The suicide of Soundgarden frontman Chris Cornell on Wednesday shocked many, and Cornell’s wife Vicky has publicly stated that she believes his anti-anxiety medicine is to blame.

In a statement, Vicky Cornell said that she called the Soundgarden singer and observed that he wasn’t acting like himself.

“When we spoke after the show, I noticed he was slurring his words; he was different,” she said. “When he told me he may have taken an extra Ativan or two, I contacted security and asked that they check on him.”

Cornell, who had previously been to rehab for drug addiction, was on Ativan, an anti-anxiety drug that’s commonly prescribed to help former addicts during and after rehabilitation. Ativan’s listed side effects include depression and suicidal thoughts; Vicky Cornell’s statement suggests that the medication may have caused Cornell to hang himself.

So what is Ativan? Also known as lorazepam, Ativan is a benzodiazepine, a class of anti-anxiety medication first given to returning veterans of the Vietnam War to help them cope with their PTSD; reports indicate that vets often got addicted to Ativan. Benzodiazepines work by boosting the activity of a neurotransmitter called GABA which is generally responsible for inhibiting neural activity. A healthy balance of GABA can prevent your brain from getting overexcited, one of the physiological hallmarks of anxiety.

In short, Ativan helps quiet and calm an overexcited brain. But if the inhibitory effects of benzodiazepines go too far, they can cause depression-like symptoms rather than finding a happy medium. Taking a couple extra pills of Ativan or mixing the drug with other depressants like alcohol could theoretically tilt this delicate balance.

Cornell’s post-mortem toxicology reports have not yet come in, but taking more Ativan than the recommended dosage may have caused the symptoms that Vicky reported from their phone call. Along with drowsiness, dizziness, and confusion — symptoms that may explain Cornell’s uncharacteristic behavior over the phone — Ativan is known to cause depression and suicidal thoughts in some severe cases, especially when people up their dosage.

In contrast, the most common antidepressant medications work by increasing the amount of serotonin available to the brain. Serotonin is a neurotransmitter that, among other things, makes people feel happy and sociable. They’re the doctor-prescribed uppers to benzodiazepine’s downer.

Again, it’s too early to implicate Ativan in Chris Cornell’s suicide. No one knows why he killed himself, and we may never have a conclusive reason.

Photos via Getty Images / Rick Diamond