Meth addicts can’t read faces

Methamphetamine abusers find it hard to read expressions on people’s faces and therefore struggle to detect emotion in others, a new joint study at Australian Catholic University (ACU National) has found.

Dr Peter Rendell, Associate Professor of Psychology at ACU National, postgraduate student Magdalena Mazur and Julie Henry from the University of NSW tested 20 adults with an average history of four years of methamphetamine (MA) abuse on measures of social reasoning.

These 20 adults were screened from more than 100 MA users who had been formally diagnosed with MA dependence, were not dependent on any other drug and did not have a medical condition.

Compared with a control group who had no history of drug use, the group who had used MA had greater difficulty detecting subtle differences in mental states and differentiating between basic facial expressions of emotion.

Dr Rendell said that recognising emotion on people’s faces and understanding that others think about things differently to you are two of the most important aspects of social-thinking.

"Being so significant to social-thinking, we wanted to see whether MA users were impaired in these specific thought processes – and they clearly were," he said.

"We therefore know that MA use has psychological consequences, and, potentially, consequences for these individuals’ social functioning.

"The size of these social reasoning deficits was comparable to the memory problems that have also been found in users of MA, consistent with other evidence showing that MA is a dangerous drug which can do lasting harm."

The study was published recently in the British Journal of Clinical Psychology.

"An interesting point to also consider is the possibility that these deficits could have been present before drug use and even a risk factor for drug use – meaning those who struggle to make sense of other people might be more vulnerable to taking drugs in the first place."

(Source: Australian Catholic University: British Journal of Clinical Psychology: June 2009)