Made from the dried leaves of the South American coca plant, cocaine is a powerful, highly addictive, illegal stimulant drug. The potent effects of this seemingly innocuous fine, white powder are almost immediate, but disappear quickly, usually within a few minutes to an hour. Cocaine use makes a person feel mentally alert, euphoric, and energetic. There’s a temporary decrease in the need for sleep and food. The drug produces hypersensitivity to sounds, lights, and touch. Yet, despite these euphoric effects, cocaine use leaves a trail of destruction in its wake.
According to the Substance Abuse and Mental Health Services Administration (SAMHSA), in 2018, there were 1.9 million past-month and 5.5 million past-year cocaine users in the United States. Put another way, 2 percent of the American population used cocaine. This number includes 112,000 adolescents aged 12 to 17 who used cocaine within the past year.
What makes such a large number of people use cocaine? And why do people continue cocaine use despite a host of negative health, social, financial, professional, and legal consequences?
A study conducted at the Mount Sinai Medical Center holds some of the answers to these questions. The study showed that individuals addicted to cocaine continue their habit despite unfavorable consequences because of impairments in brain circuitry.
Cocaine Use and the Human Brain
Cocaine is a stimulant. It makes the user feel energetic, alert, and euphoric. But it can also cause anxiety, panic, restlessness, and paranoia. In the worst-case scenario, cocaine use can lead to heart attack, stroke, coma, and death. Drug users snort cocaine powder through the nose, mix it in water and inject it into the blood, or smoke cocaine crystals (crack).
Cocaine changes the functioning of the human brain through a chemical called dopamine. Dopamine is a neurotransmitter that regulates reward, pleasure, and motivation. Cocaine use floods the brain with dopamine. This produces an intense euphoria. However, over time, the brain gets used to large amounts of dopamine. As a result, healthy ways of having fun don’t seem fun anymore. The person needs to continue cocaine use to feel normal. Without the drug, he or she starts to feel unwell and sad. A craving for the intense high that cocaine produces drives the person to keep using the drug. With time, it becomes hard to stop using cocaine. This is called cocaine addiction.
Cocaine Use and Emotional Loss
Researchers at the Icahn School of Medicine at Mount Sinai have been studying why addicted individuals continue cocaine use despite severe harmful consequences like a loss of relationships and imprisonment. Their findings indicate that the brain circuits which predict emotional loss are impaired in cocaine addicts. In other words, cocaine users have an impaired ability to predict loss.
Reward Prediction Error
The Mount Sinai study focused on the relationship between likely loss (or reward) associated with specific behavior and an individual’s ability to predict that outcome. For example, if a person falls off a ladder once due to slippery shoes, they’ll be sure to wear rubber soles the next time they climb a ladder.
This is known as a reward prediction error (RPE). It drives learning and future behavior in humans. In other words, the human brain is designed to learn from experiences and modify behavior based on the outcome of those experiences, thus maximizing rewards and minimizing or preventing losses. Past research has shown that changing dopamine levels in the brain determine a person’s ability to predict rewards and losses.
The Study Results
The researchers at Mount Sinai enrolled 75 people in their study. Of these, 50 were cocaine users and 25 were healthy controls. Brain activity was recorded with an EEG test while each person played a gambling game. The subjects were asked to predict whether they would lose or win money.
The results showed that cocaine use impaired loss prediction. Meaning, cocaine users did not trigger reward prediction signals when they had worse-than-expected outcomes. As a result, they did not learn from poor outcomes and modify their behavior to prevent future losses. In contrast, the 25 health controls quickly learned from the unfavorable outcomes and modified their behavior.
The study offers insight into how cocaine use compromises the ability of an addicted individual to learn from bad outcomes. Scientists believe this is what potentially leads to continued cocaine use and relapses despite numerous losses, such as failed relationships, financial losses, loss of employment, and legal troubles.
The study authors concluded that cocaine use impairs loss prediction signaling in the brain. This means people with cocaine addiction have difficulty understanding the difference between expected and unexpected outcomes. This difference is critical for human beings to learn and make decisions in the future. The study showed that cocaine users are at a disadvantage when it comes to decision-making.
Effects of Recent Cocaine Use
The scientists further examined differences among the 50 cocaine users. They were divided into two groups – those who had abstained from cocaine use for the past 72 hours and those who had used the drug within the past 72 hours. Interestingly, the group that had used cocaine in the past 72 hours showed higher electrical activity in the brain’s reward circuit with unpredicted outcomes compared to predicted wins. This result was similar to the 25 healthy controls. The findings are consistent with the hypothesis that drug use is necessary to normalize brain function in addicts.
For the first time, a study has shown that prediction error signaling is modulated by recent cocaine use. This supports the self-medication drug addiction hypothesis, whereby drug use improves response to rewards in addicted individuals. The fact that cocaine use impairs the ability to predict loss is of great interest to researchers because it can be used to predict susceptibility to addiction and relapse. The study findings may help in the development of targeted interventions that can improve the outcomes and devastations caused by cocaine use.