Cough medicine abuse and addiction to heroin affect the function and structure of human brain in similar fashion, according to a Chinese study published on Thursday.

Both types of addiction cause abnormalities in the areas of reward circuit (which provides the sense of pleasure), cognitive control (which allows information processing and behavior to adapt to a certain situation), and decision making.

Tian Junzhang from Guangdong No. 2 Provincial People's Hospital and his team monitored 30 heroin addicts aged between 20 and 50 years, and 80 abusers of cough syrup of the same age bracket to map the changes their brains undergo through a period of eight years.

Health experts are alarmed about the misuse of over-the-counter medicines, especially cough suppressants and expectorants, as such treatments are purchased in drugstores without a prescription.

The easy access to cough syrup mixed with psychotropic effects in large doses has made cough medicine popular among youth seeking to get high.

According to figures by a New York-based non-governmental organization, Partnership for a Drug-Free America, one out of every 10 US people between 12 and 17 years old have used cough medicine in order to get high.

In China, on the other hand, there is no official data about the number of cough syrup abusers, but it is reported that young males make up the highest population of non-prescription medicine addicts.

Few Chinese researches have focused on addiction to legal over-the-counter drugs, and the neuro-physiological mechanisms of dependency to cough medicine are not entirely clear either.

Higher-than-recommended doses could induce euphoria, “out-of-body” experiences, dissociative effects or hallucinations. However, the sense of elation comes at a sad price.

Patients addicted to cough medicine have their cerebral cortex – the area responsible for thinking and consciousness – thinner than normal people, and tend to be impetuous and inclined to gambling, Jiang Guihua, director of the medical imaging department at the hospital, explained.