Results from our study are limited in generalizability, though complement work by others on examining the impact of tobacco free policies on US college campuses. This includes a recent study from 2020 of small colleges in Massachusetts that found that a college with a smoke-free policy had significantly more antismoking attitude than a control campus, but did not have lower rates of smoking itself . Relatedly, a separate earlier study from 2005 that analyzed undergraduates in Texas found that campuses with preventive education programs had lower odds of smoking, whereas designated smoking areas and cessations programs were associated with higher odds of smoking . Collectively, these prior studies and our own work helps to better characterize knowledge, attitudes and behaviors of college campus communities toward smoking, as well as the smoke-free policies attempting to discourage smoking, which in turn should aid in the development of more targeted approaches to educate college-aged populations about the health harms of tobacco and also enable better implementation of anti-tobacco policies in these critical populations.This study was exploratory in nature and collected social media messages for which latitude and longitude coordinates could be collected from the Twitter API, but this data collection methodology is limited to collecting messages from Twitter users that enabled geolocation, a specific limitation to generating a more generalizable dataset on Twitter as it is estimated that only 1% of all tweets are geocoded . Hence, cannabis drying room the dataset used in this study after filtering for keywords was small and likely biased, limiting the generalizability of results.
This method of data collection may have introduced bias in the types of tweets collected, thereby limiting the generalizability of findings as the majority of Twitter users do not geolocate their posts. Potential sampling biases for Twitter include oversampling for certain geographic areas , filtering for specific features , and the limitations of the Twitter public streaming API in lieu of other data collection approaches . Future studies should examine the use of multiple Twitter APIs to generate a more representative Twitter dataset and compliment findings with other traditional sources of data to generate findings that are more robust and generalizable, as well as use complementary Twitter and social media datasets made publicly available by other researchers. Specific to identification of Twitter users and conversations associated with colleges and universities, using keyword searches, and selecting accounts affiliated with higher education should be explored in future studies. Also, inclusion criteria required tweets to be posted from college campuses, which would not have accounted for variability in smoking related tweets from off-campus housing or areas/neighborhoods at the borders of campus properties where college students may reside. Furthermore, though the study design permitted searches of the Twitter API to return different volume of tweets for different keywords, there was a smaller number of original keywords for substances containing marijuana/cannabis than those for e-cigarettes or products containing tobacco due to our purposeful filtering for tobacco and alternative tobacco product keywords .
Additionally, the majority of tweets analyzed for this study were from 2015, a period prior to major public scrutiny about default privacy settings for location sharing on Twitter . Finally, this study is an ecological study and should therefore be considered hypothesis generating and not generalizable to individuals on college campuses until further studies among individuals confirm these correlational findings.The study of personality has a long and rich history, and has been studied in across the lifespan, from temperament in early infants to coping ability at the end of life . How personality during adolescence, a period of dramatic physical, emotional and psychosocial development , relates to behaviors in later life, is of particular interest. While there are likely numerous moderating and mediating factors, individual differences in adolescent personality have been shown to be important predictors of adult life outcomes, including social competence, academic and professional achievement, and physical and mental health and longevity . From a clinical perspective, understanding individual differences in personality development is important for informing mental health treatment efforts and preventing substance misuse in adolescents , as personality may be modifiable by clinical intervention . Although debated , the five-factor model is one of the most widely accepted and utilized hierarchical structures for measuring personality, as it strikes a balance between specificity and generalizability that is more difficult to achieve using lower-order constructs .
The five-factor model consists of extraversion, emotional stability , conscientiousness, agreeableness, and openness. While this factor structure has been well-described in adults, the stability of, or change in, these personality constructs during childhood and adolescence is still debated . First, a meta-analysis of early longitudinal research found all Big Five personality factors increased substantially during adolescence and young adulthood . This pattern, referred to as the “maturity principle,” suggests that an increase in these personality traits across adolescence and early adulthood reflects adaptations to newly evolving social roles . More recently, several large-scale studies show declines in at least one, and up to all Big Five personality factors early in adolescence, with subsequent increases in late adolescence and early adulthood . This pattern has been referred to as the “disruption hypothesis,” and suggests that adolescence is a key period for personality development . However, there are inconsistencies between these reports in regards to which of the Big Five personality factors support the disruption hypothesis. For example, Borghuis, Denissen et al. found emotional stability and extraversion declined in early adolescence , before increasing, while agreeableness increased throughout . Conversely, Van den Akker, Deković et al. found continued declines in emotional stability and extraversion into young adulthood , but found agreeableness decreased , before increasing.How personality development varies between male and female youth also remains unclear. While the degree and practical significance of sex differences in personality are still debated, they continue to be supported by large multi-national studies . Given significant sex differences in the timing of neurobiological development during adolescence, it could be expected that sex differences in personality may also emerge during this developmental period , and understanding these effects may provide insight into the emergence of psychiatric disorders in youth . Past findings in adolescents and young adults largely suggest that female youth report greater extraversion, openness, agreeableness, and conscientiousness, and less emotional stability, compared to male youth . However, the timing of these sex-specific effects is less clear. For example, Soto, John et al. found the biggest differences in emotional stability between male and female youth emerged between the ages of 10 to 15, and then persisted well into adulthood; however, Göllner, Roberts et al. reported no sex-differences in emotional stability in early adolescence . Similarly, while several studies support the notion that sex differences in extraversion emerge during adolescence and persist in young adulthood , others found no sex differences in extraversion in mid-to-late adolescence . While these are not the only studies to investigate personality development, or sex differences therein, they highlight two major inconsistencies in past studies: 1) it is unclear which if any personality traits support the “disruption hypothesis”, and 2) there are discrepancies regarding the timing, or developmental course, of sex differences in personality. One important factor that could contribute to this effect is researchers’ choice of analytic modeling strategy. For example, vertical grow rack system two previous studies used polynomial growth parameters and reported that extraversion either decreased linearly from 9 to 20 years of age , or showed quadratic growth, with early decreases and subsequent increases from ages 12 to 22 . However, another study found that changes in personality with age could not be adequately fit with traditional growth parameters ; when reporting mean level changes, they found extraversion decreased between ages 10 to 15 before largely leveling off into young adulthood .
In the current study, we seek to address past discrepancies in the sex specific development of personality by using data-driven non-linear modeling strategies, and comparing them to more traditional growth models, to test our hypothesis that analytic strategy plays a role in the conclusions draw from developmental studies. Another area of research the current dataset is well-suited to investigate is the association between personality and substance use. Alcohol and marijuana are the most commonly used substances by youth and are associated with a myriad of cognitive and neural alterations . A recent review and meta-analytic work suggests that alcohol use is associated with low conscientiousness, agreeableness,and emotional stability, and high extraversion , with longitudinal work confirming that increases in conscientiousness and emotional stability with age are associated with decreases in problematic alcohol use . Similarly, in adolescents, higher extraversion and lower conscientiousness, openness and agreeableness are associated with alcohol use , and high adolescent extraversion, in particular, may be a common predictor of future alcohol use . Marijuana use is also associated with lower emotional stability, agreeableness and conscientiousness in adolescents and young adults . However, when combining alcohol with other illicit substance use , greater openness has been shown to be associated with heavy substance use in young adulthood . Meanwhile, when simultaneously examined in a sample of young adults concurrently using alcohol and marijuana, marijuana use was associated with greater openness, but alcohol use with lower openness . Similarly, extraversion has been shown to be differentially related to substance use, with higher extraversion associated with more alcohol use but less marijuana use . Taken together, these findings highlight the importance of simultaneous modeling of both alcohol and marijuana use in the same sample. Work looking at sex differences in the association between substance use and personality in adolescents and young adults is limited. Cross-sectional studies have found that the association between reduced emotional stability and marijuana use was greater in female adolescents than male adolescents , and that the negative association between alcohol use and emotional stability and conscientiousness in young adults is more predominant in women . However, robust longitudinal studies that allow for the assessment of substance use alongside potential non-linear developmental changes in personality are needed. Using seven waves of longitudinal data from the National Consortium on Alcohol and Neurodevelopment in Adolescence dataset, the current study sought to examine personality changes across adolescence and young adulthood. In addition to replicating previous literature on personality development in a robust, longitudinal, multi-site national cohort, the study had the following five goals: First, we aimed to use generalized additive mixed effect models to empirically assess non-linear change in personality across age and compare these effects to more traditional linear mixed effects models with polynomial growth trajectories . We hypothesized added model flexibility would yield findings that better coalesce past literature, and choice of modeling strategy would partially explain past discrepant reporting.Second, we examined sex differences in personality development. In addition to replicating previous reports of greater extraversion, openness, agreeableness, and conscientiousness, and less emotional stability, in female youth , we expected our non-linear modeling strategy would again help provide clarity in regards to the timing of sex differences in personality development. Third, we examined the association between substance use and personality. While previous studies generally suggest greater alcohol and marijuana use is associated with lower agreeableness, conscientiousness and emotional stability , associations with extraversion and openness may vary based on substance . Therefore, we simultaneously modeled both alcohol and marijuana use, and hypothesized they would be differentially related to reported extraversion and openness. Fourth, we examined the sex-specific association between substance use and personality. Based on limited past literature, we hypothesized that the association between substance use and lower emotional stability and conscientiousness would be more prominent in female youth . Finally, while previous reports highlight the importance of comprehensively assessing personality , this is not always feasible in large multi-site studies, such as NCANDA. Thus, here, we demonstrate the ability of an abbreviated measure, the Ten-Item Personality Inventory , to obtain robust results largely consistent with prior literature.Data were analyzed from participants of the NCANDA study. Youth between 12 and 21 years of age were recruited at five sites across the United States: Duke University, Oregon Health & Science University , University of Pittsburgh, SRI International, and University of California San Diego . Adults provided informed consent, while adolescents and their parents provided informed assent and consent, respectively, and all study procedures were approved by the respective institutional review board for each site.