Tobacco changes brain in same way as hard drugs
Tobacco causes long-term changes to the brain similar to those caused by other highly addictive drugs such as heroin and cocaine, researchers have said.
The changes remain in the brain long after smokers have stopped using tobacco, said the team from the US National Institute on Drug Abuse.
Using brain tissue from smokers and non-smokers, the researchers examined levels of two enzymes - protein kinase A and adenylate cclase, which help carry chemical messages through the brain and are believed to play a role in the craving and reward responses involved in addiction.
In common with rats who had been given repeated injections of cocaine and heroin, smokers and ex-smokers were found to have unusually elevated levels of the two proteins.
Some experts have said that they consider tobacco to be least as addictive as heroin.
The research is published in the Journal of Neuroscience.