Dumbing Down With Pot
Most parents, teachers, and other caregivers readily advise adolescents and teenagers that using marijuana is a decidedly dumb idea – and a variety of researchers have bolstered these words of wisdom by documenting the effect that the drug can have on developing minds.
According to the National Institute on Drug Abuse (NIDA), scientists who have analyzed the impact of long-term exposure to marijuana have discovered levels of brain damage that mirror the devastation inflicted by other commonly abused substances. A NIDA document entitled InfoFacts: Marijuana described how this takes place:
HC acts upon specific sites in the brain, called cannabinoid receptors, kicking off a series of cellular reactions that ultimately lead to the “high” that users experience when they smoke marijuana. Some brain areas have many cannabinoid receptors; others have few or none. The highest density of cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thoughts, concentration, sensory and time perception, and coordinated movement. ...
Cannabinoid withdrawal in chronically exposed animals leads to an increase in the activation of the stress-response system3 and changes in the activity of nerve cells containing dopamine. Dopamine neurons are involved in the regulation of motivation and reward, and are directly or indirectly affected by all drugs of abuse.
In February 2005, a NIDA study that appeared in the journal Neurology reported that individuals who smoked marijuana experienced altered blood flow in their brains even after abstaining from the drug for as long as a month. The research, which involved 54 marijuana users and 18 control subjects, revealed significantly higher velocity of blood flow in marijuana users – a discovery that participating scientists attributed to marijuana-influenced narrowing of blood vessels.
“The marijuana users had [pulsatility index] PI values that were somewhat higher than those of people with chronic high blood pressure and diabetes,” study co-author Dr. Ronald Herning said in a Feb. 13, 2005, article on the ScienceDaily website. “However, their values were lower than those of people with dementia. This suggests that marijuana use leads to abnormalities in the small blood vessels in the brain, because similar PI values have been seen in other diseases that affect the small blood vessels.”
Three years after the NIDA study was published, ABC News reported on an Australian analysis that concluded that long-term cannabis exposure “causes brain damage that is equivalent to mild-traumatic brain injury or premature ageing.”
“This is a very exciting study because it proves for the first time what we have been really worried out,” Professor Jon Currie, the director of addiction medicine at St Vincent's Hospital in Melbourne, Australia, said in a June 4, 2008, article on the ABC website. “That brain problems are real and that people who smoke cannabis over a long term do get problems.”
The ABC article said that MRI images of the brains the of 15 chronic marijuana users who were involved in the Melbourne study revealed the following:
- The parts of the brain that regulate memory and emotion, the hippocampus and the amygdala, were significantly smaller in the marijuana users than in the brains of non-users.
- The brain abnormalities that Currie and his colleagues discovered were similar to the damage that can be caused by “a mild traumatic brain injury or premature ageing.”
- Study subjects who were in their late 30s had memory function that would be expected of men over the age of 50.
- The level of damage that the researchers noted was proportional to the amount of marijuana that each subject smoked.
When speaking with ABC News, Currie made no secret of his hopes for the impact of his research. “My hope is that this can be used as a very, very clear warning to people,” he said. “Get help, seek medical help, try and stop smoking.”
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