Smoking cannabis can affect your ability to empathise with other people, a new study has claimed.

Researchers at Colorado State University found that the drug interfered with how people recognised emotions in other people, including sadness, happiness and anger. Around 70 volunteers took part in a series of experiments in which they looked at faces with four different types of expression – neutral, angry, frightened or happy.

During the tests, the participants were hooked up to an electroencephalogram (EEG) and their brain’s electrical activity was monitored.

Those who used cannabis reacted more to negative facial expressions than positive ones. And when the drug users were asked to focus on the gender of the face, they found it harder to identify the emotion than people who don’t smoke cannabis.

The results suggested that people who use cannabis find it harder to implicitly identify emotions. The group of cannabis users also found it more difficult to empathise than the control group.

The research team said the study, which has been published in the journal PLOS ONE, seemed to indicate that cannabis affected the ability of the brain to judge emotion. However, the brain may be able to counteract the effect of cannabis in some cases.

Research aims to make sense of the way drug affects the brain

Dr Lucy Troup, assistant professor of psychology at Colorado State University, who led the study said: “We’re not taking a pro or anti stance, but we just want to know, what does it do? It’s really about making sense of it.”

The participants who regularly took cannabis were all legal users of the drug in Colorado. This means they were either over-18s who use medical marijuana or over-21s who smoke the drug recreationally.

There have long been concerns about the affect cannabis has on the brain. It can make users feel anxious and paranoid and has been linked to serious mental health problems, including schizophrenia.

If you’re concerned that someone you love may be abusing drugs it is important to seek help and support. Drug testing a way of finding out for certain whether they are using illegal substances and may provide the wake-up call they need to kick their habit.

AlphaBiolabs offer a range of drug tests including analysis of hair strands which can tell you about a person’s drug use over a period of up to 12 months, depending on the length of the sample. Urine and blood testing is also available.