Looking at his brain health
https://protocol.bryanjohnson.com/#brain-health
It appears he has some brain markers such as white matter hyper intensities and ventricular volume that are older than his age of 46.
The Blueprint health protocol may end up giving people with healthy bodies but an aging brain, so they will be able to live many years with dementia (because the body is otherwise healthy).
Whether having a healthy body with dementia is worth spending all this money and effort for is an interesting question.