Background: Suicidal behaviour devastates families, communities, and societies, as well as the millions of individuals who survive suicide attempts. This thesis addresses an urgent need to develop new treatment and intervention strategies for millions of at-risk people by exploring potential metabolic risk factors of suicidal behaviour. Methods: A systematic review and meta-analysis was performed to assess the association between BMI and suicidal behaviour. We explored the association between attempted suicide and various metabolic factors and health behaviours using data from the Determinants of Suicide Conventional and Emergent Risk (DISCOVER) study. DISCOVER is an age and sex matched case-control study comparing adult psychiatric inpatients who had made a recent suicide attempt (n=84) to psychiatric inpatients (n=104) and community members (n=93) who have never attempted suicide. The following potential risk factors were assessed using logistic regression analyses: BMI, waist-circumference, serum total cholesterol, physical activity, tobacco use, and dietary food groups. Results: The systematic review included 38 studies. A meta-analysis established an inverse association between BMI and completed suicide, whereby being underweight is associated with the greatest risk of suicide and being obese or overweight is associated with a deceased risk of suicide relative to normal weight. Evidence for an association between BMI and attempted suicide remains equivocal. The review suggests no association between BMI and suicidal ideation. Analysis of DISCOVER data demonstrated that even a small amount of regular physical activity is significantly associated with decreased risk of attempted suicide. Tobacco use was associated with an increased risk of attempted suicide. Contrary to prior research, obesity, serum-total cholesterol, and diet were not found to be significant risk factors. Conclusion: BMI is inversely related to completed suicide. Obese individuals may be more likely to choose less lethal methods of suicide or may be less susceptible to fatal overdose or self-poisonings. Clinicians should monitor underweight patients for increased risk of suicide. Contrary to prior research, serum total cholesterol, BMI, and waist-circumference were not significantly associated with risk of attempted suicide. Increased physical activity was associated with a decreased risk of attempted suicide, and tobacco use was associated with an increased risk of attempted suicide. While people at risk of attempting suicide tend to use more tobacco products and exercise less than non-suicidal community members, so do non-suicidal psychiatric patients. For this reason, it remains unclear whether smoking habits represent a useful clinical predictor of suicide risk. / Thesis / Master of Science (MSc)

L’augmentation de l’obésité durant les dernières décennies expose la population à un risque accru de problèmes métaboliques et des maladies cardiovasculaires. Ce travail étudiait, d’une part, l’association de l’obésité avec la dysfonction diastolique et la rigidité artérielle aortique vingt ans plus tard chez des adultes initialement en bonne santé. Cette étude montrait que l’obésité générale mesurée par l’indice de masse corporelle et l’adiposité abdominale mesurée par le tour de taille étaient associées positivement à la dysfonction diastolique. Mais elles semblaient jouer un rôle protecteur sur la rigidité artérielle. Le ratio “tour de taille/indice de masse corporelle” semblait mieux isoler l’adiposité abdominale/viscérale de l’obésité générale, et était associé positivement à la rigidité artérielle. Il permettrait de montrer un rôle néfaste à long terme de l’adiposité abdominale/viscérale sur la rigidité artérielle même quand le poids est normal. La présence combinée de l’obésité abdominale (mesurée par le tour de taille) et d’un taux plus élevé de triglycérides était associée à un risque élevé de dysfonction diastolique. Dans la deuxième partie, nous nous sommes intéressés aux individus ayant déjà une hypertension artérielle. Ce travail montrait que, parmi les sujets ayant une hypertension, ceux ayant une hypertension non-diagnostiquée avaient un profil spécifique (plus souvent de sexe masculin, un tour de taille moins élevé, et moins souvent de maladies cardiovasculaires/diabète, antécédents familiaux d’hypertension et consultations de soins primaires moins fréquents). La présence concomitante d’un nombre élevé de ces critères renforçait fortement l’absence de primo-diagnostic. Nos résultats peuvent aider dans l’identification précoce des sujets à risque, la prévention et le management thérapeutique / Worldwide increasing obesity over the last decades expose the population to an increased risk of metabolic perturbations and cardiovascular diseases. This research investigated first the association of obesity with diastolic dysfunction and aortic stiffness observed 20 years later in initially healthy adults. General obesity measured with body mass index and abdominal adiposity measured with waist circumference were positively associated with diastolic dysfunction. But, these anthropometric parameters played a protective role in aortic stiffness. The ratio “waist circumference / body mass index” appeared to better isolate abdominal adiposity from general obesity and was then positively associated with aortic stiffness. It allowed to evidence a harmful role of abdominal adiposity in aortic stiffness, even in subjects with normal body weight. The presence of abdominal adiposity (measured with waist circumference) combined with an elevated level of triglycerides was associated with a higher risk of diastolic dysfunction. In the second part, our research focused on hypertensive individuals. It showed that among hypertensive subjects, those having undiagnosed-hypertension had specific features (being more often male, having less elevated waist circumference, and having fewer cardiovascular diseases/diabetes, familial hypertension history, and primary care uses). The concomitant presence of a higher number of these criteria appeared to strongly reinforce the absence of diagnosis. Our findings may help to early identify subjects at risk, and to establish prevention and therapeutic management

Background: Prostate cancer is the most common cancer in Sweden with around 10,000 new cases every year. Kidney and bladder cancer are less common with 1,000 and 2,000 new cases annually, respectively. The incidence of these cancer sites is higher in developed, than in developing countries, suggesting an association between lifestyle and cancer risk. The aims of this thesis were to investigate body mass index (BMI), blood pressure, and blood levels of glucose, total cholesterol, and triglycerides as risk factors for prostate, kidney, and bladder cancer. Furthermore, we aimed at assess probabilities of prostate cancer and competing events, all-cause death, for men with normal and high levels of metabolic factors. Material and methods: This thesis was conducted within the Metabolic Syndrome and Cancer project (Me-Can), a pooled cohort study with data from 578,700 participants from Norway, Sweden, and Austria. Data from metabolic factors were prospectively collected at health examinations and linked to the Cancer and Cause of Death registers in each country.  Results: High levels of metabolic factors were not associated with increased risk of prostate cancer, but high levels of BMI and blood pressure were associated with risk of prostate cancer death. The probability of prostate cancer was higher for men with normal levels of metabolic factors compared to men with high levels, but the probability of all-cause death, was higher for men with high levels than for those with normal levels. For both men and women, high levels of metabolic factors were associated with increased risk of kidney cancer (renal cell carcinoma). Furthermore, blood pressure for men and BMI for women were found as independent risk factors of kidney cancer. High blood pressure was associated with an increased risk of bladder cancer for men. Conclusions: High levels of metabolic factors were associated to risk of kidney and bladder cancer and to death from kidney, bladder, and prostate cancer. Compared to men with normal levels, men with high levels of metabolic factors had a decreased probability of prostate cancer but an increased probability of all-cause death. / <p>Ytterligare forskningsfinansiärer: World Cancer Research Fund (2007/09) och Wereld Kanker Onderzoek Fonds (R2010/247)</p> / Me-Can