(without moderation). Second, with the addition of moderation, the model allows an estimation of whether these common genetic influences, or those genes that influence the liability to AD symptoms specifically, are moderated by age at 1st drink – in other words, after accounting for common genetic factors, we can examine whether age at 1st drink also acts as a moderator of genetic influences on AD symptoms and the genetic ‘route’ that it moderates. We tested both the standard bivariate model and extended it to include moderation while controlling, jointly, for overlapping genetic and environmental factors.
