More than 42% of high-school students in the U.S. admit to taking cannabis. Apart from the risk of a criminal record cannabis use has also been linked to depression, cognitive impairment, cardiovascular disease and cancer. Parental monitoring - parents knowing where their children are, who they are with and what they are doing - has been associated with a reduced risk of gambling, sexual activity and drug use but the strength of the relationship between monitoring and cannabis use is unclear. Researchers from Claremont Graduate University in California reviewed 17 studies into this issue which covered a total of 35,000 participants. The review found that there was a 'strong, reliable' link between parental monitoring and decreased cannabis use and that this link was especially strong for girls.
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