Adolescents who use cocaine risk changing the part of the brain involved in reward and learning, according to research published in the January 30 edition of The Journal of Neuroscience.
Researchers at The Hospital for Sick Children (SickKids) analyzed the effects of chronic cocaine exposure on the brains of mice. “We tracked significant interactions between the age of exposure and the drug in several brain regions that are most implicated in drug addiction,” says Dr. Paul Frankland, the Principal Investigator and a Scientist in the Department of Neurosciences & Mental Health at SickKids.
Previous research using MRI (magnetic resonance imaging) in humans has shown that cocaine use is associated with brain-structure abnormalities, but until now it has not been known if these changes are actually caused by the drug. “Our findings answer the age-old question, do young people whose brains are organized differently tend to be more vulnerable to cocaine and other drugs, or does cocaine actually alter the brain’s structure and hardware? Now we are closer to a definitive answer.”
It is particularly important to understand the effects of drug use on the brain in adolescence because typically that is when recreational drug use starts, he adds.
Brain regions that govern drug-seeking
The study shows that chronic cocaine use in adolescent mice altered the size and the shape of regions that are key areas for learning and memory. “These are the areas we already know are most involved in drug addiction, governing impulse control and drug-seeking behaviour,” says study lead Dr. Anne Wheeler.
The research team used MRI to measure brain structures in both adolescent and young adult mice, and compared the animals’ brains in groups exposed to cocaine and saline. Both groups of mice were given 30 days of abstinence before regions of their brain were analyzed for shape, volume, and thickness. “The MRI gave us the precision we needed to tease apart changes throughout various brain regions, comparing the brains of drug-affected mice to the normal brains,” says Dr. Wheeler.
Brain areas that were affected include the nucleus accumbens, striatum, insular cortex, orbitofrontal cortex, ventral pallidum, substantia nigra, and medial forebrain bundle. “When you see brain tissue in these areas that is misshaped, or too small or too large, you get an idea of why drug use is associated with loss of control of voluntary behaviour,” she says. The same effects did not occur during young-adult exposure.
Dr. Wheeler conducted the research when she was at SickKids; she is now at the Centre for Addiction and Mental Health (CAMH).
Cocaine use in both adolescent and young-adult mice also triggered changes in movement patterns, she says.
Dr. Frankland adds, “In both mice and humans, the adolescent brain is still developing. This research suggests that cocaine use by adolescents is extraordinarily risky in part because it affects brain growth in this crucial phase.” He is also Associate Professor in the Department of Physiology at University of Toronto.
Future research could investigate the structural effects of alcohol, nicotine, marijuana and other drugs on the adolescent brain, Dr. Frankland adds.
The paper is titled “Adolescent Cocaine Exposure Causes Enduring Macroscale Changes in Mouse Brain Structure.” The study was funded by SickKids Foundation, Canadian Institutes of Health Research, and Ontario Mental Health Foundation.
Source of text and image: Hospital for Sick Children, Toronto
Reference:
Wheeler AL, Lerch JP, Chakravarty MM, Friedel M, Sled JG, Fletcher PJ,
Josselyn SA, Frankland PW. Adolescent Cocaine Exposure Causes Enduring Macroscale
Changes in Mouse Brain Structure. J Neurosci. 2013 Jan 30;33(5):1797-1803. PubMed
PMID: 23365219.
Researchers at The Hospital for Sick Children (SickKids) analyzed the effects of chronic cocaine exposure on the brains of mice. “We tracked significant interactions between the age of exposure and the drug in several brain regions that are most implicated in drug addiction,” says Dr. Paul Frankland, the Principal Investigator and a Scientist in the Department of Neurosciences & Mental Health at SickKids.
Previous research using MRI (magnetic resonance imaging) in humans has shown that cocaine use is associated with brain-structure abnormalities, but until now it has not been known if these changes are actually caused by the drug. “Our findings answer the age-old question, do young people whose brains are organized differently tend to be more vulnerable to cocaine and other drugs, or does cocaine actually alter the brain’s structure and hardware? Now we are closer to a definitive answer.”
It is particularly important to understand the effects of drug use on the brain in adolescence because typically that is when recreational drug use starts, he adds.
Brain regions that govern drug-seeking
The study shows that chronic cocaine use in adolescent mice altered the size and the shape of regions that are key areas for learning and memory. “These are the areas we already know are most involved in drug addiction, governing impulse control and drug-seeking behaviour,” says study lead Dr. Anne Wheeler.
The research team used MRI to measure brain structures in both adolescent and young adult mice, and compared the animals’ brains in groups exposed to cocaine and saline. Both groups of mice were given 30 days of abstinence before regions of their brain were analyzed for shape, volume, and thickness. “The MRI gave us the precision we needed to tease apart changes throughout various brain regions, comparing the brains of drug-affected mice to the normal brains,” says Dr. Wheeler.
Brain areas that were affected include the nucleus accumbens, striatum, insular cortex, orbitofrontal cortex, ventral pallidum, substantia nigra, and medial forebrain bundle. “When you see brain tissue in these areas that is misshaped, or too small or too large, you get an idea of why drug use is associated with loss of control of voluntary behaviour,” she says. The same effects did not occur during young-adult exposure.
Dr. Wheeler conducted the research when she was at SickKids; she is now at the Centre for Addiction and Mental Health (CAMH).
Cocaine use in both adolescent and young-adult mice also triggered changes in movement patterns, she says.
Dr. Frankland adds, “In both mice and humans, the adolescent brain is still developing. This research suggests that cocaine use by adolescents is extraordinarily risky in part because it affects brain growth in this crucial phase.” He is also Associate Professor in the Department of Physiology at University of Toronto.
Future research could investigate the structural effects of alcohol, nicotine, marijuana and other drugs on the adolescent brain, Dr. Frankland adds.
The paper is titled “Adolescent Cocaine Exposure Causes Enduring Macroscale Changes in Mouse Brain Structure.” The study was funded by SickKids Foundation, Canadian Institutes of Health Research, and Ontario Mental Health Foundation.
Source of text and image: Hospital for Sick Children, Toronto
Reference:
Wheeler AL, Lerch JP, Chakravarty MM, Friedel M, Sled JG, Fletcher PJ,
Josselyn SA, Frankland PW. Adolescent Cocaine Exposure Causes Enduring Macroscale
Changes in Mouse Brain Structure. J Neurosci. 2013 Jan 30;33(5):1797-1803. PubMed
PMID: 23365219.
