Cocaine has several side-effects, including the fluctuation in the dopamine levels to the symptoms associated with drug overdose. Adding to the list of side-effects, a team of European researchers has claimed that cocaine also impacts a person's ability to recognize negative emotions, including sadness and anger.

The joint team of researchers from Germany and The Netherland has claimed that even a single dose of cocaine is enough to impact an individual's ability to perceive negative emotions. The study findings were recently presented at the 28th meeting of the European College of Neuropsychopharmacology in Amsterdam.

During the study, the researchers studied the behavior of 24 students aged between 19 and 27. All of the students considered themselves as “light to moderate” cocaine user. The researchers gave either a placebo or a single dose of 300 milligrams of cocaine to the students.

Later, the group was asked to complete certain biochemical tests and facial emotional recognition tasks. The task measured the drug recipients response to a different set of emotions, including happiness, sadness, anger, disgust and fear.

The research team found that those, who took a single dose of cocaine, were finding a difficulty in recognizing the negative emotions than those, who were given a placebo. In addition, the ones on cocaine have higher levels of cortisol in the brain and also have an escalated heart rate. The researchers further found that when individuals were on cocaine, their ability to recognize the negative emotions was 10 percent worse than their ability when they were on placebo.

“This might hinder the ability to interact in social situations, but it may also help explain why cocaine users report higher levels of sociability when intoxicated — simply because they can’t recognize the negative emotions,” said lead researcher Dr. Kim Kuypers of the Maastricht University in The Netherlands.

The researchers are hopeful that the new study findings help find implication of cocaine dose for other mental illnesses, including schizophrenia and depression. Since cocaine impacts the dopamine levels, the researchers believe that the dopamine levels may be indicative of how people recognize negative emotions.