The term “drugs of abuse” gets thrown around when trying to specify drugs that are detrimental in nature. This is opposed to the “drugs of use” that would include over-the-counter and prescription medication. It is far too often that these abusive drugs lead one into a path of addiction, and it is far too often that this path of addiction leads to death. So I must ask, why are “drugs of abuse” drugs of addiction?
Our remarkable human bodies have evolved in such fascinating ways. We, as a species, have honed in on the most practical ways to learn about the world, and remember what we learn, so that we might apply it in, ultimately, reproducing and raising our offspring. A result of this evolution is our ability to remember what gave us a “good” experience.
When I say “good”, I mean in the sense that the experience will increase one’s likelihood of creating and rearing successful offspring. This “good” experience can manifest itself in multiple ways: the awareness that comes along with a cup of morning coffee, the relaxation of a massage, the satisfaction in eating a pastry, or the intrinsic pleasure of sexual activity. It is such that all of these activities increase the odds of making successful children (some more directly than others).
Thanks to evolution, our brains devised incredible ways to “lock on to” these events, remembering exactly how they felt, and the specific steps taken to allow them to occur. Because of this, we get remarkably good at reproducing these feelings of pleasure, and most of the time, it is a very good thing.
The brain must transmit its signals somehow, and since the basic building blocks of life are chemicals, it chooses to transmit the signals as chemicals. Neurotransmitters, as they are called, are the chemicals released within the synapses of the brain, and they give us the ability to be humans. During the aforementioned “periods of pleasure”, many of these neurotransmitters are released, but the most important (and plentiful) of these is dopamine.
Dopamine is used colloquially as the “feel-good” hormone, and indeed it produces pleasurable effects. It is important in other aspects, however. As was mentioned, our brains are very good at remembering exactly how pleasurable events were created. It is dopamine that locks down these memories.
This is where drugs of abuse play such an important role. Nearly every abusive drug increases dopaminergic receptor agonism (“extra dopamine release”). This is either done in a direct (mescaline and amphetamine) or indirect (most other drugs of abuse) manner. Regardless of the process, the brain is receiving signals of pleasure from an unnatural source. Note, I use the term “unnatural” to mean that the brain is not triggering its own dopamine release, but rather substances from outside the body are.
Since these drugs can be administered in any dosage, it is quite common for internal dopamine levels to increase past the point of any natural setting. This incredibly high concentration of dopamine creates the “high” felt by abusers, as well as the second effect of dopamine: the formation of intense memories associated with obtaining the feeling of pleasure.
It is well-hypothesized that these “memory-forming” effects of dopamine play just as important of a role in addiction as the pleasurable effects do. While the pleasurable effects are likely more important in the development of withdrawal symptoms, the intense memories give addicts the urge that cannot be erased from their minds. When we look at the two together, we can see why the road to addiction is far too short.
Since extra dopamine is flooding the synapses, the brain thinks something is wrong, and down-regulates its dopamine receptors. This is, again, a result of evolution as it is meant to “reset” the brain to a normal state. But once the drug wears off, and dopamine levels return to normal, the brain cannot activate as many receptors as it normally would have. The result of this is initially depression, but follows with all sorts of horrendous symptoms which the reader may look up for themselves. This process is characterized as withdrawal.
The sad case of the matter is that eventually addicts do not seek the drug to experience a high, but rather to avoid a low.
The memory-effects of dopamine also come into play here, for just as the drug wears off, an abuser will remember the “good ol’ times” vividly. It will cease to matter whether the process of getting the drug is detrimental (expensive or dangerous); the addict will seek out a repeat experience nonetheless. And of course, each time the process “works”, the abuser will have strengthened the memory further. It is through this process that the “cravings” of addiction are created.
And so, terrible withdrawal symptoms, coupled with cravings, arises from repeated abuse of drugs. The well-known saying that drugs “hijack the body’s reward mechanism” are completely true. There is little escape from the self-administration of “dopamine” because of its grip on creating habits, and when administered in high concentrations, our bodies cannot prepare. What was meant to reinforce habits capable of creating life, in the end creates habits capable of destroying it.