Young adults at risk of developing addiction problems show key differences in a particular brain region tied to impulse control, according to a new study published in the journal Neuropsychopharmacology.
The findings add to the growing evidence suggesting that an individual’s biological makeup plays a significant role in whether or not they will develop an addictive disorder.
High levels of impulsivity — responding prematurely without considering the consequences — has been linked to a greater risk for addiction in young people. While most people occasionally act impulsively, people affected by disorders including attention deficit hyperactivity disorder (ADHD), substance and behavioral addictions, and mental health problems such as depression and anxiety, show much greater levels of impulsivity.
In the new study, researchers from the University of Cambridge’s department of psychiatry in the U.K., in collaboration with a group at Aarhus University in Denmark, have found a strong link between increased impulsivity in young adults and abnormalities in nerve cells in the putamen, a key brain region involved in addictive disorders.
As part of the research, 99 young adults ages 16 to 26 completed a computer-based test of impulsivity. The researchers also scanned the participants’ brains using a tool that is sensitive to myelin content. Myelin is a protein-rich coating on the axis of a nerve cell, similar to the plastic coating that surrounds electrical wiring. It is essential to fast nerve conduction in the brain and body.
The results show that young adults who displayed higher levels of behavioral impulsivity also had lower levels of myelin in the putamen. This work builds on similar findings in rodent models of impulsivity from researchers at Cambridge and elsewhere.
“People who show heightened impulsivity are more likely to experience a number of mental health issues, including substance and behavioral addictions, eating disorders, and ADHD,” said Dr. Camilla Nord of the MRC Cognition and Brain Sciences Unit, lead author on the study.
This suggests that impulsivity is an “endophenotype,” a set of behavioral and brain changes that increases people’s general risk for developing a group of psychiatric and neurological disorders.
“We know that most mental health symptoms are not specific to particular disorders,” Nord said. “This work provides an important piece of the puzzle in establishing brain signatures that are general across a number of mental health disorders, rather than specific to any single one.”
The putamen is considered a key brain hub in addiction, sending dopamine signals elsewhere in the brain, and helping mediate how impulsively we behave.
“The significance of decreased myelination implies there are tiny microstructural changes in this part of the brain affecting its function, and thereby affecting impulsivity,” said senior author Dr. Valerie Voon, also from Cambridge.
Said co-author Dr. Seung-Goo Kim, “The degree of myelination alters the speed and efficiency of neuronal communication, meaning that if a population has decreased myelination only in one particular region, as we show, there is something highly local about any changes in neural speed and efficiency.”
Although it is not possible to say for sure whether the decreased myelination causes individuals to behave impulsively, the fact that all participants were healthy and had not been diagnosed with addiction or any other psychiatric diagnosis suggests a more causal link than has been shown previously in other studies.
In the future, the finding may help in predicting a person’s risk of developing a problem with addiction, the researchers said, but this would require more research.
Source: University of Cambridge