Anyone who has been a smoker for a long time knows that it’s an addictive habit. If you go too long without a cigarette, you start feeling that familiar craving that urges you to have a cigarette as soon as possible. This craving is intense and uncomfortable though, more like a really deep itch that you have to scratch. Smoking is addictive on two fronts: physical and psychological. The psychological aspect of addiction to smoking is actually about the habitual nature of it. But the physical part of smoking is due to the presence of nicotine, because nicotine is very addictive and causes physical dependency.
However, although the first few cigarettes may give you a “high” feeling, future cigarettes that you smoke won’t usually give you that good feeling anymore. You’ll need to continue smoking just so that you can feel normal. The degree of addiction to nicotine depends largely on how much you normally smoke, with heavy smokers (those who smoke a pack a day or more) being the most addicted to nicotine and feeling the most pronounced effects from withdrawal.
Adrenal Effects
You’ve probably heard the phrase “adrenaline rush” before. A rush of adrenaline occurs when something stimulates your central nervous system and causes it to speed up. Nicotine is a substance that has strong stimulant effects, so it makes you feel energized and alert after smoking a cigarette. When you smoke, nicotine goes to your brain almost immediately – within about 15 seconds.
Part of nicotine’s stimulant effect is that it raises dopamine levels, which is a hormone related to pleasure seeking. When you smoke, it raises your dopamine levels, which is very enjoyable and both physically and mentally pleasurable. The release of dopamine will trigger you to smoke again once it wears off, so that you can continue to receive the benefits from it.
Nicotine’s Effect on the Brain
Nicotine causes your brain to release hormones called neurotransmitters. When you smoke, nicotine acts on the same receptor cells as a neurotransmitter called acetylcholine, which activates neurological pathways linked to reward and pleasure. In short, the way nicotine works in your brain is designed to make you intensely want more of it.
Nicotine also stimulates your brain to release another neurotransmitter called glutamate. Instead of increasing pleasure, glutamate has a powerful effect by enhancing learning, performance and memory. That effect explains why so many college students turn to nicotine as a study aid: it improves attention span and helps you to remember what you learned.
Pain Relief
You may be used to popping a pill to deal with minor pain like a headache or muscle aches, but nicotine has pain relieving effects as well. Nicotine helps you release more endorphins, which is the body’s natural pain killer. The more that you smoke, the more endorphins your body produces. This can be addictive in the same way that opiate based painkillers can become addictive: it feels good physically to be free from all pain and to experience the euphoria that endorphins provide.
Researchers used a technology called PET scans, or positive emission tomography, to look at opioid receptor activity, which is the part of the brain that deals with pain management. They found that known pain killing drugs, like morphine and heroin, act on those opioid receptors to block pain, but they were surprised to discover that nicotine has a similar effect on the receptors as well. However, the brain scans also showed that the parts of the brain associated with pleasure, memory and emotion were less active, but lit up with activity after having a cigarette.
Effects in Teens
Some research shows that nicotine has a more pronounced effect on teenagers because their brains are still developing. Both smoking and exposure to second-hand smoke causes brain damage. One of the most significant effects of nicotine on teens is possible hearing loss, which leads to problems with poorer performance in school.
Genetic Predisposition
Although researchers don’t yet know why, some people seem to be more prone to becoming addicted to nicotine than others. And while it’s not clear which is the cause and which is the effect, smokers produce 40 percent less of an enzyme in the brain that breaks down dopamine when compared to non-smokers. It may be possible that this reduced enzyme that breaks down dopamine could contribute to addiction to nicotine.