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Cohort: Study of Dementia in Swedish Twins
Website: http://ki.se/ki/jsp/polopoly.jsp?l=en&d=13903&a=30105
Risk Factors: Diabetes Mellitus,
Obesity,
Physical Activity

Introduction to the Cohort
The Study of Dementia in Swedish Twins (HARMONY) study is a population-based study of twins drawn from the Swedish Twin Registry (STR). The study aimed to identify genetic and non-genetic risk or protective factors for AD and dementia, and quantify the relative importance of genetic and non-genetic influences on AD and dementia etiology.

HARMONY began in 1998 by identifying all individuals in the STR who were at least 65 years old and alive (N=20,269). Individuals who were able to be contacted (n = 14,000) received a telephone-based interview and cognitive screening in 1998-2001, and a subset of these individuals received a full clinical work-up (1998-2002). HARMONY is taken from the Swedish words for “health” (Hälsa), “genes” (ARv), “environment” (Miljö), “and” (Och), and “new” (NY).

As all individuals in HARMONY are part of the STR, information regarding health-related behaviors such as smoking, diet, physical activity, personality and exposure to environmental stressors will be available for some individuals from earlier STR questionnaires sent to members in 1961, 1963, 1967, 1970 and 1973. More recent risk exposure, covariate and outcome information was also obtained during the telephone interview and clinical evaluation.

HARMONY is one of a number of aging studies conducted within the STR. Other STR-based studies include the Swedish Adoption and Twin Study of Aging (SATSA) and Origins of Variance in the Oldest-Old (OCTO-TWIN; a subcohort of twin pairs who were at least 80 years old in 1991).

Ethnicity Breakdown
All participants were born in Sweden.

Diagnosis & Evaluation Methods
For a detailed description of HARMONY procedures, see Gatz et al., 2005. For detailed descriptions of the structure of the Swedish Twin Registry, see Lichtenstein, et al. 2002 and Lichtenstein et al. 2006.

References
Gatz M, Fratiglioni L, Johansson B, Berg S, Mortimer JA, Reynolds CA, Fiske A, Pedersen NL. Complete ascertainment of dementia in the Swedish Twin Registry: the HARMONY study. Neuorbiol Aging. 2005 Apr;26(4):439-447.

Andel R, Crowe M, Pedersen NL, Fratiglioni L, Johansson B, Gatz M. Physical exercise at midlife and risk of dementia three decades later: a population-based study of Swedish twins. J Gerontol A Biol Sci Med Sci. 2008 Jan 1;63(1):62-6.

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.

Xu W, Atti A, GatzM et al. Mid-life overweight and obesity increase late life dementia risk: A population-based twin study. Neurology 2011;76: 1568-1574.