Some real science.
Brain under construction
Marijuana shows considerable promise for treating medical conditions including pain, muscle spasms, seizure disorders and nausea from cancer chemotherapy. At least some of those benefits are thought to come from cannabidiol, a chemical component of the marijuana plant not thought to produce mind-altering effects. But there's a lot left to learn about this and other chemical compounds in marijuana. Recently, the Senate recommended $800,000 for an Institute of Medicine study on medical marijuana, and has also encouraged the National Institutes of Health to support more research on cannabidiol.
What's clear, however, is that marijuana's signature high comes from a psychoactive component known as tetrahydrocannabinol (THC). And evidence is mounting, says Weiss, that THC is not risk-free.
In the short term, marijuana use has been shown to impair functions such as attention, memory, learning and decision-making. Those effects can last for days after the high wears off. Heavy marijuana use in adolescence or early adulthood has been associated with a dismal set of life outcomes including poor school performance, higher dropout rates, increased welfare dependence, greater unemployment and lower life satisfaction.
But it's not clear that marijuana deserves the bulk of the blame. Some researchers have suggested that factors such as peer influence, emotional distress or a tendency toward problem behavior could predispose people to drug use as well as poor life outcomes. "Is marijuana the causal agent in these outcomes, or is it part of a variety of vulnerability factors?" Weiss asks.
Few longitudinal studies have been conducted to follow the trajectories of young people before and after they take their first hit of marijuana. But one long-term prospective study from New Zealand showed worrisome findings.
Duke University psychologist Terrie Moffitt, PhD, and colleagues collected data from the Dunedin Multidisciplinary Health and Development Study, longitudinal research that has followed 1,000 New Zealanders born in 1972. Participants answered questions about marijuana use at 18, 21, 26, 32 and 38. They also underwent neuropsychological testing at ages 13 and 38.
The team found that persistent marijuana use was linked to a decline in IQ, even after the researchers controlled for educational differences. The most persistent users — those who reported using the drug in three or more waves of the study — experienced a drop in neuropsychological functioning equivalent to about six IQ points (PNAS, 2012). "That's in the same realm as what you'd see with lead exposure," says Weiss. "It's not a trifle."
There are some reasons to think that adolescents may be uniquely susceptible to lasting damage from marijuana use. At least until the early or mid-20s, "the brain is still under construction," says Staci Gruber, PhD, a neuroscientist and director of the Cognitive and Clinical Neuroimaging Core and the Marijuana Investigations for Neuroscientific Discovery (MIND) Program at McLean Hospital/Harvard Medical School. During this period of neurodevelopment, the brain is thought to be particularly sensitive to damage from drug exposure. And the frontal cortex — the region critical to planning, judgment, decision-making and personality — is one of the last areas to fully develop, Gruber says.
Also immature in teens is the endocannabinoid system. As its name implies, this system comprises the physiological mechanisms that respond to THC. That system is important for cognition, neurodevelopment, stress response and emotional control, and it helps to modulate other major neurotransmitter systems, says Krista Lisdahl, PhD, director of the Brain Imaging and Neuropsychology Laboratory at the University of Wisconsin, Milwaukee.
Repeated exposure to marijuana can dial down cellular activity in the endocannabinoid system. Such interference might be a bigger problem for immature brains, says Lisdahl. "That sets the stage for why adolescents may be more sensitive to the effects of repeated marijuana exposure, from a neuroscience perspective."
Nothing personal metalwing, but there's a slight conflict of interest here.
Many people after their maverick experimental teenage or college years quit smoking marijuana but don't quit smoking. Instead of mj they smoke cigs or cigars because it's legal. People who otherwise wouldn't have smoked. Why is this relevant?
Duke, originally Trinity (as in holy) University was founded by none other than RJ Reynolds. They don't want people to know that, but they still want to keep that revenue. The university, theddisassociated shell university, is a shell Corp for the unholy company and it's deadly products. Blue (oxygen starved) Devils, a Catholic school... Yep.