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BackgroundThe LIFE-Adult-Study is a population-based cohort study, which has recently completed the baseline examination of 10,000 randomly selected participants from Leipzig, a major city with 550,000 inhabitants in the east of Germany. It is the first study of this kind and size in an urban population in the eastern part of Germany. The study is conducted by the Leipzig Research Centre for Civilization Diseases (LIFE). Our objective is to investigate prevalences, early onset markers, genetic predispositions, and the role of lifestyle factors of major civilization diseases, with primary focus on metabolic and vascular diseases, heart function, cognitive impairment, brain function, depression, sleep disorders and vigilance dysregulation, retinal and optic nerve degeneration, and allergies.Methods/designThe study covers a main age range from 40-79 years with particular deep phenotyping in elderly participants above the age of 60. The baseline examination was conducted from August 2011 to November 2014. All participants underwent an extensive core assessment programme (5-6 h) including structured interviews, questionnaires, physical examinations, and biospecimen collection. Participants over 60 underwent two additional assessment programmes (3-4 h each) on two separate visits including deeper cognitive testing, brain magnetic resonance imaging, diagnostic interviews for depression, and electroencephalography.DiscussionThe participation rate was 33 %. The assessment programme was accepted well and completely passed by almost all participants. Biomarker analyses have already been performed in all participants. Genotype, transcriptome and metabolome analyses have been conducted in subgroups. The first follow-up examination will commence in 2016.

Our study confirms the bi-dimensionality of the LOT-R and thus underpins that optimism and pessimism are two independent constructs rather than a single bipolar trait. Psychometric properties were found to be satisfactory. Together with the norm values reported in the paper, this instrument can, thus, be employed to measure dispositional optimism or pessimism in individual diagnostics as well as in epidemiological research.

The internal structure of the revised Life Orientation Test (LOT-R, German version; M. F. Scheier, C. S. Carver, & M. W. Bridges, 1994) was analyzed in a sample of 46,133 participants who ranged in age from 18 years to 103 years. Confirmatory factor analysis showed that dispositional optimism, as measured by the LOT-R, is bidimensional, consisting of an Optimism and a Pessimism factor. Consistent with previous results, there were small to moderate negative correlations between Optimism and Pessimism, but the strength of the association continuously decreased with age. The relative independence of the 2 dimensions occurred in both genders and across different age groups of patients with different medical disorders.