train of thought

The so-called weave is now being used to rationalize his inability to keep a single train of thought or give a straight answer in an interview:

The president appeared meandering and confused throughout the debate, giving incomplete answers and seeming to lose his train of thought at multiple points.

But what was interesting about that interview is that it showed really how hard it is to get Donald Trump to stay on topic, or to have one train of thought.

Your relative might lose his train of thought; another person’s relative might get stuck in verbal cul-de-sacs of nonsense.

“He was rambling; he’d start an answer then lose his train of thought, then would just say ‘whatever.’