There has been a lot of press lately about antidepressants causing people to become suicidal or violent. What are the facts?
Violent acts directed toward oneself or others are very complex behaviors with multiple factors influencing them. Before discussing whether antidepressants cause people to become violent, it is important to understand what it means to state there is a causal link between these medications and violence. One normally thinks of cause in terms of simple physics, such as a ball causing another ball to move when it strikes it. Obviously, this is not the same type of causal relationship that exists between antidepressants and violence. In the physical respect of causality, the only definitive thing that can be said of antidepressants is that they block a transporter pump, causing it to fail to reuptake a neurotransmitter at the synaptic cleft. How this causes an antidepressant effect after that is purely theoretical, although obviously based on sound scientific reasoning. If one reads the Physicians' Desk Reference regarding how antidepressants work, the text rightly states that it is unknown. Thus even providing an explanation as to how antidepressants cause depression to lift is not definitively known.
Another type of causal relationship is the relationship that exists when thinking about what causes people to behave in certain ways. For example, hunger causes someone to eat or thirst causes someone to drink. These are apparently simple causal connections between feelings and acts. Other causal connections that are more complicated involve the issue of motives as in what is the motive behind someone committing a particular crime, such as revenge, jealousy, greed, and so on. It is under these circumstances that people seek to understand the causal relationship between a violent act and the state of mind of the perpetrator just before committing the act. Typically, when one seemingly cannot find any rational motive behind a particular violent act, then the act is attributed to a mental illness. If someone is on drugs or alcohol or some other allegedly "mind-altering" medication, then those may be implicated as well. Although the mentally ill are far more likely to be victims of crimes rather than perpetrators of crimes, someone with mental illness tends to get more press when committing a crime. Most people with mental illnesses are on medication of some sort. Sorting out the causal link between a particular violent act and the underlying causes is similar to attempting to find the causal link between various genetic, physiologic, and environmental factors that ultimately lead to disease but with the added complication of factoring in motive, intent, or one's state of mind. Therefore all that can really be established are correlations. Currently, it appears that, overall, since the introduction of SSRI antidepressants, rates of suicide have been decreasing. However, in many studies regarding particular SSRIs, it has been shown that an increased rate of suicide and suicide attempts occurs at the beginning of treatment. It is important to remember that these statistical analyses do not sort out the issues that are more pertinent to whether an SSRI influences the odds that any one individual will attempt or succeed at suicide. For that, one must know the particular facts surrounding each particular attempt or completion.
Many possible reasons exist for there being increased violence during the initiation of antidepressant treatment. First, antidepressants have long been known to lead potentially to an increase in suicide during the initiation of treatment. This is attributed to the fact that there is generally an improvement in energy before there is an improvement in mood so that a depressed patient now has the drive to act on his or her suicidal thoughts. Second, it appears that SSRIs with shorter half-lives (i.e., SSRIs that are metabolized and eliminated by the body more rapidly) appear to have a stronger correlation than SSRIs with longer half-lives. This may be because there is an association between half-life and the discontinuation syndrome one experiences when stopping these medications abruptly. The discontinuation syndrome can be extremely uncomfortable and anxiety provoking, prompting individuals to misinterpret their symptoms as a worsening of their depression. At this point, this relationship is purely speculative. Third, the antidepressants themselves have side effects associated with them, including agitation, restlessness, anxiety, insomnia, headaches, and indigestion. These side effects can be misinterpreted as a worsening of depression, even though they are not. Finally, in some patients, antidepressants may cause a switch into a manic state, during which there can be irritability and poor impulse control in the presence of suicidal or homicidal ideation.
Statistically speaking, the increased use of antidepressants in the population leads to an increased probability that people exposed to antidepressants will attempt or complete suicide merely by the fact that they would have acted on these thoughts whether they were on the antidepressants or not. If the entire population of the United States were given antidepressant medications and the rates of violent acts increased slightly during the year that they received them (violent acts have an annual statistical variability), the correlation between the medication and the acts would be 100%. This would have absolutely no meaning in terms of figuring out a causal link. Thus, at present, no clear causal links are established between antidepressant use and violence.