We report a genomewide linkage study of type 2 diabetes (T2D [MIM 125853]) in the Icelandic population. A list of type 2 diabetics was cross-matched with a computerized genealogical database clustering 763 type 2 diabetics into 227 families. The diabetic patients and their relatives were genotyped with 906 microsatellite markers. A nonparametric multipoint linkage analysis yielded linkage to 5q34-q35.2 (LOD = 2.90, P=1.29 x 10(-4)) in all diabetics. Since obesity, here defined as body mass index (BMI) > or =30 kg/m(2), is a key risk factor for the development of T2D, we studied the data either independently of BMI or by stratifying the patient group as obese (BMI > or =30) or nonobese (BMI <30). A nonparametric multipoint linkage analysis yielded linkage to 5q34-q35.2 (LOD = 3.64, P=2.12 x (10)-5) in the nonobese diabetics. No linkage was observed in this region for the obese diabetics. Linkage analysis conditioning on maternal transmission to the nonobese diabetics resulted in a LOD score of 3.48 (P=3.12 x 10(-5)) in the same region, whereas conditioning on paternal transmission led to a substantial drop in the LOD score. Finally, we observed potential interactions between the 5q locus and two T2D susceptibility loci, previously mapped in other populations.

ObjectiveFew studies have explored the potential interrelated associations of screen time and physical activity with mental health in youth, particularly using objective methods. We examined cross-sectional associations of these variables among Icelandic adolescents, using objective and subjective measurements of physical activity.MethodsData were collected in the spring of 2015 from 315 tenth grade students (mean age 15.8 years) in six elementary schools in metropolitan Reykjavík, Iceland. Participants reported, via questionnaire, on demographics, weekly frequency of vigorous physical activity, daily hours of screen time and mental health status (symptoms of depression, anxiety and somatic complaints, self-esteem and life satisfaction). Total physical activity was measured over one week with wrist-worn accelerometers. Body composition was determined by DXA-scanning. Poisson regression analysis was used to explore independent and interactive associations of screen time and physical activity with mental health variables, adjusting for gender, body fat percentage and maternal education.ResultsLess screen time (below the group median of 5.3 h/day) and more frequent vigorous physical activity (≥4x/week) were each associated with reporting fewer symptoms of depression, anxiety, low self-esteem, and life dissatisfaction. No significant associations were observed between objectively measured physical activity and mental health outcomes. Interactive regression analysis showed that the group reporting both less screen time and more frequent vigorous physical activity had the lowest risk of reporting symptoms of depression, anxiety, low self-esteem, and life dissatisfaction.ConclusionsReports of less screen time and more frequent vigorous physical activity were associated with lower risk of reporting mental health problems among Icelandic adolescents. Those who reported a combination of engaging in less screen time and more frequent vigorous physical activity had the lowest risk, suggesting a synergistic relationship between the two behaviors on mental health outcomes. Our results support guiding youth towards more active and less sedentary/screen-based lifestyle.

The majority of Icelandic adolescents did not get the recommended number of hours of sleep, especially on SchD. While TST increased on NSchD, many participants still did not achieve the recommendations. These findings provide information on the sleep patterns of adolescents and may serve as reference for development of policies and interventions to promote better sleep practices.

Objectives: Emerging evidence suggests that inconsistent sleep may affect physical and psychological health. Thus, it is important to identify modifiable determinants of sleep variability. Screen time and physical activity are both thought to affect sleep, but studies of their relationship to sleep variability using objective measures are lacking. We examined cross-sectional associations between these variables in mid-teen adolescents using objectively measured sleep and activity.Methods: Wrist-worn accelerometers were used to measure one week of sleep and activity in 315 tenth grade students (mean age 15.8y) from six Reykjavik compulsory schools. Participants reported their daily hours of screen time. Regression analysis was used to explore associations of screen time and physical activity with variability in duration, quality, and timing of sleep, adjusting for DXA-measured body fat percentage, parental education, and physical activity or screen time.