In terms of symptoms, there exists a clear overlap between the psychiatric conditions of borderline personality disorder (BPD) and dissociative identity disorder (DID). DID used to be referred to multiple-personality disorder.
Borderline Personality Disorder, Dissociative Identity Disorder And ‘Splitting’
‘Splitting’ is a psychological defense mechanism in which one ‘part’ of the personality becomes separated / un-integrated with / isolated from another ‘part’ of the personality. In the case of individuals suffering from BPD, these two parts can, in simple terms, be described as PART ONE and PART TWO, where :
PART ONE represents the part of the person’s personality which is relatively accepting of him/herself and others
PART TWO represents the part of the person’s personality which is full of self-hatred, as well as anger and hostility (and, underlying the latter two emotions, fear of being psychologically harmed) in relation to others.
When PART ONE is ‘operational’, it tends to enter a state of denial about the existence of PART TWO.
This may be because when PART ONE is ‘in charge’, the individual develops a state of mind similar to amnesia regarding the existence PART TWO ; alternatively, the denial may be underpinned by feelings of profound shame. However, more research needs to be conducted in relation to these possibilities.
‘Splitting’ and amnesia (when one part of the personality is unaware of how another part of the personality has manifested itself) are also symptoms of dissociative identity disorder.
Borderline Personality Disorder And ‘Switching’ Between ‘Part One’ And ‘Part Two’
As stated above, ‘PART ONE’ and ‘PART TWO’ have become un-intergrated in the personality of individuals suffering from BPD (the BPD sufferers personality, in this respect, may be described as having ‘disintegrated’). A more formal way to put this would be to describe the BPD sufferer as having an un-integrated ego-state (in contrast to the relatively integrated ego-state that psychologically ‘healthy’ individuals enjoy).
Those with BPD ‘switch’ between ‘PART ONE’ and ‘PART TWO’ and this can occur quite suddenly (but is not usually dramatically instantaneous).
Furthermore, these un-integrated ego-states interfere with each other (because they are not completely separate from one another) and this may cause symptoms such as the following :
- unstable sense of identity (some sufferers describe this with phrases such as : ‘I have no idea who I am…’).
How ‘Splitting’ Affects The BPD Sufferer’s Relationships With Others :
When ‘PART ONE’ is ‘in charge’, the BPD sufferer desires emotional attachments with others. However, when ‘PART TWO’ is dominant, s/he becomes hostile towards others and withdraws from them – this leads to the classic ‘love-hate’ scenario.
Why Does This Unintegrated Ego-State Arise In Those Suffering From BPD?
The two separate parts can develop in a person who has suffered severe and prolonged abuse as a child.
When the abused child becomes an adult, PART TWO (hostility etc) can be kept in abeyance for much of the time to allow daily social functioning. However, PART ONE makes itself apparent when the BPD sufferer is reminded of the abuse s/he suffered as a child (such a reminder is called a ‘trigger’).
This reminder/trigger may be detected by the BPD sufferer consciously or unconsciously and occurs as a defense mechanism against real or perceived psychological threat (especially the treat of betrayal, rejection or abandonment as occurred in the individual’s childhood).
If the individual had not developed this defense mechanism as a child, s/he faced what may reasonably be termed as ‘psychological destruction.’ In other words, the development of the ‘splitting’ defense mechanism makes complete evolutionary sense as it allowed the individual to survive childhood – it is a normal, predictable, adaptive response to childhood loss, fear, distress and betrayal.
There is an overlap between symptoms of borderline personality disorder and dissociative identity disorder in as far as they both involve ‘splitting’ and ‘dissociating‘. However, in the case of DID, the separation between the different PARTS of personality are MORE DISTINCT AND CLEAR CUT THAN THEY ARE IN THE CASE BPD. Those suffering from DID may have more than two un-integrated / separate PARTS of their personality / ego-state ; however, arguably, this can also be the case in those suffering from BPD (although this is beyond the scope of this article).
In conclusion, though, we can say, with some confidence, that BPD sufferers do have a ‘split personality’, but the division between these two parts is more nebulous than in the case of DID sufferers.
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David Hosier BSc Hons; MSc; PGDE(FAHE).