Religiosity is a term used to describe adherence to any given form of religious doctrine or faith. Levels of adherence vary significantly from person to person within a faith, as well as within any given individual at various points in time. In a study published in March 2014 in the journal Drug and Alcohol Dependence, researchers from Virginia Commonwealth University used data from a large-scale project called the National Comorbidity Survey- Replication (NCS-R) to determine how changes in religiosity over time affect any person\u2019s chances of using and abusing drugs or alcohol. The Basics There is no single, set way of defining religiosity. Instead, the term has slightly different meanings in different contexts. Factors that can indicate a strongly religious orientation include attendance at church services or other faith-sponsored functions, living a lifestyle in accord with a particular religion\u2019s teachings, having a personal experience of religious feeling, having a theoretical or intellectual understanding of the principles of one\u2019s religion and having an overall life trajectory largely anchored in religious belief. These factors can appear in any given person to a greater or lesser degree, or change in relation to one another in specific situations or circumstances. However, since some of the relevant factors are internal in nature, religiosity remains a complex phenomenon to describe or quantify. As a rule, each major faith throughout the world gives its adherents at least some leeway to decide how they express their religious orientation. The National Comorbidity Survey \u2013 Replication Comorbidity is a term doctors and researchers use to identify two health problems that appear together in the same person and cause more harm in combination than they would typically cause on their own. The original National Comorbidity Survey, conducted in the early 1990s by the National Institute of Mental Health, was the first nationwide attempt to fully investigate the extent of mental illness in the U.S., as well as the first attempt to find out which additional problems most commonly appear in people affected by mental illness. In the early 2000s, the National Institute of Mental Health conducted the NCS-R (which included a representative group of 10,000 participants) as a follow-up to the original project. Drug and alcohol abuse and addiction are addressed in the survey because they often appear as comorbid conditions in the mentally ill. Under guidelines issued in 2013 by the American Psychiatric Association, substance abuse and substance addiction also qualify as mental illnesses under a joint heading called substance use disorder. Effect on Substance Abuse Risks In the study published in Drug and Alcohol Dependence, the Virginia Commonwealth University researchers used information previously gathered from 6,203 participants in the National Comorbidity Survey- Replication to gauge the impact that changes in religiosity can have on a person\u2019s risks for abusing drugs or alcohol or eventually getting addicted to drugs or alcohol. Specifically, they looked at reported changes in religiosity among the survey participants between childhood and adulthood and sought to determine how those changes match up with reported patterns for drug and alcohol use (as well as tobacco use). The researchers also took steps to exclude the potential impact of other factors known to influence substance-related risks, including the presence of major depressive disorder (major depression) and a childhood marked by a disruptive or dysfunctional family environment. After completing their analysis, the researchers concluded that, compared to people with relatively fixed levels of religiosity between childhood and adulthood, people who experience a significant decline in religiosity over the same span of time have a substantially heightened chance of using drugs, alcohol and\/or tobacco during any particular year or any point during their lifetimes. However, they also concluded that the same increased risks for involvement in substance use appear in people who experience a significant increase in religiosity in the transition from childhood to adulthood. Significance and Considerations In line with their findings, the authors of the study published in Drug and Alcohol Dependence concluded that any substantial upward or downward change in religiosity from childhood to adulthood can boost a person\u2019s risks for using legal or illegal substances, as well as his or her chances of abusing those substances. They also concluded that future researchers seeking to comprehend the connection between religiosity, substance involvement and substance-related problems will likely need to take a long view instead of only focusing on childhood or only focusing on adulthood.