Importance The amyloid hypothesis posits that disrupted β-amyloid homeostasis initiates the pathological process resulting in Alzheimer disease (AD). Autosomal dominant AD (ADAD) has an early symptomatic onset and is caused by single-gene mutations that result in overproduction of β-amyloid 42. To the extent that sporadic late-onset AD (LOAD) also results from dysregulated β-amyloid 42, the clinical phenotypes of ADAD and LOAD should be similar when controlling for the effects of age.
