May 27 (UPI) -- Users of marijuana and other cannabis products with high levels of THC are four times more likely to abuse the drug and nearly twice as likely to develop anxiety disorders, a study published Wednesday by JAMA Psychiatry has found.
Regular consumption of "high-potency" marijuana -- so-called because it contains large amounts of THC, or tetrahydrocannabinol, the ingredient that alters brain function -- also increased a person's risk for illicit drug use by almost 30 percent, the authors reported.
"Recently, it's been observed that the high potency cannabis is widely sold in illegal cannabis markets, and comprises a large number of products for sale in legal cannabis markets," co-author Lindsey Hines, a senior research associate at the University of Bristol in England, told UPI.
"In countries where cannabis is sold legally, limiting the availability of high-potency [products] may help reduce the number of individuals who develop cannabis use disorders, prevent cannabis use escalating to a regular behavior and reduce impacts on mental health," Hines said.
Cannabis is legal for both medicinal and recreational use in 11 states, and for medicinal use only in 23 others, according to the National Council of State Legislatures. An additional 13 states allow the drug to be used for medical purposes, but place limits on allowable levels of THC -- capping it at anywhere from 0.3 to 3 percent.
Hines and her colleagues defined high-potency cannabis products as those containing 10 percent or more of THC.
The researchers analyzed the habits of 1,087 adult cannabis users, finding that 141, or 13 percent, reported using high-potency products. In general, these products were associated with increased frequency of cannabis use and increased risk for "problem" use, the authors reported.
High-potency cannabis users were also 29 percent more likely to have "psychotic experiences" than users of low-potency products, and more than 40 percent were more likely to develop tobacco dependence.
Despite the increased risk for anxiety disorders found among high-potency users, the authors found no evidence of a relationship between use of these products and depression, a separate mental health disorder that often is linked with anxiety.
"If you're in Canada or states in the United States where cannabis is legal, THC should be labelled on the product," Hines said. "Cannabis referred to as 'skunk' is usually high potency, while herbal or resin cannabis is usually lower potency, and there are visual differences between these types of cannabis."