Lead exposure during childhood is a significant global public health concern as the potential effects of exposure can result in the need for long-term treatment, diminished productivity in society, and financial strain on the health care system. There is strong evidence of a relationship between lead exposure and attention-deficit/hyperactivity disorder (ADHD); however, there is a gap in the current literature regarding the relationship between lead exposure and specific symptoms of ADHD and the strength of that relationship. The purpose of this meta-analysis was to examine and help quantify this relationship. Cohen's d was used as the standardized mean effect size measure for this study, and allowed for comparison of 2 groups on a specific measure. For the final analysis 20 studies were included that provided a comparison between lead exposure and overall ADHD, inattentive, or hyperactive/impulsive symptoms. The magnitude of the effect size of childhood lead exposure on ADHD symptoms was significant and of medium strength. There was significant variability in the research results for inattentive and hyperactive/impulsive symptoms, and it was hypothesized that this variability may be due to factors related to lead levels and covariates known to affect ADHD symptoms. Study results may contribute to positive social change by providing health care practitioners with a greater understanding of the effect of childhood lead exposure on ADHD symptoms, which they may use to achieve advancements in prevention and treatment. Improved prevention programs for lead exposure and early identification and treatment of related concerns may decrease negative outcomes, as well as the occurrence of ADHD symptoms on a population level, thus improving public health.

Attention-deficit hyperactivity disorder (ADHD) and obesity both present a significant burden to the health of children and adolescents. Research suggests a possible association between ADHD and obesity. This dissertation focused on examining the association between ADHD and obesity, and the roles physical activity, sedentary behavior, gender, and medication might play in this relationship. The first manuscript is a review of the literature examining research on the association between ADHD and obesity in children and adolescents. The search included studies that reported on the prevalence of obesity among those with ADHD, the prevalence of ADHD among those who are obese, clinical studies comparing those with ADHD versus non-ADHD, and the association if any between ADHD, obesity, physical activity, eating behavior, medication, and gender. The search resulted in 657 studies, 233 after duplicates removed and 31 after screening. The studies suggested that there is a significant association between ADHD and obesity. Further, behavioral symptoms of ADHD, such as inattention and impulsivity might contribute to decreased physical activity, increased sedentary time, and dis-regulated eating. In addition, research indicated that medication possibly moderates the relationship between ADHD and body mass index BMI via a biophysical effect on the catecholamingeric system. The second manuscript is an original study testing a model assessing the mediating effects of ADHD on physical activity, sedentary behavior, and BMI. The study sample consisted of 3,788 adolescents ages 11-17 from the 2011-2012 National Survey of Children’s Health. Structural equation modeling was used to test the path associations. The model fit the data well, [RMSEA]=.043; [CFI]=.937; [TLI]= .889, and [SRMR]=.025. The total effect for ADHD was 0.073 and was significant. ADHD severity plays a role in increasing BMI status, working through physical activity and sedentary behavior. The third manuscript is another original study assessing moderating effects of gender and medication on the relationship between ADHD and BMI. The model fit the data well for gender and medication [RMSEA]=0.052; [CFI]=0.850; [TLI]=0.775; [RMSEA]=0.053; [CFI]=0.825; [TLI]=0.715. Although the total effect for ADHD on BMI was significant, medication and gender did not moderate this relationship. Also, medication did not moderate the relationship between physical activity, sedentary behavior and ADHD severity.

The current set of experiments was designed to test the hypothesis that there is a sex difference in impulsivity and in brain areas associated with impulse control in prepubertal and adult rats, such that females have greater inhibitory control than do males. Preliminary studies established that neonatal testosterone exposure is able to masculinize and increase impulsive behavior in prepubertal female rats. In the current study, male and female prepubertal rats exposed to treatments that resulted in either neonatal androgen or estrogen receptor activation made more impulsive choices than did control females and their performance mirrored that of control males. Assessment of impulsivity in adult rats indicated that impulsive choice behavior was similar in males and females whereas impulsive action behavior was greater in males than in females. Analysis of protein levels of markers of dopaminergic and noradrenergic reuptake in the orbital frontal cortex (OFC) and dorsal striatum (dSTR), two brain areas important for impulse control, revealed no differences between male and female prepubertal or adult rats, whereas analysis of protein levels of markers of myelination in the OFC and dSTR revealed similar levels between the sexes in prepubertal rats but increased myelin levels in the OFC but not dSTR of adult female rats as compared to males. Furthermore, analysis of the projections from the OFC to dSTR discovered that the strength of these projections was significantly greater in adult females as compared to males. However, inactivation of the OFC during an impulsive action task in adult rats failed to have an effect on impulsive action responding. Collectively, these results demonstrate for the first time that there is a sex difference in impulsive choice control in prepubertal rats that is organized neonatally by actions of both androgens and estrogens, this sex difference subsides in adulthood, but a sex difference in impulsive action control is present in adulthood. Furthermore, the novel discovery that adult female rats have increased levels of myelination within the OFC and increased strength of projections from the OFC to dSTR as compared to males establishes a molecular sex difference that could underlie the enhanced impulse control in females. / acase@tulane.edu

Preference for smaller-sooner over larger-later rewards characterizes one type of impulsivity—impulsive choice. Impulsive choice is related to a number of maladaptive behaviors including substance abuse, pathological gambling, and poor health behaviors. As such, interventions designed to reduce impulsive choice may have therapeutic benefits. The purpose of this dissertation was to explore two methods to change nonhuman impulsive choice. In doing so, we hope to provide a baseline that future research can use to assess variables that are less amenable to human research (e.g., drug self-administration following reductions in impulsive choice). In Chapter 2, we failed to reduce nonhuman impulsive choice using working-memory training, a finding both inconsistent and consistent with the extant human literature. Chapters 3-5 sought to better understand a training regimen that generates large between-group differences in nonhuman impulsive choice—delay- and immediacy-exposure training. The results from Chapters 3 and 4 suggest that prolonged exposure to delayed food rewards produces large and long-lasting reductions in impulsive choice. Chapter 5 showed that the delay-exposure training effect can be obtained in fewer sessions than has previously been employed. A better understanding of the effects of delay-exposure training on nonhuman impulsive choice may have implications for the design and implementation of a human analog.

Delay discounting is a measure of impulsive decision making that is associated with different forms of problem behavior. This study examined the transdiagnostic effect of Acceptance and Commitment Therapy (ACT) on delay discounting in a community sample. Forty adults were randomized into eight individual sessions of ACT or an inactive control. Participants completed pre-, mid-, and post-assessments for delay discounting, psychological flexibility, distress tolerance, overall psychological symptoms, behavior change, and valued living. Data were analyzed with multilevel modeling of growth curves. Significant interaction effects of time and condition were present for psychological flexibility, distress tolerance, psychological symptoms, and the obstruction subscale of valued living. No significant interaction effect was found for two delay discounting tasks nor the progression subscale of valued living. The ACT condition had a significantly larger reduction of problem behavior at post-, but not mid-assessment. Treatment was provided in a competent and ACT-consistent manner and was rated as highly satisfactory by treatment completers. The results support use of ACT as a transdiagnostic treatment. The lack of changes in delay discounting are in contrast to previous research. The clinical implications of delay discounting need to be explored further.

Adolescence is a time of high risk behavior and increased exploration. This developmental period is marked by a greater probability to initiate drug use and is associated with an increased risk to develop addiction and dependency in adulthood. Human adolescents are predisposed toward an increased likelihood of risk taking behaviors (Zuckerman M, 1986), including drug use or initiation. The purpose of this study was to examine differences in developmental risk taking behaviors and neurochemical responsivity to cocaine based on these behavioral characteristics. Adolescent and adult animals were exposed to a novel stimulus in a familiar environment to assess impulsivity, novelty preference and exploratory behaviors, subsequently, in vivo microdialysis was performed to assess dopaminergic responsivity to cocaine. Adolescent animals had greater novelty-induced locomotor activity, greater novelty preference, were more impulsive and showed higher exploratory behaviors compared to adult animals. Furthermore, the results demonstrate neurochemical differences between adolescent and adult animals in novel environment exploratory behavior, novel object preference, novelty-induced impulsivity and novelty-induced exploration. These data support the notion that adolescents may be predisposed toward sensation seeking and consequently are more likely to engage in risk taking behaviors, such as drug use initiation.

Previous literature has shown that risk factors for delinquency include individual characteristics of impulsivity and risk-taking as well as contextual influences such as neighborhoods, parenting and engagement in physical activity (e.g., exercise, sports). Theory suggests that individual characteristics interact with contextual factors to influence child development, however evidence is limited. The current study examined the interaction between these individual and contextual risks to influence childhood delinquency in a community sample of 89 children ranging from 9 to 12 years of age (M = 10.4, SD = 1.1). Questionnaire measures showed that both caregiver report of impulsivity and self-reported risk-taking were positively associated with self-reported delinquency, yet no interactions with contextual factors were found. When using computer tasks, neither impulsivity nor risk-taking were significantly associated with delinquency. However, a risk-taking by physical activity interaction was found, such that at low levels of physical activity risk-taking was positively related to delinquency, yet at high levels of physical activity, risk-taking and delinquency were unrelated. Thus, programs that involve physical activity may be useful prevention and intervention strategies for risk-taking children.

La dificultad de una concepción de la creatividad basada únicamente en rasgos de personalidad o cognitivos nos ha llevado a plantear un estudio donde apuntamos a la capacidad explicativa de determinadas variables, situadas entre el rasgo y el proceso, y vinculadas fundamentalmente a las bases biológicas de la personalidad y de la atención, como son la impulsividad y la activabilidad, como variables posiblemente prometedoras en este ámbito. Nuestros resultados matizan y amplían el modelo eysenckiano y sirven a su vez para la propuesta de un nuevo modelo de creatividad que trata de integrar las aportaciones de los mencionados sistemas de procesamiento dentro de un orden que aúna tanto los síntomas "positivos" como "negativos" (psicopatológicos) de la creatividad y la forma en que pudieran dar origen y desarrollo a los procesos creativos. / The difficulty with a concept of creativity is based solely on cognitive or personality traits has led us to pose a study where we target the explanatory power of certain variables, lying between the trait and the process, and primarily related to biological basis of personality and attention, as are the impulsivity and activity, as variables possibly promising in this area. Our results extend Eysenck's model and serve to the proposal for a new model of creativity that comes from integrating input from the aforementioned processing systems within an order that combines both the symptoms "positive" as "negative" (mental) of creativity and how they could lead to the development of creative processes.

Due to the saturation of the market and the economic downturn in 2008, the expansion rate of shops of convenience store chains in Taiwan has shrunk rapidly. In coping with this harsh external environment, all of the proprietors strive to implement varieties of promotion activities to boost their revenue. One of the most popular schemes is the "Whole Store Integrated Promotion Strategy" initiated by 7-Eleven in 2007. That is, by means of point collecting, customers can exchange for exclusive gifts or get a discount on certain products. The market response toward this activity is so strong that makes other competitors to follow suit immediately. Hence, this promotion skill has become the panacea for lifting sales. Thus, this study uses customers of convenience stores as the subject to analyze the impacts on impulsive buying behavior on different promotion activities and to understand the degree of customers¡¦ satisfaction after they finish their shopping. Meanwhile, the impulsivity traits and the social demographic variables of customers are included in this survey as well in order to find out their relationship with the impulsive buying behavior. The result reveals that the traditional price-discount promotion activity is favored and easier to induce impulsive buying behavior than the novel point collecting one. Besides, this study also finds out that the higher impulsivity trait the customer possesses the more possibility for them to conduct impulsive buying. As for customers' satisfaction, it shows that the higher degree of impulsive buying, the more satisfy the customer is.

The aims of the current study are to examine the relation of risk taking behaviors (RTBs) with perceived risk, perceived benefit, and impulsivity and also to investigate the moderator role of impulsivity on the relationships between engagement in RTBs and the predictors of the engagement in RTBs (i.e. perceived risk and benefit) after controlling the effects of age, gender, and self esteem. In order to measure engagement in RTBs, perceived risk, and perceived benefit, Modified Risk Involvement and Perception Scale (&Ouml / zmen, 2006) was adapted to Turkish culture in Study 1 by using Middle East Technical University (METU) students. The sample of Study 2 was composed of 234 METU students and a questionnaire set including demographic information sheet, Modified Risk Involvement and Perception Scale (M-RIPS) (&Ouml / zmen, 2006), Barratt Impulsiveness Scale version 11 (BIS-11) (G&uuml / le&ccedil / et al., 2008), and Rosenberg Self Esteem Scale (RSES) (Rosenberg, 1965) was administered. Multiple hierarchical regression analysis was conducted with perceived risk, perceived benefit, and impulsivity as independent variables and engagement in RTBs as the dependent variable. The findings suggested that perceived risk was negatively whereas perceived benefit and impulsivity was positively related to risk taking behaviors. Moreover, as compared to perceived risk, perceived benefit was a more powerful predictor of RTB. However, it was not found any moderator role of impulsivity on the relationships between engagement in RTBs and its predictors. The strengths and limitations, as well as implications of the findings were discussed.