Harvard School of Public Health Associate Professor of Society, Human Development, and Health Stephen Buka and colleagues have published a study that finds a link between maternal cigarette smoking and later nicotine dependence of offspring.
Participants in the study were the grown children of mothers enrolled in the Providence, Rhode Island site of the National Collaborative Perinatal Project (NCPP), a multi-site study that involved the observation and examination of more than 50,000 pregnancies through the first seven years of life. Participants for the NCPP were enrolled between 1959 and 1966 and were visited regularly by NCPP investigators. Beginning with the first prenatal meeting and in each subsequent meeting until delivery, the mothers in the study were asked if they smoked, and if so, the number of cigarettes per day. From these data the researchers were able to establish the maximum number of cigarettes smoked at any point during the pregnancy. More than 60 percent of the women smoked during their pregnancies; approximately 35 percent smoked more than a pack per day (20 cigarettes) and nearly 25 percent smoked less than a pack per day.
Offspring whose mothers reported smoking a pack or more of cigarettes per day during their pregnancy were significantly more likely to meet DSM criteria for lifetime nicotine dependence than offspring of mothers who never smoked during their pregnancy. Among offspring who tried cigarettes, the odds of progressing to nicotine dependence was almost twice as great for those whose mothers smoked heavily during pregnancy. In contrast, the use of marijuana was not increased among children whose mothers smoked cigarettes during pregnancy. Marijuana use among the adult offspring was of particular interest to the researchers because of its similar route of administration (inhalation) and because research has shown an association between cigarette smoking and marijuana use.
Stephen Buka, lead author of the study and an associate professor in the Department of Society, Human Development and Health at the Harvard School of Public Health said, “More than half a million infants each year are exposed to cigarette smoke before birth. In the short term, this increases the risk of low birthweight and birth defects, and in the longterm, this adds to the likelihood that children will become heavy smokers, dependent on nicotine. Eliminating smoking during pregnancy and afterwards remains a critical challenge for clinicians and for public health practionners.”
The exposure that altered the brain may not necessarily have come during pregnancy. Since women who smoked during pregnancy were likely to smoke after birth the babies might have had their brains modified by the exposure during the period of postnatal brain development.
The lack of an increase in marijuana smoking among children exposed to nicotine during fetal development is not too surprising. The mechanisms for causing craving for different kinds of drugs are not all identical. A predisposition to become addicted to nicotine may not necessarily translate into a predisposition to become addicted to opiates either.
It is very valuable to identify factors that cause brains to develop in ways that predispose people to become addicts of various sorts. For some types of addiction (e.g. heroin) the success rate of getting off and staying off is less than 50%. The kinds of changes that happen to brains of addicts to make them desire drugs are often very long lasting and possibly permanent in many cases. Techniques are sorely needed to be able to change brains in ways that reduce the cravings for addictive drugs.
In an interview, Buka explained that pregnant women were interviewed many years ago, when people were not yet aware of the health effects of smoking. Consequently, more than 60 percent of the women smoked, and around 35 percent smoked at least one pack on at least one day of their pregnancies.
These poisonous chemicals pose unique and real threats to the unborn child. Smoking during pregnancy is associated with low birth weight, premature delivery, placenta previa (a complication that could cause bleeding and become a medical emergency), miscarriage and post-delivery death. It has also been associated with a 50 to 70 percent higher chance of delivering babies with a cleft lip or palate, and this risk is believed to increase with the number of cigarettes smoked per day
|Share |||Randall Parker, 2003 December 10 11:17 PM Brain Addiction|