Le décrochage scolaire est un phénomène touchant une proportion importante d’adolescents au Québec. Les facteurs permettant de prédire ce phénomène peuvent être d’ordre individuel, familial, social, scolaire et sociodémographique. Bien que plusieurs études ont permis d’établir un lien significatif entre la consommation de substances psychoactives et le décrochage scolaire, aucune étude ne s’est attardé sur le possible rôle modérateur protecteur de l’environnement socioéducatif sur le lien existant entre ces deux comportements malgré plusieurs indications soutenant un tel effet. Cette étude vise donc à déterminer, à l’aide d’un devis longitudinal prospectif, si le climat relationnel maître-élève joue un rôle modérateur protecteur sur ce lien. L’échantillon utilisé pour cette étude est tiré de la Stratégie d’Intervention Agir Autrement (SIAA) et comprend 728 adolescents. Les données ont été obtenues à l’aide de questionnaires auto-révélés et des données officielles du Ministère de l’éducation, des loisirs et des sports. Des analyses de régressions logistiques ont été effectuées et ont démontré que le climat relationnel maître-élève semble diminuer les risques de décrochage scolaire pour les élèves consommateurs. Effectivement, le climat relationnel semble être un facteur de protection pour les élèves consommateurs réguliers de cannabis identifiés comme un groupe à risque de décrochage scolaire alors qu’il ne l’est pas pour le groupe des non consommateurs et des faibles consommateurs. En revanche, ces analyses n’ont pas permis de détecter un tel effet pour l’intoxication à l’alcool. Les implications de ces résultats sont discutées. / School dropout is affecting a large proportion of adolescents in Quebec. Factors which predict school dropout come from individual, familial, social, school, and sociodemographic dimensions. Although many studies have found a significative link between substance use and school dropout, no study have examined the potential protective role of the socioeducational climate on the relationship between these behaviors despite support for such an effect. Thus, this study aims to verify if the student-teacher relationship climate plays a protective (moderator) role on the link between substance use and school dropout by using a longitudinal prospective design. The sample for this study is taken from New approach, new solutions (NANS) and includes 728 participants. Data were obtained thru self-report questionnaires as well as from the Ministère de l’éducation, des loisirs et des sports for official data on school dropout. Logistic regression analyses showed that the student-teacher relationship climate seems to protect against the effect of regular cannabis use on school dropout but not against low or non-use. Conversely, the analyses haven’t shown such a protective effect in the case of alcohol intoxication. Implications for these results are discussed.

L’usage de drogues illicites et la symptomatologie dépressive sont associés, mais la nature de cette association demeure mal comprise. Une clarification des mécanismes en jeu est nécessaire afin de pouvoir intervenir sur la cooccurrence des deux phénomènes, dont les conséquences individuelles et sociales sont lourdes. Ces efforts de clarification débutent à l’adolescence, moment où sont typiquement initiés la consommation de substances et les problèmes affectifs. L’objectif de cette thèse est de contribuer à clarifier la nature des associations entre l’usage de certaines des drogues illicites les plus fréquemment consommées et les symptômes dépressifs chez les adolescents. Les données utilisées proviennent d’une cohorte de l’échantillon longitudinal de la Stratégie d’Intervention Agir Autrement (SIAA) comprenant plus de 3000 jeunes fréquentant des écoles en milieu défavorisé du Québec, qui ont été suivis pendant leur secondaire (2003-2007). Le premier article empirique de la thèse porte sur la relation entre l’usage de cannabis et la symptomatologie dépressive. Cette étude a examiné l’existence d’associations prospectives bidirectionnelles entre les deux phénomènes du début (13-14 ans) à la fin du secondaire (16-17 ans). Les analyses ont considéré des liens directs, mais également des liens indirects via deux facteurs reflétant des appartenances sociales normatives et non normatives : l’attachement à l’école et l’affiliation à des pairs déviants et consommateurs de drogues. Les résultats indiquent que les symptômes dépressifs et l’usage de cannabis peuvent représenter des facteurs de risque mutuels et suggèrent qu’un mécanisme indirect impliquant une érosion des attaches normatives pourrait jouer un rôle dans des cascades développementales reliant les deux manifestations. Le deuxième article empirique visait à déterminer si l’usage de deux drogues de synthèse, le MDMA (ecstasy) et les méth/amphétamines (speed), à 15-16 ans était associé au développement de symptômes dépressifs élevés un an plus tard, en prenant en considération des facteurs confondants potentiels. Tel qu’attendu, les résultats montrent une prédiction de la symptomatologie dépressive par l’usage de MDMA et de méth/amphetamines, particulièrement lorsque cet usage est concomitant. Ces résultats représentent une des premières évidences d’un risque posé par l’usage de drogues de synthèse par rapport au développement de symptômes affectifs chez les jeunes. / Illicit drug use and depressive symptoms are associated, but the nature of this association remains poorly understood. Clarifying the underlying mechanism(s) is necessary in order to design interventions which can potentially reduce the co-occurrence of the two phenomena, which accounts for sizeable individual and social costs. Clarification efforts should start in adolescence, when drug use and affective problems are typically initiated. The aim of this thesis is to help clarify the nature of the association between some of the most frequently used illicit drugs and depressive symptomatology in adolescents. This work was carried out using a cohort from the New Approaches, New Solutions (NANS) longitudinal dataset, which comprises more than 3000 students attending school in disadvantaged areas of Quebec (Canada) who were followed throughout high school (2003-2007). The first article of the thesis focuses on the association between cannabis use and depressive symptoms. This study examined prospective associations in both directions between the two phenomena from the beginning (grade 8) to the end (grade 11) of high school. Direct links were analysed, as well as indirect links involving two factors reflecting normative and non normative social connectedness: school bonding and affiliation with deviant and substance-using peers. Results indicate that depressive symptoms and cannabis use can be mutual risk factors and that a social mechanism involving an erosion of normative social connectedness may play a mediating role in bidirectional developmental cascades linking the two manifestations. The second article tested whether the use of two synthetic drugs, MDMA (ecstasy) and meth/amphetamines (speed), in grade 10 was associated with the development of elevated depressive symptoms the following year, independently from potential confounders. As hypothesized, the use of MDMA and meth/amphetamine was independently predictive of subsequent depressive symptoms. Concurrent use of the two substances was more predictive than singular use. Given the paucity of well-controlled longitudinal studies on the subject, these results provide some of the first compelling evidence that synthetic drug use may pose a risk for the development of affective symptoms in youth.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

S’inscrivant dans le cadre d’une étude pancanadienne portant sur la normalisation du cannabis et la stigmatisation du tabac, le principal objectif de cette recherche était de comprendre quelle place occupe l’évaluation des risques dans la compréhension des perceptions et comportements liés aux deux substances. Pour ce faire, à partir d’un devis mixte – quantitatif et qualitatif, nous avons 1) décrit les perceptions et opinions des participants quant à leur propre consommation de cannabis et/ou de tabac et quant à la consommation que font les gens en général des mêmes substances. Nous avons aussi 2) décrit comment les participants évaluent les risques liés à chacune des substances. Enfin, sachant que la perception du risque est intimement liée au comportement d’un individu, nous avons cherché 3) à préciser comment l’évaluation du risque agit sur les comportements et les opinions des quelques 50 participants, hommes et femmes âgés entre 20 et 49 ans, bien intégrés socialement, envers le tabac et le cannabis. Il s’avère que les fumeurs de cannabis, qui ont insisté sur la distinction à faire entre la manière dont ils font usage de la substance et une consommation abusive, valorisait le contrôle que leur permettait, selon eux, la consommation de cannabis. La consommation de cigarettes, quant à elle, était perçue négativement pour des raisons opposées puisque de l’avis des participants à l’étude, elle engendrerait chez le fumeur une incapacité à se maîtriser et un besoin compulsif de fumer. Dans cette optique, les risques liés au cannabis étaient perçus, par la plupart, comme étant contrôlables, à l’exception du jugement d’autrui qui demeurerait incertain et sur lequel il serait impossible d’avoir du contrôle. La réaction de certaines personnes de leur entourage étant ou bien imprévisible ou négative, c’est ce qui les amènerait à fumer principalement en privé. Le contrôle social formel aurait finalement peu d’influence étant donné le fort sentiment qu’ont les répondants qu’il ne s’appliquera tout simplement pas à eux. / In the context of a pan-Canadian study pertaining to the normalization of cannabis and the stigmatization regarding tobacco, the main objective of this research was to understand the importance given in the evaluation of the risks in the understanding of the perceptions and behaviors as they relate to the aforementioned substances. Based on a mixed method, qualitative and quantitative, the process undertaken was 1) to describe the perceptions and opinions of respondents regarding their own use of cannabis and/or tobacco as well as the use of the same substances by the general public. We then 2) described how the respondents evaluate the risks as they relate to each substance. Finally, knowing that the perception of the risks are intimately related to the behavior of an individual, we 3) sought to determine how the evaluation of risks affects the behaviors and opinions of the 50 study participants, all of whom are socially well adjusted men and women between the ages of 20 to 49, regarding tobacco and cannabis. The cannabis smokers insisted on the importance of making a distinction between the way they use the substance versus an abusive use. They ascertained that there was a degree of control regarding the use of cannabis. The use of tobacco was perceived negatively for opposite reasons as it created a dependency to the smoker, an incapacity to control its use and the creation of a compulsive urge to smoke. Given these optics, the risks related to use of cannabis were perceived by most as controllable with the exception of judgment from others which remained uncertain and which would be impossible to control. The reaction of certain people within their surroundings was either unpredictable or negative which lead them to smoke mainly in private. Finally, formal social control would very little influence on the respondents given the strong feeling they had that this did not apply to them.

La consommation de substances psychoactives débute généralement à l’adolescence. Cette pratique, bien qu’illégale, est répandue à cet âge. Toutefois, elle peut avoir de graves répercussions sur le développement de l’individu. Il est important de mieux connaître les facteurs pouvant influencer sa fréquence d’utilisation afin d’en diminuer les risques. Ce mémoire vise à examiner le rôle des amis déviants et de la pratique d’un sport organisé dans le développement de l’intoxication à l’alcool et la consommation de cannabis à l’adolescence. Plus précisément, l’étude vise à déterminer si la pratique d’un sport organisé a des effets modérateurs sur la relation entre les amis déviants et l’intoxication à l’alcool et la consommation de cannabis. Les analyses ont été réalisées séparément pour l’alcool et le cannabis. L’échantillon utilisé provient de l’étude longitudinale de la Stratégie d’Intervention Agir Autrement et comprend 4219 adolescents. Des régressions probit ont été effectuées. Tel qu’attendu, les résultats montrent que la fréquentation d’amis déviants est associée au risque d’intoxication à l’alcool et de consommation de cannabis. De plus, les résultats ont démontré le rôle modérateur protecteur de la pratique d’un sport organisé pour l’alcool. Un jeune qui a des amis déviants et qui participe à un sport organisé consommerait généralement moins d’alcool qu’un jeune qui a des amis déviants et qui ne participe pas une activité sportive organisée. Les implications de ces résultats pour la recherche sont discutées. / Substance use generally emerges during adolescence and, even if prohibited, is widespread at that age. However, it can have severe consequences on human development. It is important to better understand the factors that influence the frequency of drug use in order to reduce risk. This research project aims to examine the role of deviant friends and organized sport practice in the development of alcohol abuse and cannabis use in adolescence. More specifically, this study aims to determine whether an organised sport practice held a moderating effect on the relationship between deviant friends and alcohol abuse and cannabis use. Analyzes were performed separately for alcohol and cannabis. The sample is drawn from the longitudinal study of New Approach, New Solutions and includes 4219 adolescents. Probit regressions were performed and showed, as expected, that deviant friends are associated with alcohol abuse and cannabis use. In addition, the results support the protective moderating role of organized sport practice for alcohol. Youth who has deviant friends and participate in organized sport generally consume less alcohol that youth who has deviant friends and is not involved in organized sport activity. The implications of these findings are discussed.

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Made available in DSpace on 2015-07-22T20:50:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-24. Added 1 bitstream(s) on 2015-08-11T03:26:09Z : No. of bitstreams: 1 Publico-12675.pdf: 644045 bytes, checksum: 4760c174c211a52ff1a44e954522d1af (MD5) / A aderência ao tratamento para dependência química é questão preocupante e requer atenção especial dos profissionais que atuam com esta população. OBJETIVO: identificar características dos pacientes usuários de maconha que possam ser consideradas fatores preditivos de abandono do tratamento. METODOLOGIA: foi realizada a análise secundária dos dados de um Ensaio Clínico Randomizado em que foram incluídos 169 dependentes de maconha avaliados no ingresso e reavaliados três vezes nos seguimentos realizados após o tratamento breve ao qual foram submetidos. Os pacientes foram randomizados em três grupos de tratamento: no Grupo 1, os pacientes foram submetidos a quatro sessões de tratamento em um mês, no Grupo 2, as mesmas quatro sessões em três meses e no Grupo 3 ficaram os pacientes em espera, os quais, posteriormente foram randomizados para um dos dois grupos de tratamento. RESULTADOS: Os pacientes alocados no grupo três, ou seja, de espera, apresentaram 3.47 vezes mais chance de abandono do que aqueles inseridos nos outros grupos. Baseado nos dados sócio demográficos, concluiu-se que para cada ano de idade do paciente, as chances de abandono poderiam ser multiplicadas por 0,91, representando riscos mais baixos. Para cada ano de consumo da maconha, as chances também seriam multiplicadas por 0,92 representando menores riscos. CONCLUSÃO: Diante dos dados obtidos, pode-se inferir que quanto mais velho e quanto mais anos de consumo de maconha o sujeito tem, menores são suas chances de desistência do tratamento. Desta forma, pode-se apontar a importância de intervenções específicas para os grupos com riscos mais altos de abandono do tratamento foi discutida bem como a relevância de outros estudos envolvendo usuários de maconha e indicações para os profissionais ajudarem os pacientes a aderirem ao programa proposto. / The present study involved secondary analysis of data from a Randomized Clinical Trial including 169 cannabis-dependents not only dependents assessed at baseline and submitted to brief treatment. Patients were first randomized into three treatment groups. OBJECTIVES: The objective was to identify characteristics which could be considered predictors of treatment dropout. RESULTS: Patients initially allocated into the control group presented a 3.47 greater chance of drop out than those of the treatment groups. Based on the socio-demographic data, it was concluded that for every year of patient age, the chances of drop out would be multiplied by 0.91, representing lower risk. For every year of cannabis use, chances of drop out would be multiplied by 0.92, again representing reduced risk. CONCLUSIONS: The importance of specific interventions for groups with a higher risk of treatment drop out was discussed, along with the relevance of other studies involving cannabis users and possible guidelines for professionals help patient to adhere. / TEDE / BV UNIFESP: Teses e dissertações

Made available in DSpace on 2015-07-22T20:50:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-28 / Objetivo: Avaliar, através de uma revisão sistemática da literatura, os efeitos antitumorais dos canabinóides em qualquer tipo de neoplasia, utilizando como amostra seres humanos e animais de laboratório com tumores, bem como culturas de células tumorais. Método: A pesquisa incluiu as seguintes bases eletrônicas de dados: PUBMED, EMBASE, LILACS e “The Cochrane Collaboration Controlled Trials Register”. Todos os estudos publicados que envolveram os efeitos antitumorais (mecanismos celulares e moleculares) dos canabinóides foram considerados para esta revisão. Desta forma, foram levados em conta não somente ensaios clínicos (randomizados ou não) como também estudos experimentais in vivo e in vitro. A estratégia de busca bibliográfica compreendeu todas as publicações de cada base de dados até 31 de dezembro de 2009. O exame minucioso de todas as referências bibliográficas dos artigos importantes para esta revisão (incluindo artigos de revisão) foi igualmente realizado com o objetivo de selecionar artigos que não tivessem sido capturados pela estratégia de busca eletrônica. Resultados: De 3.920 artigos inicialmente identificados, 117 preencheram os critérios de inclusão para esta revisão. Todos os estudos incluídos nesta revisão sistemática foram experimentais (in vivo e/ou in vitro), excetuando-se um estudo clinico piloto fase I/II em humanos. Em todos os estudos experimentais incluídos, os canabinóides exerceram atividade antitumoral in vitro e/ou evidência antitumoral in vivo em vários modelos de células tumorais e tumores, respectivamente. As atividades antitumorais incluíram: efeitos antiproliferativos (sequestro do ciclo celular), diminuição da viabilidade e morte celular por toxicidade, apoptose, necrose, autofagia, efeitos antiangiogênicos e antimigratórios. As evidências antitumorais incluíram: diminuição do tamanho tumoral, efeitos antiangiogênicos e antimetastáticos. Adicionalmente, a maioria dos estudos descreveu que os canabinóides apresentaram seletividade na ação antitumoral em vários modelos tumorais. Desta forma, as células normais usadas como controle não foram atingidas. O fator segurança na administração dos canabinóides também foi demonstrado in vivo, em ratos com tumores marcados com células tumorais. O único estudo realizado em humanos, por sua vez, demonstrou segurança na administração intratumoral do delta-9-THC em pacientes com glioblastoma multiforme recorrente. Conclusões: Os vários canabinóides testados em múltiplos modelos de tumores apresentaram efeitos antitumorais in vitro e in vivo. Estes achados indicam que os canabinóides são compostos promissores para o tratamento das neoplasias. No entanto, pesquisas em seres humanos através de ensaios clínicos randomizados, metodologicamente bem conduzidos, devem ser realizadas para a avaliação de eficácia dos mesmos antes que eles possam ser indicados para esta finalidade. Este é o caso do delta- 9-THC e do canabidiol, que já foram testados e aprovados para uso em humanos em outras condições clínicas. Outros canabinóides, no entanto, necessitam ainda de pesquisas farmacocinéticas, farmacodinâmicas e toxicológicas antes de poderem ser testados em seres humanos. / Objective: To evaluate, through a systematic review of the literature, the antitumoral effects of cannabinoids on any type of cancer, involving both human beings and animal samples, as well as cultured tumor cells. Method: Research included the following electronic databases: PUBMED, EMBASE, LILACS and "The Cochrane Collaboration Controlled Trials Register. All published studies involving the antitumoral effects (cellular and molecular mechanisms) of cannabinoids were considered for this review. Thus, not only clinical trials (randomized or not) but experimental studies (both in vivo and in vitro) were taken into account. The bibliography search strategy included all publications of each of these databases until December 31, 2009. The scrutiny of all the references from the relevant articles for this review (which included review articles) was also performed, in order to select items that could not have been captured by the chosen electronic search strategy. Results: From 3,920 initially identified articles, 117 fulfilled the inclusion criteria for this review. All the studies included in this systematic review were experimental (in vivo and/or in vitro), except for a pilot clinical trial phase I/II involving humans. In all experimental studies included, cannabinoids exerted antitumoral activity in vitro and/or antitumoral evidence in vivo in several models of tumor cells and tumors, respectively. The antitumor activity included: antiproliferative effects (cell cycle arrest), decreased viability and cell death by toxicity, apoptosis, necrosis, autophagy, as well as antiangiogenic and antimigratory effects. Antitumoral evidence included: reduction in tumor size, antiangiogenic, and antimetastatic effects. Additionally, most of the studies described that the canabinnoids exercised selective antitumoral action in several distinct tumor models. Furthermore, normal cells used as controls were not affected. The safety factor in the cannabinoids’ administration has also been demonstrated in vivo in rats with tumors which were marked with tumor cells. The sole study in humans demonstrated safety in intratumoral administration of delta-9- THC in patients with recurrent glioblastoma multiforme. Conclusions: The various cannabinoids tested in multiple tumor models showed antitumoral effects both in vitro and in vivo. These findings indicate that cannabinoids are promising compounds for the treatment of cancer. However, methodologically well conducted research on humans through clinical trials has yet to be performed in order to evaluate their effectiveness. This is the case of delta-9-THC and cannabidiol, which have been tested and approved for use in humans in other clinical conditions. In the case of other cannabinoids, however, further pharmacokinetic as well as pharmacodynamic and toxicological studies are required before their being tested in humans. / TEDE / BV UNIFESP: Teses e dissertações

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research aims to verify the hearing condition of goers of support groups for former drug users. It was evaluated 17 individuals, all former drug users, being marijuana, crack and cocaine the most used drugs. The individuals were divided into two groups according to the kind of the most commonly used drug: Group 1 (G1) - 10 former users of marijuana, Group 2 (G2) - Seven former users of crack/cocaine. For the results analysis, they were also subdivided according to the time of drug use: one to five years, six to 10 years and more than 15 years. The subjects were submitted to anamnesis, pure tone audiometry (PTA), acoustic impedance measurements, transient evoked otoacoustic emissions (TEOAE), suppressive effect of TEOAE and brainstem evoked response audiometry (BERA). By comparing the results of PTA of the G1 and G2 with one to five years of drug use, G2 presented pure tone levels greater than 25 dB with a significant statistically difference in the pure tone levels for the frequencies of 250, 500, 6000 and 8000 Hz in the right ear. In the group of six to 10 years of drug use it was not found significant difference in pure tone levels for frequencies of 4000 and 8000 Hz in the left ear, with worse pure tone levels for the G2. For the group with more than 15 years of drug use, it was observed pure tone levels above 25 dB for the frequencies from 3000 to 8000 Hz in the right ear. In evaluations with TEOAE, TEOAE suppression effect and BERA, it was not observed a difference in the results when they were compared according to the time of drug use. G1 presented an average in the relation signal/noise of TEOAE greater than the average in the G2, but without a significant statistically difference. The two groups did not differ in the occurrence of suppressor effect of TEOAE and absolute latency and inter-peak interval of BERA. It is emphasized that only five individuals had adequate results for the age group in the BERA. As the time of drug use increases, more changes were observed in the G1 results in PTA and BERA, but it did not interfere in the results of the evaluations of the G2. The results suggest that the use of drugs can cause peripheral and central hearing loss, and that the use of crack/cocaine is more deleterious to the hearing that the use of marijuana. / O presente trabalho tem como objetivo verificar a condição auditiva de frequentadores de grupos de apoio a ex-usuários de drogas. Foram avaliados 17 indivíduos ex-usuários de drogas, estando entre as mais usadas a maconha, o crack e a cocaína. Os indivíduos foram divididos em dois grupos, conforme o tipo de droga mais consumida: Grupo 1 (G1) 10 ex-usuários de maconha; Grupo 2 (G2) sete ex-usuários de crack/cocaína. Para a análise dos resultados, houve uma subdivisão conforme o tempo de uso de drogas: um a cinco anos, seis a 10 anos e mais do que 15 anos. Os indivíduos foram submetidos à anamnese, audiometria tonal liminar (ATL), medidas de imitância acústica, emissões otoacústicas transientes (EOAT), efeito supressor das EOAT e potenciais evocados auditivos de tronco encefálico (PEATE). Ao comparar os resultados da ATL do G1 e G2 com um a cinco anos de uso de drogas, o G2 apresentou limiares tonais maiores que 25 dBNA com diferença estatisticamente significante nos limiares tonais para as frequências de 250, 500, 6000 e 8000 Hz na orelha direita. No grupo de seis a 10 anos de uso de drogas houve diferença estatisticamente significante nos limiares tonais para as frequências de 4000 e 8000 Hz da orelha esquerda, com limiares piores para o G2. Para o grupo com mais de 15 anos de uso de drogas, observou-se limiares tonais acima de 25 dBNA para as frequências de 3000 a 8000 Hz na orelha direita. Nas avaliações com EOAT, efeito supressor das EOAT e PEATE não se observou diferença nos resultados quando foram comparados conforme o tempo de uso de drogas. O G1 apresentou média da relação sinal/ruído das EOAT superior ao G2, porém sem diferença estatisticamente significante. Os dois grupos não diferiram quanto à ocorrência do efeito supressor das EOAT, bem como quanto às latências absolutas e aos intervalos interpicos do PEATE. Ressalta-se que apenas cinco indivíduos apresentaram resultados adequados para a faixa etária no PEATE. O tempo de uso da droga exerceu influência nos resultados do G1 na ATL e PEATE; observou-se que quanto maior o tempo, maiores as alterações. Porém, o tempo de uso não interferiu nos resultados das avaliações do G2. Os resultados encontrados sugerem que o uso de drogas pode provocar alterações auditivas periféricas e centrais, e que o uso de crack/cocaína é mais deletério para a audição que o uso de maconha.

La fibra di canapa europea è l'unica fibra naturale con una certificazione di sostenibilità. La qualità della fibra è influenzata principalmente da genotipo, tecniche agronomiche, epoca di raccolta e metodo di macerazione. L'obiettivo principale della tesi è delineare le pratiche agronomiche e di post-raccolta per migliorare l'estrazione e la qualità della fibra, con particolare attenzione alla produzione di canapa multiuso ritardando la raccolta fino alla maturazione dei semi. Le prove di densità, fertilizzazione azotata e varietali sono state condotte in differenti ambienti Europei. La procedura di decorticazione standardizzata è stata confrontata con la linea longitudinale di estrazione della fibra per applicazioni di alto valore aggiunto. I test su bio-compositi di canapa sono stati effettuati con fibra pettinata per confrontarne le proprietà tra genotipi, epoca di raccolta e metodi di macerazione. I risultati di questa indagine suggeriscono che i) la densità di semina e la concimazione azotata ottimale sono tra 90-150 piante m-2 e 30-60 kg N ha-1; ii) le nuove varietà dallo stelo giallo presentano un'alta efficienza di decorticazione e una ridotta contaminazione da canapulo nella fibra, iii) la fibra di canapa, con proprietà comparabili a quelle del lino, si è dimostrata adatta per applicazioni in compositi di alto valore. / European hemp fibres are the only natural fibre with an established sustainability certification. Hemp fibre quality is affected by genotype, agronomic techniques, harvest time and retting method. The main objective of this thesis is to outline the agronomic and post-harvest practices for improved fibre extraction and fibre quality, with special attention to multipurpose hemp production delaying the harvest from the flowering stage until seed ripening is complete. Planting density and nitrogen fertilization trials and variety trials were conducted in contrasting environments in Europe. Stems were decorticated following a standardised procedure and longitudinal hemp line for textile and high-added values application was compared with lab-scaled decortication. Impregnated fibre bundle tests were carried out with hemp hackled fibre bundles to compare composites and back-calculated fibre properties between genotypes, harvest times and retting methods. Results of this investigation suggest that i) optimum plant density and nitrogen fertilization are between 90 and 150 plants m-2 and 30 and 60 Kg N ha-1 respectively; ii) new yellow stemmed varieties are characterized by high decortication efficiency and relative high cleanness of the extracted fibre and iii) long hemp fibre, having properties comparable to those of flax, proved to be suitable for high-tech composites applications.