In particular, the poignant question of “why would anyone
want to know they have AD a decade before they might develop
symptoms, if there is nothing they can do about it?”
should be carefully considered well before any results
from research is translated into clinical practice. First, there
may be important reasons, including social and financial
planning, why some individuals would want to know their
likelihood of developing AD dementia within the next
decade, even in the absence of an available disease modifying
therapy. It is our hope, however, that the advances
in preclinical detection of AD-P will enable earlier, more
effective treatment, just as nearly all of therapeutic gains
in cancer, cardiovascular disease, osteoporosis, and diabetes
involve treatment before significant clinical symptoms are
present. It is entirely possible that promising drugs, particularly
amyloid-modifying agents, will fail to affect the clinical
course of AD at the stage of dementia or even MCI, when
the neurodegenerative process is well entrenched, but may
be efficacious at the earliest stages of the AD-P, before the
onset of symptoms.
The definitive studies to determine whether the majority
of asymptomatic individuals with evidence of AD-P are
indeed destined to develop AD dementia, to elucidate the
biomarker and/or cognitive endophenotype that is most
predictive of cognitive decline, and to determine whether
intervention with potential disease-modifying therapies in
the preclinical stages of AD will prevent dementia are
likely to take more than a decade to fully accomplish.