New findings from a group of British researchers indicate that young adults and older teenagers who smoke cigarettes have increased chances of developing a cannabis or marijuana addiction. Cigarette smoking and marijuana\/cannabis use are two of the most common forms of substance intake among young adults and teenagers. Both activities carry a significant risk for the onset of addiction. In a study published in January 2015 in the journal Drug and Alcohol Dependence, researchers from two British institutions sought to determine if cigarette consumption helps predict the eventual development of a cannabis addiction in young substance users. They concluded that, regardless of the frequency of marijuana\/cannabis intake, smoking increases addiction risks among users of the drug. Smoking in Young Adults Researchers from the Substance Abuse and Mental Health Services Administration (SAMHSA) use a yearly, nationwide survey project called the National Survey on Drug Use and Health to track cigarette use among all American preteens, teenagers and adults. As of early 2015, the most recent figures from SAMHSA cover the year 2013. In that year, 21.3 percent of all people in this broad age range smoked cigarettes at least once a month. This percentage is equal to almost 56 million people. The highest rate of monthly cigarette use in any age group (33.2 percent of the population segment) occurred among adults between the ages of 30 and 34. However, younger adults accounted for the next three highest rates of use. Young adults between the ages of 21 and 25 maintained a monthly rate of cigarette consumption (32.8 percent) only slightly lower than the rate maintained by adults in their early 30s. Young adults between the ages of 26 and 29 maintained a nearly identical monthly rate of use (32.7 percent). The youngest adults, between the ages of 18 and 20, maintained a monthly cigarette consumption rate of 27.1 percent in 2013. Overall, cigarette use has declined steadily in most age groups since the beginning of the 21st century. Marijuana Use in Young Adults SAMHSA\u2019s National Survey on Drug Use and Health also tracks year-to-year changes in the rate of marijuana use in all Americans over the age of 11. By far, marijuana is the most popular illicit\/illegal substance consumed across the U.S. In any given month, young adults between the ages of 18 and 25 (19 percent of the population segment) consume the drug at a rate more than twice as high as the rate maintained by the general population. Within this population segment, usage is higher among young adults between the ages of 18 and 20 than among young adults between the ages of 21 and 25. Cigarette Smoking and Cannabis Addiction Current figures indicate that about nine out of 100 marijuana consumers will ultimately develop cannabis addiction (one of the two aspects of a condition called cannabis use disorder). Among habitual consumers of the drug, the addiction rate is much higher (25 percent to 50 percent). In the study published in Drug and Alcohol Dependence, researchers from the United Kingdom\u2019s University College London and University of Exeter used interviews with 298 cigarette and marijuana\/cannabis consumers between the ages of 16 and 23 to gauge the impact that cigarette use has on the odds of developing a cannabis addiction. All of these study enrollees took part in an initial round of interviews conducted in person or over the phone. Sixty-five of the enrollees also participated in a second round of follow-up interviews. The researchers used a screening tool called the Severity of Dependence Scale to look for signs of marijuana\/cannabis addiction. After analyzing all of the available information, the researchers concluded that almost one-third (29 percent) of young adults\u2019 and older teenagers\u2019 risk for cannabis addiction comes from the prior use of cigarettes. Some of this risk contribution stems from the frequency of cigarette use, while the remainder stems from the amount of time over which cigarettes are used. Critically, the researchers determined that the chances that smokers in the targeted age range will develop a cannabis addiction do not depend on the frequency of marijuana\/cannabis intake. (In other words, essentially all cannabis-consuming smokers share similar addiction risks.) The study\u2019s authors believe that cigarette use and marijuana\/cannabis use are comorbid activities for young adults and older teenagers. This means that people in this age range who consume both substances expose themselves to significantly greater amounts of harm than people who only smoke cigarettes or only use marijuana\/cannabis, and should seek treatment for their addictions immediately.