SfN18: The adolescent brain, mental health and substance abuse

Written by Lauren Pulling, Future Science Group

Research presented at SfN Neuroscience 2018 (3–7 November, San Diego, CA, USA) has demonstrated links between adolescent brain development, mental health and substance abuse. A collection of three studies were highlighted by the society as ones to watch in this field, covering childhood trauma, opioid receptor variants and the reward system, and their connections with mental health and the adolescent brain.
Sarita Silveira et al. present research indicating that childhood trauma impacts the development of critical brain networks during adolescence, elevating the risk for alcohol abuse. Employing a national dataset of brain scans from 396 individuals aged 12–22 years, all with varying severity of childhood trauma, researchers assessed how drinking behavior develops in adolescence and early youth, and how this behavior is affected by brain function and childhood trauma.

The strength of the connections between brain regions important for sustained cognitive control were used as brain function measures, and were derived from fMRI scans collected when participants were resting in the scanner. For each participant, brain scans were acquired at baseline and then again at 1-, 2- and 3-year follow-ups.

Results demonstrated that during adolescence, the strength of connections in the brain network important for sustained cognitive control is hampered by childhood trauma.

In addition, adolescents with greater trauma actually developed a more conservative alcohol drinking habit over 4 years than those with less trauma, potentially to deal better with their unpredictably stressful everyday environment. The trauma-impacted brain networks for sustained cognitive control were not responsible for this development of unusual drinking behavior. The researchers are now investigating which brain networks protect individuals from heavy drinking despite their early-life trauma.

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In another study, John VanMeter (Georgetown University Medical Center, DC, USA) and colleagues demonstrated that reward response is muted in young adolescents with an opioid-receptor gene variant. In the study, researchers explored the effects of the G-variation of OPMR1; the carrying of which has previously been linked with stronger cravings for alcohol and requiring higher doses of opioids for pain management.

The team first explored the effects of the variant in early adolescence, prior to substance abuse. They performed fMRI scans on 115 adolescents, aged 11–13, while the participants played a computerized gambling game. In the game, subjects made either risky or safe choices, and were then shown whether they won or lost money.

Both the variant carriers and non-carriers made an equal number of risky choices. However, when the participants were shown if they won or lost, the frontal cortex in the right hemisphere was less active in the variant carriers compared to the non-variant carriers, indicating a muted response to reward and a potentially higher risk for substance use disorders in adolescence.

“Our results suggest that the OPRM1 gene influences the way the brain processes rewards even before exposure to drugs and alcohol,” said lead author Veronica Mucciarone (Georgetown University Medical Center). “It suggests that prevention programs specifically targeting these reward processes may be effective in reducing the risk of substance use during adolescence, especially in carriers of the G-variant.”

The third study in this area highlighted at the conference was led by Benjamin Ely (Icahn School of Medicine at Mount Sinai, NY, USA), and demonstrated links between connections in the reward system of the adolescent brain and depression and anxiety.

The study examined connections between the habenula and other brain regions during adolescence and how these connections relate to psychiatric symptoms. The subjects (49 adolescents with psychiatric diagnoses of mainly anxiety and depression, and 15 healthy adolescents) rated the severity of their anxiety and depression symptoms, including anhedonia, the inability to experience pleasure.

Using non-invasive fMRI, the researchers observed that habenula connections in adolescents were nearly identical to those seen in adults, including strong links to the reward system. Moreover, stronger connections between the habenula and the dopamine center of the reward system were associated with more severe anhedonia symptoms across all adolescents. Among adolescents with psychiatric disorders, weaker habenula connections to the reward system were associated with higher anxiety scores.

Jay Giedd (University of California San Diego, CA, USA), the press conference moderator, concluded that: “These advances provide potential new methods to identify young people who have biological susceptibility to addiction and mental illnesses, so we can implement intervention strategies even before problems emerge.”


Sources:

  1. Mucciarone VC, Schroeder RA, Stevens BW, Fishbein DH, Vanmeter JW. Differential brain response between OPRMI genotypes to reward feedback during early adolescence. Programs and Abstracts of SfN Neuroscience 2018. San Diego, CA, USA, 3–7 November 2018 (7517).
  2. Silveira S, Nooner KB, Nagel BJ, Tapert S, Debellis MD, Mishra J. Cognitive control networks and related vulnerabilities for alcohol abuse in adolescents with childhood trauma. Programs and Abstracts of SfN Neuroscience 2018. San Diego, CA, USA, 3–7 November 2018 (14469).
  3. Ely BA, Xu JG, Gabbay V. Habenula connectivity in adolescent mental illness. Programs and Abstracts of SfN Neuroscience 2018. San Diego, CA, USA, 3–7 November 2018 (9991).