All participants were born in Sweden. While this study did not specifically report any information on ethnicity, another study that used a cohort made up of subsamples from the Swedish Twin Registry has described the OCTO-TWIN participants as Caucasian (Jansson et al., 2003).
Diagnosis & Evaluation Methods
For descriptions of OCTO-TWIN procedures, please see Hassing et al. 2002 and McClearn et al. 1997. For detailed descriptions of the structure of the Swedish Twin Registry, see Lichtenstein, et al. 2002 and Lichtenstein et al. 2006.
Hassing LB, Johansson B, Nilsson SE, et al. Diabetes mellitus is a risk factor for vascular dementia, but not for Alzheimer’s disease: a population-based study of the oldest old. Int Psychogeriatr 2002; 14: 239–48.
McClearn GE, Johansson B, Berg S, et al. Substantial genetic influence on cognitive abilities in twins 80 or more years old. Science 1997; 276:1560–1563.
Jansson M, Gatz M, Berg S, et al. Association between depressed mood in the elderly and a 5-HTR2A gene variant. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics 2003; 120B: 79–84.
Lichtenstein P, De Faire U, Floderus B, et al. The Swedish Twin Registry: a unique resource for clinical, epidemiological and genetic studies. J Intern Med 2002; 252: 184–205.
Lichtenstein P, Sullivan PF, Cnattingius S, Gatz M, Johansson S, Carlström E, Björk C, Svartengren M, Wolk A, Klareskog L, de Faire U, Schalling M, Palmgren J, Pedersen NL. The Swedish Twin Registry in the third millennium: an update. Twin Res Hum Genet. 2006 Dec;9(6):875-82.