Cigarette smoking represents a major health problem in the United States. Although most cigarette smokers\r\nexpress a desire to quit, only about 14 to 49% will be successful after 6 or more months of treatment. An improved\r\n \r\n \r\n \r\n\r\n \r\n \r\n\r\n \r\n \r\n \r\n\r\n \r\n \r\n \r\n\r\n \r\n\r\n \r\n \r\nand behavioral treatments for smoking dependence. Many research groups have utilized functional brain imaging to\r\nexamine the effects of tobacco exposure on brain activity. Acute administration of nicotine and cigarette smoking itself\r\nhave been found to increase activity in the prefrontal cortex, thalamus, and visual system; reduce global brain activity;\r\nand increase dopamine (DA) release in the ventral striatum/nucleus accumbens. Chronic tobacco exposure lead to an\r\noverall up-regulation of 42 nicotinic acetylcholine receptors (nAChRs) across brain regions (other than thalamus), and\r\nreduced monoamine oxidase (MAO) A and B levels in the basal ganglia. Functional brain imaging studies of cigarette\r\ncraving and withdrawal, too, demonstrate important changes in brain activity. Taken together, current research suggests\r\nthat smoking enhances neurotransmission through cortico-basal ganglia-thalamic circuits by either direct stimulation\r\nof nAChRs, indirect stimulation through DA release of MAO inhibition, or a combination of these, and perhaps, other\r\nfactors. The purpose of this review is to provide a summary of current functional brain imaging studies of tobacco use\r\nand dependence, and use this information to develop a greater understanding of brain function in smokers.
Loading....