Recent findings from a multinational research team point to clearly increased risks for marijuana\/cannabis addiction in people who rapidly move from a single instance of use to additional episodes of drug intake. Researchers and public health officials are well aware that marijuana\/cannabis, increasingly viewed as a benign or beneficial substance, will produce diagnosable problems with abuse or addiction in a significant number of users. In a study published in April 2015 in the journal Addiction, researchers from the United Kingdom, the U.S. and Australia assessed the impact that the length of the time between a single instance of cannabis use and subsequent instances of use has on the odds that any given person will eventually develop abuse or addiction symptoms. Marijuana Use in the U.S. Marijuana is by far the most widely consumed cannabis product across the U.S. Federal researchers track the total number of marijuana users over the age of 11 as part of an annual project called the National Survey on Drug Use and Health. The most recent figures from this survey show that approximately 19.8 million Americans use the drug at least once in the average month. Roughly four-fifths of all consumers of illicit\/illegal substances are marijuana users; in addition, almost 65 percent of the country\u2019s illicit\/illegal drug consumers only use marijuana. Segments of the population most likely to consume marijuana (or any other drug) include teenagers 16 and older and young adults in their 20s or early 30s. Usage rates reach their peak in 18, 19 and 20 year olds. Approximately 7,800 people in the U.S. become first-time drug users on any given day. Figures from the National Survey on Drug Use and Health indicate that marijuana is the introductory drug for fully 70 percent of all new consumers. For all people between the ages of 12 and 49, the average age of initial marijuana use is 18. All told, almost 2.5 million Americans start using marijuana every year (a number that may rise with the increasing social acceptability of the drug). Marijuana Abuse and Addiction The American Psychiatric Association reserves a category of illness called cannabis use disorder for people with diagnosable problems with marijuana\/cannabis addiction or dysfunctional, non-addicted marijuana\/cannabis abuse. Roughly 9 percent of the nation\u2019s total pool of marijuana consumers will develop an addiction to the drug, the National Institute on Drug Abuse reports. Addiction risks increase almost 100 percent in teenagers, even when teens only use the drug occasionally. At a minimum, one out of every four habitual (daily or near-daily) marijuana consumers will develop an addiction to the drug. Some reputable studies place the addiction rate in habitual consumers at a striking 50 percent. Impact of a Quickly Developing Pattern of Use In the study published in Addiction, researchers from the Washington University School of Medicine, the United Kingdom\u2019s King\u2019s College London and Australia\u2019s University of the Sunshine Coast and Queensland Institute of Medical Research used data gathered from 2,239 twins and non-twin siblings between the ages of 22 and 45 to help determine the impact that a rapidly developing pattern of marijuana intake has on future risks for cannabis use disorder. All of the study participants had consumed marijuana or some other form of cannabis (hashish or hashish oil) on at least two occasions. The researchers assessed the impact of four possible time intervals between the first and second instance of use: within seven days or less, within 90 days, between 90 days and 365 days, and more than 365 days. The researchers concluded that people who use marijuana\/cannabis again within seven days of initial use have sharply increased odds of becoming habitual consumers of the drug. They also concluded that people who transition into their second use of marijuana\/cannabis this rapidly experience a more than 200 percent increase in their chances of developing cannabis use disorder, as well as a nearly 90 percent increase in their chances of eventually looking for help to combat their abuse\/addiction problems. In addition, the researchers concluded that people who use marijuana\/cannabis a second time within 90 days of their first use experience a roughly 60 percent increase in their cannabis use disorder risks. The study\u2019s authors included twins and non-twin siblings in the project in order to determine if genetics play a role in the risks associated with a rapidly developing pattern of marijuana\/cannabis consumption. They ultimately concluded that non-genetic, person-specific environmental factors are much more important.