How does one learn to be an addict? Like a lot of things one is often learning without an awareness that learning is happening. Brain circuits, chemical changes, and even DNA activation or inactivation are beginning to be mapped out, delineating physical changes in the brain and body that happen with addiction. The repetitive use of anything that hyper-stimulates the dopamine cells of the brain reward system can be addictive. This includes alcohol, drugs, some high choleric foods, nicotine, gambling, pornography, and video games. There are 3 major brain areas that are poorly changed with an addiction.
The “Like” Center
First, it was discovered in the mid 1990’s that there is one grouping of neurons in our brain that is the primary place for pleasure, the “like” center. It is a cluster of neurons called the nucleus accumbens. It is one of the targets of dopamine, the brain chemical that has been shown to drive all addiction. When the “like” center is frequently over stimulated it tries to protect the brain. Too much reoccurring dopamine activation, such as that produced by habitual use of drugs, alcohol, and excessively stimulating activities like, gambling or video gaming, is toxic to the brain. With excessive repeated dopamine stimulation the body releases dynorphin, an endogenous opioid (narcotic) chemical, reducing dopamine activity in the “like” center. In this way the area is somewhat protected from the disastrous effects of repeated dopamine over stimulation.
However, as dynorphin decreases dopamine activity in the “like” center, the pleasure experienced by the hyper-stimulating intake of alcohol, drugs, etc., recedes. This is one of the ways that tolerance develops. Another example is that of the gastro intestinal system and liver of a frequent alcohol drinker. These systems begins to generate more of the enzyme that breaks down alcohol. Also, the brain creates more of the receptors that are targeted by alcohol in the glutamate system. Glutamate is the body’s most prolific activating neurochemical. Alcohol decreases the activation of the glutamate receptors. The body compensates by producing more of these receptors, attempting to keep the brain chemistry homeostatic or balanced. Alcohol also increases stimulation of the GABA receptors, the body’s most prolific inhibitory neurochemical. As the alcohol increases GABA stimulation, cellular activation is decreased.
How does the body deal with repetitive alcohol abuse? It decreases the receptors available for GABA and increases the receptors available for glutamate. Detoxing from alcohol abuse is dangerous. If it is stopped abruptly, the body goes into destabilization and over drive as now there are too many Glutamate receptors that may cause excessive activation without alcohol. The reduction in GABA receptors that occurs with recurrent alcohol abuse mean that the inhibitory system is unable to quell the potentially toxic glutamate stimulation that occurs if alcohol is abruptly withdrawn. It takes time for the body to reach homeostasis without alcohol again by reducing glutamate receptors and increasing GABA receptors.
These dysregulating changes happen in different chemical systems depending on the drug or hyper-stimulating activity that is habitually abused. Our bodies are always trying to reestablish and maintain equilibrium. The user often increases the dose so as to obtain the previous sensation of reward. But dynorphin and similar changes like those described in the GABA and Glutamates systems continue to numb the “like” center. Small amounts of alcohol or drug no longer satisfy. Small life pleasures no longer seem important. Years ago I worked with an alcoholic woman who went into recovery. She began to seriously play the piano again. She mused in therapy how she was becoming aware that playing the piano was a small, satisfying, and rewarding experience, but not nearly as exciting as the euphoria induced in her past alcohol abuse. Indeed, euphoria seems to be a sensation that reflects excessive dopamine stimulation. It is something that historically happened very occasionally in life (the birth of a child?) and not for excessive lengths of time. Perhaps we must learn to pay attention and approach euphoric experiences carefully. In today’s world there are many ways to engage in excessive and prolonged over stimulation, and over stimulation is dangerous to the brain.
The second poor brain outcome with addiction involves the “want” circuit, the Ventral Tegmental Area (VTA). This is a primitive part of the brain that synthesizes dopamine and transports it to the “like center.” While the “like” center becomes harder to stimulate with repetitive addictive experiences, the “want” circuit becomes increasingly easily sensitized. This results in stronger and stronger dopamine cellular reactivity in the VTA leading to surges in craving. If the behavior is persistent and frequent the dopamine cells become chronically overstimulated and easily triggered. The urge to use becomes irresistible. These 2 negative changes in the brain begin feed a growing addiction. The catch is that most people don’t realize that profound changes are happening to their brains with repetitive addictive behaviors.
Dopamine not only stimulates pleasure, it stimulates associative learning. People and places connected with drug or alcohol use or other hyper-pleasure experiences become deeply embedded connections in memory, and they are potent cues that set off craving and motivation to repeat the pleasure seeking behavior. For instance, drinking friends, places, and habitual times linked with alcohol abuse become powerful associations that lead to predictable indulgence.
The reward centers are intricately connected to other parts of the brain. The deleterious impact of drug and alcohol abuse, and hyper-normal stimulation of other kinds is indeed scary. The “like” center continues to decrease the sensation of reward. While, the “want” circuit increases craving. As the body adjusts to the chronic over stimulation of dopamine, it changes to protect itself. Slowly the body needs the drug to find a newly established path to internal equilibrium. Now it needs the drug to be “normal”. If the drug is abruptly withdrawn the opposite effects are quickly experienced. Euphoria is replaced by depression and angst, activation by immobility. Even after time, it only takes a reward related memory cue to set off an onslaught of craving in the “want” circuit of someone who has habitually engaged in addiction.
Finally, the third major brain adaptation in addiction involves negative changes in the prefrontal cortex, the center of complex thinking, decision making, and self control.The prefrontal cortex is the thinking part of the brain that can consider future consequences and makes it possible to behave reflectively, not just reactively. Brain imaging of addicted animals have revealed malformed neurons in this area related to decreases in the cognitive abilities. Similarly the neuroimaging studies of addicted people disclose decreased activity and volume in the prefrontal cortex. Testing of addicted individuals commonly reveals decreases in sustained attention, memory, and concept formation. As drug seeking behaviors become habitual and compulsive, there is a waning of adaptive emotional flexibility and self control, and a remarkable decline in decision making faculties. These frightening declines are exacerbated with the escalation of addictive activity.
With the brain changes that are occurring during addiction there is a predictable shift in the personality. Dynorphin moves the brain from active to passive coping, promoting helplessness, decreasing proactive behaviors, and escalating paralysis and depression. These behavioral alterations have been documented with both animals and humans. Addiction is a character changer. Inevitably addicts become increasingly self centered as they are more and more preoccupied with recapturing the pleasure experience. The drug of choice increasingly hijacks the brain, too often leading to chronic dishonesty with self and others, and angry disinhibited and defensive behavior. The addict’s ability to consider the complexity of the chemical and brain changes that are happening becomes shockingly compromised. The smartest of people will deny and lie in the face of clear evidence of their destructive behaviors to themselves and their loved ones. Perhaps this is related to the decline in ability for self control, and complex assessment associated with prefrontal cortex damage.
Born to Be an Addict
Clearly there is a genetic component that compounds the probability of becoming an addict. There appear to be many genes related to an increased potential for addiction with exposure to hyper-stimulating experiences and substances. The same genes seem to be involved in a plethora of addictions. That is, genes associated with increased proclivity for nicotine addiction are the very same genes connected with a heightened chance for alcoholism. Of course, it is always a matter of genes and repetitive life exposure to addictive substances and experiences. Genetic research points to a dramatic increase in susceptibility for those who have inherited addictive genes.
Clarity and Caution
Research indicates that some 80 million Americans are addicts. The cost in health care, crime, and lost human potential is immeasurable. Because of imaging we can now clearly delineate the adaptations that are being made by the brain to compensate for the habitual presence of dopamine over stimulation in addiction. This knowledge illuminates new insight into the underlying physical substrates of addictive pleasure, tolerance, craving, and decreased self control. As this information becomes publicized, perhaps people will become more aware and cautious about repetitive addictive indulgences. The modifications in the brain’s reward circuitry with addiction are not changes that anyone would want.
- Dr. Linda Klaitz, Medical Psychologist