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A new study from Linköping University in Sweden shows that higher levels of the body’s own cannabinoids protect against increased addiction in individuals who previously experienced childhood abuse.
The study has been published in Molecular Psychiatry. The brains of those who did not develop addiction after childhood abuse seemed to process social cues related to emotion better.
Child abuse has long been suspected of increasing the risk of drug or alcohol addiction later in life. Researchers at Linköping University previously showed that this risk is three times higher if you experienced childhood abuse than if you didn’t, even when accounting for confounding from genes and other family factors.
“There has been a lot of focus on addiction as a disease driven by research on hedonic and euphoric effects, but for many it has to do with the ability of drugs to suppress negative emotions, stress sensitivity, anxiety, and low mood. Based on this, we and other researchers have a theory that it is If affected in childhood, the function of the brain’s distress systems changes, and that this may contribute to addiction risk in adulthood, says Markus Heilig, professor and director of the Center for Social and Affective Neuroscience, CSAN, at Linköping University and a consultant in the Psychiatry Clinic at the University Hospital Linköping.
Endocannabinoids, that is, cannabinoids of the body, are interesting players in this context. The endocannabinoid system plays an important role in regulating reactions to stress and discomfort. Recent research indicates that this internal system may act as a stress buffer.
The researchers behind the study aimed to investigate the potential mechanisms behind the susceptibility or resilience to developing a substance use disorder later in life after experiencing childhood abuse. One difficulty with the research is that people who develop problems later in life tend to overreport negative life experiences when asked about past events. So the researchers used the psychiatric care records of children and young adults who had been treated for traumatic childhood experiences to find study participants with objectively and prospectively documented exposure.
The study included about 100 young adults divided into four groups of equal size: individuals who were exposed to childhood abuse and developed an addiction, individuals who were exposed but not exposed to it, individuals who were not exposed but developed addiction, and individuals who were neither exposed nor developed addiction. The researchers measured endocannabinoid levels in the participants’ blood and ran several experiments to test stress reactions. The participants’ brains were also scanned using magnetic resonance imaging (MRI), while their reactions to social stimuli were tested.
It turned out that one group was distinguished from the other three: the group that had experienced childhood abuse but did not subsequently develop an addiction. Researchers refer to this group as “resilient.” Compared to the other groups, this group showed increased endocannabinoid system function as well as different brain activity. Surprisingly, the resilient group was significantly different from the control group, which had no exposure to childhood abuse, and had no addictions.
In the face of social-emotional stimuli, the resilient group showed higher activity in three regions of the brain. Two of these areas are part of the brain network that focuses attention and cognitive abilities on what is important in the moment and modifies the behavior of individuals according to the current situation. The third area of the brain is located in the frontal lobe and is associated with the regulation of emotions. This area communicates extensively with other areas of the brain that process emotions. Compared to other animals, humans have a well-developed frontal lobe that regulates impulses and emotions, for example by suppressing fear impulses in situations where fear is not appropriate.
“Increased activity in certain regions of the brain in the resilient group, which did not develop into addiction despite the children’s abuse, may be related to a more adaptive way of interacting with social-emotional information. We could see that also in the resting state they show increased inter-lobe connectivity. frontal and other parts of the brain, which may indicate that this group has better emotional regulation,” says Irene Perini, CSAN team scientist at Linköping University.
The question this finding raises is whether the resilient group had elevated endocannabinoid system function from the onset, or whether they were better able to activate the system in response to stress, thereby avoiding the long-term consequences of child maltreatment. Because of the nature of the cross-section, this could not be determined from the current study.
Resilience to substance use disorder after childhood maltreatment: association with peripheral biomarkers of endocannabinoid function and neural markers of emotion regulation. Molecular Psychiatry (2023). DOI: 10.1038/s41380-023-02033-y