A study of individuals with cocaine use disorder found that, when given the option, those with a thicker insula region in the brain administered more cocaine infusions to themselves. Women generally self-administered more cocaine infusions than men. The research was published in the American Journal of Drug and Alcohol Abuse.
Cocaine is a powerful stimulant drug derived from the coca plant, known for its ability to increase alertness, energy, and feelings of euphoria. It works by interfering with the brain’s dopamine system, causing a buildup of the neurotransmitter dopamine that amplifies pleasure and reward sensations. Cocaine is highly addictive, and its use can lead to serious health problems, including heart attacks, strokes, and mental health disorders such as anxiety and paranoia. It is commonly consumed as a white powder (snorted) or in its crystalline form (smoked as “crack cocaine”) but can also be administered via infusions.
Prolonged cocaine use can result in severe physical, psychological, and social consequences, leading to a condition known as cocaine use disorder. Cocaine use disorder is characterized by compulsive cocaine use despite negative consequences, such as health problems, strained relationships, or legal issues. It involves both physical dependence, marked by withdrawal symptoms, and psychological dependence, which includes intense cravings and loss of control over usage. It is often accompanied by severe mental health issues, including anxiety, paranoia, and depression.
Study author Robert J. Kohler and his colleagues sought to investigate associations between cocaine self-administration behavior and characteristics of subcortical and cortical brain regions. They hypothesized that the number of cocaine self-infusions a person chooses would be associated with gray matter volume in the striatum, amygdala, and hippocampus regions of the brain. To explore this, they conducted a neuroimaging study.
The study involved 33 adults with cocaine use disorder who were recruited from the community. These participants were not seeking treatment for their disorder and were otherwise medically healthy. Of the participants, 10 were women. All reported using cocaine either through smoking or infusions for at least one year. The researchers confirmed recent cocaine use by analyzing the participants’ urine samples. The average age of the participants was 44 years.
Participants were brought to an inpatient clinic for the experiment. There, they were provided with an analgesia pump they could use to inject intravenous cocaine hydrochloride into their veins. They were assigned appropriate doses based on their body weight and were given one hour to administer cocaine infusions. During this time, they could self-administer up to 12 cocaine infusions, with a mandatory 5-minute lockout period between infusions.
The researchers tracked the number of infusions each participant administered during the hour. Participants also underwent magnetic resonance imaging (MRI), which the researchers used to examine the morphometric characteristics of their brains.
On average, participants administered seven cocaine infusions to themselves during the 60-minute session, with an average interval of 10 minutes between infusions. Participants with higher gray matter volume in the caudate region of the brain and lower gray matter volume in the putamen region tended to administer more infusions. Individuals with a thicker insula region also gave themselves more infusions. Additionally, women self-administered cocaine more frequently than men.
Gray matter in the brain consists of neuronal cell bodies, dendrites, and synapses, playing a crucial role in processing information, muscle control, and sensory perception. The caudate and putamen regions are involved in motor control, learning, and reward processing, while the insula plays a key role in emotional regulation, sensory integration, and perception of internal body states.
“In sum, the present study identified brain structural measures associated with cocaine self-administration in people with CUD [cocaine use disorder]. The results suggest potential relationships between behavioral phenotypes (e.g., impulsivity and compulsive reward-seeking) and brain structural features that may underlie cocaine use, and these possibilities warrant direct examination in future studies,” the study authors concluded.
The study contributes to the scientific understanding of the neural underpinnings of drug-related behaviors. However, the sample size was very small, and the association between the listed brain characteristics and cocaine use behavior was relatively weak. Additionally, studies examining the relationship between brain structures and behavior are known for producing inconsistent results. Research with larger or more diverse samples may yield different findings.
The paper, “Cocaine self-administration behavior is associated with subcortical and cortical morphometry measures in individuals with cocaine use disorder,” was authored by Robert J. Kohler, Simon Zhornitsky, Marc N. Potenza, Sarah W. Yip, Patrick Worhunsky, and Gustavo A. Angarita.
