Psychology professor Joshua Gulley, left, graduate student Shuo Kang and their colleagues found that amphetamine abuse in young rats led to changes in dopamine signaling in the brain that persisted into adulthood.
Photo by L. Brian Stauffer
The study, reported in the journal Neuroscience, found that amphetamine leads to changes in dopamine signaling. Dopamine is a neurotransmitter that plays a role in memory, attention, learning and feelings of pleasure.
“The dopamine system, which continues to develop throughout adolescence and young adulthood, is a primary target of psychostimulant drugs like amphetamine,” said University of Illinois psychology professor Joshua Gulley, who led the new research. “Changes in dopamine function in response to repeated drug exposure are likely to contribute to the behavioral consequences — addiction and relapse, for example — that abusers experience.”
Parallels between rat and human development make rats a worthy model for the study of human drug addiction, which often begins in adolescence, Gulley said.
“Rats exhibit many of the characteristics that human adolescents do. They tend to be more impulsive than adult rats; they tend to make more risky decisions,” he said. They also can engage in “addiction-like behaviors,” he said.
“They show increased drug use in response to stress,” Gulley said. “And, just as in humans, there is evidence that animals that start using drugs in adolescence are more likely to relapse than animals that start in adulthood.”
A limitation of the new study was that, unlike humans, who generally choose whether or not to partake in drug use, “the rats had no say in whether they got amphetamine,” Gulley said.
A previous study from Gulley and his colleagues looked at the effects of amphetamine abuse on working memory — the ability to retain information just long enough to use it — in young and adult rats.
“In that study, we found that animals that were exposed to the drug during adolescence had much more significant deficits in working memory than those exposed during adulthood,” Gulley said.
The researchers hypothesized that drug exposure during adolescence, a time of vast changes in the brain, “somehow influences the normal developmental trajectory,” Gulley said. “But how?”
To get at this question, the team focused on the prefrontal cortex, a brain region behind the forehead that is among the last to fully develop during adolescence. The researchers found that repeated exposure to amphetamine — beginning in adulthood or in adolescence — reduced the ability of key cells in the rats’ prefrontal cortex to respond to dopamine. In this part of the brain, dopamine influences “inhibitory tone,” telling cells to stop responding to a stimulus, Gulley said.
“Inhibition in the nervous system is just as important as activation,” he said. “You need cells that are firing and communicating with one another, but you also need cells to stop communicating with one another at certain times and become quiet.
“Our research suggests that a subtype of dopamine receptor, the D1 receptor, is altered following amphetamine exposure,” Gulley said. “It’s either not responding to dopamine or there are not as many of these receptors after exposure as there used to be.”
This change in dopamine signaling persisted for 14 weeks after exposure to amphetamine in the adolescent-exposed rats, he said.
“That’s akin to a change in humans that persists from adolescence until sometime in their 30s, long after drug use stopped,” he said.
“Along with other studies, this shows pretty clear evidence that drug use during adolescence, a time when the brain is still developing, has extremely long-lasting consequences that go far beyond the last drug exposure,” Gulley said.
The above post is reprinted from materials provided by University of Illinois at Urbana-Champaign. The original item was written by Diana Yates.
- S. Kang, K. Paul, E.R. Hankosky, C.L. Cox, J.M. Gulley. D1 receptor-mediated inhibition of medial prefrontal cortex neurons is disrupted in adult rats exposed to amphetamine in adolescence. Neuroscience, 2016; 324: 40 DOI: 10.1016/j.neuroscience.2016.02.064
- Luke K. Sherrill, Jessica J. Stanis, Joshua M. Gulley. Age-dependent effects of repeated amphetamine exposure on working memory in rats. Behavioural Brain Research, 2013; 242: 84 DOI: 10.1016/j.bbr.2012.12.044
Teenagers and young adults who use marijuana may be messing with their heads in ways they don’t intend.
Evidence is mounting that regular marijuana use increases the chance that a teenager will develop psychosis, a pattern of unusual thoughts or perceptions, such as believing the television is transmitting secret messages. It also increases the risk of developing schizophrenia, a disabling brain disorder that not only causes psychosis, but also problems concentrating and loss of emotional expression.
In one recent study that followed nearly 2,000 teenagers as they became young adults, young people who smoked marijuana at least five times were twice as likely to have developed psychosis over the next 10 years as those who didn’t smoke pot.
Another new paper concluded that early marijuana use could actually hasten the onset of psychosis by three years. Those most at risk are youths who already have a mother, father, or sibling with schizophrenia or some other psychotic disorder.
Young people with a parent or sibling affected by psychosis have a roughly one in 10 chance of developing the condition themselves—even if they never smoke pot. Regular marijuana use, however, doubles their risk—to a one in five chance of becoming psychotic.
In comparison, youths in families unaffected by psychosis have a 7 in 1,000 chance of developing it. If they smoke pot regularly, the risk doubles, to 14 in 1,000.
For years, now, experts have been sounding the alarm about a possible link between marijuana use and psychosis. One of the best-known studies followed nearly 50,000 young Swedish soldiersfor 15 years. Those who had smoked marijuana at least once were more than twice as likely to develop schizophrenia as those who had never smoked pot. The heaviest users (who said they used marijuana more than 50 times) were six times as likely to develop schizophrenia as the nonsmokers.
So far, this research shows only an association between smoking pot and developing psychosis or schizophrenia later on. That’s not the same thing as saying that marijuana causes psychosis.
This is how research works. Years ago, scientists first noted an association between cigarette smoking and lung cancer. Only later were they able to figure out exactly how cigarette smoke damaged the lungs and other parts of the body, causing cancer and other diseases.
The research on marijuana and the brain is at a much earlier stage. We do know that THC, one of the active compounds in marijuana, stimulates the brain and triggers other chemical reactions that contribute to the drug’s psychological and physical effects.
But it’s not clear how marijuana use might lead to psychosis. One theory is that marijuana may interfere with normal brain development during the teenage years and young adulthood.
The teenage brain is still a work in progress. Between the teen years and the mid-20s, areas of the brain responsible for judgment and problem solving are still making connections with the emotional centers of the brain. Smoking marijuana may derail this process and so increase a young person’s vulnerability to psychotic thinking. (You can read more about how the adolescent brain develops in this article from the Harvard Mental Health Letter.)
While the research on marijuana and the mind has not yet connected all the dots, these new studies provide one more reason to caution young people against using marijuana—especially if they have a family member affected by schizophrenia or some other psychotic disorder. Although it may be a tough concept to explain to a teenager, the reward of a short-time high isn’t worth the long-term risk of psychosis or a disabling disorder like schizophrenia.
Source: Harvard Health Publication
Our goal in the organization of this educational seminar was to present a more in depth presentation of child rearing with special attention to the mental and emotional needs of our children. The different aspects of parenting, parenting styles and preventative measures especially with regard to the disease of addiction were explored, as well as the latest trends of substance abuse in the Orange County area.
Photos by Navid Soheilian
The main objective of this seminar was to address the importance of encouraging our individual ability to change and to accept change. Special attention was directed towards the negative side effects of old cultural prejudices and approaches which only exacerbate one’s attempt to be a positive energy in the lives of those who are suffering from mental health issues such as addiction.
Ayeneh was invited by the Iranian Student Association at CSUN to organize an educational presentation regarding the destructive power of the international disease of addiction. Captain Rod Kush, from the Detective Division – Narcotics Bureau was one of our guest speakers who reviewed the latest trend in drug abuse.
Ayeneh Foundation has been invited to give educational and preventional presentations at high schools and colleges starting from Taft high school and moving on to Pierce College in Los Angeles in 2012.