Fig. 2.

Bivariate model representing the relationship between education and dementia, with both genetic and environmental mediation. Notes. Only one member of the twin pair is represented. A= additive genetic variance; C= shared environmental variance; E = unique environmental variance. A1 indicates additive genetic variance for the first trait; A2 indicates additive genetic variance for the second trait, with analogous numbering for the other components of variance. Parameters are standardized path coefficients for the full model, with mediational paths bolded.