I have always been wary of addictive stuff. I probably would have tried out much more stuff than I have if they were not labelled addictive. The only addictive substance I have been using for quite some time are caffeine and the Internet and I have been taking those in small doses. So I cannot profess to know the effects of drugs of abuse personally. I can only say what research on those topics has found out or I could say what a certain drugman told me when I was much younger. Being a curious lad that I was, I had to ask Asika to tell me what it felt like when one smoked marijuana since he was the only person I knew who used the substance and it was the only drug I knew. His description was very vivid and did not leave much to the imagination.
"When you smoke weed, you will become more careful than you would normally be," he began. He was standing in front of a small shop in the village square, and there were four of us seated there listening to him.
"First, you would leave the place where you sat to smoke it, but you would be careful not to forget anything or do anything unbecoming because your fellow smokers would be looking to confirm if the drug is working. So you would be careful to ensure you haven't forgotten a leg or something. Then you walk out on the street and know that everyone is expecting you to misbehave because you just smoked. You would comport yourself and walk with your should straight, and your head held straight. Suddenly your brain would tell you that you are probably standing too straight and your head may soon touch the distribution electrical conductors overhead. You don't want your head to touch those cables now, do you?" he paused. We nodded vigorously, without realising that we were supposed to say no. Anything to have him continue the story.
"Well, as soon as you lower your head, you would realize that your neighbours are watching, so you must be careful to ensure that they did not notice what happened!"
Fascinating stuff, but who really knows what happens to the brain when an individual takes a drug of abuse? If you think it through, your answer would have to be: "It depends." It depends on the drug and the medium of delivery, I suppose. First, let us see what science has to say about that.
The Science of Drug Abuse and Addiction
The effect of drugs of abuse happens in the reward circuits. These are several brain structures which communicate closely with each other through nerve impulses. It is made up of the nucleus accumbens and the olfactory tubercle which is located in the ventral striatum in the forebrain, on one end. At the other end, it is made of the ventral tegmental area in the midbrain. If the ongoing is a bit confusing to you, it is not because you are less smart than you were yesterday. It is rather because drug addiction is a complex illness and the process through which occurs is complex too. Drug addiction begins with taking the drug for the first time. At this point, the individual can decide not to take the drug again but, because of certain euphoric feelings resulting from the intake of most drugs of abuse, the individual would be tempted to take it again and again until his/her ability to choose not to take the drug is compromised due to the long-term effect of the drug on the brain. At this point, there is constant craving and seeking for the drug even in the face of obvious negative effects.
The Brain By Functions
Different parts of the brain perform specific functions. Hippocampus is involved in memory. The occipital lobe contains the anatomical region of the visual cortex.
The parietal lobe is involved in language processing. The cerebellum helps with coordination. The nerve cells are responsible for communication between the different parts of the brain. So information from one part of the brain to the other is transmitted through a complex circuit of neurons using electrical impulses that are transmitted from one neuron to the other. This is called neurotransmission and it is not quite like the way you transmit electrical signals in a physical conductor. The transmission is done with the aid of chemicals and chemical reactions that would become clear as we proceed.
It is really scary to imagine what might happen if one of these portions of the brain fails to deliver its function or if the neurotransmission process malfunctions.
The Mesolimbic Pathway
One thing is for sure, all drugs of abuse have a common place they affect on the brain of an individual and it is called the Mesolimbic Pathway.
The mesolimbic pathway is commonly called the reward pathway, which are dopaminergic pathways or dopaminergic projections in the brain.1. The dopaminergic pathway connects the ventral tegmental area to the nucleus accumbens and olfactory tubercle as shown in the image above.
The reward pathway is activated by pleasurable stimuli. For instance, a rewarding stimulus such as food, sex or water would activate the pathway and make information to travel from the VTA to the nucleus accumbens and then up to the prefrontal cortex. It is important to remember that the reward pathway is activated by pleasure. So what does this have to do with drugs of abuse and addiction? Well, it depends: it depends on the drug that the user has taken.
Drugs by Effects
Say someone snorts cocaine or injects it, the drug enters his or her bloodstream and goes to his head (no wonder they shake it). Of course, the drug circulates the whole brain, but it is the reward pathway which is most affected by its euphoric effects. Now is the time to remember what was earlier said about communication within the brain. It was said that communication is achieved by transmission of electrical signals between neurons in a process called neurotransmission, but there was a warning: that this transmission is slightly different from transmitting through a physical conductor. The difference is in the neurotransmitters. You see, the transfer of information is achieved through a chemical reaction of the neurotransmitters, one of which is dopamine.
Wikipedia CC0: Chemical Structure of Dopamine
Dopamine is an organic chemical (DA, a contraction of 3,4-dihydroxyphenethylamine). Without going into the chemistry of the substance, for this post, we may be content with the knowledge that dopamine functions as a neurotransmitter in the brain. That is just a fancy way of saying that it is a chemical that is released by nerve cells to send signals to other nerve cells. Why would a nerve cell want to pass signals to other nerve cells? Well, that's how different parts of the brain responsible for different functions receive information.
Free Image from Aspet Journals: Neurotransmitter Binding
Well, to do its normal job, when a neuron wants to transmit information, it releases dopamine into a synapse (the space between two neurons). There, the dopamine would bind with dopamine receptor of the neighbouring neuron. This binding process sends the information to the next neuron. Dopamine are the primary endogenous ligand to dopamine receptor, meaning that they easily bind to form a biomolecule that serves certain biological purposes. But that is not the end of neurotransmission. After dopamine has bound with the receptor and information transferred to the next neuron, the dopamine is transported back to the sending neuron by a specialized protein called dopamine transporter.
Now, here is the mean of this story: drugs of abuse can interfere with this intricate communication process in the brain. It is for this reason that we said that the effect a drug has on the brain would depend on the drug.
Love on the Brain
I wonder what effect love had on Rihanna's brain.
Cocaine
Science has it that when someone snorts cocaine and it hits the brain, the drug molecules would bind with the molecules of the dopamine transporters which helps to remove dopamine from the synapses thereby preventing the removal of dopamine by the dopamine transporters which would result to the dopamine remaining in the synapses and the consequent continuous stimulation of the receiving neurons causing a tingling or if you will, euphoria in the minds of the cocaine user. Apart from this euphoria, cocaine causes extremely pleasurable rush as the mesolimbic reward system is flooded with more and more dopamine. Research has shown that this short-term pleasure may be damaging to the brain in the long run.
Nicotine
This one is present in tobacco, especially cigarettes. It is amazing how people get hooked on nicotine in the various products that contain it. It is the stuff that makes smoking addictive as can be. The magic in nicotine comes from having a similar structure to a neurotransmitter called acetylcholine which makes nicotine binding to acetylcholine receptors a walk in the park. As you would expect, this on its own is not the problem. The problem begins when the body is deceived into thinking: "There is so much acetylcholine out there. Perhaps we should take a break in producing them."
But remember, the reason there is so much of the neurotransmitter in the body is that something else has been binding with the acetylcholine receptors. Therefore, the smoker has to smoke to feel normal every once in a while. Also, nicotine could affect the production of dopamine thereby tickling the reward pathway.
The list goes on concerning what these drugs do to our bodies, but I would like to stop here and thank you for reading.
What do you think about opioids, marijuana, psilocybin and others? How do they become addictive?
References
- Wikipedia | Dopaminergic Pathways
- Drug Abuse | Understanding Drug Abuse - Cocaine
- Wikipedia | Dopamine Receptor
- ASPET Journals | Drug Addiction
- Wikipedia | Neurotransmitter
- Live Science | Your Brain on Drugs
- NeuroScientifically Challenged | Know Your Brain - Reward System
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