We then examined whether these resulting genetic factor scores differentially predicted a representative set of external validators. If these three genetic factors reflected different aspects of the liability to AD, we reasoned that they should differ from one other in their ability to predict important variables that had no role in the assignment of the DSM AD criteria. Results are presented in Table 4. We began by analyzing AD itself as a baseline against which the other eight variables could be judged. The three factors differed significantly in their prediction of AD, with the strongest association with the second genetic factor (loss of control/social dysfunction), and the weakest with the first, or tolerance/excess drinking genetic factor. These results are expected in the first, second and third genetic factor that have strong loadings on, respectively, one, four and two of the DSM-IV criteria for AD. Of the eight external variables examined (Table 4), the three genetic factor scores differed significantly in the magnitude of their prediction for all factors but one, and for that one (conduct disorder symptoms) they differed at a trend level.
