Table 1

Demographic and clinical characteristics of study participants

CharacteristicGroup; mean ± SD*p value
High riskLow risk
MZ twins
 Group size1317
 Female sex811
 Age, yr49.7 ± 14.843.4 ± 9.90.17
 BDI score1.6 ± 2.21.3 ± 1.80.68
 Neuroticism†3.1 ± 3.14.7 ± 4.20.29
DZ twins
 Group size1819
 Female sex1211
 Age, yr48.9 ± 10.950.1 ± 10.30.57
 BDI score2.4 ± 3.51.1 ± 1.20.16
 Neuroticism†6.2 ± 4.93.5 ± 2.80.05

  • BDI = Beck Depression Inventory; DZ = dizygotic; MZ = monozygotic; SD = standard deviation.

  • ↵* Unless otherwise indicated.

  • ↵† Interaction effect (group × zygosity: F1,62 = 5.0, p = 0.03). High-risk DZ twins had higher neuroticism scores than high-risk MZ twins (p = 0.05).