30 Nov 2006

Smoking alters brain

Smoking alters brain chemistry linked to pleasure and pain, a new German study finds.

Researchers used proton magnetic resonance spectroscopy (MRS) to examine the brains of 21 men and 22 women, ages 21 to 59, two weeks after they began a smoking-cessation program and again six months later. The study also included 35 non-smokers.

Proton MRS measures brain metabolism at the cellular level and provides detailed data about the brain's chemistry.

The researchers found that, two weeks after quitting smoking, the former smokers had significantly decreased concentrations of the amino acid N-acetylaspartate (NAA) in the anterior cingulate cortex (ACC), the brain region that processes pleasure and pain.

The more you smoke, the bigger the impact
These decreased NAA levels were evident whether or not the former smoker used a nicotine patch. The study also found that the level of reduction was associated with a person's smoking history. The greater a person's number of pack years (one pack of cigarettes per day for one year equals one pack year), the lower their NAA levels.

Previous research has noted reduced NAA levels in people with different kinds of psychiatric and mood disorders - such as bipolar disorder, schizophrenia and dementia - and in people with substance abuse problems, particularly alcohol dependence.

There was good news for smokers: The study found that quitting smoking restored normal brain chemistry. At the six month follow-up, levels of NAA and other brain metabolites had normalised in the 25 ex-smokers who did not relapse.

"These findings further emphasise the importance of quitting smoking. The degree of reduction of NAA in the ACC depends on the amount of tobacco consumed over time, but it appears to normalise after smoking cessation," researcher Dr Okan Gur, department of radiology, University of Bonn, said in a prepared statement. – (HealthDayNews)