By Dr. Marc Siegel , Angela Bertorelli | Fox News Ethan Andrew started smoking marijuana during his sophomore year of high school in Colorado to help with his anxiety. Like many teens, he said he thought it was "just weed" and did not see the harm in smoking the popular drug containing THC, the active chemical found in cannabis that produces a "high." His causal marijuana use … [Read more...] about Marijuana with high THC levels linked to addiction, psychiatric illness, study finds