An 81-yeаr-оld wоmаn wаs diagnоsed with Alzheimer's disease 4 years ago. During a follow-up appointment, her daughter reports that her mother initially only had mild forgetfulness, but now frequently gets lost in familiar places, repeats the same questions throughout the day, and requires assistance managing medications and finances. The daughter asks why she keeps getting worse every year. Which response best answers this question?