system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Loss of capability of doing goal-directed things, to express ideas, making irrelevant comments, but ultimately succeeding in going back to the original point is known as -
assistant
The correct answer is  Both circumstantiality and tangentiality have degression into unnecessary irrelevant details. However:-


In circumstantiality, thought reaches its ultimate goal in a long and roundabout manner, i.e. the patient return back to the original theme after degression.
In tangentiality, the goal is not reached and the thought is sidetracked more and more away from the natural end and never returns to the original theme.