LONDON: Cocaine may damage or even destroy the nerve cells which create “the high” enjoyed by users of the drug, according to research by US scientists.

Analysis of brain tissue samples showed that levels of dopamine — a pleasure-signalling chemical — were significantly lower in the brains of cocaine abusers than they were in those of non-drug using control subjects.

Regular drug users also had lower levels of a protein, VMAT2, which interacts with dopamine to produce “the high”.

Dopamine is a neurotransmitter or “chemical messenger” which allows different nerve cells to communicate with each other. It affects the brain processes controlling movement, emotional responses, pain and pleasure.

Cocaine acts as a stimulant by altering the flow of dopamine, causing levels to build up so that pleasure signals are repeated. But it now appears that it may also damage the cells producing dopamine.

The researchers, from the University of Michigan and VA Ann Arbor Health Systems, hope that the evidence of cocaine-induced damage could help to explain how people become addicted to the drug.

It could also aid the development of treatment plans and increase understanding of other disorders involving the same brain cells, such as depression. Dopamine and VMAT2 levels were lowest in drug users with depression.

“This is the clearest evidence that the specific neurons are disturbed by the drug’s effects,” said Karley Little, research leader.—Dawn/The Guardian News Service.