The heritability of LTH-AD increased with increasing values of diagnostic reliability as reflected in our index of caseness. This finding corroborates the notion that unreliable measures of LTH-AD will attenuate estimates of heritability in twin and family studies. Furthermore, creating a continuous index of caseness for a patient or clinical research subject, instead of solely using a dichotomous diagnosis, makes it possible to extract more diagnostically relevant information about each individual case.
