NYU study identifies teens at risk for hashish use

The recent increase in popularity of marijuana use coupled with more liberal state-level polices has begun to change the landscape of adolescent marijuana use. More potent forms of marijuana, such as hashish, may present a threat to adolescent health. A wealth of research has been conducted to examine risk factors for teen marijuana use; however, studies rarely differentiate between different forms of marijuana.

A new study by researchers affiliated with New York University's Center for Drug Use and HIV Research (CDUHR), was among the first to examine prevalence and correlates of hashish use in a nationally representative sample of US high school students.

Analyses focused on data collected from high school seniors (weighted N=10,597) in years 2007-2011 (2011 was the last year recreational marijuana use was still illegal in all US states). The researchers determined how sociodemographic factors and reasons for marijuana use were related to recent (12-month) hashish use.

"Nearly one out of ten teens reported ever using hashish and it was used by a quarter of lifetime marijuana users," said Joseph J. Palamar, PhD, MPH, a CDUHR affiliated researcher and an assistant professor of Population Health at NYU Langone Medical Center (NYULMC). "Hashish and other marijuana use tended to share many of the same correlates; however, our results found that risk factors for regular marijuana use were often much stronger risk factors for hashish, a much more potent form of the drug."

The study, "Prevalence and Correlates of Hashish Use in a National Sample of High School Seniors in the United States," used data from Monitoring the Future (MTF), a nationwide ongoing annual study of the behaviors, attitudes, and values of American secondary school students. The MTF survey is administered in approximately 130 public and private schools throughout 48 states in the US. Roughly 15,000 high school seniors are assessed annually.

Both hashish and non-hashish marijuana can be smoked, vaporized, or cooked in food. Hashish can be used either in its natural state or converted into a more concentrated oil. However, compared to other marijuana, hashish usually contains a higher concentration of Δ9-tetrahydrocannabinol (THC), which is the most potent psychoactive cannabinoid. While a typical marijuana cigarette ("joint") contains only 0.5-5% THC, hashish tends to contain 2-20% with some estimates as high as 50%.

The difference between marijuana and hashish goes far beyond country of origin. Marijuana is the most common and least powerful form of cannabis. It is made from dried plant leaves and flowers. Most of American cannabis is strictly the flower or bud of the plant and does not contain whole plants. THC (tetrahydrocannabinol) is the main active ingredient in marijuana that acts upon the nervous system. Marijuana usually contains a maximum of 25% to 30% THC.

. These flowers, or ‘heads’, are the most potent parts of the plant. As a result, the THC content of hashish typically varies from 20% to 60%. There are two common methods for producing hash: