Insidious definition
Insidious means, inter alia, “developing so gradually as to be well established before becoming apparent” and “acting by imperceptible degrees: having a gradual, cumulative, and usually hidden effect.” Webster’s Third New International Dictionary: Unabridged 1169 (1981). The Court takes this to mean that Abe’s dementia slowly got worse over several years, an extrapolation supported by Abe’s children’s testimony.