Drug and alcohol addiction are not matters of choice; they’re a matter of process. Depending on the type of drug and dose and even the person’s genetic make-up, drugs can take hold abruptly, or gradually, without warning, rendering the individual powerless to stop the addiction.
How drug addiction affects serotonin and dopamine levels in the brain is one question at the start of unraveling the mystery of addiction. It begins with a process known as incentive sensitization and ends when the body is dependent on the drug to regulate brain chemistry. When you begin to realize how much of our mood and life-sustaining processes are regulated by brain chemistry, it is no wonder that drugs acting on these processes can literally take over, altering personalities and inciting manipulative and deceptive behaviors not normally seen in the individual.
From an evolutionary standpoint, neurotransmitters like serotonin and dopamine work together based on perceptions of our surroundings. It is a process by which our brain and body assess whether food is scarce or abundant, regulating everything from our appetite for food to determining the appropriate level of aggression necessary to obtain that food.
Now, imagine what happens when you introduce a foreign substance that hyper-stimulates either levels of seratonin, levels of dopamine, or both. Not only does use of theses substances hamper your perception of reality, long term use of the drug can inhibit natural release of these neurotransmitters, creating a physical dependence on the drug. The person addicted to drugs isn’t addicted to the initial high any longer, he or she is now dependent on the drug to function.
Role Of Serotonin And Dopamine In Addiction
Serotonin and dopamine are neurotransmitters that act upon cells, called nerve cells which, in turn, control various responses from different parts of the brain and central nervous system. Serotonin is a type of inhibitory neurotransmitter, lowering excitability within the neural network. Whereas dopamine can act as both an inhibitory and excitatory neurotransmitter, exciting nerve cells along the neural network.
Serotonin is found throughout the brain and along the spinal cord and is best known for its mood regulating qualities. Drugs that treat depression and anxiety disorders are designed to inhibit the reuptake of serotonin by neighboring nerve cells, to increase its availability throughout the neural network. Serotonin keeps thoughts orderly and prevents excitability or rapid firing of nerve cells that lead to anxious feelings. It also manages behavior and perception, controlling appetite, body temperature, sleep, and smooth muscle tissue. Serotonin even influences, to some degree, cognitive functioning, affecting learning and memory retention.
Ever wonder why you have those strange dreams about standing in front of your biology class in nothing but a transparent tunic? Insecurities and unresolved issues appear to manifest during REM sleep, a time when mood-regulating serotonin is taking its turn to rest. At about the time an elf brandishing a giant carrot rides in atop a pink unicorn, serotonin neurotransmission has ceased. Taking a drug like LSD, which inhibits the release of serotonin, can generate similar effects during periods of wakefulness, with those giant carrot-wielding elves showing up at your front door.
The Pleasure Centers: Dopamine And Drug Addiction
Dopamine is best known for its relationship with the pleasure centers of the brain, located in the hippocampus. Dopamine release is triggered whenever a person experiences something they find enjoyable, including eating, the act of sex, and a good nap; key activities that relate to survival.
When someone engages in activity relating to survival, like eating foods high in fats or carbohydrates, dopamine is released. If you’ve ever experienced that satiated feeling following a good meal, you’ll recognize the hint of euphoria dopamine inspires.
The brain is hard-wired to remember fine details of everything it finds pleasurable. Think of this memory, though, in terms of early humans, with a scarce food supply. If food is eaten that is high in protein, or fats and carbohydrates, this release of dopamine tells the body this is something good for it and signals to the brain to remember key aspects of the surroundings to aid in the search for similar food types in the future.
Normally, dopamine is released, then picked up by nerve cells. When drugs, like meth, are introduced to the system, they block this absorption, increasing availability of dopamine and amplifying the pleasure signals a thousand times over. This increase doesn’t pass by unnoticed. The brain takes note of the experience and through a process known as incentive sensitization, develops a sensitivity to the substance, leading to a rapid release of dopamine in subsequent uses. It is the first step in physical dependency, leading to strong cravings for the drug.
Incentive Sensitization: The Trojan Horse Of Drug Addiction
When someone first introduces a drug like meth, cocaine, or alcohol to their system, there is an initial dopamine response relating to how the drug interacts with the brain and central nervous system. With the right genetic factors in play, the rewards of that initial use might be positively associated with key elements of your surroundings. If you have a favorite place to sit, or activity you enjoy, while drinking that first cup of morning coffee, you’ll understand this association.
As mentioned earlier, the brain is hard-wired to retain not only the experience of the drug; it is hyper-focused on the surroundings and circumstances that made that drug available to the system. This process has been key to our survival for hundreds of thousands of years, but with potent drugs like cocaine and heroin, evolution leaves us powerless to our own defenses. It is our Trojan horse. Apart from use of the substance, being around the people who provided you with the drug or in the same environment where the drug was abused can generate triggers for drug cravings.
During these first few uses, as the brain quickly assesses a perceived need for the drug, it develops a keen sensitivity for the substance. This sensitivity influences levels of dopamine and serotonin in the brain, generating a euphoric high during subsequent use. Depending on the nature of the drug, addiction follows quickly or over a prolonged period of time. Either way, the brain now associates use of the drug with its survival, and because the dopamine response is so great, it perceives a need for the drug above that of the most basic necessities like food and water.
This is why people continue to abuse drugs, even when their health deteriorates. And it is this hypersensitivity to the substance, information now stored in the brain, that means exposure to the substance following recovery can lead quite abruptly to relapse.
Serotonin, Dopamine, And Drug Dependency: The Higher They Go, The Harder They Fall
With continued use of any substance, levels of serotonin and dopamine are altered significantly beyond normal levels. When this “high” wears off, levels of these powerful neurotransmitters, which are now dependent on the drug for production, drop to below normal levels without continued exposure to the substance. When this drop occurs, it can leave a person experiencing the side effects of withdrawal including shakiness, anxiety, depression, and other flu-like symptoms. This perpetuates a cycle of use to sustain any resemblance of normal function for the body.
Science is just beginning to unravel the complexities of addiction. We know now overcoming addiction isn’t simply about will-power, and that someone who is addicted to drugs isn’t weak. They are engaged in a struggle that has turned one of the most basic and fundamental processes – a process key to our survival as a species – against them. Moving forward out of this addiction will take the help of treatment specialists and ongoing support from professionals as well as family and friends.
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