Risky behavior is the general term used to describe actions that increase a person\u2019s chances of experiencing harmful or unwanted, short- or long-term life outcomes. People with a tendency toward such actions have heightened odds of getting involved in substance use. In turn, substance use is itself a risky behavior that can produce seriously damaging short- or long-term results. In a study published in February 2014 in PNAS\u2014the official Proceedings of the National Academy of Sciences\u2014researchers from several U.S. institutions sought to identify the brain factors that account for habitual participation in high-risk behavior. These researchers concluded that such habitual behavior stems largely from a failure in the brain\u2019s self-control functions. The Basics Broadly speaking, any behavior is risky if it does little to sustain health and well-being while simultaneously increasing your chances of getting hurt, failing to develop fully mentally or physically, missing out on current or future opportunities, getting sick or dying. Examples of the behaviors generally acknowledged as being high-risk include taking recreational drugs, drinking excessive amounts of alcohol, drinking alcohol or taking drugs at an early age, driving while under the influence of drugs or alcohol, having sex without using a condom or following other safe-sex guidelines, eating a consistently unhealthy diet and gaining enough weight to be classified as obese or morbidly obese. The Brain\u2019s Role All people naturally experience urges or impulses to engage in some sort of behavior that\u2019s likely to produce unpleasant, unwanted or dangerous consequences. Young children lack the mental development and experience to categorize and control these urges and impulses, and therefore need recurring input from adults to guide their actions. Teenagers have a greater ability to control their impulses and also have more life experience than younger children. Still, as a rule, they don\u2019t yet have the life experience to consistently put their actions in proper context; in addition, their brain development is still incomplete, and they partially lack a critical adult mental skill called executive function. In essence, executive function gives a person the ability to take past experiences, put those experiences into context with information gained from other formal or informal sources, and use the combination of experience and acquired information to decide how to act both now and in the future. Current evidence indicates that the parts of the brain responsible for powering executive function don\u2019t fully develop until an individual reaches his or her early- to mid-20s. However, even past this point, not all adults have the same set of executive function skills. In some cases, incomplete development or damage acquired after development can lead to a significant inability to properly monitor and control one\u2019s urges and impulses. What\u2019s Responsible? In any given case, habitual involvement in risky behavior can stem from one of two basic sources: unusually strong impulses or urges that essentially override the brain\u2019s executive function or an unusually weak reaction from the parts of the brain required to maintain executive function. In the study published in PNAS, researchers from the University of Texas at Austin, Yale University, the Feinstein Institute for Medical Research and UCLA used a real-time brain scanning technology called fMRI (functional magnetic resonance imaging) to determine which of these two problems is most likely to occur. A total of 108 adults took part in the study; the researchers used data gathered from each one of these individuals while he or she played a video game specially designed to uncover tendencies toward high-risk behaviors. After completing their analysis of the study participants, the researchers concluded that, on average, high-risk behavior is much more likely to stem from relatively poor executive function skills than from relatively strong impulses and urges. They also concluded that, in nearly three-quarters (71 percent) of all cases, the results of a targeted fMRI exam can accurately predict which individuals will experience executive function problems prominent enough to result in unusually risky behavior. Significance and Considerations The authors of the study published in PNAS did not specifically study the connection between poor executive function, risky behavior and the chances that a given person will develop problems with drug or alcohol use. However, since risky behavior is strongly associated with increased chances of using drugs or alcohol, an individual with poor executive function logically has heightened odds of getting involved with problematic drug or alcohol consumption. The study\u2019s authors believe that improved understanding of the basis for most high-risk behavior could potentially change the ways in which doctors view and treat various forms of substance use disorder (substance abuse and addiction).