (USDHHS 1999). Doubling the treatment rate would still leave a substantial portion of the ill untreated.”
hat tip – Andrew Sullivan