[Diagnostic criteria in dementing illness. What's new?].

The spectrum of neurodegenerative diseases that primarily affect cognition and behaviorspreads from asymptomatic preclinical disease to very mild cognitive impairment to frank dementia. Alzheimer's disease (AD) is the most common cause of a decline in cognitive ability. Also, it is a devastating condition that affects patients and their entirefamilies of caregivers, exacting tremendous financial hardships.