Diagnostic overlap: Complex post-traumatic stress disorder and borderline personality disorder

To the Editor

Complex post-traumatic stress disorder (cPTSD) has been proposed as an independent diagnosis in the International Classification of Diseases, 11th Revision (ICD-11). Its overlap with symptoms of borderline personality disorder (BPD) can make the diagnosis of cPTSD challenging.

Our patient Sam (pseudonym) is a 25-year-old man with a month-long history of auditory hallucinations on the background of extensive early life and recent trauma. He was neglected and abandoned by both parents by age 4 years. Sam was constantly bullied throughout his schooling about his homosexuality. Recently, Sam’s aunt (his carer), died, leading to a self-described sense of loneliness and emptiness. During a recent psychiatry admission, he gave a history of re-experiencing trauma, hypervigilance, avoidance, affect dysregulation, poor self-image and unstable interpersonal relationships plus a fear of abandonment and feeling worthless. These are symptoms of both cPTSD and BPD. Sam was initially diagnosed with BPD; however, this was later reformulated to cPTSD, highlighting the diagnostic overlap and uncertainty between BPD and cPTSD.

cPTSD is generally associated with multiple forms of early life trauma at an interpersonal level (Jowett et al., 2020). Cloitre et al. (2014) described being able to distinguish BPD from cPTSD by the presence of BPD symptoms of frantic efforts to avoid abandonment, unstable sense of self, unstable and intense interpersonal relationships and impulsiveness.

A major underlying driver of both BPD and cPTSD symptoms is trauma. We postulate that significant, complex trauma early in life, (Sam’s case), is more likely to lead to the trauma responses becoming symptoms and behaviours integrated into the individual’s persona. BPD and cPTSD are not mutually exclusive diagnoses, and many people, like Sam, meet criteria for both. Clinically, our best efforts could be to recognise and prevent the maladaptive trauma response behaviours becoming intractable, resulting in the highly stigmatised BPD diagnosis, with its often-associated hopelessness in clinicians and patients (Aviram et al., 2006).