WHAT IS BORDERLINE PERSONAL DISORDER? Borderline (Borderline personality disorder) It is a disorder that causes problems in the way a person perceives his environment, his way of thinking, his feelings about people and human relations. It usually begins to develop during adolescence and young adulthood. In the name of the disease and ‘What is a borderline?’ the meaning of the word that prompted the question; It can be expressed as “borderline, indeterminate”. Borderline personality disorder…"What is borderline personality disorder and what are its symptoms? – Health News"