LSADT began in 1995 with the assessment of members of like-sex twin pairs born in Denmark prior to 1920 (i.e., at least 75 years old at the beginning of 1995). The surviving members of the initial cohort were followed up every two years in 1997, 1999, and 2001. Additional cohorts were also added at the 1997, 1999, and 2001 assessments and subsequently followed at two-year intervals. Twin pairs where both were alive and born between 1920 and 1923 (i.e., at least 73 years old at the beginning of 1997) were added in 1997; twins born 1921 to 1928 (i.e., at least 70 years old at the beginning of 1999) were added in 1999; and twins born between 1929 and 1930 (i.e., at least 70 years old at the beginning of 2001) were added in 2001.
Participation rates among survivors at a given wave ranged from approximately 70% to 80%. Christensen et al. (1999) reports a comparison of participants and non-participants in the 1995 survey, showing that participants were slightly but significantly more likely to be male and to have been hospitalized between 1977 and 1994 than non-participants, but did not differ significantly from non-participants in terms of age and twin zygosity. Although surviving non-participants at follow-up scored at intake lower than follow-up participants on measures of physical and cognitive functioning, the differences are generally modest in magnitude.
A total of 4,731 individual twins have completed an LSADT intake assessment, either through in-person interview or by proxy. Because twins were selected without regard to their co-twin's mortality (to enhance the epidemiological potential of the study) many of the participating twins did not have a surviving co-twin who participated in the survey. Among the intake participants there were 2,304 individual twins from 1,152 twin pairs (451 monozygotic (MZ), 661 dizygotic (DZ), 19 of unknown zygosity and 21 opposite sex) and 2,427 single twins.
Description of the Data:
The data are available on an individual level, but due to confidentiality issues, ages can be given in 5 year age-groups for some variables. The data are available in SPSS format.
Due to the confidential nature of the data, it is expected that researchers interested in using the data will sign a Data Use Agreement. To avoid double publication of the same data, proposals have to be specific and coordinated with other efforts within the project. Applications can be sent to the Scientific Board of the Danish Twin Registry.
For further information please contact:
- Kaare Christensen, MDSc