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The Chemical Compound of Addictive Drugs and What Makes Them Different From Over-The-Counter and General Prescription Drugs

A 3D depiction of the human brain

The chemistry of addictive drugs can help give details as to why our bodies can become dependent on them so quickly, causing damage to health, relationships, and entire communities. For some time now, we’ve been aware that drugs can effectively change the structure of the brain, especially with prolonged use. This is why we must approach addiction as we would any acute illness and look at it from a scientific standpoint to provide effective treatment for those who need it. Looking deeper into the science behind the drugs themselves can also help us understand the dangers of over-prescribing opioids to patients and why opioids should be taken with caution.

The Chemistry of Addiction

The science behind addiction is so complex that scientists have been studying addiction since around 1875. Aside from the sociological, psychological, and environmental factors that contribute to addiction, the investigation of the chemical properties addictive drugs have been found to be at the very core of addiction studies. When a brain’s reward pathway has repeated exposure to an addictive drug, it can drive the compulsion to continue seeking more of that drug due to the way that part of the brain is designed. When receptor-active drugs such as opioids are ingested, their molecules look just like natural molecules in our brain. Agonist drug molecules bind to certain receptors in the human brain, causing it to activate and trigger a response in the cell. With opioids, these agonists are of specific opioid receptors, triggering feelings of euphoria and happiness when they bind together. These drugs are structured in such a way that they mimic natural agonists to create a natural feeling, like happiness, but in a much stronger way. This is how the “high” of opioid drugs is best explained.

These terms and the science behind them may sound confusing, but a good way to imagine this is by using an analogy of a key and a lock. Think of the natural agonists in your brain as the “master key” to the cell in your brain, which is the lock. These natural agonists are naturally present in your body, so when you are happy and content, those keys naturally fit into the locks and open the door to a natural happy feeling. Agonist drugs are a “spare set” of keys. They are just like the master key, only slightly irregular and they will still open the “door” of the cell to create the same feelings of happiness, but unnaturally, and often much more intensely.

What Makes Addictive Drugs Unique?

Now that we see the way drugs can act as “keys” to certain “locks” in our brains, it becomes clearer that addiction isn’t merely a choice or lack of impulse control; it’s actual science. When these agonists are in action in our brains, they slowly begin to change the way the brain works, especially because of the way the reward pathway of the brain is impacted. Our brains instinctively want and need to ensure that we are repeating life-sustaining behavior on a day-to-day basis. This goes down to a very basic level of eating, sleeping, bathing, and so on. None of these actions really provide us “pleasure” in a literal sense, but for the body, they are allowing us to survive, thus maintaining a normal level of “feeling content” in our brains. Every time we do something that satisfies these instincts, the brain “remembers” that function and urges us to continue doing them to maintain that  level of happiness. Since addictive drugs stimulate those very same receptors and brain circuit, our brains will begin to tell us that we need to use more drugs to continue satisfying the need to feel “content.” The brain will do this without discriminating whether we are opening these cells with “master keys” or “spare keys” from drugs because they are almost indistinguishable to the brain until the effects are “unlocked”. Then the brain remembers the euphoric feeling of the “spare key”, leading to a cycle of addiction.

What’s the Difference Between Addictive Drugs and Others?

So, what makes these addictive drugs different from other prescription drugs? Opioids can release between 2 to 10 times the amount of dopamine than natural receptors do in our brains. These “spare keys” are powerful and work almost instantly. They can also prolong the sense of pleasure much longer than when they are achieved naturally. This can cause the brain’s reward pathway to dwarf those effects when they occur naturally. For example, if going for a jog causes someone to feel very happy and a release of dopamine, it will begin to fall to the wayside when these agonist drugs can supply much more of that release in a much faster and intense way. This begins to train the brain to prefer the drug to all else, causing the body to demand it again and again.

The systematic way these addictive drugs dull and abuse the natural reward pathway of the brain sets them far apart from drugs that don’t affect these areas of the brain at all. As someone uses these agonist drugs more and more, they begin to lose their desire to seek out natural sources of these dopamine receptors because they are simply not as pleasurable as those provided by the drug. Eventually, when tolerance to the drug is built up, the person using them needs more and more of the drug to feel anything at all. This is why most people who misuse opioids are often only staving off withdrawals far into their addiction, rarely being able to achieve a high.

Understanding the way these addictive drugs work has opened up doors to understanding why MAT, or medical-assisted treatment, is the most effective way to help someone overcome their addiction. The way these medicines work is on a chemical level which impairs the “spare keys” and helps the brain return to a more natural function. While prevention is the first and best step to avoid opioid addiction, it’s also important to be aware of how these drugs work on a scientific level to understand the way even simple use can quickly lead down the dark path to addiction.

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