Not exclusively but often related. Typically from childhood trauma. For the past month and change I've been living alone in a house by myself. There's a downstairs neighbor in the basement. Whenever I hear her car door close or the door open/close? I feel a jolt of anxiety. Small emotional flashbacks to when I was a kid and the only time I was happy and things were peaceful was when I was alone. Hearing the door was a signal things were about to get bad soon and your body just gets used to that. Extremely hard to break.