1. Department of Integrative Medical Biology, Umeå University, 90187 Umeå, Sweden.
2. Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden.
3. Department of Psychology, Umeå University, 90187 Umeå, Sweden.
4. Umeå Center for Functional Brain Imaging (UFBI), Umeå University, 90187 Umeå, Sweden.
5. Aging Research Center, Karolinska Institute, 11330 Stockholm, Sweden.