A Community-Based Study of Parental Age in Alzheimer-Type Dementia in Western Japan

To the Editor.  —A number of studies have identified structural and biochemical similarities between dementia of the Alzheimer type (DAT) and Down's syndrome. Heston¹ has reported interesting data that support a common genetic origin for DAT and Down's syndrome. Cohen et al² first described the fact that offspring born to comparatively old mothers may be at high risk for developing DAT. However, the association between DATAge of Parents at Time of Subject's Birth for Patients With DAT and MID* Mother's Father's Group No. Age, y† Age, y† DAT 77 26.58 ± 6.63‡ 31.44 ± 8.65§ MID 52 24.12 ± 5.73 27.21 ± 6.99 *DAT indicates dementia of the Alzheimer type; MID, multi-infarct dementia. †Values are means ± SDs. ‡P <.05 vs MID group. §P<.01 vs MID group. and maternal age is not yet clarified, and is still controversial.^3-7 No information on association between DAT and parental