A recent study conducted at Penn State suggests a link between adolescent nicotine use and adulthood depression, memory loss, anxiety and attention problems.
Dr. Laura Klein, assistant professor of biobehavioral health, concluded that a direct relationship exists between adolescent rats that were administered nicotine and increased production of a stress hormone in the brain notorious for causing depression, anxiety and impairing cognitive ability in adulthood. Similar hormones were found to exist within humans and affect them similarly.
Although Klein's study was the first to use rats to determine the effects of adolescent nicotine use on adults, other studies support her findings. Present studies involving human subjects uphold Klein's claim that adolescent nicotine use is responsible for depression.
In Klein's study, 30 male and 30 female rats were exposed to nicotine throughout their lives. Varied dosages of nicotine, equivalent to those that result in biochemical and behavioral inconsistencies in humans, were then injected directly into the rats' blood streams.
After 19 days, the rats were taken off nicotine and within 7 days they were given unlimited access to an opiate.
Klein said the opiate used in her experiment was fentanyl, a medical anesthesia commonly known among addicts as China White that — when abused — results in severe addiction.
After experiencing a 5-day opiate withdrawal, the hormone levels in the rats were tabulated.
The evidence startled and intrigued Klein. Because of the long time period of 44 days that elapsed between the initial exposure to nicotine and the time that the stress hormone levels were measured, Klein had not expected to discover such a distinct relationship.
Klein said the rats that were given a low dosage of nicotine during adolescence experienced a doubled production of stress hormones while those who received high dosages quadrupled their production of stress hormones. "When elevated over long periods of time, these hormones, cortisol (in humans) and corticosterone (in rats and mice), can damage and shrink neurons in critical areas of the brain related to emotions and memory. This damage, in turn, can lead to cognitive impairments and psychological disorders like depression."
When asked whether or not she felt psychological and cognitive malfunctions would occur if adolescence discontinued nicotine use before adulthood, Klein said, "Because of the experimental design, results from my study indicate that this negative consequence may occur (even) if an adolescent quits smoking or using any form of tobacco or nicotine product (i.e., nicotine gum, patch, nasal spray) before adulthood."
She added that rats used in the experiment were exposed to nicotine only during adolescence and still produced elevated corticosterone levels in adulthood.
The study also uncovered a correlation among adolescent nicotine users and male tendencies toward opiate use. Male rats that were administered low dosages of nicotine gravitated toward opiate use in adulthood. This study also supported Klein's earlier hypothesis that females are more likely to consume opiates than males.
When asked what effect Klein feels her study will have on cigarette manufacturers, she said, "This study's results reinforce the importance of bans on adolescent tobacco advertisement and cigarette sales to minors. Although I am not naive enough to think that this single study will directly impact the tobacco industry, I am optimistic that it provides additional supporting evidence for the movement against the initiation of adolescent cigarette smoking and tobacco use."
Klein's study was published in the journal, Experimental and Clinical Psychopharmacology. She won the Young Investigator Award awarded by the Society for Research on Nicotine and Tobacco for her thesis research yielding these astounding discoveries.
