Although decriminalization in some states has affected the legal stature of cannabis, Spanish researchers say daily use may be a predicate for schizophrenia or other psychological disorders.
The study found that half of the subjects, who otherwise led normal lives and were not otherwise predisposed to the disorders, had developed a psychosis, and two-thirds of those patients had smoked cannabis on a daily basis.
In comparison, less than half of more at-risk patients who had become psychotic reported frequent consumption of the drug.
Lead author Miguel Ruiz-Veguilla also said that daily smoking caused mental illnesses to form in a specific way, which may lead to further research that may isolate the drugs role in causing the disease.
Previous research from the University of Melbourne opened the possibility that long-term cannabis use reduced the size of two portions of the brain linked to memory and base emotions.
One herbal supplement linked by some studies to reduced anxiety is valerian, which is legal in all states. 