report greater AD symptomatology?).3 parameters, X, Y and Z, which represent the change in A, C and E respectively as a function of changing age at 1st drink. If the effect of X is significant (represented by a Δχ2 greater than 3.84 for 1 degree of freedom), then there is evidence for gene x environment interaction (i.e. heritability of AD symptoms varies as function of age at 1st drink).
