Until recently, many facets of substance abuse have remained poorly understood, even by addiction experts. For example, why do some people experience addiction but others do not? Who responds best to certain treatment techniques versus others? And, importantly, how does drug abuse affect the brain and how can that inform our approach to treatment?
Recently, the answer to that final question has become clearer following scientific reports of a new tool to visualize the effects of drug abuse on the brain. Experts hope that the technique will improve understanding of how drug use impacts brain activity, leading to more effective interventions for individuals struggling with drug addiction.
Brain Biology and Drug Abuse
The brain, like other important organs in the human body, is a large collection of cells. Astonishingly, the human brain contains approximately 100 billion neurons, the brain cells that communicate with each other to perform the important functions of thinking, memory, and attention. In addition to these neurons, there are billions of other cells called glia, which provide neurons with important nutrients and repair broken cells.
There is one key area of the brain that is known to be heavily impacted by drug abuse. Called the nucleus accumbens, this brain area processes information related to pleasure and reward. Cells in the nucleus accumbens release a particular neurotransmitter, or brain chemical, called dopamine. Dopamine is responsible for that rush of pleasure that a person experiences when winning a baseball game, eating a favorite food, or using drugs.
Most drugs of abuse, including cocaine, heroin, marijuana, and ecstasy, enter the brain and stimulate the nucleus accumbens to release dopamine. This pleasurable feeling causes the brain to want more of the drug to experience that rewarding sensation. This is what leads to cravings for the drug, beginning the cycle of substance abuse.
New Findings Signal Brain Changes Following Drug Use
Importantly, neurons in the brain are like any other cells in the human body. They need oxygen and other nutrients to thrive and stay active. As a result, a variety of arteries and veins serve the brain, allowing blood cells to transport nutrients to neurons. Thus, increased blood flow to a particular brain region signals that the neurons are more active and requiring additional energy. In contrast, reduced blood flow may signal lower activity or an impairment in neural signalling.
Scientists at Stony Brook University in New York exploited this relationship between blood flow and neuronal activity, developing a new tool to investigate the effects of drug abuse on the brain. The technique employs a method called Doppler optical coherence tomography (OCT). This method involves directing a laser at moving blood cells in the brain. As the light bounces off the blood cells and back to a receiving device, scientists can create images of blood flow as it occurs in the brain.
Preliminary data from the research team found that after 30 days of injecting lab mice with cocaine, the rodents showed a significant decline in blood flow speed. This suggests that they had a cocaine-induced shutdown of blood flow, a condition called microischemia. Microischemia is a precursor to stroke and leads to changes in brain structure and function. In humans, microischemia can cause significant impairments in thinking abilities and behaviors.
Although the Stony Brook University research team has not yet employed the imaging technique in humans, they hope that it may improve understanding of the relationship between substance abuse and brain activity. Unlike existing imaging techniques such as MRI, CT scans, or PET imaging, this new method has an excellent ability to detect very small changes in blood flow in tiny brain vessels.
Implications for Substance Abuse Intervention
To date, scientists have been unable to visualize the subtle changes in regional blood flow that may result from prolonged drug abuse. One goal of the current line of research is to determine how even one or two injections of cocaine might change the chemistry of the brain, predisposing a person to become addicted to the drug. Another application is determining the extent of brain damage in people who are struggling with chronic drug use. After months or even years of substance use, cocaine and other substances cause dramatic changes to brain structure and function that may be visualized with this new technique.
Of course, it is important to keep in mind that the findings from Stony Brook University researchers are only a first step in understanding the effects of drug abuse on the brain. Current findings are limited to rodent models, and it may be several years before the laser technique is approved for use in humans. Until then, entering a professional treatment program remains the number one way that a person struggling with addiction can work toward sobriety, improve overall health, and receive supportive care.