Thus, the detrimental effects seen in young brains, in which cannabinoids are already plentiful, may turn out to be beneficial in older brains that have a dearth of them. Likewise, cannabis can spark an appetite in cancer patients but in other people may produce nausea.

For example, a little marijuana may alleviate anxiety, but too much can bring on paranoid delusions. РІР‚СљTo anyone who studies the endocannabinoid system, the findings are not necessarily surprising, because the system has homeostatic properties everywhere we look,РІР‚Сњ meaning its effects may vary depending on the situation. That idea does not seem so outlandish, considering the role of cannabinoids in maintaining the bodyРІР‚в„ўs natural balance, says Mark Ware, a clinical researcher at McGill University, who was not part of the study. РІР‚СљSo we thought, РІР‚ВWhat if we stimulate the system by supplying cannabinoids?РІР‚в„ў РІР‚Сњ РІР‚СљThe idea is that as animals grow old, similar to in humans, the activity of the endogenous cannabinoid system goes down-and that coincides with signs of aging in the brain,РІР‚Сњ Zimmer says. That decline in the endogenous cannabinoid system with age fits with previous work by Zimmer and others showing that cannabinoid-associated molecules become more scant in the brains of aged animals. РІР‚СљThen as we age, itРІР‚в„ўs on a steady decline.РІР‚Сњ Research has shown that the cannabinoid system develops gradually during childhood, РІР‚Сљand then it blows up in adolescence-you see increased activity of its enzymes and receptors,РІР‚Сњ McLaughlin says. РІР‚СљWe know the endogenous cannabinoid system is very dynamic it goes through changes over the life span,РІР‚Сњ says Ryan McLaughlin, a researcher who studies cannabis and stress at Washington State University and was not involved in the current work. The plant compounds mimic our brainРІР‚в„ўs own marijuanalike molecules, called endogenous cannabinoids, which activate specific receptors in the brain capable of modulating neural activity. THC, the most highly studied type, is largely responsible for marijuanaРІР‚в„ўs psychoactive effects. Cannabinoids include dozens of biologically active compounds found in the Cannabis sativa plant. The findings raise the intriguing possibility that THC and other РІР‚СљcannabinoidsРІР‚Сњ might act as antiaging molecules in the brain. РІР‚СљThat is something we absolutely did not expect: the old animals THC looked most similar to the young untreated control mice,РІР‚Сњ Zimmer says. Even more striking, the gene-expression pattern in the hippocampi of THC-treated aged mice was radically different from that of untreated elderly mice. When the researchers examined the brains of the treated elderly mice for an explanation, they noticed that neurons in the hippocampus-a brain area critical for learning and memory-had sprouted more synaptic spines, the points of contact for communication between neurons. further research will be critically needed.РІР‚Сњ Nevertheless, she added, РІР‚Сљwhile it would be tempting to presume the relevance of these findings to aging humans. РІР‚СљThis well-designed set of experiments shows that chronic THC pretreatment appears to restore a significant level of diminished cognitive performance in older mice, while corroborating the opposite effect among young mice,РІР‚Сњ wrote Susan Weiss, director of the Division of Extramural Research at the National Institute on Drug Abuse, who was not involved in the study, in an e-mail. Other experts praised the study but cautioned against extrapolating the findings to humans. РІР‚СљThe effects were very robust, very profound,РІР‚Сњ Zimmer says. But after the elderly animals were given THC, their performances improved to the point that they resembled those of young, untreated mice. Without the drug, mature and aged mice performed worse on the tests than young ones did. For example, after receiving THC, young mice took longer to learn where a safe platform was hidden in a water maze, and they had a harder time recognizing another mouse to which they had previously been exposed. As expected, young mice treated with THC performed slightly worse on behavioral tests of memory and learning. Researchers led by Andreas Zimmer of the University of Bonn in Germany gave low doses of delta-9 tetrahydrocannabinol, or THC, marijuanaРІР‚в„ўs main active ingredient, to young, mature and aged mice. Instead of impairing learning and memory, as it does in young people, the drug appears to reverse age-related declines in the cognitive performance of elderly mice. But new research published in June in Nature Medicine suggests the drug might affect older users very differently than young ones-at least in mice. Marijuana has long been known for its psychoactive effects, which can include cognitive impairment.

Picture the stereotypical pot smoker: young, dazed and confused.

Mj human nature reverse