We know of no previous quantitative summary of the heritability of Alzheimer’s Disease. Table 1 lists the five studies that met our inclusion criteria (Bergem et al., 1997, Breitner et al., 1995, Gatz et al., 2005, Gatz et al., 1997, Gatz et al., 2006, Meyer and Breitner, 1998, Raiha et al., 1996). The most comprehensive investigation, with the largest number of affected twins, is the recent study by Gatz et al. based on the Swedish Twin Registry (Gatz et al., 2005, Gatz et al., 2006). There was some overlap, in terms of affected subjects, with a smaller previous study based on that registry (Gatz et al., 1997). The weighted mean heritability estimate was 75%, whether or not we included the earlier study (Gatz et al., 1997).
