Nicotine is a substance that can promote cognitive function under certain conditions, and if taken at an inappropriate or extreme dosage, it can impair cognitive function. (Pixabay) 
Medicine

Effects of Nicotine on the Brain and Body

Nicotine is one of the most commonly consumed substances in the world. Every day, billions of people consume nicotine.

Dr. Ankit kadarge

Nicotine is one of the most commonly consumed substances in the world. Everyday, billions of people consume nicotine but unfortunately, the majority of those people obtain nicotine by smoking tobacco. There are other sources of nicotine as well. For example, some people consume nicotine through a dip, placing tobacco inside the lip or the cheek. In addition, some people consume nicotine via snuff.

Nicotine is present in the tobacco plant but is also present in nightshades. That is tomatoes, potatoes, eggplant, and sweet peppers. However, nicotine concentrations in these are vastly lower than in the tobacco plant.

Why is nicotine present in potatoes, tomatoes, and the tobacco plant?

Nicotine is, after all, an alkaloid. And these alkaloids evolved in plants to prevent insects from eating them. The rationale behind this explanation is that nicotine is not only a substance in tobacco that people consume, but it is also used as a pesticide due to its ability to disrupt the insect's nervous system and motor function significantly. It can prevent them from reproducing or destroying them.

When we talk about nicotine, we are not constantly referring to smoking. However, some risks are associated with smoking, vaping, and other nicotine delivery methods.

When we ingest nicotine, it gets into the bloodstream; eventually, some will get into the brain and some into the body. And in both the brain and body, there are the so-called nicotinic acetylcholine receptors.

Nicotine's primary effects on the brain are mediated by nicotine binding to alpha-4, beta-2 receptors. Indeed, nicotine increases metabolism and decreases hunger by binding to alpha-4, beta-2 receptors in a specific brain area. So if you have heard that nicotine suppresses appetite, that is true.

Mesolimbic reward pathway

A connection between the Ventral tegmental area and the Nucleus accumbens. Here, nicotine triggers the release of dopamine from the nucleus accumbens, which gives nicotine its rewarding properties. It tends to provide a not-so-subtle but very transient increase in feelings of well-being, alertness, and motivation. That is because of the constant rise in dopamine. Nicotine also causes the ventral tegmental area to let out certain neurochemicals, which affects the nucleus accumbens and make dopamine levels go up even more. 

The point is that nicotine is a substance that can promote cognitive function under certain conditions, and if taken at an inappropriate or extreme dosage, it can impair the cognitive functions.

Nicotine's second significant effect on the brain is that it increases acetylcholine.

Acetylcholine is a neuromodulator in multiple sites in the brain, and the two major sites are the nucleus basalis and brain stem areas. (Unsplash)

Acetylcholine is a neuromodulator in multiple sites in the brain, and the two major sites are the nucleus basalis and brain stem areas. Acetylcholine released from the nucleus basalis leads to spotlighting or highlighting particular neural circuits in the brain, which increases our attention, focus, and mental performance. This enhancement in cognitive performance and concentration will be very transient, probably about 30 or 45 minutes. That is why smoking or ingesting nicotine in any other way feels good.

The third neurochemical pathway strongly activated is when nicotine triggers the central nervous system.

Nicotine increases alertness, arousal, and energy within the brain by triggering the release of norepinephrine from a little cluster of neurons in the back of the brain called the locus coeruleus. It can sprinkle the brain with norepinephrine, essentially serving as a wake-up signal, elevating energy levels.

At least in the short term, nicotine appears to be very good at enhancing cognitive function, but that doesn't mean this has no side effects. For example, smoking, vaping, or other forms of ingesting nicotine by dipping or chewing tobacco are known to cause 50 times the increase in mouth cancers such as leukoplakia and are generally harmful to our health.

70% of nicotine addicts want to stop smoking or use any other form of nicotine. They would like to give up. And yet they find it extremely difficult. And the reason they find it so difficult is due to all of the previously discussed brain neurochemistry. They have also tried and failed repeatedly, or because it's just too scary, meaning the reinforcing properties are too strong. Therefore, they can't imagine living without them, or the withdrawal effects are too strong, which they can't imagine living with.

I should also mention the other adverse effects on our health, specifically the disruption of endothelial blood vessel function. That brings us to the topic of vaping because, as many of you are aware, the way vaping pens are designed is that It contains some liquid, uses heat, and does not involve the burning off of tobacco. And blood nicotine concentrations rise very quickly, much faster than cigarette smoking or other nicotine delivery methods.

One of the significant differences between vaping and cigarette smoking is that the onset of dopamine release from vaping is faster. And even a subtle increase in the rate of dopamine increases in the mesolimbic reward pathway can make a given amount of nicotine much more habit-forming and addictive. This probably explains why many more people, mainly young people aged 25 and younger, are vaping at phenomenal rates.

Because the rate of nicotine release influences the rate of dopamine release in the nucleus accumbens and ventral tegmental area when it comes to the mesolimbic reward pathway, it's not just about the peak or the maximum amount of dopamine released but also about the time course, how steep the curve is, and how quickly that dopamine increases, which determines how reinforcing, habit-forming, and addictive a particular substance is. What we're seeing out there makes total sense.

So, is it possible to quit smoking, vaping, snuffing, or dipping?

Yes, there are excellent ways to accomplish this. But unfortunately, some of them are one-time treatments.

"Nicotine does not cause cancer. Nicotine is not a carcinogen; it is the other ingredients in tobacco or the nicotine delivery device that cause cancer."

Most people who try to stop smoking are unable to do so. And of the 5% who succeed in quitting, 65% relapse within a year. That's a pretty bleak picture.

Some are behavioural, while others are pharmacologic. The behavioural ones prove to be a very effective method for quitting nicotine ingestion through cigarette smoking, which also applies to vaping.

There may be many reasons why you did, but you keep smoking because you've become dependent on nicotine. This addiction doesn't make quitting impossible but can make it difficult and mess with your motivation.
Dr. Keerthi Kumar, MBBS (Karnataka)

There are a couple of pharmacologic approaches. One of the main ones that have received much attention recently is Bupropion.

Bupropion is a compound that increases dopamine release and, to a lesser extent, epinephrine and other neurochemicals. It's used for the treatment of depression and smoking cessation. Now I want to point out that I'm not a psychiatrist, so I'm not telling you to take Bupropion. This is a prescription drug; a board-certified psychiatrist or other physicians will prescribe it if it's appropriate for you.

The other thing about Bupropion is that it has to be used with caution in patients with liver disease or renal disease that can impact the amount that anyone can take, meaning sometimes people have to take a much lower dose if they have renal disease or liver disease. And sometimes they can't take it at all.

Now it's important to ask why this would work. It's not as if Bupropion is increasing nicotine per se.

What it's doing is tapping on that mesolimbic reward pathway, increasing dopamine, or at least allowing dopamine levels to be, say, substantially elevated enough that people doesn't experience some of the drops in dopamine that lead to the withdrawal symptoms, the lessening of mood, etc. So it's no coincidence that Bupropion is also an antidepressant.

A very common approach for people to try and quit smoking or vaping is to use nicotine to prevent people from seeking nicotine through a cigarette or a vape pen. I mean that people use a nicotine patch, nicotine gum, or other nicotine delivery device to maintain nicotine levels in their bloodstream; these approaches are reasonably successful.

And just a very brief mention, there is a vast literature on the fact that when people have quit smoking or vaping or other forms of consuming nicotine when they consume alcohol, there's a much higher probability of relapse. So there are interactions between alcohol and nicotine.

References

  1. Pharmacology of Nicotine: Addiction, Smoking-Induced Disease, and Therapeutics. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2946180/

  2. Nicotine’s Effects on the Brain & Body & How to Quit Smoking or Vaping. Available at: https://hustlersamerica.com/how-to-quit-smoking-or-vaping-nicotine/

  3. What You Need to Know About Smoking and Your Brain. Available at:

    https://www.healthline.com/health/smoking/smoking-effects-on-brain

  4. Nicotine’s Effects on the Brain & Body & How to Quit Smoking or Vaping. Available at: https://youtu.be/uXs-zPc63kM

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