Yes. Legalistically as a Chartered Patent Attorney and European Patent Attorney, I am bound by a code of professional practice analogous to that of any barrister or solicitor and must keep anything you say to me in a professional relationship confidential. If not, I would be struck off and prevented from working as a patent attorney.  

Pragmatically, I depend upon my clients to earn a living. If I were to be careless of a client's confidence, it would soon become known and before long I would have no clients at all.

I am willing to sign a suitably worded NDA but there really is no need.