There has been a lot of commentary on the NEJM article on the association between stimulant treatment of Attention Deficit Hyperactivity Disorder (ADHD) and less crime in a cohort of patients with ADHD. Two of my favorite bloggers have commented on the study on the Neuroskeptic and Evolutionary Psychiatry blogs. As a psychiatrist who treats mostly patients with addictions who may have ADHD and teaches the subject in lectures - I thought that I would add my opinion.
Much of my time these days is spent seeing adults who are also being treated for alcoholism or addiction. I also teach the neurobiological aspects of these problems to graduate students and physicians. In the clinical population that I work with - ADHD is common and so is stimulant abuse/dependence and diversion. Cognitive enhancement is a widely held theory on college campuses and in professional schools. That theory suggests that you can study longer, harder, and more effectively under the influence of stimulants. They are easy to obtain. Stimulants like Adderall are bought, sold, and traded. It is fairly common to hear that a feeling of enhanced cognitive capacity based on stimulants acquired outside of a prescription is presumptive evidence of ADHD. It is not. It turns out that anyone (or at least most people) will have the same experience even without a diagnosis of ADHD.
There is very little good guidance on how to treat ADHD when stimulant abuse or dependence may be a problem. Some literature suggests that you can treat people in recovery with stimulants - even if they have been previously addicted to stimulants. Anyone making the diagnosis of ADHD needs to makes sure that there is good evidence of impairment in addition to the requisite symptoms. Ongoing treatment needs to assure that the stimulants are not being used in an addictive manner. I would define that as not accelerating the dose, not taking medications for indications other than treating ADHD (cramming for an exam, increased ability to tolerate alcohol, etc), not attempting to extract, smoke, inject, or snort the stimulant, not obtaining additional medication from an illegal source, and not using the stimulant in the presence of another active addiction. Addressing this problem frequently requires the use of FDA approved non stimulant medication and off-label approaches.
With the risk of addiction that I see in a a population that is selected on that dimension, why treat ADHD and more specifically why treat with medications? The literature on the treatment of ADHD is vast relative to most other drugs studied in controlled clinical trials. There have been over 350 trials and the majority of them are not only positive but show very robust effects in terms of treatment response. The safety of these medications is also well established.
Enter the article from the NEJM on criminality and the observation that stimulants treatment may reduce the criminality rate. This was a Swedish population where the research team had access to registries containing data on all persons convicted of a crime, diagnosed with ADHD, getting a prescription for a stimulant, and to assign 10 age, sex, and geography matched controls to each case. Active treatment was rather loosely defined as any time interval between two prescriptions as long as that interval did not exceed six months. The researchers found statistically significant reductions during the time of active treatment for both men (32%) and women (41%).
I agree that this is a very high quality article from the standpoint of epidemiological research - but my guess is the editors of the NEJM already knew that. This study gets several style points from the perspective of epidemiological research. That includes the large data base and looking for behavioral correlates of another inactive medication for ADHD - serotonin re-uptake inhibitors or SSRIs. There is a robust correlation with stimulants but not with self discontinued SSRIs. They also analyzed the data irrespective of the order of medications status to rule out a reverse causation effect (treatment was stopped because of criminal behavior) and found significant correlations independent of order.
Apart from the usual analysis clinical and researchers in the field ranging from neurobiologists to researchers doing long term follow up studies do not find these results very surprising. The Medline search below gives references of varying quality dating back for decades. The pharmacological treatment certainly goes back that far. The accumulating data suggests that where the disorder persists, it requires treatment on an ongoing basis. A limited number of studies suggest that cognitive behavioral therapy (CBT) may be useful for adults with ADHD but not as useful for children or adolescents. The practice of "drug holidays" prevalent not so long ago - no longer makes sense when the diagnosis is conceptualized as a chronic condition needing treatment to reduce morbidity ranging from school failure to decreased aggression to better driving performance.
One of the typical criticisms of epidemiological research of this design is that association is not causality, I think it is time to move beyond that to what may be considered causal. In fact, I think it may be possible at this time to move beyond the double blind placebo controlled trial to an epidemiological standard and I will try to pull together some data about that approach.
George Dawson, MD, DFAPA
Lichtenstein P, Halldner L, Zetterqvist J, Sjölander A, Serlachius E, Fazel S, Långström N, Larsson H. Medication for attention deficit-hyperactivity disorder and criminality. N Engl J Med. 2012 Nov 22;367(21):2006-14. doi: 10.1056/NEJMoa1203241.
Criminality and ADHD: Medline Search