Cocaine users enjoy social interactions less

Regular cocaine users have difficulties in feeling empathy for others and exhibit less prosocial behavior, scientists say.

Researchers at the Psychiatric Hospital of the University of Zurich in Switzerland found that cocaine users have social deficits because social contacts are less rewarding for them.

Chronic cocaine users display worse memory performance, concentration difficulties, and attentional deficits but also their social skills are affected as previous studies at the University of Zurich suggested.

These investigations also found that cocaine users have difficulties to take the mental perspective of others, show less emotional empathy, find it more difficult to recognise emotions from voices, behave in a less prosocial manner in social interactions, and they reported fewer social contacts.

Moreover, worse emotional empathy was correlated with a smaller social network.

The scientists now believe that social cognitive deficits contribute to the development and perpetuation of cocaine addiction.
In the new study published in the Proceedings of the National Academy of Sciences, psychologists Katrin Preller and Boris Quednow, Head of the Division of Experimental and Clinical Pharmacopsychology at the Psychiatric Hospital of the University of Zurich, concluded that impaired social interaction skills of cocaine users could be explained by a blunted response to social reward.

The research team demonstrated that cocaine users perceived joined attention – the shared attentional focus of two persons on an object after gaze contact – as less rewarding compared to drug-naive healthy controls.

In a subsequent functional imaging experiment they showed that cocaine users showed a blunted activation of a crucial part of the reward system – the so called medial orbitofrontal cortex – during this basal kind of social interaction.

A weaker activation of the medial orbitofrontal cortex during social gaze contact was also associated with fewer social contacts in the past weeks.

“Cocaine users perceive social exchange as less positive and rewarding compared to people who do not use this stimulant,” Quednow said.

Source: Business standard


Gene involved in response to cocaine identified

Scientists, led by an Indian-origin researcher, have identified a gene that may determine the intensity of our response to cocaine.

Researchers at the University of Texas Southwestern suspect that the newly identified gene, Cyfip2, determines how mammals respond to cocaine, although it is too soon to tell what the indications are for humans or for addiction.

The findings evolved from examining the genetic differences between two substrains of the standard C57BL/6 mouse strain: a ‘J’ strain from the Jackson Laboratory (C57BL/6J) in US and an ‘N’ strain from the National Institutes of Health (C57BL/6N).

The study, with Dr Vivek Kumar as the lead author, compared the two strains of mice and used their differential responses to cocaine to identify the causative gene.

“We found that the ‘N’ strain has accumulated mutations over time, one of which has a very strong effect on cocaine response,” said Dr Joseph Takahashi, chair of neuroscience and a Howard Hughes Medical Institute investigator at UT Southwestern and the senior author of the study.

“We propose that CYFIP2 – the protein produced by the Cyfip2 gene – is a key regulator of cocaine response in mammals,” he said.

“We identified this gene by first using a forward genetics strategy to search for differences in traits between the two mouse strains. We found a difference in cocaine response between them, with the C57BL/6N strain showing a reduced behavioural response,” Takahashi said.

“We then carried out genetic mapping and whole genome sequencing, which allowed us to pinpoint the Cyfip2 gene as the causative one in a rapid and unambiguous way,” he added.

The study was published in the journal Science.

Source: Deccan chronicle