NEW YORK (Reuters Health) - Adolescents with genetic variants in hepatic cytochrome P450 2A6 (CYP2A6), which slow nicotine clearance, are at significantly increased risk of becoming nicotine dependent, but smoke less once dependent, research shows.
“Fundamentally, kids should not take that first puff because all kids are at risk of dependence,” Dr. Jennifer O’Loughlin told Reuters Health. “But there are subgroups that are at much higher risk of becoming dependent quickly at low levels of cigarette consumption (2-3 per day), because of a genetic predisposition towards slow nicotine metabolism,” she said.
Dr. O’Loughlin from McGill University in Montreal, and colleagues analyzed self-reports of tobacco use and nicotine dependence symptoms in nearly 1300 novice smokers in the 7th grade. Additionally, they analyzed the genetic profile of 281 of these individuals and those that were not already tobacco dependent (n=228) were followed for roughly 2 years.
During this period, 67 students became nicotine dependent. According to the report in the December issue of Tobacco Control, nicotine dependence was significantly more likely among students with 1-2 copies of the inactive CYP2A6 gene variants CYP2A6*2 and CYP2A6*4, with a hazard ratio of 2.8.
Students with 1-2 copies of the partially inactive variants CYP2A6*9 and CYP2A6*12 were not at increased risk of becoming nicotine dependent.
Consistent with studies in adults, adolescents with genetically decreased nicotine metabolism smoke less than normal nicotine inactivators.
Specifically, students with normal CYP2A6 smoked an average of 29 cigarettes per week, while those with partially inactive CYP2A6 variants smoked 17.2 cigarettes per week. Those with fully inactive CYP2A6 variants, the slowest nicotine inactivators, smoked the fewest cigarettes per week (12.7).
It is possible, the authors say, that these genetically determined slow inactivators of nicotine require fewer cigarettes to become dependent because they have a higher brain exposure to nicotine and/or prolonged exposure, which may boost the physiological processes leading to dependence.
“Eventually smoking cessation treatments will incorporate new ways to take slow nicotine metabolism into account,” Dr. O’Loughlin told Reuters Health, adding that her colleagues in Toronto are working on this right now.
Source: Tobacco Control 2004;13:422-428. [ Google search on this article ]
MeSH Headings:Behavioral Sciences: Biological Sciences: Biology: Community Health Services: Data Collection: Diagnosis: Diagnostic Services: Behavioral Disciplines and Activities: Environment and Public Health: Epidemiologic Methods: Health Care Facilities, Manpower, and Services: Genetic Screening: Genetics: Genetics, Behavioral: Genetics, Biochemical: Health: Health Occupations: Health Services: Health Services Administration: Health Surveys: Information Science: Mass Screening: Medicine: Investigative Techniques: Molecular Biology: Population Characteristics: Preventive Health Services: Preventive Medicine: Public Health: Quality of Health Care: Smoking: Specialties, Medical: Public Health Practice: Health Care Quality, Access, and Evaluation: Health Care Evaluation Mechanisms: Diagnostic Techniques and Procedures: Analytical, Diagnostic and Therapeutic Techniques and Equipment: Biological Sciences: Health Care: Information Science: Psychiatry and PsychologyCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
