Your Brain on Marijuana
Marijuana is among the most commonly abused illegal drugs in the United States. Like heroin and LSD, it is classified as a Schedule I substance under the Controlled Substances Act, meaning the government has determined it has a high potential for abuse and serves no legitimate medical purpose.
Although marijuana's popularity ebbs and flows with each decade that passes, 46 percent of U.S. residents aged 12 and older have admitted to using marijuana at least once in their lifetime, according to the 2005 National Household Survey on Drug Use and Health. Marijuana use is particularly prevalent among teens, according to the University of Michigan's Monitoring the Future Survey, with nearly half (45 percent) of high school seniors reporting use in 2005.
Of the many risks associated with marijuana use, its effects on the neurological system are some of the most worrisome, especially in young, developing brains. The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol). With each hit, THC passes rapidly from the lungs into the bloodstream, which carries the chemical to sites called cannabinoid receptors on nerve cells in the brain. Like most drugs, THC stimulates cells that release the feel-good chemical dopamine, which leads to a high. The drug's effects begin immediately after the drug enters the brain and usually last one to three hours.
Short-Term Memory Damage
Heavy or chronic marijuana use can damage short-term memory and impair a person's ability to form memories, recall events, and shift attention from one thing to another. Scientists believe this damage occurs because THC alters the way information is processed by the hippocampus, a brain area responsible for emotion and memory formation. The link to the hippocampus has been confirmed in laboratory tests. In one study, rats treated with THC struggled to perform tasks requiring short-term memory to the same degree as rats whose nerve cells in the hippocampus had been destroyed.
The memory damage caused by marijuana makes parts of the brain act as if they have aged beyond their years. As people grow older, they naturally lose neurons in the hippocampus, which decreases their ability to remember events. Chronic THC exposure may accelerate this loss of hippocampal neurons. In one series of studies, rats exposed to THC every day for 8 months showed nerve cell loss at 11 or 12 months of age equivalent to that of unexposed rats twice their age.
A recent study published in the Archives of General Psychiatry showed that long-term marijuana use can cause abnormalities in the brain, resulting in learning difficulties and psychotic symptoms, such as paranoia, delusions, and odd social behaviors. Researchers discovered that the hippocampus of marijuana users was 12 percent smaller, and the amygdala (which controls fear and aggression) was 7.1 percent smaller in a group that smoked at least five joints daily for at least the past 10 years when compared to a nonsmoking group. "There is ongoing controversy concerning the long-term effects of cannabis on the brain," said the study's author. "These findings challenge the widespread perception of cannabis as having limited or no harmful effects on brain and behavior. Although modest use may not lead to significant neurotoxic effects, these results suggest that heavy daily use might indeed be toxic to human brain tissue."
Lasting Effects
Even though the high from marijuana lasts only a couple of hours, the drug's effects on the brain can linger for up to one month. Recent research suggests marijuana has a long-term effect on blood flow to the brain. In a study published in the journal Neurology, researchers monitored the blood flow in brain arteries in marijuana users and found higher levels of resistance to blood flow in marijuana users than in nonusers (probably caused by a narrowing of blood vessels), even after users abstained from the drug for one month.
According to researcher Ronald Herning, PhD, of the National Institute on Drug Abuse in Baltimore, Md., the heavy marijuana users who smoked up to 350 joints a week had blood flow resistance levels "that were somewhat higher than those of people with chronic high blood pressure and diabetes." He also expressed concern that the drug may increase users' risk of stroke, which is caused by damage to blood vessels in the brain. These findings may explain, at least in part, why marijuana users commonly experience cognitive difficulties with memory and thinking.
When it comes to the science of the brain, there are many unanswered questions. While current research helps explain the potentially dangerous effects of heavy marijuana use, scientists are continually exploring the drug's long-term impact on light or moderate users. One thing is clear: Until we know more, experts recommend abstaining from marijuana use, especially for teens whose brains are still developing.
What Parents can Expect While Their Teen is in Residential Treatment
During residential treatment, a teen is encouraged to "try on" different feelings and talk about them in counseling. Gradually, a repertoire of appropriate feelings and behaviors will begin to emerge. In the interim, it is quite likely that your child may appear to "get worse" before he gets better. What kinds of emotions and behaviors are you likely to encounter in your newly recovering teen? There is a wide range, but three stand out: anger, manipulation, and joy in new growth. Learn more about what you and your child can expect while in treatment.
How to Talk Yourself Into Helping Your Teen
If you are like most parents, you will go along with your child until the substance abuse reaches a crisis such as a car accident, an unplanned pregnancy, or police involvement. Many parents allow excuses to continue until their teenagers flunk out of college, sink into the street drug sub-culture, or become full-fledged alcoholics. Learn how to talk yourself into helping your child.
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