I had lost the thread of this conversation fairly early on.
But I seem to have lost the thread of my discourse.
But just like that he had lost the thread of the conversation.
"I seem to have lost the thread of the conversation."
But she seemed to have lost the thread of mental contact.
She lost the thread of the conversation after a time.
I kept losing the thread but it didn't seem to matter.
And then his mind lost the thread of its consciousness.
She began losing the thread, having to shake her head and start over.
He had long since lost the thread of the broadcast.