doddering

vanhuudenheikko mentally or physically infirm due to old age; senile
(present participle of)
A shaking or trembling movement, as of old age.
2001, Seth Kohn, Escape on the Silk Road (page 7)

Now that he was next in line to the minister of state security himself, an 82 year old man whose dodderings Fang graciously covered up to save everyone's face, Fang had a huge problem.