Monday, September 17, 2012
Genetic Influences on Learning and Addiction?
Smoking cues, such as the sight of cigarettes or smokers, affect smoking behavior and are linked to relapse and cigarette use. Nicotine metabolism, by a liver enzyme, also influences smoking behavior. Variations in the gene that codes for this enzyme determine slow or fast rates of metabolism and therefore, the level of nicotine in the blood that reaches the brain. In the study smokers were screened for their nicotine metabolism rates and their enzyme genotype. Participants were aged 18 – 35 and smoked 5-25 cigarettes daily for a minimum of 2 years. People with the slowest and fastest metabolism had their brain response to visual smoking cues measured using functional MRI. Fast metabolizers had significantly greater response to visual cigarette cues than slow metabolizers in brain areas linked to memory, motivation and reward, namely the amygdala, hippocampus, striatum, insula, and cingulate cortex. more