The study’s objective was to assess whether resting-state regional functional connectivity and current source density (CSD) measured during smoking abstinence predict smoking progression across 18 months, depressive traits, and nicotine-enhanced reward sensitivity (NERS) in young light-nicotine (NIC) smokers using low-resolution brain electromagnetic tomography analysis (LORETA). A secondary goal was to assess whether depressive traits moderate the ability of connectivity and regional CSD to predict NERS. Brain regions of interest (ROIs) hypothesized to predict smoking progression, NERS, and depressive traits include structures with high-density nicotinic acetylcholine receptors (nAChRs) and reward-related areas. A total of N=108, 14-hour NIC-deprived young (age 18-24) light (5-35 NIC uses/week) smokers underwent electroencephalogram (EEG) recording while at rest (i.e., viewed a white crosshair on a black background) for 8 minutes then completed the PRT, an assessment of reward sensitivity, after smoking a placebo (0.05 mg NIC) and NIC (0.8 mg NIC) cigarette using a within-subjects design allowing for the assessment of NIC-induced changes in reward sensitivity. All EEG power and LORETA activity bands underwent regression analysis to discover if EEG-assessed brain activity can predict smoking progression, depressive traits, NERS, and their potential interaction. Localized brain regions include 1) reward-related structures, 2) depressive trait-related structures, and 3) large-scale neural (e.g., salience network (SN), default mode network (DMN), executive control network (ECN)) and substance use disorder networks (e.g., orbital frontal cortex (OFC), insula, dorsal lateral prefrontal cortex (dlPFC) anterior cingulate cortex (ACC)). Weaker resting-state connectivity (rsC) between the insula and ACC (i.e., SN) predicted greater smoking progression at 18 months (theta1 and theta2) and greater depressive traits (delta and theta1), while greater rsC within the SN predicted greater NERS (alpha2 and beta 2/3[23.19 – 25.14 Hz]). Greater NERS was also predicted by greater alpha2 connectivity between the 1) ACC and posterior cingulate cortex (PCC) and 2) ACC and left dlPFC. Greater depressive traits were also predicted by 1) weaker delta and theta2 connectivity between the bilateral insula, 2) weaker delta, theta1, and theta2 between the insula and dlPFC, 3) weaker delta and theta1 between the insula and subgenual cortex, 4) greater theta2 in the right vs. left default mode, and 5) greater delta (2.44 – 3.41 Hz) in the left vs. right default mode network. Both greater depressive traits and greater NERS were predicted by weaker 1) theta2/alpha1 (6.59 – 9.52 Hz) between the insula and dlPFC and 2) alpha1 (7.5 – 9.5 Hz) between the left orbital frontal cortex and right dlPFC. These findings provide the first evidence that differences in EEG-assessed brain connectivity in young light smokers are associated with nicotine-enhanced reward sensitivity, depressive traits, and smoking progression. Notably, weaker low-frequency rsC within the salience network predicted depressive traits and smoking progression, while greater high-frequency rsC predicted greater nicotine-enhanced reward sensitivity. These findings suggest that salience network rsC and drug-enhanced reward sensitivity may be useful tools and potential endophenotypes for reward sensitivity and drug-dependence research.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-01-09T18:05:43Z No. of bitstreams: 1 taynaradutrabatistaformagini.pdf: 571742 bytes, checksum: 1a16afcacce56be5569ffbf39a0478e5 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2017-01-31T11:21:50Z (GMT) No. of bitstreams: 1 taynaradutrabatistaformagini.pdf: 571742 bytes, checksum: 1a16afcacce56be5569ffbf39a0478e5 (MD5) / Made available in DSpace on 2017-01-31T11:21:50Z (GMT). No. of bitstreams: 1 taynaradutrabatistaformagini.pdf: 571742 bytes, checksum: 1a16afcacce56be5569ffbf39a0478e5 (MD5) Previous issue date: 2016-04-28 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Apesar do declínio das taxas de prevalência de tabagismo, o número de fumantes leves tem aumentado devido à políticas de controle e restrição de uso e desnormalização do tabaco. A situação no Brasil é preocupante devido ao não reconhecimento da existência de diferentes padrões de tabagismo, não definição do termo fumante leve e número reduzido de pesquisas na área, sendo um campo recente no país. Objetivo: Descrever os padrões de consumo de cigarro industrializado no Brasil e fatores associados, psicossociais e de saúde. Métodos: Análise de dados da Pesquisa Nacional de Saúde (2013). Resultados: Cerca de 47% dos fumantes são fumantes leves, 39,8% são fumantes pesados e 12,8% são fumantes não diários. Tabagismo não diário está associado à doenças do coração, hipertensão e doenças pulmonares. Tabagismo leve diário está associado à acidente vascular cerebral, doenças do coração, entre outras. Fatores discriminantes entre os padrões demonstraram que fumantes não diários tendem a realizar exercícios físicos e morarem com fumantes não diários. Fumantes leves não estão associados com atividade física, convivem com outros fumantes de padrão diário e possuem maior risco de depressão. Fumantes pesados representam o padrão com maior risco de condições crônicas de saúde, maior dependência à nicotina e dificuldade em parar de fumar. Discussão: Fumantes leves representam uma grande proporção de fumantes. A fim de reduzir a prevalências e os danos causados pelo tabaco no Brasil é indispensável compreender quem são os fumantes no país. / Despite the decrease of smoking prevalence around the world, the number of light smokers has increased due to the tobacco control policies and denormalization of smoking. This field is recent in Brazil and the situation is complicated due to the non-recognition of different patterns of smoking, no definition of terms such as light smoker and little research in the area. Aim: To explore the different patterns of smoking in Brazil, its psychosocial and health associated factors. Methods: Secondary data analysis of National Health Research (2013). Results: About 47.4% of smokers are light smokers, 39.8% are heavy smokers and 12.8% are nondaily smokers. Nondaily smoking is associated with heart disease, hypertension and lung disease. Daily light smoking is associated with stroke, heart disease, among others. Discriminant factors between the patterns show that nondaily smokers tend to perform more physical activities and live with nondaily smokers. Light smokers perform little physical activity, live with other daily smokers and are at higher risk of depression. Heavy smokers have increased risk of chronic health conditions, greater nicotine dependence and more difficulty in quitting smoking. Discussion: Light smokers represent a large proportion of smokers. In order to reduce the prevalence and harm caused by tobacco in Brazil, it is essential to understand who are the smokers in the country.