BDNF polymorphisms are linked to poorer working memory performance, reduced cerebellar and hippocampal volumes and differences in prefrontal cortex in a Swedish elderly population

BACKGROUND: Brain-derived neurotrophic factor (BDNF) links learning, memory and cognitive decline in elderly, but evidence linking BDNF allele variation, cognition and brain structural differences is lacking. METHODS: 367 elderly Swedish men (n = 181) and women (n = 186) from Prospective Investigation of the Vasculature in Uppsala seniors (PIVUS) were genotyped and the BDNF functional rs6265 SNP was further examined in subjects who completed the Trail Making Task (TMT), verbal fluency task, and had a magnetic resonance imaging (MRI) scan. Voxel-based morphometry (VBM) examined brain structure, cognition and links with BDNF. RESULTS: The functional BDNF SNP (rs6265,) predicted better working memory performance on the TMT with positive association of the Met rs6265, and was linked with greater cerebellar, precuneus, left superior frontal gyrus and bilateral hippocampal volume, and reduced brainstem and bilateral posterior cingulate volumes. CONCLUSIONS: The functional BDNF polymorphism influences brain volume in regions associated with memory and regulation of sensorimotor control, with the Met rs6265 allele potentially being more beneficial to these functions in the elderly

Detailed Analysis of Variants in FTO in Association with Body Composition in a Cohort of 70-Year-Olds Suggests a Weakened Effect among Elderly

The rs9939609 single-nucleotide polymorphism (SNP) in the fat mass and obesity (FTO) gene has previously been associated with higher BMI levels in children and young adults. In contrast, this association was not found in elderly men. BMI is a measure of overweight in relation to the individuals' height, but offers no insight into the regional body fat composition or distribution.To examine whether the FTO gene is associated with overweight and body composition-related phenotypes rather than BMI, we measured waist circumference, total fat mass, trunk fat mass, leg fat mass, visceral and subcutaneous adipose tissue, and daily energy intake in 985 humans (493 women) at the age of 70 years. In total, 733 SNPs located in the FTO gene were genotyped in order to examine whether rs9939609 alone or the other SNPs, or their combinations, are linked to obesity-related measures in elderly humans.Cross-sectional analysis of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) cohort.Neither a single SNP, such as rs9939609, nor a SNP combination was significantly linked to overweight, body composition-related measures, or daily energy intake in elderly humans. Of note, these observations hold both among men and women.Due to the diversity of measurements included in the study, our findings strengthen the view that the effect of FTO on body composition appears to be less profound in later life compared to younger ages and that this is seemingly independent of gender

The common FTO variant rs9939609 is not associated with BMI in a longitudinal study on a cohort of Swedish men born 1920-1924

<p>Abstract</p> <p>Background</p> <p>Common FTO (fat mass and obesity associated) gene variants have recently been strongly associated with body mass index and obesity in several large studies. Here we set out to examine the association of the <it>FTO </it>variant rs9939609 with BMI in a 32 year follow up study of men born 1920-1924. Moreover, we analyzed the effect of physical activity on the different genotypes.</p> <p>Methods</p> <p>The <it>FTO </it>rs9936609 was genotyped using an Illumina golden gate assay. BMI was calculated using standard methods and body fat was estimated by measuring skinfold thickness using a Harpenden caliper. Physical activity was assessed using a four question medical questionnaire.</p> <p>Results</p> <p><it>FTO </it>rs9939609 was genotyped in 1153 elderly Swedish men taking part of a population-based cohort study, the ULSAM cohort. The risk of obesity and differences in BMI according to genotype at the ages of 50, 60, 70, 77 and 82 were investigated. We found no increased risk of obesity and no association with BMI at any age with the <it>FTO </it>rs9939609 variant. We found however interaction between physical activity at the age of 50 years and genotype on BMI levels (p = 0.039) and there was a clear trend towards larger BMI differences between the TT and AA carriers as well as between AT and AA carriers in the less physically active subjects.</p> <p>Conclusion</p> <p>Here we found that the well established obesity risk allele for a common variant in <it>FTO </it>does not associate with increased BMI levels in a Swedish population of adult men which reached adulthood before the appearance of today's obesogenic enviroment. There is an interaction between physical activity and the effect of the FTO genotype on BMI levels suggesting that lack of physical activity is a requirement for an association of FTO gene variants to obesity.</p

The obesity gene, TMEM18, is of ancient origin, found in majority of neuronal cells in all major brain regions and associated with obesity in severely obese children

<p>Abstract</p> <p>Background</p> <p>TMEM18 is a hypothalamic gene that has recently been linked to obesity and BMI in genome wide association studies. However, the functional properties of TMEM18 are obscure.</p> <p>Methods</p> <p>The evolutionary history of TMEM18 was inferred using phylogenetic and bioinformatic methods. The gene's expression profile was investigated with real-time PCR in a panel of rat and mouse tissues and with immunohistochemistry in the mouse brain. Also, gene expression changes were analyzed in three feeding-related mouse models: food deprivation, reward and diet-induced increase in body weight. Finally, we genotyped 502 severely obese and 527 healthy Swedish children for two SNPs near TMEM18 (rs6548238 and rs756131).</p> <p>Results</p> <p>TMEM18 was found to be remarkably conserved and present in species that diverged from the human lineage over 1500 million years ago. The TMEM18 gene was widely expressed and detected in the majority of cells in all major brain regions, but was more abundant in neurons than other cell types. We found no significant changes in the hypothalamic and brainstem expression in the feeding-related mouse models. There was a strong association for two SNPs (rs6548238 and rs756131) of the TMEM18 locus with an increased risk for obesity (p = 0.001 and p = 0.002).</p> <p>Conclusion</p> <p>We conclude that TMEM18 is involved in both adult and childhood obesity. It is one of the most conserved human obesity genes and it is found in the majority of all brain sites, including the hypothalamus and the brain stem, but it is not regulated in these regions in classical energy homeostatic models.</p

Neurobeachin, a Regulator of Synaptic Protein Targeting, Is Associated with Body Fat Mass and Feeding Behavior in Mice and Body-Mass Index in Humans

Neurobeachin (Nbea) regulates neuronal membrane protein trafficking and is required for the development and functioning of central and neuromuscular synapses. In homozygous knockout (KO) mice, Nbea deficiency causes perinatal death. Here, we report that heterozygous KO mice haploinsufficient for Nbea have higher body weight due to increased adipose tissue mass. In several feeding paradigms, heterozygous KO mice consumed more food than wild-type (WT) controls, and this consumption was primarily driven by calories rather than palatability. Expression analysis of feeding-related genes in the hypothalamus and brainstem with real-time PCR showed differential expression of a subset of neuropeptide or neuropeptide receptor mRNAs between WT and Nbea+/− mice in the sated state and in response to food deprivation, but not to feeding reward. In humans, we identified two intronic NBEA single-nucleotide polymorphisms (SNPs) that are significantly associated with body-mass index (BMI) in adult and juvenile cohorts. Overall, data obtained in mice and humans suggest that variation of Nbea abundance or activity critically affects body weight, presumably by influencing the activity of feeding-related neural circuits. Our study emphasizes the importance of neural mechanisms in body weight control and points out NBEA as a potential risk gene in human obesity

Obesity and Increased Susceptibility : Role of FTO and MGAT1 Genetic Variants

Obesity is a complex and a highly individualized disease and the molecular mechanisms behind this disorder need to be better elucidated. Identification of genes and genetic variants that are involved provide opportunities to establish a genetic understanding of the disease. These findings may also provide more rational approaches to therapy, either by identifying underlying causes or point out the need for different treatments. In addition, the timing and severity of obesity may provide insights into the aetiology of obesity and also identify age-specific determinants of weight gain. Recently, genome-wide association studies have led to a rapid progress in our understanding of the genetic basis of various diseases and candidate genes for obesity have been identified. The overall aim of this thesis was to investigate the genetic impact on severity of childhood obesity and the associations between obesity and genetic variants in the fat mass and obesity associated gene, FTO, and MGAT1, the gene encoding mannosyl (α-1,3-)-glycoprotein β-1,2-N-acetyl-glucosaminyltransferase. We show that the impact of parental body mass index (BMI) on the severity of obesity in children is strengthened as the child grows older, whereas the age at obesity onset is of limited importance. By association studies, we show that single nucleotide polymorphisms downstream MGAT1 influence susceptibility to obesity. Moreover, these variants affect the levels of unsaturated fatty acids and desaturase indices, variables previously shown to correlate with obesity. Furthermore, one variant in the first intronic region of FTO is associated with obesity among children but not with BMI or other measures of adiposity at older ages. However, this variant shows a weight-dependent association with cognitive function among elderly men. By direct sequencing, we identified novel variants in FTO, affecting glucose homeostasis in a BMI-independent manner. Furthermore, we found gender specific effects for FTO, both regarding obesity susceptibility and related phenotypes

Obesity and Increased Susceptibility : Role of FTO and MGAT1 Genetic Variants

Obesity is a complex and a highly individualized disease and the molecular mechanisms behind this disorder need to be better elucidated. Identification of genes and genetic variants that are involved provide opportunities to establish a genetic understanding of the disease. These findings may also provide more rational approaches to therapy, either by identifying underlying causes or point out the need for different treatments. In addition, the timing and severity of obesity may provide insights into the aetiology of obesity and also identify age-specific determinants of weight gain. Recently, genome-wide association studies have led to a rapid progress in our understanding of the genetic basis of various diseases and candidate genes for obesity have been identified. The overall aim of this thesis was to investigate the genetic impact on severity of childhood obesity and the associations between obesity and genetic variants in the fat mass and obesity associated gene, FTO, and MGAT1, the gene encoding mannosyl (α-1,3-)-glycoprotein β-1,2-N-acetyl-glucosaminyltransferase. We show that the impact of parental body mass index (BMI) on the severity of obesity in children is strengthened as the child grows older, whereas the age at obesity onset is of limited importance. By association studies, we show that single nucleotide polymorphisms downstream MGAT1 influence susceptibility to obesity. Moreover, these variants affect the levels of unsaturated fatty acids and desaturase indices, variables previously shown to correlate with obesity. Furthermore, one variant in the first intronic region of FTO is associated with obesity among children but not with BMI or other measures of adiposity at older ages. However, this variant shows a weight-dependent association with cognitive function among elderly men. By direct sequencing, we identified novel variants in FTO, affecting glucose homeostasis in a BMI-independent manner. Furthermore, we found gender specific effects for FTO, both regarding obesity susceptibility and related phenotypes

Associations of self-reported sleep disturbance and duration with academic failure in community-dwelling Swedish adolescents : Sleep and academic performance at school

OBJECTIVE: To examine associations of self-reported sleep disturbance and short sleep duration with the risk for academic failure. METHODS: A cohort of ~40,000 adolescents (age range: 12-19 years) who were attending high school grades 7, 9, and 2nd year of upper secondary school in the Swedish Uppsala County were invited to participate in the Life and Health Young Survey (conducted between 2005 and 2011 in Uppsala County, Sweden). In addition to the question how many subjects they failed during the school year (outcome variable), subsamples of adolescents also answered questions related to subjective sleep disturbance (n = 20,026) and habitual sleep duration (n = 4736) (exposure variables). Binary logistic regression analysis was utilized to explore if self-reported sleep disturbances and habitual short sleep duration (defined as less than 7-8 h sleep per night) increase the relative risk to fail subjects during the school year (controlled for possible confounders, e.g. body-mass-index). RESULTS: Adolescents with self-reported sleep disturbances had an increased risk for academic failure (i.e., they failed at least one subject during the school year; OR: boys, 1.68; girls, 2.05, both P &lt; 0.001), compared to adolescents without self-reported sleep disturbances. In addition, adolescents who reported short sleep duration on both working and weekend days were more likely to fail at least one subject at school than those who slept at least 7-8 h per night (OR: boys, 4.1; girls, 5.0, both P &lt; 0.001). CONCLUSION: Our findings indicate that reports of sleep disturbance and short sleep duration are linked to academic failure in adolescents. Based on our data, causality cannot be established

Genome-wide analysis reveals DNA methylation markers that vary with both age and obesity

The combination of the obesity epidemic and an aging population presents growing challenges for the healthcare system. Obesity and aging are major risk factors for a diverse number of diseases and it is of importance to understand their interaction and the underlying molecular mechanisms. Herein the authors examined the methylation levels of 27578 CpG sites in 46 samples from adult peripheral blood. The effect of obesity and aging was ascertained with general linear models. More than one hundred probes were correlated to aging, nine of which belonged to the KEGG group map04080. Additionally, 10 CpG sites had diverse methylation profiles in obese and lean individuals, one of which was the telomerase catalytic subunit (TERT). In eight of ten cases the methylation change was reverted between obese and lean individuals. One region proved to be differentially methylated with obesity (LINC00304) independent of age. This study provides evidence that obesity influences age driven epigenetic changes, which provides a molecular link between aging and obesity. This link and the identified markers may prove to be valuable biomarkers for the understanding of the molecular basis of aging, obesity and associated diseases