Exposure to nicotine, from conventional or electronic cigarettes during adolescence can impair the developing human brain. E-cigarette use is recognized as a substantial threat to adolescent behavioral health. The use of tobacco products, no matter what type, is almost always started and established during adolescence when the developing brain is most vulnerable to nicotine addiction. Young people's brains build synapses faster than adult brains. Because addiction is a form of learning, adolescents can get addicted more easily than adults. The nicotine in e-cigarettes can also prime the adolescent brain for addiction to other drugs such as cocaine. Exposure to nicotine and its great risk of developing an addiction, are areas of significant concern.
Nicotine is a parasympathomimetic stimulant that binds to and activates nicotinic acetylcholine receptors in the brain, which subsequently causes the release of dopamine and other neurotransmitters, such as norepinephrine, acetylcholine, serotonin, gamma-aminobutyric acid, glutamate and endorphins. Nicotine interferes with the blood–brain barrier function, and as a consequence raises the risk of brain edema and neuroinflammation. When nicotine enters the brain it stimulates, among other activities, the midbrain dopaminergic neurons situated in the ventral tegmental area and pars compacta.
Nicotine negatively affects the prefrontal cortex of the developing brain. Prenatal nicotine exposure can result in long-term adverse effects to the developing brain. Prenatal nicotine exposure has been associated with dysregulation of catecholaminergic, serotonergic, and other neurotransmitter systems. E-liquid exposure whether intentional or unintentional from ingestion, eye contact, or skin contact can cause adverse effects such as seizures and anoxic brain trauma. A study on the offspring of the pregnant mice, which were exposed to nicotine-containing e-liquid, showed significant behavioral alterations. This indicated that exposure to e-cigarette components in a susceptible time period of brain development could induce persistent behavioral changes.
Effects of nicotine
The health effects of long-term nicotine use is unknown. It may be decades before the long-term health effects of nicotine e-cigarette aerosol (vapor) inhalation is known. Short-term nicotine use excites the autonomic ganglia nerves and autonomic nerves, but chronic use seems to induce negative effects on endothelial cells. Nicotine may result in neuroplasticity modifications in the brain. Nicotine has been demonstrated to alter the amounts of brain-derived neurotrophic factor in humans. Side effects of nicotine include mild headache, headache, dysphoria, depressed mood, irritability, aggression, frustration, impatience, anxiety, sleep disturbances, abnormal dreams, irritability, and dizziness.
The neuroregulation and structural interactions in the brain and lungs from nicotine may interfere with an array of reflexes and responses. These alterations may raise the risk of hypoxia. Continued use of nicotine may result in harmful effects to women's brains because it restricts estrogen signaling. This could lead to making the brain more vulnerable to ischemia. A 2015 review concluded that "Nicotine acts as a gateway drug on the brain, and this effect is likely to occur whether the exposure is from smoking tobacco, passive tobacco smoke or e-cigarettes."
Nicotine may have a profound impact on sleep. The effects on sleep vary after being intoxicated, during withdrawal, and from long-term use. Nicotine may result in arousal and wakefulness, mainly via incitement in the basal forebrain. Nicotine withdrawal, after abstaining from nicotine use in non-smokers, was linked with longer overall length of sleep and REM rebound. A 2016 review states that "Although smokers say they smoke to control stress, studies show a significant increase in cortisol concentrations in daily smokers compared with occasional smokers or nonsmokers. These findings suggest that, despite the subjective effects, smoking may actually worsen the negative emotional states. The effects of nicotine on the sleep-wake cycle through nicotine receptors may have a functional significance. Nicotine receptor stimulation promotes wake time and reduces both total sleep time and rapid eye movement sleep."