A friend recently posted a link to a story about shootings and drugs, asking friends to help her understand whether there could be something to the assertions the writer made.

The story was originally published in April 2013, but seems to be getting circulated more in the wake of the Isla Vista, California shootings in May 2014.

I decided to take the article and apply what (limited and self-taught) skeptical and critical-thinking skills I have to it. Then I thought that others might find the process interesting. So here we go. The article text is in italics.

“Manasquan, NJ —(Ammoland.com)- Nearly every mass shooting incident in the last twenty years, and multiple other instances of suicide and isolated shootings all share one thing in common, and its not the weapons used.

The overwhelming evidence points to the signal largest common factor in all of these incidents is the fact that all of the perpetrators were either actively taking powerful psychotropic drugs or had been at some point in the immediate past before they committed their crimes.”

The source

The original story is from a “news service” called Ammoland which covers guns and gun rights. The strongly pro-gun position of the website and the writer (easily seen on the site) suggests there could be an interest in promoting the idea that something other than guns should be the focus after a tragedy.

The story is replete with spelling and other basic writing errors, suggesting a lack of professional editing or journalistic standards. The writer, Dan Roberts, is a truck driver with a high school education and no apparent training in science, journalism, or analysis of pharmaceutical side effects.

It should also be noted that on some sites which republished Roberts’s article, the headline and lede were changed from “Nearly every” to “every.”

Multiple credible scientific studies going back more than a decade, as well as internal documents from certain pharmaceutical companies that suppressed the information show that SSRI drugs ( Selective Serotonin Re-Uptake Inhibitors ) have well known, but unreported side effects, including but not limited to suicide and other violent behavior. One need only Google relevant key words or phrases to see for themselves. www.ssristories.com is one popular site that has documented over 4500 “ Mainstream Media “ reported cases from around the World of aberrant or violent behavior by those taking these powerful drugs.

While the first paragraphs discuss SSRI side effects in some detail, many of the drugs in the list are not SSRIs, or even antidepressants.

Before the list of incidents, the story delves heavily into conspiracy theories, suggesting the man who compiled the list was one of many people killed by mysterious forces.

The list.

The story then lists 39 incidents. The first is the shootings and bombings at Columbine High School. The last is an incident in which a 16-year-old fired a shotgun at a teacher.

The list itself is problematic. The headline suggests a story about mass shootings. But the list includes attacks with knives, bats, and other weapons, and also includes incidents of suicide and incidents in which nobody was killed.

Another problem with the list is that it is not “nearly every mass shooting in the last 20 years.” I went to Wikipedia. I hand-counted the entries in its list of school shootings (which excludes shootings in any other place), and found 119 entries. There are 32 listings for “rampage murders”, in the US during the 20 years previous to the story, 8 workplace mass shootings, 4 shootings on military bases, and 19 “familicides.” That totals 182 incidents. 39 out of 182 is less than a quarter of incidents.

The drugs

In the list, a number of drugs are mentioned. I’ll group them by drug type.

Zoloft, Luvox, Paxil, Lexapro, Prozac: SSRI antidepressants

Wellbutrin: non-SSRI antidepressant

Ritalin: stimulant

Trazadone: SARI antidepressant

Xanax: benzodiazepene tranquilizer.

Ambien: nonbenzodiazepene hypnotic.

Remember, the start of the article mentions SSRIs and the term psychotropic drugs. Of course, the term psychotropic drugs covers everything from caffeine to alcohol to these and many other drugs.

Each of these drugs operates on a different part of the brain, and in a different way. It’s not made explicit in the story, but the logic seems to be that there is something across all of these drugs that makes their users susceptible to violent behaviour.

Demographics

Depending on source, antidepressants are either the most or the second-most commonly prescribed drugs in the US (and many other parts of the world). According to the New York Times, 1 in 10 Americans take an antidepressant. That’s more than 30 million people. If we assume the article’s list is exhaustive at 39, that doesn’t seem a particularly high number. In 2010 alone, there were 48 million prescriptions for Xanax in the US.

Correlation does not equal causation.

Even if the association between these drugs and violent behaviour was strong, there’s no causal link demonstrated. It might be that these drugs in some way induce violence. It might also be that the perpetrators had violent tendencies that were being treated by drugs.

Greater than normal?

Given the frequency of use of psychotropic drugs in Western society, is it possible that the number of violent incidents where drugs were involved fits the curve of the number of violent incidents where drugs weren’t involved? For example, if there were 3.9 incidents per 100,000 people where these drugs were involved, that might be really bad. But if you then look at the general population without drugs and see that it’s 4.2 per 100,000, doesn’t seem so bad.

Bad things happen all the time. I wish that wasn’t the case, but it is. In the US, there were more than 16,000 homicides in 2010. There were more than 1.2 million violent crimes in the US in 2012.

When you find 39 instances of something that is sadly common—homicide — and compare it with something else that’s also common — psychotropic drug use — it’s difficult to tease out the evidence.

I can’t say that the writer of the article is wrong. But as the skeptic Marcello Truzzi said, “An extraordinary claim requires extraordinary proof.”

In the end

When tragic events take place, we seek out explanations. And our brains are wired for pattern recognition. That’s why our ancestors survived (“Hey, look over there in that grass. HOLY CRAP THAT’S A TIGER!”). Now, our prodigious brains seek and find patterns where no real pattern exists.

When you’re consuming media, it’s always best to apply some critical thinking skills to EVERYTHING you read or watch. Perhaps you’re being manipulated by the media maker, or perhaps it’s just your brain finding patterns. Or perhaps there’s something to it. My only real advice: don’t simply accept any statement.