New findings from a multinational research team indicate that cocaine-induced changes in brain function increase the risks for a relapse in abstinent, addicted users by altering the typical reaction to stressful situations.
People addicted to the powerful street drug cocaine have significant chances of relapsing back into substance use after establishing a pattern of abstinence. In a study published in April 2015 in The Journal of Neuroscience, researchers from Spain, the U.S., the United Kingdom and Germany used laboratory experiments on rats to explore some of the underlying reasons for cocaine-related relapse. These researchers concluded that the drug triggers profound changes in the brain’s stress and pleasure networks that make a relapse substantially more likely to occur.
Stress is a natural human reaction to challenging or demanding circumstances. In some cases, the challenges that act as stress triggers are serious or even life-threatening; however, most people have a much higher level of exposure to mundane, everyday types of stress-inducing situations. To a certain extent, the typical person can adapt to stress in healthy ways and maintain his or her sense of equilibrium and well-being. However, every person has an overload point where stress reactions become dysfunctional and lead to a substantial decline in mental and/or physical health. The particular circumstances that prompt dysfunctional stress reactions can vary considerably from individual to individual.
Like virtually all other addictive substances, cocaine is problematic because its repeated presence alters the normal function of a brain area called the pleasure center, which determines how much of a rewarding feeling humans derive from participating in various activities. Over time, a frequent cocaine user can become dependent on continued intake in order to support the pleasure center’s “new normal” and avoid the onset of withdrawal, a collection of unpleasant symptoms that appear when the brain’s baseline cocaine needs go unfulfilled. Specific symptoms associated with cocaine withdrawal include lethargy, a “down” or depressed state of mind, nightmares, unusual restlessness and an unusually agitated mental outlook.
In an addict, intense urges for substance use known as cravings commonly occur between episodes of active substance intake. To a considerable degree, these urges are the brain’s signal to consume enough drugs or alcohol to avoid experiencing withdrawal symptoms. In a person recovering from cocaine addiction or an addiction to any other mind-altering substance, the presence of both cravings and withdrawal symptoms substantially increases the odds that a relapse back into active substance intake will happen. Relapse risks are also intensified by the cues for drug use that support drug cravings. Typical sources of consciously or unconsciously registered drug cues include people and places associated with past substance intake, as well as the emotional states associated with past substance intake.
Cocaine-Induced Stress and Relapse Risks
In the study published in The Journal of Neuroscience, researchers from Spain’s University of Barcelona, America’s National Institute on Drug Abuse, the United Kingdom’s University of East Anglia and Germany’s Max Planck Institute of Psychiatry conducted laboratory experiments on rats designed to explore the circumstances that lead to increased relapse risks in people recovering from cocaine addiction. Specifically, the researchers wanted to know if cocaine produces changes in brain function that make recovering users of the drug relapse-prone. They focused their attention on the pathways in the brain responsible for regulating stress reactions, as well as the pathways in the brain responsible for regulating rewarding feelings in the pleasure center. This focus was a direct result of previous investigations that indicated that the stress networks and the pleasure networks in the brains of cocaine users may interact in unusual ways.
After completing an analysis of the rats’ brains, the researchers concluded that, in addition to changing normal function in the pleasure center, repeated use of cocaine led to destabilizing “crosstalk” between the animals’ pleasure center pathways and stress response pathways. Essentially, this situation increased the odds that the animals would resort to cocaine use while under significant stress.
The study’s authors believe their findings indicate that cocaine has unique effects in the human brain that increase the likelihood of experiencing a relapse after halting consumption of the drug. They also believe that future researchers may be able to take advantage of the observed crosstalk between the pleasure-related pathways and the stress-related pathways in addicted users’ brains and develop new treatments that lower relapse risks by altering typical stress reactions.