But watching someone spend 10 years with almost no quality of life while science slowly makes advances in those areas does not really help that particular family.
Early detection and prevention are both useless for someone who is already suffering from significantly degraded brain function -- they'd have to hang around long enough that the damage could be repaired.
With the brain in particular... some kinds of damage cannot be fixed, no matter what advances we have in medicine, until there's a backup of the data available.
We're already seeing many advancements in earlier detection as well as reduction in symptoms for the issues you mention, if not improved prevention.