Primary Degenerative Dementia Of The Alzheimer Type In Twins - Initial Findings From The Maudsley Hospital Twin Register

In detailed published accounts to date of 40 twin pairs one or both of whom were said to have Alzheimer's disease (AD), 16 of 35 monozygotic (MZ) pairs were described as concordant for the disease and the remaining 19 pairs as discordant, while of the five pairs of dizygotic (DZ) twins two pairs were designated as concordant. However, these data have emerged almost exclusively from selective case reports and volunteer samples, resulting in an over-representation of MZ twins that complicates the overall interpretation of the data. In an effort to reduce such ascertainment bias, we screened for diagnoses consistent with AD in the Maudsley Hospital Twin Register, which consists of twins registered at the Bethlem Royal and the Maudsley Hospitals (London, UK) since 1948. Seven twins were identified who met criteria for primary degenerative dementia of the Alzheimer type. Available details of their affected status as well as of the status of their co-twins are presented and discussed.