Antidepressants may worsen addiction

Antidepressants prescribed for anxiety and depression may worsen alcohol and drug use in some people with substance-use disorders, a new study has found.

Associate Professor David Menkes, of the University of Auckland's Department of Psychological Medicine, co-authored the research. It reviewed evidence from randomised controlled trials of antidepressant treatment involving 2,891 people with various substance-use disorders. Only two out of 35 trials found a significant improvement in depression symptoms.

“The findings challenge a common assumption that antidepressants are an effective treatment for anxiety and depression in people with substance-use disorders,” Menkes says. “What this review shows is that the evidence for that assumption is much weaker than many clinicians realise.”

People with substance-use problems commonly experience anxiety and depression and are often prescribed antidepressants, most commonly selective serotonin reuptake inhibitors (SSRIs) or serotonin-noradrenaline reuptake inhibitors (SNRIs).

"What surprised me most was that the problem wasn’t limited to alcohol. The same pattern was apparent across a range of abusable substances, including stimulants, opioids and cannabis."

The findings build on earlier research by Menkes and colleagues that uncovered unexpected interactions between antidepressants and alcohol.

That research analysed 200 reports from clinical practices, medicine regulators, safety agencies and online forums. Of those, half met the team's criteria for a probable interaction between antidepressants and alcohol.

While some people reported an increased drive to drink, others experienced exaggerated effects of alcohol, becoming unexpectedly intoxicated after drinking previously well-tolerated amounts.

In some cases, the interaction caused what Menkes describes as ‘pathological intoxication’.

"For example, some people would become drunk on a couple of glasses of wine and behave in ways that were completely out of character for them,” he says.

"They might become loud, rude or violent, despite drinking amounts they had previously tolerated without any problem."

About half the alcohol-related cases involved periods of amnesia, with people unable to remember events that occurred while intoxicated.

While this earlier research focused on alcohol, the new study suggests that aggravation of substance misuse by antidepressants may be a general phenomenon, also extending to stimulants, opioids and cannabis.

Combined with their often disappointing effectiveness in relieving symptoms of anxiety and depression, the findings suggest antidepressants may do more harm than good for people with substance-use problems, he says.

Many doctors in New Zealand and elsewhere have traditionally prescribed antidepressants for people with addictions who present with these symptoms.

Menkes says the current research suggests it may be preferable to focus instead on the substance use itself and to consider psychological therapies instead of antidepressants.

Read the study