The empirical literature to date has indicated that narcissism is associated with reactive aggression; however, exactly why narcissists respond with aggression to provocation is yet to be determined. The present paper is an exploration of two possible means through which a lack of self-control could be an important predictor involved in narcissists‟ aggressive behavior: 1) a lack of self-control could explain the link between narcissism and aggression, and 2) the combination of insufficient self-control and narcissism could increase the likelihood of aggressive response to provocation. To explore these possibilities, an experiment was conducted in which 214 participants were first administered measures of narcissism and self-control. Then, random assignment determined whether the participant would be provoked through negative feedback on his/her performance. Participants were provided opportunities to aggress on two measures: 1) an evaluation of another‟s performance, 2) open-ended responses to a situational vignette. There were two major areas of focus in the results of the study. First, the effect of provocation was examined. As expected, provoked participants provided more aggressive responses on the evaluation of their peer than nonprovoked participants; however, provocation did not affect aggression on the situational vignette. Narcissism was associated with aggression on the situational vignette and not on the evaluation. These findings point to the strength of the situation in the prediction of behavior as it was only when provocation did not produce an effect that personality had a significant influence on aggression.  Second, the relationships among narcissism, self-control and aggression were examined. Narcissism was associated with low self-control as expected. Stepwise linear regression revealed a significant interaction between narcissism and self-control in the prediction of physical aggression in response to the situational vignette. The moderation effect of self-control and narcissism on physical aggression indicates that the combination of high narcissism and low self-control is important in predicting physical aggression. Additional post-hoc exploratory analyses suggest some overlap in the measures. Thus, suggestions for future research and methods of reducing the overlap in construct during measurement are provided.

When making decisions, individuals evaluate several possible outcomes of their choice; however, some display heightened reward sensitivity, despite the potential for future negative consequences, which can lead one to make risky choices. Rewards are processed in the mesolimbic dopamine reward system, and this system is in part modulated by genetic polymorphisms that are associated with dopamine transmission. The current study tested if genetic polymorphisms that are associated with enhanced dopamine neurotransmission will be more neurally reward sensitive, score higher on self-reported impulsivity, and make riskier choices. In a sample of 85 participants, five genetic polymorphisms were genotyped and used to create a genetic risk score that represented dopamine transmission efficiency. Two groups (high and low efficiency) were created via median split and then compared on neural reward sensitivity (assessed by event-related potentials, specifically, the medial-frontal negativity [MFN] and the error-related negativity), impulsivity (assessed via self-report), and risky choice (measured using the Balloon Analogue Risk Task and self-report measures). Results indicated that individuals with higher levels of dopamine displayed a less negative MFN and more drinking behaviors than those with lower levels of dopamine. These results suggest that individuals with higher levels of dopamine are less sensitive to punishments, which could lead them to make riskier choices.

Impulse control, an executive process that restrains inappropriate actions, is impaired in numerous psychiatric conditions. This thesis reports three experiments that utilized a novel animal model of impulse control, the response inhibition (RI) task, to examine the substrates that underlie learning this task. In the first experiment, rats were trained to withhold responding on the RI task, and then euthanized for electrophysiological testing. Training in the RI task increased the AMPA/NMDA ratio at the synapses of pyramidal neurons in the prelimbic, but not infralimbic, region of the medial prefrontal cortex. This enhancement paralleled performance as subjects underwent acquisition and extinction of the inhibitory response. AMPA/NMDA was elevated only in neurons that project to the ventral striatum. Thus, this experiment identified a synaptic correlate of impulse control. In the second experiment, a separate group of rats were trained in the RI task prior to electrophysiological testing. Training in the RI task produced a decrease in membrane excitability in prelimbic, but not infralimbic, neurons as measured by maximal spiking evoked in response to increasing current injection. Importantly, this decrease was strongly correlated with successful inhibition in the task. Fortuitously, subjects trained in an operant control condition showed elevated infralimbic, but not prelimbic, excitability, which was produced by learning an anticipatory signal that predicted imminent reward availability. These experiments revealed two cellular correlates of performance, corresponding to learning two different associations under distinct task conditions. In the final experiment, rats were trained on the RI task under three conditions: Short (4-s), long (60-s), or unpredictable (1-s to 60-s) premature phases. These conditions produced distinct errors on the RI task. Interestingly, amphetamine increased premature responding in the short and long conditions, but decreased premature responding in the unpredictable condition. This dissociation may arise from interactions between amphetamine and underlying cognitive processes, such as attention, timing, and conditioned avoidance. In summary, this thesis showed that learning to inhibit a response produces distinct synaptic, cellular, and pharmacological changes. It is hoped that these advances will provide a starting point for future therapeutic interventions of disorders of impulse control. / Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2011-07-11 09:44:54.815

Mammalian brain and behaviour are plastic, particularly early in development when offspring are under the care of their mothers. Adverse early life events, such as maternal and social deprivation, have short- and long-term consequences for neurobiology and consequently for behaviour. The purpose of this thesis was to investigate the effects of maternal and social deprivation, through artificial rearing (AR), on adult impulsive behaviour. Rats were raised in isolation from mothers and siblings (AR) or with their mothers and siblings in the nest [maternal rearing (MR)]. In addition, half of the AR rats were provided with replacement somatosensory stimulation designed to simulate mothers’ licking (see Gonzalez et al., 2001). As adults, rats were tested on impulsive action using the differential reinforcement of low rates (DRL) operant task and locomotor activity. Both male and female AR rats were more impulsive than MR rats; they made more responses and they were less efficient at earning rewards. In addition, they displayed greater levels of locomotor activity. These effects were partially reversed by replacement somatosensory stimulation. Furthermore, impulsivity was positively correlated with locomotor activity. Impulsive choice was then assessed using a delay discounting operant schedule. On this task, AR rats were less likely to discount the value of large-delayed reward, suggesting that they were better able to tolerate delays to large reward and were less impulsive. However, performance on a modified version of delay discounting revealed that AR rats were less efficient at switching their responses; that is, they displayed reduced behavioural flexibility. To address this finding, impulsive choice was next assessed in fixed consecutive chain operant schedule of reinforcement, but there were no differences between AR and MR animals. Finally, the relationship between impulsive action and a species-characteristic behaviour, maternal behaviour, was investigated. Consistent with the literature, AR rats were less maternal and more impulsive. Moreover, there was a negative correlation between impulsivity and maternal behaviour. Overall, this set of studies demonstrates that maternal and social deprivation produces an increase in impulsive action without an effect on impulsive choice. Furthermore, increased action impulsiveness is a significant moderator of disrupted maternal behaviour observed in artificially reared rats.

Mammalian brain and behaviour are plastic, particularly early in development when offspring are under the care of their mothers. Adverse early life events, such as maternal and social deprivation, have short- and long-term consequences for neurobiology and consequently for behaviour. The purpose of this thesis was to investigate the effects of maternal and social deprivation, through artificial rearing (AR), on adult impulsive behaviour. Rats were raised in isolation from mothers and siblings (AR) or with their mothers and siblings in the nest [maternal rearing (MR)]. In addition, half of the AR rats were provided with replacement somatosensory stimulation designed to simulate mothers’ licking (see Gonzalez et al., 2001). As adults, rats were tested on impulsive action using the differential reinforcement of low rates (DRL) operant task and locomotor activity. Both male and female AR rats were more impulsive than MR rats; they made more responses and they were less efficient at earning rewards. In addition, they displayed greater levels of locomotor activity. These effects were partially reversed by replacement somatosensory stimulation. Furthermore, impulsivity was positively correlated with locomotor activity. Impulsive choice was then assessed using a delay discounting operant schedule. On this task, AR rats were less likely to discount the value of large-delayed reward, suggesting that they were better able to tolerate delays to large reward and were less impulsive. However, performance on a modified version of delay discounting revealed that AR rats were less efficient at switching their responses; that is, they displayed reduced behavioural flexibility. To address this finding, impulsive choice was next assessed in fixed consecutive chain operant schedule of reinforcement, but there were no differences between AR and MR animals. Finally, the relationship between impulsive action and a species-characteristic behaviour, maternal behaviour, was investigated. Consistent with the literature, AR rats were less maternal and more impulsive. Moreover, there was a negative correlation between impulsivity and maternal behaviour. Overall, this set of studies demonstrates that maternal and social deprivation produces an increase in impulsive action without an effect on impulsive choice. Furthermore, increased action impulsiveness is a significant moderator of disrupted maternal behaviour observed in artificially reared rats.

Executive functions (EFs) involve multiple cognitive systems and are involved in attentional control, strategic planning, abstract reasoning, cognitive flexibility and hypothesis generation. In this sense, from the point of view anatomicoclinical be correlated to the prefrontal cortex, a region that is also responsible for performing the control actions of our emotional nature, such as aggressive and / or impulsive behaviors. This study aims to correlate executive functioning and aggressive and impulsive behaviors in individuals with depression, according to an updated neurocognitive model performing an interpretation of the traditional conception of Beck on suicidal behavior, and involvement in aggression and dysfunctions executive in this process. The sample consisted of 57 subjects, aged 18 to 49 years, divided between the control compound (29 subjects) and the clinical group (28 subjects). After approval by the Ethics Committee, the proband underwent a flexible battery of tests, which are: Nonverbal Intelligence Test (Beta-III), Beck Depression Scale, Scale for Suicidal Ideation Beck, analysis of working memory (Digit Span), analysis of inhibitory control (Stroop color test), analysis of aggressive behavior (aggression scale of Buss Perry), assessing the level of impulsivity (Barratt Scale, version 11) and decision making (Test betting Iowa). With the results it was observed that there were positive correlations in the comparison of means between verbal aggression (p 0.02) in individuals with depression and control. And the hostile aggression there was also a significant difference (p 0.00), and the same occurred in the correlation between executive functions, working memory and sustained attention in the application of spam digit direct order (p 0.03) and in the reverse order (p 0.02); and finally the comparison between the groups was a positive correlation in suicidal ideation (p 0.00). When assessed only the clinical group was observed: significance in the correlation between depression and suicidal ideation (p 0.51), between depression and FEs with respect to the number of errors in selective attention (r 0.53) between suicidal ideation and FEs with respect to the number of errors in selective attention (r 0.66) and there was significant difference between verbal aggression and attentional impulsivity (r -0.48). Given the above, it can be concluded that significant data on the comparison between the groups with regard to aggressiveness, executive functions in relation to working memory, sustained attention and increased risk of suicide in individuals with depression. Future studies may help to broaden the understanding of this complex relationship between executive neuropsychological functioning, aggression and impulsivity in individuals with depression. / As funções executivas (FEs) envolvem múltiplos sistemas cognitivos e estão envolvidas no controle da atenção, no planejamento estratégico, no raciocínio abstrato, na flexibilidade cognitiva e na geração de hipóteses. Neste sentido, do ponto de vista anatomoclínico estariam correlacionadas ao córtex pré-frontal, região que também é responsável por realizar o controle de nossas ações de cunho emocional, como os comportamentos agressivos e/ou impulsivos. O referido estudo teve como objetivo correlacionar o funcionamento executivo e os comportamentos agressivos e impulsivos em indivíduos portadores de depressão, segundo um modelo neurocognitivo mais atualizado realizando uma interpretação da tradicional da concepção de Beck sobre o comportamento suicida, e do envolvimento da agressividade e das disfunções executivas neste processo. A amostra contou com 57 sujeitos, com idades entre 18 e 49 anos, divididos entre o grupo controle composto (29 sujeitos) e o grupo clínico (28 sujeitos). Após aprovação do Comitê de Ética, os probandos foram submetidos a uma bateria flexível de testes, quais sejam: Teste de inteligência não-verbal (Beta-III), Escala de Depressão de Beck, Escala de Ideação Suicida de Beck, análise da memória operacional (Digit Span), análise do controle inibitório (Teste de cores de Stroop), análise do comportamento agressivo (Escala de agressividade de Buss Perry), avaliação do nível de impulsividade (Escala de Barratt, versão 11) e tomada de decisão (Teste de Apostas de Iowa). Diante dos resultados foi observado que houve correlações positivas na comparação das médias entre agressividade verbal (p 0,02) em indivíduos com depressão e o controle. Quanto a agressividade hostil também houve uma diferença significativa (p 0,00), e o mesmo ocorreu na correlação entre as funções executivas, memória operacional e atenção sustentada, na aplicação do digit spam ordem direta (p 0,03) e na ordem inversa (p 0,02); e por fim na comparação entre os grupos houve uma correlação positiva na ideação suicida (p 0,00). Quando foi avaliado apenas o grupo clínico foi observado: significância na correlação entre Depressão e ideação suicida (p 0,51), entre depressão e FEs no que se refere ao número de erros na atenção seletiva (r 0,53), entre ideação suicida e FEs com relação ao número de erros na atenção seletiva (r = 0,66), assim como houve significância entre agressividade verbal e a impulsividade atencional (r -0,48). Diante do exposto, pode-se concluir que houve dados significativos na comparação entre os grupos com relação a agressividade, funções executivas no que se refere a memória operacional, atenção sustentada e um risco maior de suicídio em indivíduos portadores de Depressão. Estudos futuros poderão contribuir para ampliar a compreensão deste complexo relacionamento entre funcionamento neuropsicológico executivo, agressividade e impulsividade em indivíduos com depressão.

The present study used a delay discounting procedure to characterize choice behaviors in behavioral impulsivity regarding hypothetical monetary outcomes in relation to political, religious and sexual attitudes. Participants were presented with three separate metrics to measure their political, religious and sexual attitudes and then with delay discounting choices, regarding hypothetical monetary outcomes. In the delay discounting measure, participants were presented with a hypothetical scenario, a preference for a certain monetary amount now, or $1,000 at a later specified time. The survey was administered with 26 participants; however, four of the participants’ data were removed due to errors. Results indicated there was no significant relationship between AUC values and political attitudes - r (22) = .14, r2 = .02, p > .05, p = .26. Results indicated there was no significant relationship between AUC values and religious attitudes - r (22) = .27, r2 = .07, p > .05, p = .11. A significant relationship was found between AUC and sexual attitudes - r (22) = -.39, r2 = .15, p < .05, p = .048. Furthermore, the results indicated there was a significant relationship between AUC values and the communion subscale of sexual attitudes – r (22) = -.48, r2 = .23, p < .05, p = .01. The current investigation has implications for further understanding of choice and decision-making behavior and how to predict and influence the respective choices and decisions to improve the quality of life of all individuals.

Introdução: Estima-se que os comportamentos de risco no trânsito, como erros e violações, sejam responsáveis por aproximadamente 90% dos acidentes automobilísticos. Dentre as principais variáveis preditoras de comportamento de risco no trânsito estão os traços de personalidade do condutor. A associação positiva entre impulsividade, busca de sensações e comportamentos de risco no trânsito já é bem documentada na literatura. No entanto, estudos que explorem essas associações entre condutores infratores versus não infratores são escassos, principalmente no Brasil. Objetivo: Explorar as associações entre impulsividade, busca de sensações e comportamentos de risco no trânsito em uma amostra de condutores infratores versus não infratores da cidade de Porto Alegre. Método: A amostra foi composta por 158 condutores infratores que tiveram o direito de dirigir suspenso nos últimos 12 meses por acúmulo de pontos (68,4%) ou tipo de infração específica (31,6%), selecionados no Departamento Estadual de Trânsito do Rio Grande do Sul (79,7% homens) e 181 não infratores (76,2% homens) captados em três Centros de Formação de Condutores e em dois parques públicos locais. As medidas utilizadas foram: a Escala de Impulsividade de Barrat (BIS-11), o Inventário de Busca de Sensações de Arnett (AISS) e um questionário padronizado para coleta de informações demográficas e de comportamentos de risco no trânsito. As variáveis foram analisadas através de regressão logística de acordo com um modelo hierarquizado. O nível de significância adotado foi 5%. Resultados: Maior impulsividade (OR = 4,8, IC 95%: 2,68-8,6), anos de estudo (OR=0,91, IC 95%: 0,85-0,97); dirigir com maior frequência (OR = 4,01, IC 95%: 2,05-7,83), assumir infrações de outro condutor (OR = 2,91, IC 95%: 1,63-5,19), solicitar que outro condutor assumisse suas infrações (OR = 6,74, IC 95%: 2,39-19,25), envolvimento em acidentes de trânsito com vítima (OR = 2,73, IC 95%: 1,24-6,01) e consumir bebida alcoólica nos últimos 12 meses (beber não binge = OR 0,77, IC 95%: 0,38-1,55; binge drinking = OR 1,97, IC 95%: 0,87-4,47) foram significativa e independentemente associados à suspensão do direito de dirigir. Não foi constatada associação entre busca de sensações e ter o direito de dirigir suspenso. Conclusão: Os achados sugerem que a impulsividade, alguns comportamentos associados a risco – tais como envolvimento em acidentes graves, beber bebida alcoólica nos últimos 12 meses, assumir infrações de outro condutor, solicitar que outro condutor assumisse suas infrações - e a frequência com que o condutor dirige foram preditores para o cometimento de mais infrações; também se evidenciou que possuir mais anos de estudo representou um fator de proteção à direção segura. Nesse sentido, nossos resultados demonstram a natureza complexa e multideterminada do fenômeno. Espera-se que este trabalho, pioneiro no Brasil, contribua para a identificação de potenciais fatores de risco e associados ao cometimento de infrações, bem como contribua na discussão de medidas de avaliação, reabilitação e fiscalização para o trânsito. / Introduction: It is estimated that risk behaviors in traffic, such as errors and violations, are responsible for approximately 90% of all automobile accidents. Among the leading predictors of risk behavior in traffic are driver personality traits. The positive association between impulsivity, sensation seeking and risk behaviors in traffic is already well documented in literature. However, studies that explore these associations among offender drivers and non-offender drivers are scarce, especially in Brazil. Objective: To explore the association between impulsivity, sensation seeking and risk behavior in traffic in a sample of offender drivers versus non-offender drivers in the city of Porto Alegre. Method: The sample comprised 158 offender drivers whose right to drive had been suspended over the past 12 months due to an accumulation of points (68.4%) or a specific violation (31.6%), selected at the Rio Grande do Sul State Traffic Department (79.7% men) and 181 non-offender drivers (76.2% men) from three Driving Schools and in two local parks. Measures used were: the Barrat Impulsiveness Scale (BIS-11), the Arnett Inventory of Sensation Seeking (AISS) and a standardized questionnaire for the collection of information of demographics and risk behavior in traffic. The variables were analyzed through logistic regression according to a hierarchical model. The adopted level of significance was 5%. Results: More impulsiveness (OR = 4.8, IC 95%: 2.68-8.6), years in school (OR=0.91, IC 95%: 0.85-0.97); frequent driving (OR = 4.01, IC 95%: 2.05-7.83), take on other driver’s violations (OR = 2.91, IC 95%: 1.63-5.19), request that other driver’s take on one’s violations (OR = 6.74, IC 95%: 2.39-19.25), involvement in traffic accidents with a victim (OR = 2.73, IC 95%: 1.24-6.01) and drinking alcoholic beverages during the last 12 months (non-binge drinking = OR 0.77, IC 95%: 0.38-1.55; binge drinking = OR 1.97, IC 95%: 0.87-4.47) were significantly and independently associated with the suspension of driving privileges. We verified no association between sensation seeking and the suspension of driving privileges. Conclusion: The findings suggest that impulsivity and behaviors associated with risk – such as involvement in serious accidents, drinking alcoholic beverages within the last 12 months, taking on violations of other drivers, requesting that other drivers take on his/her violations - and the frequency of driving were indicative of committing additional violations; it was also shown that more years of study represented a factor favoring safe driving. In this sense, our results show the complex and multidetermined nature of the phenomenon. It is hoped that this pioneering study in Brazil contributes to the identification of potential risk factors and those associated with committing violations, as well as contributing to the discussion of measures for evaluation, rehabilitation and monitoring of traffic.

Contexto. A impulsividade é um conceito formado a partir de diversas dimensões comportamentais. Desta forma a avaliação do comportamento impulsivo apresenta características complexas e distintas, que devem ser levadas em conta durante o processo de diagnóstico ou pesquisa. Objetivo. Este artigo de revisão apresenta os principais instrumentos de avaliação do comportamento impulsivo tanto em animais, quanto em humanos, relacionando as indicações e limitações de cada instrumento, assim como apontando referências de artigos empíricos que exemplificam cada protocolo. Método. Foram realizadas buscas nos sistemas Medline, PsycINFO e BVS/Bireme durante o período de 2007 a 2012. Resultados. Para humanos foram apontados quatro questionários e oito tarefas, e para animais foram apontadas seis tarefas. Entre os questionários a Escala de Impulsividade Barrat 11 se destaca, assim como a tarefa Delay Discounting, tanto para humanos quanto para animais. Conclusão. Estudos que utilizam instrumentos de modelos diferentes são sugeridos, assim como validação de escalas de impulsividade para diferentes populações brasileiras. / Background. The concept of impulsivity encompasses several behavioral dimensions. Therefore, the evaluation of impulsive behavior is quite complex and can vary greatly. Hence, such complexity should be considered during research or while establishing a diagnosis. Objectives. The objective of the present review article was to describe the main impulsive behavior assessment instruments both in animals and humans, including the indications and limitations of each instrument, and to suggest references of empirical articles that illustrate each protocol. Methods. The following databases were searched from 2007 to 2013: MEDLINE, PsycINFO and BVS/Bireme. Results. Our search retrieved four questionnaires and eight tasks for humans, and six tasks for animals. Among the most frequently used questionnaires and tasks, we found the Barratt Impulsiveness Scale-11 and the Delay Discounting Task, both for humans and animals. Conclusion. It is recommended that further research be undertaken using different models of instruments. In addition, impulsivity scales should be validated for different Brazilian populations.

Desvalorização pelo atraso (DA) se refere à preferência por gratificações menores e disponíveis imediatamente, em detrimento de gratificações maiores, disponíveis depois de algum tempo. Altos índices de DA se associam positivamente à impulsividade e estão presentes em dependentes químicos e em outros transtornos que envolvem impulsividade. Com o objetivo de conhecer melhor a DA no contexto do tabagismo na gestação, foram elaborados quatro estudos. Os dois primeiros, Desvalorização temporal: conceitos e medidas e Desvalorização pelo atraso, dependência química e impulsividade são estudos de revisão que descrevem a DA e suas características, suposições, conseqüências, relação com as dependências químicas e formas de intervenção. O estudo Atitudes de gestantes e da população geral quanto ao uso de substâncias durante a gestação mostra como gestantes e população geral pensam o uso de álcool, de cigarros e de outras substâncias durante os períodos de gestação e de amamentação, investigados através de uma enquete com cenários hipotéticos, sendo a maioria dos participantes restritiva ao uso de álcool, de cigarros e de substâncias nos dois momentos, e os permissivos condicionaram à redução de freqüência e doses. No estudo Uso de cigarros, DA e características sociodemográficas em gestantes, gestantes fumantes foram comparadas a ex-fumantes e a não fumantes com o objetivo de identificar as características do tabagismo na gestação e a DA, através de uma tarefa computadorizada, sendo controladas variáveis sóciodemográficas, estresse, transtornos mentais e uso de substâncias. Entre as fumantes, foram controlados nível de dependência do cigarro, urgência em fumar e crenças associadas ao tabagismo. Foram identificados fatores associados ao tabagismo na gestação tais como baixa escolaridade, multiparidade e parceiro fumante, sem relação entre tabagismo na gestação e estresse ou transtornos mentais. Gestantes fumantes foram as que apresentaram maior DA na situação de ganhos, demonstrando maior impulsividade. Não houve diferenças entre os grupos na situação de perdas. Os artigos são discutidos ao final da tese. / Delay discounting (DD) refers to choosing smaller and immediately available rewards, instead of larger rewards available after some time. DD relates positively to impulsivity and is present in patients with various types of addictions and other disorders involving impulsivity. Four articles were drafted aiming the understanding of DD in the context of smoking during pregnancy. The first two articles, DD, concepts and measures and DD, drug addiction and impulsivity are review studies that describe DD and its characteristics, assumptions, consequences, relation to drug addictions and intervention. The article Attitudes of pregnant women and other adults toward the use of psychoactive substances during pregnancy draws, through a survey made of hypothetical scenarios, the ideas of pregnant women and the general population on the use of alcohol, cigarettes and other substances during pregnancy and breastfeeding. Most participants showed restrictions to the use of alcohol, cigarettes and substances on both occasions, with the more permissive ones conditioning the use to less frequency of use and smaller doses. In the study Pregnant women: cigarette use, DD and socioemographic variables, aiming to identify the characteristics of smoking in pregnancy and DD, pregnant women were compared to both former smokers and non-smokers. A computer task was devised were sociodemographic variables, stress, mental disorders and substance use were taken into account. Low education (incomplete high school), having more than one children and a partner who smokes were social demographic variables significantly related to smoking during pregnancy. Stress and TMCs were not related to smoking during pregnancy. Those who smoked showed a steeper DD curve in gains but not in losses. Articles are discussed at the end of the thesis.