Lars Nyberg and Rolf Adolfsson, PI (www.org.umu.se/betula)
The project started 1988 in Umeå, located in the northern part of Sweden. The participants were randomly recruited amongst persons living in the municipality of Umeå. The majority of the participants were 35-80 years of age at the time of entering the project. Every fifth year participants were assessed with multiple cognitive, biological and social tests. New cohorts was included at each wave (except in the sixth wave) to estimate the size of test-retest effects. At the fifth test wave (2008-2010), the cohorts were expanded to also include participants that were 25 and 30 years of age. A total of about 4700 persons have been assessed. The sixth, and final wave, took place in 2013-2014.