03 Mar Cocaine Alters Brain Connections, Boosts Impulsivity
New research from a team of American scientists indicates that cocaine addiction is linked with changes in brain function that may help explain an unusually high level of participation in impulsive behavior. The unique way that regions of the brain connect and communicate in people addicted to cocaine is an observation uncovered for the first time.
As a rule, all people affected by an addiction to drugs or alcohol have increased chances of acting impulsively without reflecting on the consequences of their behavior. In a study published in April 2015 in the journal NeuroImage: Clinical, researchers from several U.S. universities explored altered brain function as a potential underlying source of the impulsive behavior found in people addicted to cocaine. These researchers found that people with a cocaine addiction rely on an unusual pattern of brain activation when trying to control their impulses in challenging situations.
Cocaine is classified as a stimulant because it significantly boosts the level of communication between nerve cells in the central nervous system (which includes the brain and the spinal cord). However, much of the motivation to use the drug comes from its ability to travel to a brain area called the pleasure center and trigger a sharp increase in the levels of a naturally occurring chemical responsible for producing highly rewarding euphoric feelings. Many cocaine consumers try to repeatedly reproduce this euphoria. Unfortunately, repeated exposure to the drug gradually changes the pleasure center’s chemical output and makes the user increasingly tolerant to any current level of cocaine intake. Attempts to overcome rising tolerance commonly lead to increased drug consumption, and this vicious cycle sets the stage for the onset of stimulant use disorder, a condition that includes cocaine addiction as well as non-addicted cocaine abuse.
The most recent available figures from the federal Substance Abuse and Mental Health Services Administration indicate that roughly 1.5 million American adults, teenagers and preteens consume cocaine in the typical month. This is equivalent to approximately 0.6 percent of the total population over the age of 11. Cocaine is less popular than marijuana and mind-altering medications such as prescription opioids, prescription stimulants and sedative-hypnotics (i.e., sedatives and tranquilizers). However, more people consume the drug than heroin, hallucinogens or the makeshift class of drugs collectively referred to as inhalants.
All humans have a built-in capacity to act impulsively or recklessly. In the vast majority of cases, the ability to control impulsive behavior develops gradually over time during the normal course of child and adolescent growth and development. The brain areas responsible for exerting impulse control reach their mature state by the time a person reaches his or her mid-20s, and involvement in impulsive behavior typically starts to decline substantially at this age. However, for any one of a variety of possible reasons, some adults never gain the age-appropriate ability to control their reckless impulses. Unusually high levels of impulsivity are associated with increased risks for diagnosable substance problems, as well as personality disorders and the mania commonly linked to bipolar disorder.
Impulsivity, Cocaine Addiction and Brain Function
In the study published in NeuroImage: Clinical, researchers from Virginia Commonwealth University, two branches of the University of Texas, the Baylor College of Medicine and the University of Southern California used a small-scale project involving 23 adults to help determine the connection between impulsive behavior and brain function in people affected by cocaine addiction. Thirteen of the project participants had diagnosed cases of cocaine addiction (i.e., cocaine dependence), while the remaining 10 participants acted as a comparison group of non-cocaine users. The members of both groups had their real-time brain function measured while performing a task specifically designed to uncover impulsive tendencies. The task, known as a Go/NoGo task, has a relatively easy opening level, as well as a more difficult second level.
The researchers found that the brain functions of the cocaine-addicted group and the cocaine-free group did not differ to any substantial degree during performance of the easy level of the Go/NoGo task. However, when they performed the difficult second level of the task, the study participants affected by cocaine addiction did not experience a shift in brain function that normally accompanies the need to control behavior in challenging situations.
The study’s authors believe their findings indicate that people addicted to cocaine may not have the brain flexibility required to adapt to changing situations and limit the risk of acting in impulsive ways. No one knows for sure if the impulse control problems in cocaine addicts predate or follow the initiation of drug intake.