Regarding the appeals court upholding the federal government's right to crack down on California medical marijuana dispensaries ("Court says feds can raid state pot shops," Jan. 16), the fact that marijuana use increases the chance of becoming psychotic is not widely known.

Researchers from the University of Bristol, Imperial College and Cambridge University examined 35 studies that tracked tens of thousands of people for periods ranging from one year to 27 years to examine the effects of marijuana use on mental health. They found that people who used marijuana had roughly a 40 percent higher chance of developing a psychotic disorder later in life. Dr. Wilson Compton, a senior scientist at the National Institute on Drug Abuse in Washington, called the study persuasive.

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