Scientists are finding that nicotine alters parts of the brain responsible for learning, memory, and attention. And because adolescent brains are still developing, the effects of long-term nicotine use can be severe. Studies show that adolescent smokers are more likely to develop psychiatric disorders and have elevated rates of comorbidity. This is because different portions of the adolescent brain mature at varying speeds, making them vulnerable to drugs that affect reward and prefrontal cognitive control.
Changes the Structure of the Brain
Nicotine’s impact on the brain is far-reaching, affecting chemistry and structure. Studies reveal that nicotine can alter the brain’s physical architecture, impacting areas involved in learning, memory, and attention. These structural changes are particularly concerning during adolescence when the brain undergoes significant development. While the long-term effects of nicotine on the brain are still under investigation, the potential for lasting damage highlights the importance of understanding and preventing nicotine exposure, especially during critical developmental periods. The portion of the brain responsible for cognitive control over one’s behavior matures during adolescence. This portion of the brain drives adolescents’ desire to engage in social activities and make the right decisions. Unfortunately, this part of the brain is also vulnerable to being influenced by psychoactive substances like nicotine and can be harmed by them long-term. Nicotine rapidly binds to nicotinic acetylcholine receptors (nAChRs) in brain cells. Nicotine receptors are made up of nine a-type and three b-type subunits. These subunits can combine in different ways to form pentameric channels. When these receptors are activated, they release different neurotransmitters, which can cause cellular damage through DNA damage, cell apoptosis, and increased levels of reactive oxygen species and lipid peroxide. Chronic nicotine exposure leads to acute and long-lasting changes in the function of nAChRs. This includes an increase in the number of a4b2 type nAChRs in the mPFC, which results in more binding of 3H-epibatidine labeled mPFC nAChRs compared to rats not exposed to nicotine.
Reduces the ability to Release Happy Hormones
Nicotine fits into particular receptor molecules on brain cells like a key into a lock, tricking the cell into sending out chemical signals that mimic those released by the natural neurotransmitter acetylcholine. These chemical messages travel across a gap between nerve cells called a synapse, delivering messages from one cell to another. Doing so causes you to feel pleasure and a boost in mood. However, long-term nicotine exposure changes the way these synapses work, which reduces the cell’s ability to release the natural pleasure-giving chemicals. As a result, your brain starts to require more nicotine to get the same effect. In addition, nicotine alters how prefrontal cortex (PFC) neurons process incoming information. Specifically, PFC neurons that connect to the mediodorsal thalamus—a part of the brain that processes sensory input—become less capable of filtering out irrelevant information and allowing you to focus your attention on what’s important. This decrease in short-term plasticity is a significant factor behind the impulsive behavior that often occurs with prolonged nicotine use.
Reduces the Brain’s Ability to Focus
Adolescents have a tough time controlling their impulses, which may explain why adolescent smoking is so common. This is because during adolescence, the brain regions responsible for cognitive control, such as the prefrontal cortex, are still developing. This makes them more susceptible to the rewarding effects of nicotine, which tricks brain cells into thinking they’re releasing natural acetylcholine. Interestingly, when performing the 5-CSRTT, both ex-smokers and smokers showed activation in the anterior cingulate gyrus. However, the percentage of correct responses did not correlate with any of these brain areas when using a placebo. This suggests that other brain circuits are involved in attentional performance and that the differences seen between smokers and ex-smokers during the placebo task could be due to hemispheric lateralization of brain activity.
Ability to Control Impulses is Reduced
Nicotine stimulates the brain’s reward center, which is responsible for impulsive behavior. This can make it hard for teens to control their behavior and stop smoking or vaping. It also reduces the prefrontal cortex’s ability to inhibit inappropriate responses. The immediate effects of nicotine are well-known, such as a quick increase in heart rate and blood pressure, increased salivation, dizziness, nausea, and vomiting. Chronic nicotine use also decreases the amount of oxygen in the brain, which can lead to a feeling of fatigue and decreased mental alertness. Aside from its direct effects, nicotine can disrupt normal brain development in adolescents. Chronic nicotine exposure during adolescence can result in thinning of the prefrontal cortex, which can impact cognitive ability and emotional processing. Brain development continues throughout adolescence, and different portions of the brain mature at varying speeds. This is why nicotine is hazardous to adolescents. The portion of the brain that is most affected by nicotine is responsible for social behaviors, decision-making strategy, and impulse control.
Reduces the Brain’s Ability to Learn
Research suggests that nicotine interferes with adolescent brain development by altering the brain’s circuitry associated with stress, learning, and self-restraint. Nicotine mimics acetylcholine and interacts with adolescent brain cells with b2-containing nicotinic receptors in the prefrontal cortex (PFC). This leads to altered prefrontal network function during cognitive tasks. The impaired PFC network may also lead to memory disturbances and difficulty paying attention. For example, adolescent smokers who participated in a study that tested working memory showed less accuracy in the task than non-smokers, and their errors were correlated with activation of the left prefrontal and anterior cingulate cortices. This indicates that adolescent nicotine exposure impairs learning and memory in humans, and this impairment persists after smoking cessation. The lack of mature cognitive control caused by nicotine might explain why teens are so vulnerable to temptations like drugs and alcohol, unwanted pregnancies, mood disorders, and eating disorders such as anorexia and bulimia. The adolescent brain is still maturing, and nicotine disrupts this natural process by increasing the activity of reward systems and slowing the development of prefrontal control functions.
