The Brain and Addiction | Chasie Enterprises

Have you ever had a recurrent urge to do something that interfered with your focus or daily life? How about a desire so intense that even the awareness of potential harm did not deter your resolve? There is a thin line between an insatiable yearning and addiction. Contrary to popular belief, addiction does not strictly relate to drugs, medication, and alcohol abuse. It also includes social media, gaming, food, love––and even work.

What is Addiction?

By definition, addiction is a state of active dependence––a compulsive chase of hedonistic pursuits. It could be through substance abuse, food obsession, sex, money, love, belonging, things, or sensations despite their adverse effect.

You can be addicted to watching YouTube videos. Your obsession with your love interest is an addiction. The same principle applies to fixations with social media, phones, medication, or work.

Addiction is a brain disease––one that requires immediate intervention. It rewires certain aspects of your brain, altering functions and commands. Addictive substances and behavior have one thing in common––they are psychoactive. They rewire the brain, influencing mood, thoughts, emotions, and behavior.

The hallmarks of addiction include:

• Loss of control: where desire overrides reason

• Compulsion: an unhinged and overwhelming push toward consuming substance or engaging in behavior repeatedly, despite negative consequences or rationale to stop

• Preoccupation: obsession with the addictive substance, interfering with your ability to concentrate on anything else. 

• Negative outcomes: addiction is detrimental to your mental and physical health and quality of life. It affects relationships, work, finances, and more.

  
  

How the Brain Works

Understanding how the brain works is crucial before diving into the science of addiction. The brain executes commands with the help of nerves, which transmit information through impulses. The information transfer occurs with the help of brain chemicals called neurotransmitters. Nerves work in specific pathways or circuits when executing functions.

For instance, when you place your finger on a hot surface, sensory nerves called thermoreceptors sense the heat change on that finger. They then transmit the signals to the spinal cord, where relay nerves convey the information to the thalamus, the brain's relay center, where all nerve stimuli, except smell, converge.

Neurons from the thalamus then transmit the signal to the cerebral cortex for interpretation, assigning it temperature and pain stimuli. The brain initiates a response to the stimuli – in this case – a mechanical output, causing you to remove your finger from the hot surface. The process is quite efficient, transpiring within a split second.

The Science Behind The Brain and Addiction

How does addiction happen? Where does addiction occur in the brain?

Addiction plays out in several brain circuits. The primary brain region with heightened activity when consuming psychoactive substances or pursuing addictive behavior is the ventral tegmental area (VTA). The pre-frontal lobe, hippocampus, and amygdala also have active roles in addiction. These circuits utilize a variety of neurotransmitters, such as monoamines (dopamine, serotonin, and adrenaline), cortical glutamate, and endorphins, to function.

The Reward Pathway

The role of the reward pathway in addictive behavior is known thanks to an experiment by Olds and Milner in 1954. The two scientists were trying to establish the function of different brain parts using experimental rats. They activated various brain portions of the rats using electric circuits.

Simply put, the rats electrocuted their brains using a switch while the scientists determined the function of the brain area that got electrocuted based on the rats' response. Once they reached what is now known as the reward pathway in the VTA, the experimental rats kept electrocuting themselves uncontrollably, reacting as though they derived pleasure from the electrocution. The two scientists established the rodents felt nice when that brain area was active.

The reward pathway is a feel-good circuit responsible for feelings of happiness and pleasure––that famous 'high' or 'ecstasy.' The rodents became euphoric, pressing the switch repeatedly to maintain that 'high.' An activated reward pathway also evokes satisfaction, calmness, peace, and rest.

The Reward Pathway and Addiction

Dopamine is the neurotransmitter that operates in the reward pathway. It is the primary feel-good molecule. All other excitatory brain molecules amplify and prolong its effects directly and indirectly. Another name for this pathway is the dopaminergic circuit, derived from the neurotransmitter.

Several psychoactive substances and behaviors activate and sustain this pathway, primarily by boosting dopamine production, release, and action on the synapsis. Some of these substances also increase dopamine receptors, boosting its effect. Other active ingredients, like ethanol in alcohol, bind to dopamine transporters responsible for reabsorbing the neurotransmitter back into the neuron. This process is known as dopamine reuptake.

A picture of the synapse with neurotransmitters being released from one neuron and binding to receptors on the adjacent neuron

The reuptake process is essential for dopamine regulation. Such an interference increases dopamine in the synapse (that space between two neurons), boosting and extending dopamine receptor activation.

Addictive substances also release other feel-good helper molecules and neurotransmitters, like endorphins, which enhance and sustain dopamine release and activity in the brain.

The Down Side of The Reward Pathway

Unfortunately, a dopamine surge through substances or behavioral-induced stimulation is usually too high and protracted compared to the amount the body naturally releases. The sheer volume of excitement dulls your brain's response to natural stimulation. Once the high is gone, the resulting dip is lower than the standard threshold.

Furthermore, this surge in dopamine release interferes with the neurotransmitter's regulation. The body lowers dopamine concentration in subsequent releases in what is called dopamine depletion as a down-regulation mechanism of the previous surge. 

One vital function of the reward pathway is to inhibit the stress response––another brain circuit responsible for anxiety or other low moods like depression. Dwindling dopamine levels trigger an aggressive stress response, resulting in a profound depressive mood.

The Brain's Mastery

The brain is a faithful learner. It always strives to master and take the reigns. Once in charge, this organ will work tirelessly to enslave you. What the brain learns, it adapts, perfects, and relentlessly enforces. The scientific term for this is neuroplasticity.

Neuroplasticity is the brain's ability to grow and reorganize its neuron networks. Mood and behavioral changes in addiction and recovery occur because of this feature. 

For instance, you are going through a breakup. A breakup is an excellent stimulus for an overactive stress response. It will get your adrenaline, cortisol, and other stress hormones working overtime. As you grapple with your new reality, you turn to alcohol to numb your pain, feelings of regret, or failures.

Ethanol in alcohol activates the reward pathway by forging a new circuit that favors ethanol as the stimulus. The brain learns it can activate the reward circuit through this uncharted path. It works hard to ensure ethanol is your only solution to anything relating to the breakup.

The Pre-Frontal Cortex and Cravings

Behavioral depiction of sugar addiction

The pre-frontal cortex (PFC) is the brain's memory or emotion regulation center. It is responsible for affective tone and framing. PFC tags an emotion or memory as 'pleasant or unpleasant.' It also interprets emotions and adds meaning or context, influencing your cause of action.

In our hypothetical scenario, the pre-frontal cortex labels drinking an alcoholic substance as a good thing, associating it with 'pleasant' memories. The PFC retrieves this memory every time the breakup triggers your stress response. It collaborates with the hippocampus during memory retrieval, leveraging the hippocampus's role in indexing and organizing memories, and uses these cues to induce a deep craving for alcohol every time your ex comes to mind. Unfortunately, the intense craving usually impedes reason and your will to resist.

Serotonin and Dependence

Another hormone essential in sustaining the effects of the reward pathway is serotonin. Serotonin's action is crucial in maintaining addiction.   

In a study where mice with a deactivated reward pathway self-administrated cocaine, the mice continued to use the psychoactive substance. The experiment showed there are non-dopamine-related pathways involved in addiction. Furthermore, blocking serotonin circuits stopped the addictive behavior. The mice lost all desire for the addictive substance.

Psychoactive substances and behavior increase serotonin levels initially by boosting serotonin synthesis and receptor expression and inhibiting serotonin reuptake in the synapse. The sudden surge increases motivation for continued use of the psychoactive substance or behavioral pursuit, setting the foundation for dependence. Research shows this initial surge interferes with serotonin regulation. The body always initiates negative feedback in serotonin production and release whenever there is an influx.

The resulting serotonin crush induces terrible withdrawal symptoms, from anxiety to depression, hallucinations, and paranoia. The low levels also trigger impulsivity and cravings. It is through these intolerable withdrawal symptoms that dependence on the psychoactive substance or behavior ensues, turning you into a slave of your desires. Research indicates it takes about three weeks to balance serotonin levels and maintain normalcy.

Addiction vs Dependence

Although people use addiction and dependence interchangeably, the two words describe different mental conditions. The two conditions are comorbidities. Understanding addiction versus dependence is crucial, especially in clinical settings.

Addiction means losing all control over a substance or behavior, even when it causes significant harm. Conversely, dependence arises when an abrupt removal of a psychoactive substance leads to withdrawal symptoms.

The key difference between these two conditions lies in what follows withdrawal. Dependence has no subsequent cravings for the substance or behavior. On the other hand, cravings follow withdrawals in addiction. The bottom line is not everyone exhibiting dependence has an addiction. However, all substance use abusers or behavioral addictions exhibit dependence.

Addiction and Tolerance

Tolerance is the body's decreased response to a substance or experience due to repeated exposure, necessitating an increase in dosage (in case of substance use) or action frequency and intensity (in the case of behavior). Neuroplasticity in serotonin and dopamine circuits produces tolerance.

The brain automatically down-regulates after every dopamine and serotonin surge. 

The negative feedback mechanism:

• Reduces the release of both serotonin and dopamine

• Decreasing the respective neurotransmitter receptors at the synapses, preventing them from binding

• Reduces other feel-good molecules

Down-regulation desensitizes the brain, requiring an increase in dosage or behavioral frequency or intensity to reach the coveted 'high.' The brain conditions you to seek out substance or pursue behavior in the required magnitude as it pushes your tolerance limits further with every subsequent indulgence. Each surge and resulting crash traps you in a vicious addiction cycle, reducing your life to chasing a fleeting high.

Furthermore, prolonged and excessive substance use or indulgence in behavior creates what is known as paradoxical decompensation, where your drug of choice has the opposite effect. Instead of euphoria, it evokes anxiety, depression, fear, paranoia, and agitation.

Glutamate and Sensitization

Glutamate is a multifaceted biomolecule with numerous functions in the body. It is an excitatory molecule of the reward pathway, stimulating dopamine release and function. Dopamine stimulation, in turn, induces glutamate action in the VTA. 

Its other role in addiction is locomotor sensitization and substance seeking. Locomotor sensitization manifests as compulsive behavior or drug-seeking and self-administration. Sensitization is not the same as tolerance. Tolerance makes you need a high dose to experience the same effect. On the other hand, sensitization means that the same dose now produces an amplified response. In simple terms, glutamate boosts the euphoric feeling that comes from using psychoactive substances or engaging in addictive behavior. 

Glutamate's effects can last up to several months. Its longevity lengthens the substance-induced activation of the reward pathway. 

Endorphins: Cravings and Relapse

Endorphins are the body's natural opioids known for their pain-relieving effect. They also excite the reward pathway, keeping you calm through the distress. If you hurt yourself right now, your body floods the affected area with endorphins to reduce pain intensity and enhance calmness. The body releases a similar gush of these feel-good molecules when you are anxious or depressed.

Psychoactive substances trigger an enormous endorphin release in two parts of the brain. The molecule's action in the VTA intensifies compulsivity in drug self-administration or behavioral pursuit. Its action in the limbic forebrain increases cravings, sustains addiction circuits, and initiates relapse.

Endorphins stimulate and augment dopamine release, enhancing its effect in sustaining addiction. However, as dopamine levels dwindle, endorphin concentrations remain high for months, maintaining the substance-induced pathway. Its action can impact recovery, leaving you vulnerable to relapses.

Why Understanding Addiction and The Brain Matters

The brain has a central role in addiction. It learns and adapts through sensitization, tolerance, and dependence. Each indulgence enhances your motivation and cravings for the addictive substance or behavior. Unfortunately, the brain never forgets what it learns. This is why recovery from addiction is a lifelong journey, not a destination, and susceptibility to relapse is a known fact.

Addiction is a complex mental condition. This blog is in no way exhaustive in explaining the intricacies of the brain and addiction. It is an incentive to seek professional help from a certified psychologist. Begin your road to recovery today.