1. Department of Psychology, University of Southern California, Los Angeles, CA, USA
2. Department of Psychiatry and Center for Behavior Genetics of Aging, University of California San Diego, San Diego, CA, USA
3. Department of Psychology, University of California Riverside, Riverside, CA, USA
4. The Danish Twin Registry, University of Southern Denmark, Odense, Denmark
5. School of Health Sciences, University of Skövde, Skövde, Sweden
6. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Solna, Sweden
7. Centre for Healthy Brain Ageing (CHeBA), University of New South Wales, Sydney, Australia
8. Department of Psychology, University of Nevada LasVegas, Las Vegas, Nevada
9. Center for Economic and Social Research, University of Southern California, Los Angeles, CA, USA