Browsing by Subject "alcohol"
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Item Mechanisms of alcohol-induced neuroteratology: an examination of the roles of fetal cerebral blood flow and hypoxia(Texas A&M University, 2005-02-17) Parnell, Scott EdwardHypoxia (decreased tissue oxygen levels) has long been considered as a possible mechanism of alcohol-induced developmental deficits, yet research has not conclusively disproved this hypothesis, nor has it provided substantial evidence for a mechanism of developmental alcohol insults involving hypoxia. Previous research has shown that moderate acute doses of alcohol does not induce hypoxemia (decreased arterial oxygen levels), yet these same studies have shown that this same alcohol exposure does transiently decrease cerebral blood flow (CBF). This is significant because although developmental alcohol exposure did not result in hypoxemia, the decreases in CBF seen in these previous studies may induce hypoxia within the brain. Unfortunately, these experiments were only performed after acute doses of alcohol, so it is unknown if a more chronic or repeated alcohol exposure paradigm would have similar effects. The present study examined blood flow in the sheep fetus after repeated alcohol exposure in a bingelike paradigm throughout the third trimester. Additionally, this study examined the fetal neurovascular response to a subsequent infusion of alcohol after the repeated alcohol exposure. This latter experiment was designed to examine the hypothesis that alcohol exposure throughout the third trimester affects the normal responsiveness of the neurovasculature to alcohol (compared to previous research demonstrating acute alcohol-induced decreases in CBF). The results from the present experiments indicate that although few regions were significant, the majority of the regions (especially the brain regions) exhibited a trend for increases in blood flows after alcohol exposure. This phenomenon was especially prominent in the group receiving the lower dose of alcohol. Additionally, the data from this study demonstrated that after repeated alcohol exposures the near-term sheep fetus did not respond to a subsequent dose of alcohol in a similar manner seen in previous experiments when the acute alcohol exposure was administered in alcohol na?ve animals. After the final alcohol exposure the subjects in this study had either no effect in terms of blood flow or an increase in CBF. This is opposite to previous observations which demonstrated reduced blood flow in numerous brain regions. The present experiments suggest that alcohol does not induce fetal hypoxia, but does negatively affect the normal neurovascular response to alcohol. This latter phenomenon could have negative consequences on future development of the brain.Item Types and Gender Composition of Social Networks: Their Influence on Adolescent Substance Use(2015-01-22) Jacobs, Wuraola OThis dissertation presents three separate studies designed to examine how the different factors and determinants known to influence adolescent alcohol and tobacco use and the gender compositions of different adolescent network types are associated with alcohol and tobacco use among adolescents. Additionally, the similarities and/or differences in networks of adolescent substance users and non-users are also examined. First, a systematic review of empirical studies (n=48) employing social network analysis to examine adolescents? alcohol, tobacco, and other drugs (ATOD) use behavior will be presented discussing: (a) how this body of literature examined gender differences in ATOD use, (b) whether these network studies examine the gender composition of these adolescents? networks, and (c) what network affiliation types are used to characterize adolescent networks. Secondly, descriptive characteristics and network analysis of the social networks of 10th grade substance using and non-using adolescents will be presented. Employing a bounded whole network approach, data was collected from 1,707 10th graders in a school district in Los Angeles, California. The students were asked different network questions in order to generate different network types. The network types elicited from these network questions are: Friendship, Admiration, Succeed, Popularity, and Romantic networks. Attributes and network characteristics of users and non-users across these five different networks are presented and the commonalities and/or differences are described also. Lastly, using data from the same students, a quantitative analysis of the associations between interpersonal (e.g. age, gender) and interpersonal (e.g. parent and sibling substance use) factors, network measures, and gender composition of the networks and their alcohol and tobacco use will be discussed. These associations are then further examined across the five different types of networks mentioned above. Prior to this study, research studies employing social network analysis did not attempt to examine the gender composition of the networks in which adolescents are embedded; and only a few other studies used networks other than friendship networks to characterize adolescent social networks. Thus, this study represents the first step towards addressing these limitations associated with examining how adolescents? social networks facilitate or constrain their substance use behavior and filling these apparent conceptual gaps.Item Unintended consequences of negative messages: why some health interventions miss the mark(Texas A&M University, 2007-09-17) Burpo, Jill ElizabethThe debate about how to frame health messages to maximize their effectiveness is ongoing. Research supports the use of both positive and negative frames under different conditions. This project was developed to further clarify the circumstances under which a negative frame may be harmful, or even backfire. In Study 1 it was proposed that past drinking behavior would moderate the relationship between message frame and behavioral intention to drink alcohol in the future such that people with a heavy drinking past would react to a negatively framed message by increasing their intention to consume alcohol. A total of 212 students participated in the study where they completed a questionnaire to provide information on some of the key variables, such as drinking history, and then were asked to read mock health materials with either a positive or negative frame. They concluded the study by responding to a final questionnaire where they provided feedback on the health materials and indicated their intentions to drink in the future. Results of this study supported the hypothesis. The goals of Study 2 were to replicate the findings of Study 1 and to test the hypothesis that self-esteem would be a second-order moderator of this effect such that people with a heavy drinking past and high self-esteem would be most likely to respond to a negatively framed message by increasing their intention to drink alcohol in the future. A total of 490 students participated in the study, which followed the same procedure as the first study. Results of Study 2 failed to replicate the findings from Study 1, and indicated that self-esteem did influence the relationship between past behavior, message frame and behavioral intention but not in the proposed direction. The marginally-significant effect found in Study 2 suggested that heavy drinkers with high self-esteem were actually more likely to decrease their intentions to drink alcohol after reading a negatively framed message. Because of the inconsistency in the results of the two studies presented, proposed directions for future research are discussed.