More students at college and universities are taking advantage of the opportunity to study abroad. During their time overseas, many will confront culture shock. Upon their return, they may also encounter a difficult transition, resulting in reverse culture shock. This study explores the various long term effects of reverse culture shock among study abroad alumni at a land grant institution. The alumni in this sample represent a variety of study abroad programs as well as experiences with reentry shock. By contributing further evidence regarding the influence of reverse culture shock over an extended period, it can provide incentive for universities to increase the level of reentry support for their students. Furthermore, by assisting students through the challenges of their reentry, educators can enhance the level of cultural learning from the experience as well as contribute to the students’ personal development.

No description available.

Methamphetamine (METH) abuse has become a fast growing drug problem that has developed into a global epidemic. In fact, METH is one of the most commonly abused substances with an estimated 35 million abusers worldwide and is said to be the second most popular illicit drug. The Western Province of South Africa has seen a dramatic increase in drug abuse in recent years where METH is the primary or secondary drug of abuse. Interestingly, more than 50% of these individuals are under the age of 20 years. The longer duration of euphoric effects of METH has attracted many users away from cocaine in favour of METH. In addition to the rapid euphoric effect of METH, the direct short-term effects include arousal, reduced fatigue, an increase in blood pressure, reduced appetite as well as sustained attention. Chronic METH abuse may result in debilitating and long-lasting effects that includes mood disorders such as depression. Studies suggest a strong relationship between exposure to adverse environmental factors early in life and the later development of a neuropsychiatric disorder, such as depression. However, these severe consequences do not seem to invoke cessation of the drug. The euphoric and addictive properties of METH causes users to abuse the drug with an increase in frequency and dose, even though it might not have been their original intention. The primary objective of this study was to investigate the effect of early-life administration of METH to stress-sensitive (Flinders Sensitive Line - FSL) and control (Flinders Resistant Line - FRL) rats on depressive-like behaviour and regional brain monoamine levels later in life. The study implemented a sixteen-day period for administration of METH or a vehicle control from postnatal day 19 (PnD19) to postnatal day 34 (PnD34). The latter developmental stage corresponds to pre-adolescence in the rat when neurological development are similar to that seen in human adolescents, and represents the stage when drug abuse is most common in humans. Chronic dosing of METH and saline was performed twice daily at 09:00 and at 15:00. The animals received a sub-cutaneous (SC) escalating dose regimen of METH during the 16 day period (mimicking binging behaviour in humans), with every dose escalating in increments of 0.2 mg/kg from 0.2 mg/kg to 6.0 mg/kg. The study then investigated whether early-life administration of METH would cause depressive-like behaviours directly after the injection period (immediate drug effects before withdrawal on PnD35) or later in life (after the withdrawal period in early adulthood on PnD60). The behavioural effects were assessed in a battery of tests and thereafter the rats were sacrificed and the frontal cortex removed and snap frozen for later analyses of altered neurochemistry. The study demonstrated that chronic METH treatment during pre-adolescence induces significant behavioural changes related to depression in humans directly after the injection period (PnD35) and later in life (PnD60). The animals displayed antidepressant-like behaviour in the forced swim test (FST) before withdrawal, yet a depressogenic effect was observed 25 days post-withdrawal. This effect also seems to be additive to the congenital depressive-like phenotype of FSL rats, suggesting a role for genetic susceptibility. This observation would be in line with the two-hit hypothesis of depression, suggesting that the manifestation of depression will result when a genetic predisposition is followed by an environmental stressor (i.e. METH) later in life. The data suggests a working hypothesis that individuals that already have a predisposition to depression may be more susceptible to developing depression when abusing METH. The fact that the FSL control rats were more immobile than FRL control rats also confirmed the face validity of the FSL genetic rat model of depression. Locomotor activity assessment indicated that METH treatment decreased locomotor activity in FSL and FRL rats compared to their vehicle controls on PnD35 but not on PnD60. It is important to note that the effects observed in locomotor activity could not have contributed to the immobility observed in the FST, confirming that the immobility in the FST indeed reflects psychomotor and not locomotor effects. The study also demonstrated that METH significantly lowers social interaction behaviour in both FRL and FSL rats, both immediately following drug treatment (PnD35) and after withdrawal (PnD60). It is therefore clear that this effect of METH is long-lasting, putatively related to neurodevelopmental effects. In addition, the rats investigated the familiar object for a greater amount of time in the novel object recognition test (nORT) on PnD35 and PnD60 and may be the result of loss of recognition memory for the familiar object. This data confirms that METH results in cognitive memory deficits probably due to sustained adverse neurodevelopmental effects. Neurochemical analyses of the frontal cortex indicated decreased serotonin (5-HT) and norepinephrine (NE) levels on PnD35. METH is widely recognised for its pro-inflammatory effects, while the reduced 5-HT levels observed may have been the result of an increase in circulating pro-inflammatory cytokines. Neurochemical analyses provided thought-provoking data concerning the role of the permissive hypotheses of depression, indicating that dopamine (DA) is most likely not responsible for the behavioural effects observed, at least under the current study conditions, whereas 5-HT is decidedly more involved than expected. The data also suggest that depletion in NE plays a role in the development of depressive-like behaviours following METH exposure. Based on these findings, we propose that disturbances in 5-HT and NE are a crucial mechanism in how METH abuse may precipitate or worsen depressive-like symptoms in individuals who abuse METH. It should be noted that this study does not discard the role of DA in the development of depression after METH exposure, although under the current study conditions it appears that DA does not play a central role. The current study demonstrated that pre-adolescent exposure to METH can reproduce most of the behavioural changes seen in depressed individuals, and that these behavioural data can be used to identify causal neurochemical factors. Environmental stressors such as METH abuse should be regarded as an additional diagnostic criterion and is relevant to an accumulative risk factor hypothesis. Furthermore, although further study is required, the data suggests that early-life exposure to METH may predispose an individual to mood disorders and behavioural abnormalities later in life. / MSc (Pharmacology), North-West University, Potchefstroom Campus, 2015

Methamphetamine (METH) abuse has become a fast growing drug problem that has developed into a global epidemic. In fact, METH is one of the most commonly abused substances with an estimated 35 million abusers worldwide and is said to be the second most popular illicit drug. The Western Province of South Africa has seen a dramatic increase in drug abuse in recent years where METH is the primary or secondary drug of abuse. Interestingly, more than 50% of these individuals are under the age of 20 years. The longer duration of euphoric effects of METH has attracted many users away from cocaine in favour of METH. In addition to the rapid euphoric effect of METH, the direct short-term effects include arousal, reduced fatigue, an increase in blood pressure, reduced appetite as well as sustained attention. Chronic METH abuse may result in debilitating and long-lasting effects that includes mood disorders such as depression. Studies suggest a strong relationship between exposure to adverse environmental factors early in life and the later development of a neuropsychiatric disorder, such as depression. However, these severe consequences do not seem to invoke cessation of the drug. The euphoric and addictive properties of METH causes users to abuse the drug with an increase in frequency and dose, even though it might not have been their original intention. The primary objective of this study was to investigate the effect of early-life administration of METH to stress-sensitive (Flinders Sensitive Line - FSL) and control (Flinders Resistant Line - FRL) rats on depressive-like behaviour and regional brain monoamine levels later in life. The study implemented a sixteen-day period for administration of METH or a vehicle control from postnatal day 19 (PnD19) to postnatal day 34 (PnD34). The latter developmental stage corresponds to pre-adolescence in the rat when neurological development are similar to that seen in human adolescents, and represents the stage when drug abuse is most common in humans. Chronic dosing of METH and saline was performed twice daily at 09:00 and at 15:00. The animals received a sub-cutaneous (SC) escalating dose regimen of METH during the 16 day period (mimicking binging behaviour in humans), with every dose escalating in increments of 0.2 mg/kg from 0.2 mg/kg to 6.0 mg/kg. The study then investigated whether early-life administration of METH would cause depressive-like behaviours directly after the injection period (immediate drug effects before withdrawal on PnD35) or later in life (after the withdrawal period in early adulthood on PnD60). The behavioural effects were assessed in a battery of tests and thereafter the rats were sacrificed and the frontal cortex removed and snap frozen for later analyses of altered neurochemistry. The study demonstrated that chronic METH treatment during pre-adolescence induces significant behavioural changes related to depression in humans directly after the injection period (PnD35) and later in life (PnD60). The animals displayed antidepressant-like behaviour in the forced swim test (FST) before withdrawal, yet a depressogenic effect was observed 25 days post-withdrawal. This effect also seems to be additive to the congenital depressive-like phenotype of FSL rats, suggesting a role for genetic susceptibility. This observation would be in line with the two-hit hypothesis of depression, suggesting that the manifestation of depression will result when a genetic predisposition is followed by an environmental stressor (i.e. METH) later in life. The data suggests a working hypothesis that individuals that already have a predisposition to depression may be more susceptible to developing depression when abusing METH. The fact that the FSL control rats were more immobile than FRL control rats also confirmed the face validity of the FSL genetic rat model of depression. Locomotor activity assessment indicated that METH treatment decreased locomotor activity in FSL and FRL rats compared to their vehicle controls on PnD35 but not on PnD60. It is important to note that the effects observed in locomotor activity could not have contributed to the immobility observed in the FST, confirming that the immobility in the FST indeed reflects psychomotor and not locomotor effects. The study also demonstrated that METH significantly lowers social interaction behaviour in both FRL and FSL rats, both immediately following drug treatment (PnD35) and after withdrawal (PnD60). It is therefore clear that this effect of METH is long-lasting, putatively related to neurodevelopmental effects. In addition, the rats investigated the familiar object for a greater amount of time in the novel object recognition test (nORT) on PnD35 and PnD60 and may be the result of loss of recognition memory for the familiar object. This data confirms that METH results in cognitive memory deficits probably due to sustained adverse neurodevelopmental effects. Neurochemical analyses of the frontal cortex indicated decreased serotonin (5-HT) and norepinephrine (NE) levels on PnD35. METH is widely recognised for its pro-inflammatory effects, while the reduced 5-HT levels observed may have been the result of an increase in circulating pro-inflammatory cytokines. Neurochemical analyses provided thought-provoking data concerning the role of the permissive hypotheses of depression, indicating that dopamine (DA) is most likely not responsible for the behavioural effects observed, at least under the current study conditions, whereas 5-HT is decidedly more involved than expected. The data also suggest that depletion in NE plays a role in the development of depressive-like behaviours following METH exposure. Based on these findings, we propose that disturbances in 5-HT and NE are a crucial mechanism in how METH abuse may precipitate or worsen depressive-like symptoms in individuals who abuse METH. It should be noted that this study does not discard the role of DA in the development of depression after METH exposure, although under the current study conditions it appears that DA does not play a central role. The current study demonstrated that pre-adolescent exposure to METH can reproduce most of the behavioural changes seen in depressed individuals, and that these behavioural data can be used to identify causal neurochemical factors. Environmental stressors such as METH abuse should be regarded as an additional diagnostic criterion and is relevant to an accumulative risk factor hypothesis. Furthermore, although further study is required, the data suggests that early-life exposure to METH may predispose an individual to mood disorders and behavioural abnormalities later in life. / MSc (Pharmacology), North-West University, Potchefstroom Campus, 2015

L’apport de graines oléagineuses dans la ration de la vache laitière pendant 1 à 3 mois pourrait améliorer la qualité nutritionnelle du lait, mais également pénaliser dans certains cas les performances zootechniques. Peu de données sont disponibles sur les effets de ces stratégies alimentaires sur de plus longues périodes. L’objectif de cette thèse est de quantifier au cours de 2 lactations consécutives, les effets de supplémentations en lin ou en trois différentes formes de colza de rations à base d’herbe conservée en hiver et pâturée en été sur les performances zootechniques de la vache laitière et la composition fine en acides gras du lait. Les effets des suppléments étudiés persistent au sein de chaque période (hiver et été) et sont répétables d’un été à l’autre. Ils sont par ailleurs similaires à ceux observés lors d’études de durée plus courte (1 à 3 mois). Ces stratégies ne permettent pas d’améliorer les performances zootechniques et diminuent parfois le taux protéique du lait, notamment en hiver. Toutefois, elles réduisent les teneurs du lait en acides gras saturés au profit de l’acide oléique et, dans le cas du lin de l’acide α-linolénique. Ces modifications peuvent être considérées comme une amélioration de la qualité nutritionnelle du lait. Cependant, le lin extrudé et le tourteau de colza gras augmentent les acides gras trans et les suppléments diminuent souvent l’acide ruménique du lait au pâturage. La distribution des isomères des acides gras insaturés cis et trans du lait dépend du type de graine et du niveau d’amidon de la ration, mais pas de la forme d’apport du colza, qui influence toutefois l’amplitude des effets observés. Par ailleurs, l’analyse détaillée du profil en acides gras du lait a permis de mieux comprendre le métabolisme des acides linoléiques et linoléniques conjugués, en lien avec la lipogenèse mammaire. / Addition of oilseed supplements to dairy cow diets for 1 to 3 months may improve the milk nutritional quality, but detrimental effects on animal performance may also occur. However, data is scarce on long-term effects of these nutritional strategies. The objective of this thesis was to quantify the effects of extruded linseed and three forms of rapeseed-derived supplements on dairy cow performance and detailed milk fatty acid composition, during 2 consecutive lactations. Basal diet was conserved grass during winter and pasture during summer. Oilseed supplements effects persist within each period (winter and summer) and are repeatable between the 2 summer periods. Long-term effects observed over 2 consecutive lactations are similar to those observed during short-term (1 to 3 months) studies. These oilseed-derived supplements not improve dairy cow performance, but decrease the milk protein content in some instances, especially during winter period. Nevertheless, oilseed supplementations reduce milk saturated fatty acid content and increase milk content in oleic acid and with linseed in α-linolenic acid. Such changes could be considered as an improvement of the milk nutritional quality. However, extruded linseed and fat-rich rapeseed meal increase milk trans fatty acid content, and oilseed supplements often decrease milk rumenic acid at pasture. Isomer distribution of cis and trans unsaturated fatty in milk fat is dependent on the oilseed nature and diet starch content, but not on the rapeseed form. However, rapeseed form modifies the magnitude of observed effects. Furthermore, the detailed analyses of milk fatty acid profile allowed to explore conjugated linoleic and linolenic fatty acids metabolism, and their relationship with mammary lipogenesis.

No description available.

La présente thèse porte sur les effets à long terme des traumatismes craniocérébraux légers (TCCL), incluant les commotions cérébrales, ainsi que sur certains facteurs influençant l’évolution post-blessure chez deux populations considérées vulnérables, soit les athlètes féminines ainsi que les adultes vieillissants. Dans une première étude, les capacités olfactives d’athlètes féminines commotionnées, mais asymptomatiques, ont été évaluées en moyenne deux ans après la dernière commotion. L’intérêt de cette étude réside principalement dans l’investigation du rôle potentiel du polymorphisme BDNF Val66Met (BDNFMet), associé à une sécrétion réduite de la protéine BDNF impliquée dans la neuroplasticité, pour expliquer les variations du fonctionnement olfactif post-commotion. Dans une deuxième étude, les effets cognitifs d’avoir subi un seul TCCL ont été caractérisés chez des individus âgés de 50 à 70 ans ayant subi leur blessure environ cinq ans plus tôt. Cette caractérisation est particulièrement pertinente alors que la majorité des études s’intéressant aux effets à long terme de cette blessure ont étudié des individus ayant subi de multiples TCCL. De plus, cette étude visait à évaluer si un programme d’entraînement physique aérobie de douze semaines permettrait d’améliorer les fonctions cognitives altérées chez les TCCL comparativement aux contrôles. Les résultats de la présente thèse permettent d’abord de mieux caractériser certains effets à long terme du TCCL. Plus précisément, la première étude suggère un patron de fonctionnement olfactif distinct selon le génotype BDNF chez les athlètes féminines commotionnées. Ainsi, les porteuses du BDNFMet ont significativement mieux performé que les BDNFval aux différentes tâches olfactives. Puisque cette relation génétique n’était pas présente chez les participantes contrôles, ces résultats suggèrent que le fonctionnement olfactif, suite à une commotion cérébrale, est, du moins en partie, médié par le polymorphisme BDNFMet. La deuxième étude suggère, pour sa part, des effets cognitifs à long terme d’avoir subi un seul TCCL chez des individus sédentaires, mais en santé, âgés de 50 à 70 ans. Ainsi, les participants TCCL ont moins bien performé que les participants contrôles, appariés pour l’âge et le sexe, aux tâches neuropsychologiques mesurant des aspects de la vitesse de traitement de l’information, du fonctionnement exécutif (planification, fluence verbale) et de la mémoire visuelle. Cette étude n’a toutefois pas relevé de différence sur le plan de l’attention, de l’inhibition, de la mémoire verbale et des habiletés visuoconstructives. Ces résultats cognitifs sont un ajout intéressant à la littérature, car ils surviennent chez des individus qui ne présentaient aucun des facteurs de risque (maladie chronique, problème de santé mentale) typiquement associés aux effets à long terme des TCCL. En ce qui a trait au deuxième volet de l’étude, l’exercice physique aérobie a permis d’améliorer les capacités cardiorespiratoires (VO2max) des patients TCCL davantage que les étirements (condition contrôle). Toutefois, dans ce petit échantillon de seize participants, l’exercice aérobie n’a pas permis d’améliorer les fonctions cognitives altérées des patients TCCL. Différentes explications possibles sont abordées afin de guider les futures études. / The following thesis investigates the long-term effects of mild traumatic brain injury (mTBI), including concussions, and factors influencing post-injury evolution in two vulnerable populations: female athletes and aging individuals. In a first study, olfactory capacities of asymptomatic concussed female athletes were evaluated an average of two years after their last concussion. The appeal of this study lies mainly in its investigation of the potential role of the BDNF Val66Met (BDNFMet) polymorphism, which is associated with reduced secretion of the BDNF neuroplasticity protein, on post-concussion olfactory variations. In a second study, cognitive effects of sustaining a single mTBI were assessed in individuals between 50 and 70 years old who sustained their injury on average five years earlier. This characterization is particularly relevant given that most studies focusing on long-term effects of this injury have studied individuals having sustained multiple mTBI. Furthermore, this study also aimed to evaluate if a twelve-week aerobic exercise program would allow improvements of altered cognitive functions in mTBI patients. Results from the following thesis first allow to better describe some long-term effects of mTBI. More precisely, the first study suggests different patterns of olfactory functioning according to BDNF genotype in female concussed athletes. Thus, BDNFmet carriers performed significantly better than BDNFval carriers at the different olfactory tasks. Given that this genetic relationship was not present in control participants, these results suggest that olfactory functioning following a concussion is, at least in part, mediated by the BDNFmet polymorphism. As for the second study, it suggests long-term cognitive effects of having sustained a single mTBI in sedentary, but healthy, individuals between the ages of 50 and 70. Indeed, mTBI participants showed lower performance when compared to age and sex-matched control participants on neuropsychological tasks measuring aspects of processing speed, executive functioning (planning, verbal fluency) and visual memory. This study did not find any difference regarding attention, inhibition, verbal memory and visuoconstructive abilities. These cognitive results are an interesting contribution to the literature as they occur in individuals presenting no risk factor (chronic disease, mental health disorders) typically associated with long-term effects of mTBI. Regarding the second phase of this study, aerobic exercise improved cardiorespiratory fitness (VO2max) more than stretching (control condition) in mTBI patients. However, in this small sample of sixteen participants, aerobic exercise did not allow to improve altered cognitive functions in mTBI participants. Different possible explanations are addressed to guide future studies.

Introduktion: Den alarmerande spridningen av coronaviruset (COVID-19) utgör ett allvarligt hot mot nationer och samhällen runt om i världen (WHO, 2020). Risken för att bli svårt sjuk i covid-19 ökar med ålder. Viruset som orsakar covid-19 klassas som en infektionssjukdom och smittan sprids genom små droppar som skapas när en infekterad person hostar, nyser eller andas ut. Den påminner ofta om förkylning eller influensa med feber och hosta. Flera länder svarar genom restriktioner av icke-väsentliga aktiviteter och genom så kallade lockdowns eller rekommendationer samt med åtgärder som ska förhindra virusets framfart vilket varit ett viktigt verktyg tillsammans med smittspårning. Det har inneburit stora kostnader och negativ påverkanför både samhälle , den enskilde individen och i synnerhet de äldre. Syfte: Studiens syfte är att undersöka isoleringen och ensamhet påverkan på äldre individer under Covid-19 och dess konsekvenser för hälsa och välbefinnande. Metod: En systematisk litteraturstudie som inkluderade 11 vetenskapliga artiklar publicerade 2020–2021 som söktes i databaserna PubMed och CINAHL. Resultat: Resultatet uppvisar gruppens heterogenitet men även belyser det faktum att flertalet äldre rapporterar ökad ensamhet och oro som konsekvenser av rekommendationer och åtgärder under covid-19 pandemin. Slutsats: Det finns en ökad ohälsa bland äldre individer. Många har klarat sig positivt och anpassat sig, medan andra har upplevt försämrade känslor av ensamhet och med oförmåga att anta ny teknik för att underlätta social interaktion. Att identifiera äldre individer som upplever ihållande ensamhet under pandemin kan vara avgörande för att förbättra deras allmänna välbefinnande och minska risken för ytterligare ohälsa. / Introduction: The alarming spread of the coronavirus leading to COVID-19 posed a serious threat to nations and societies around the world (WHO, 2020). The risk of becoming seriously ill with COVID-19 increases with age. The coronavirus that causes COVID-19 is spread through small drops created when an infected person coughs, sneezes, or exhales. It is reminiscent of a cold or flu with fever, cough, and many other symptoms. Several countries responded by imposing restrictions on non-essential activities, lockdowns, and social distancingrecommendations, as well as others measures to prevent the virus's spread. These have been important tools along with infection tracing. However, this also has entailedhigh costs and a negative impact at the level of society, the individual and especially the elderly. Purpose: The purpose of this study was to investigate the impact of COVID-19 on isolation and loneliness among elderly and consequences for health and well-being. Method: A systematic literature study using the databases, PubMed and CINAHL, included 11 peer-reviewed articles published between 2020–2021. Results: The results showed that the impact of COVID-19 washeterogeneous among elderly and highlighted that most elderly people reported increased loneliness and anxiety as a consequence of national and global health recommendations and measures, such as mandated quarantine and social distancing, during the COVID-19 pandemic. Conclusion: COVID-19 increased ill mental health among older individuals. Many have coped positively and adapted, while others have experienced worsening feelings of loneliness,especially due to an inability to adopt technologies to facilitate social interaction. Identifying elderly individuals who experience persistent loneliness during the COVID-19 pandemic iscrucial to improve their overall well-being and reduce the risk of further ill mental and physical health.

The present study aims to contribute to knowledge about the psychosocial health inworking life after growing up with a parent with a mental illness. The study also wants toinvestigate what impact from society is needed in order to support a positive developmentfor this group of children. Theoretical perspectives used were the Socio-ecological modeland Attachment theory. A qualitative method with semi structured interviews was used.Six informants from a purposive sampling group participated in the study. The collectedmaterial was transcribed, and thematic analysis was carried out. The results mainlyshowed that security seeking, low self-esteem, insecurity, pronounced sense ofresponsibility, a great need for adaption and control, and a striving for acceptance fromthe environment was important. The results also show the importance of support and helpfrom the environment. Growing up with a mentally ill parent does not necessarily have anegative effect on a person’s occupational health, but several experiences in working lifewere reported, that could be related to childhood conditions in a family with mentalillness

Questions : Cette thèse visait à répondre à deux questions fondamentales : 1) Est-ce que les athlètes qui présentent un historique de commotions cérébrales du sport en conservent des effets délétères à long terme? ; et 2) Est-ce que les effets néfastes des commotions cérébrales récurrentes sur le fonctionnement tant cognitif que moteur sont cumulatifs? Devis expérimental : À l’aide d’un plan d’investigation double-cohorte réalisé avec un groupe d’athlètes évoluant au niveau universitaire et un autre formé d’anciens athlètes universitaires testés plus de trois décennies plus tard, les quatre études qui composent cette thèse ont employé des méthodes raffinées d’investigation des fonctions cognitives et motrices pour en déceler des atteintes persistantes. Méthodologie : Les potentiels évoqués cognitifs ainsi que les tests neuropsychologiques ont permis de sonder le fonctionnement cognitif de ces athlètes alors que la stimulation magnétique transcrânienne, une plateforme de force permettant de mesurer la stabilité posturale ainsi qu’un système d’enregistrement tridimensionnel des mouvements rapides alternatifs ont servi à l’évaluation de l’intégrité du système moteur. Résultats : Cette thèse a permis de déceler des altérations persistentes et cumulatives des fonctions cognitives et motrices. De plus, ces subtiles atteintes observées chez les jeunes athlètes, affectant essentiellement des marqueurs neurophysiologiques sous-cliniques du fonctionnement cognitif et moteur, s’étaient accentuées chez les anciens athlètes universitaires qui montraient un déclin quantifiable tant des fonctions cognitives que motrices. Discussion : Ces résultats suggèrent d’une part que les commotions cérébrales du sport entraînent des altérations cognitives et motrices chroniques qui s’accentuent en fonction du nombre de commotions cérébrales subies. D’autre part, les effets délétères des commotions cérébrales du sport sur le fonctionnement cognitif et moteur combinés à ceux associés au processus de vieillissement entraînent un déclin cognitif et moteur quantifiable en comparaison aux anciens athlètes n’ayant jamais subi de commotions cérébrales. / Question: This thesis aimed to address two fundamental issues: 1) Are there long-lasting effects of sports-related concussion on cognitive and motor functions? and 2) Are the adverse effects of recurrent concussions cumulative? Experimental Design: The cross-sectional thesis design included a group of active university-level athletes as well as a group of former athletes recruited more than three decades after their university years who were tested on neurophysiological measures of both cognitive and motor system functions. Methods: Event-Related potentials and neuropsychological tests were used to assess cognitive functions while transcranial magnetic paradigms were used to assess motor cortex excitability, a force platform was used to assess postural stability and a 3-dimensional recording device was used to track hand position when performing a rapid alternating movement task. Results: This thesis disclosed persistent and cumulative alterations of both cognitive and motor functions after sports concussions. Furthermore, subclinical, neurophysiological alterations found in young concussed athletes were exacerbated in former athletes with concussions who displayed quantifiable cognitive and motor functions decline more than three decades post-concussion. Discussion: These results suggest that sports concussions induce cognitive and motor functions abnormalities that worsen as a function of the number of concussions sustained. Moreover, findings from the present thesis indicate that the deleterious effects of sports concussion on cognitive and motor system functions combined to those associated with the aging process lead to quantifiable decline on both cognition and motor functions.