In the meantime, some physicians are forging ahead — and cashing in. Joe Cohen is a doctor at Holos Health, a medical marijuana clinic in Boulder. I asked him what CBD is good for, and he read me a long list of conditions: pain, inflammation, nausea, vomiting, intestinal cramping, anxiety, psychosis, muscle spasms, hyperactive immune systems, nervous system degeneration, elevated blood sugar and more. He also claimed that CBD has anti-cancer properties and can regenerate brain cells and reduce the brain’s levels of amyloid beta — a kind of protein that’s been linked to Alzheimer’s disease. I asked for references, noting that most of these weren’t listed in the Academies report or a similar review published in the Journal of the American Medical Association. “I think you just have to Google search it,” he said. It’s true that a preliminary study found hints that cannabinoids might reduce beta amyloid proteins in human brain cells, but the study was done in cells grown in a lab, not in people. As for cancer, the FDA sent warning letters last year to four companies that were selling products that claimed to “prevent, diagnose, treat or cure” cancer.
A chief argument that has been advanced in favor of developing hemp as a paper and pulp source has been that as a non-wood or tree-free fiber source, it can reduce harvesting of primary forests and the threat to associated biodiversity. It has been claimed that hemp produces three to four times as much useable fiber per hectare per annum as forests. However, Wong (1998) notes evidence that in the southern US hemp would produce only twice as much pulp as does a pine plantation (but see discussion below on suitability of hemp as a potential lumber substitute in areas lacking trees).
Short-term use of the drug impairs thinking and coordination. In long-term studies, teens who smoke marijuana have lower IQs later on, as well as structural differences in their brains, though scientists debate whether this is an effect of the drug or a result of habitual pot smokers seeking out less intellectually stimulating pursuits. A 2016 study on almost 300 students by the University of Montreal published in the journal Development and Psychopathology found that teens who start smoking around age 14 do worse on some cognitive tests by age 20 than non-smokers. They also have a higher school dropout rate. If they wait until age 17 to start, though, the smokers do not seem to have the same impairments, according to the study.
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