‘Borderland’

The term ‘borderline personality’, now a source of confusion, was first used in 1938 by Adolph Stern to describe a group of patients who ‘fit frankly neither into the psychotic nor into the psychoneurotic group’, but who inhabited a realm between the two.1

The definition and classification of BPD have been heavily debated, reflecting persisting uncertainty in how best to conceptualise the underlying psychopathology. Personality disorder is defined in the International Classification of Diseases (ICD)−11 as:

“a relatively enduring and pervasive disturbance in how individuals experience and interpret themselves, others, and the world that results in maladaptive patterns of cognition, emotional experience, emotional expression, and behaviour”.2

These maladaptive patterns commonly have their first manifestations in childhood and adolescence, and are typically associated with instability in interpersonal relationships. In ICD-10, ‘borderline type’ personality disorder comes under the umbrella term of ‘emotionally unstable personality disorder’, alongside ‘impulsive type’ personality disorder. As there is considerable overlap between the categories, the term ‘emotionally unstable personality disorder’ is sometimes used interchangeably with BPD in the clinical setting. The move away from categorical descriptions of personality disorder towards dimensional classification in ICD-11 signifies a major nosological overhaul.3 Box 1 shows the DSM-5 criteria for BPD; five or more of these criteria are required to make the diagnosis.4

What’s in a name?

It is noteworthy that the term ‘personality disorder’ is all too often used in a pejorative sense, with authors of a 2015 Lancet series on the subject going so far as to lament that ‘it has now become more a term of abuse than a diagnosis’.2 It is important for all doctors to maintain an open mind and compassionate approach when dealing with patients diagnosed with personality disorder. This requires skill and patience as the psychopathology of these patients usually chiefly manifests itself in the manner in which they interact with others.

Genetics

Twin studies have shown moderate to high heritability for BPD.15 No robust evidence has yet been established for single-candidate genes, and genome-wide association studies in this area are in their relative infancy.16 17 Several small gene–environment studies have identified interactions which need verifying in larger, prospective cohorts.17

Epigenetic studies examine how environmental conditions affect gene expression and are increasingly being considered a promising avenue for exploring the cause of personality disorders.18 Several small studies suggest epigenetic modifications in people with BPD in genes related to stress and neurodevelopment, with environmental factors such as childhood trauma having a measurable impact on genes responsible for neurofunctioning.17 18 For example, people with BPD have significantly higher DNA methylation, that is, evidence of epigenetic modification, of the brain-derived neurotrophic factor gene, which is involved in neurodevelopment.19 Such epigenetic changes may pave the way for new treatment approaches, but further research is needed to establish this.19

Psychosocial factors

Early environmental and familial risk factors for BPD have been consistently demonstrated over the years. These include childhood trauma such as neglect and abuse (emotional, physical or sexual), familial adversity, a history of psychopathology in the caregiver, as well as parental emotional under-involvement.1 8

The marked association between childhood sexual abuse and the development of BPD, and the positive correlation between the severity of BPD and the severity of the abuse experienced, have led some researchers to argue that people with BPD might be better thought of as having a chronic form post-traumatic stress disorder.20 Clearly not all people who experience abuse go on to develop BPD, and the fact that abuse alone is neither necessary nor sufficient for its development points to other predisposing (such as genetic) and contextual mediating factors.1 For example, emotional denial of a child’s experience of trauma by their caregiver has been identified as a predictor for BPD.21 The family and wider social environment are considered to play a critical role, as well as whether a child’s perspective on their emotional world is perceived to be validated.1

Note on attachment

Attachment theory, developed by John Bowlby, posits the universal human need for close affectional bonds as a prerequisite for normal development.

When a child has a mental representation of the caregiver as being available and responsive to their needs, secure attachment occurs. BPD is strongly associated with insecure attachment,1 which occurs when self-perceptions of internal states are instead undermined. It is not clear to what extent attachment difficulties in BPD are causal to or result from the emotional disturbance and impulsivity associated with the condition.

Neurobiology

Several neural correlates associated with BPD have been reported. Structurally, reduced amygdala and hippocampal volumes have been observed.1 Functionally, evidence exists for increased limbic activity and decreased prefrontal activity in patients with BPD in response to emotional stimuli, in keeping with clinical observations of emotional dysregulation.22

People with BPD have also been consistently shown to experience a negative response bias to ambiguous or neutral facial expressions, as well as an enhanced sensitivity to fearful expressions.23 Contrary to popular misconception, people with BPD have demonstrable accuracy in determining mental states in response to complex social stimuli,23 and these patients are exquisitely sensitive to the states of mind of those around them.

On examination, patients with BPD have been found to exhibit higher rates of neurological soft signs in keeping with underlying non-focal neurological dysfunction.24

Psychiatric comorbidities

Depression, anxiety and substance use disorders, as well as eating disorders, post-traumatic stress disorder and bipolar disorder, are all important diagnostic comorbidities.1 15

It can be challenging for the clinician to distinguish comorbidity in patients with BPD; for example, the emotional dysregulation seen in people with BPD may mimic depression, mania or anxiety. In this respect, it is invariably helpful to obtain an informant account in order to establish the duration and onset of symptoms.

Many people with BPD engage in repeated episodes of self-harm and endure recurrent thoughts of suicide and suicide attempts; the mortality rate for people with BPD from suicide has been estimated to be as high as 8%–10%, 50 times higher than that in the general population.15

Physical comorbidities

People with personality disorders have an average life expectancy starkly reduced by around two decades compared with the general population.25 26 The excess mortality cannot be attributed to increased suicide rates alone and it is now apparent that people with BPD experience significantly poorer physical health compared with individuals not diagnosed with BPD. Rates of cardiovascular and cerebrovascular disease are substantially increased,24 and associations have also been reported between BPD and gastrointestinal and hepatic diseases, arthritis, sleep disorders and chronic pain, as well as syncope and seizures.27 The underlying mechanisms for this disproportionate burden of illness are unknown; lifestyle factors such as higher rates of smoking and poorer diet are likely to be implicated, as well as the toll taken by chronic levels of psychological stress on the body.27

People with BPD may also present to neurologists given their increased rates of migraine-related disability and a lower likelihood of responding to pharmacological headache treatment compared with controls,28 or due to neurological sequelae of self-injury and substance use disorders.

Functional neurological associations

Across the boundary between psychiatric and physical comorbidities of BPD lie the somatoform disorders, renamed ‘somatic symptom disorder’ in DSM-5 and ‘bodily distress disorder’ in ICD-11.29

Under this category is ‘conversion’ (functional neurological symptom) disorder, which refers to patients with neurological symptoms such as seizures, limb weakness and movement disorders without identifiable organic disease.30 Conversion disorder is one of the most common reasons for referral to neurology,30 and co-occurring BPD has been found to affect a significant proportion of people with conversion disorder (22%).31

Substantial comorbidity has been demonstrated between BPD and somatic symptom disorders, and these conditions also share two important commonalities: an association with a history of childhood trauma and features of emotional dysregulation.31 Such common denominators have also been noted between BPD and the specific example of dissociative (non-epileptic) seizures, which can fall within both conversion and dissociative disorders.32

Functional neurological symptom disorder

For much of the last century since Breuer and Freud’s hypothesis that psychological distress was ‘converted’ into physical symptoms, psychiatric formulations of the so-named disorder have dominated.

The nosological shift from ‘conversion’ to ‘functional neurological symptom’ disorder in DSM-5 represents an important swing of the pendulum back towards neurology, with both fields having valuable perspectives. To neurologists, functional neurological symptom disorders are no longer diagnoses to be excluded and referred back. Rather, neurologists are increasingly recognised as having an important therapeutic role.33 Reflecting this shift, diagnostic criteria now demand positive neurological examination features (eg, Hoover’s sign of functional leg weakness).34

Diagnostic overshadowing

In closing this section about neurological associations of BPD, we think that it is important to remind the reader of this process where the cause of physical symptoms is misattributed to mental illness, a process termed ‘diagnostic overshadowing’. Examples include people with psychiatric disorders and ischaemic heart disease being less likely to receive the required revascularisation procedure than those without mental illness, and hospital admission for diabetic complications being less likely to be offered to those with comorbid psychiatric disorders than those without.34

A range of contributors to this phenomenon have been postulated, including clinicians’ biases, naivety about how psychiatric disorders present, and complexities of doctor–patient communication.35

Patients will therefore benefit from neurologists retaining their sharp clinical eye for organic neurological diseases regardless of the thickness of the clinical notes, psychiatric history or current affective presentation.

Risk management

Many patients with BPD self-harm, for example, by cutting, scratching or burning. Such behaviour can serve many different functions, from dampening down painful emotions to attempting to reconnect with one’s emotions in the face of dissociation or feelings of emptiness, or as a way of regulating relationships by either pulling people in as rescuers or pushing them away.39 They may also suffer from chronic thoughts of suicide. However, it is important to consider obtaining urgent advice from a psychiatrist if there has been a recent change in the patient’s self-harming (eg, escalation now requiring medical attention) or when a patient states an intensified intent to end their life in relation to their suicidal thinking.

Some therapies de-jargonised

Can people with BPD recover?

Prospective longitudinal research has shown that the majority of patients with BPD experience a significant remission in symptoms (notably self-harm) over a 10-year period. However, functional impairment remains an enduring feature of BPD and many people with BPD experience lifelong difficulties in maintaining work and intimate relationships.40 41

Recognising its importance

It is well known that a robust and positive doctor–patient relationship is associated with better treatment adherence and outcomes, and that a poor relationship is linked to higher dropout rates from treatment.42

In a previous review for this journal, Stone compellingly outlined how, with a good therapeutic alliance, a neurological assessment itself can also be a form of treatment for functional disorders. Useful tips included emphasising that the symptoms are real and potentially treatable, outlining the positive nature of the diagnosis (rather than treating it as a diagnosis of exclusion), simple signposting to appropriate help and information possibly including psychological services, and offering outpatient follow-up.33

In the context of psychotherapy, the trust and empathy developed within therapeutic relationships is believed to contribute to a corrective relational experience in these patients who might otherwise have had very little reason to trust in others.15 These principles can also be usefully applied in the management of organic neurological disorders in people with comorbid BPD.

Collaboration

Whatever the reason for referral, inviting and encouraging the patient’s lived experience and understanding of the problem will invariably be a constructive place to start.32 In the example of people with BPD and dissociative (non-epileptic) seizures, the building of a shared explanatory framework for the cause of seizures is preferable to the imposition of a medically modelled explanation—with higher chances of patients both understanding and accepting their diagnosis.32 43 A collaboratively-built, blame-free narrative of the person’s difficulties also forms a foundation on which to negotiate realistic treatment goals.29

In addition, collaboration within the treating clinical team is of particular importance for these patients. Because people with personality disorder often have disordered attachment styles and difficulties in relationships, powerful dynamics can emerge with and within the medical teams. One example is ‘splitting’, a suggested unconscious psychological response to stress which leads to experiencing the self or others as either entirely ‘good’ or entirely ‘bad’. It is proposed to originate in early life, for example, through allowing a child to ‘split off’ threatening perceptions of a caregiver and thereby maintaining a ‘good’ representation of that caregiver.44 This process is thought to translate interpersonally, with patients perceiving certain members of staff as ‘good’ while others are perceived to be ‘bad’. The net result of this is that sometimes staff can be unwittingly drawn into bitter arguments about a patient’s behaviour or management.15 However, if team members are able to maintain a supportive approach to the patient, this may go some way to mitigating this phenomenon. Moreover, as is done in dialectical behavioural therapy, clinicians confronted with denigration of another healthcare professional by the patient are encouraged neither to agree with the patient nor to defend the other, as shown in figure 1, to avoid becoming trapped in an unhelpful conversation.44

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Figure 1

Suggestion on how to notice and avoid being drawn into a conversation possibly around ‘splitting’. GP, general practitioner.

A summary of splitting and other patterns, along with suggested solutions, is provided in table 1. Being alert to these manifestations may help with identifying, understanding and assisting patients with personality difficulties.32

Service-level collaboration is also critical. Poor communication between psychiatrists and neurologist colleagues has been attributed to worse outcomes for patients with dissociative (non-epileptic) seizures.45 Innovative collaborative approaches have been proposed, such as ongoing psychological supervision for neurologists, which could be provided, for example, by a psychiatrist consulting for an epilepsy service.46

Being mindful of how a patient’s background history can impact their current behaviour

During difficult consultations, we find it helpful to be cognisant that people act in the way that they do for all sorts of complex reasons; people with personality disorder may have been repeatedly let down in the past.

This does not mean that the neurologist should be expected to accept abusive or attacking behaviour (we will come on to boundary setting later). However, it can be liberating to understand that the anger or resentment manifest in front of us is unlikely to be personal but may instead result from a defensive pattern of behaviour historically adopted by the patient in the face of extreme adversity.

Such phenomena can be conceptualised by psychological theories such as projection—a proposed unconscious defence mechanism where, as a way of coping with undesirable and painful emotions, these are ‘projected’ onto someone else.14 In our experience, understanding of these issues often enables a calm hearing and response, which can de-escalate heated conversations and allow for more rational discourse. Such outcomes are facilitated by cultivation of one’s own emotional awareness as a doctor.

Knowing oneself—using one’s own feelings as a clinical tool

The doctor–patient relationship can essentially be stripped down to an interaction between two human beings, each with their own respective set of values and vulnerabilities. It is thus logical that if a patient has difficulties with emotional regulation, going from one extreme emotion to the next without obvious trigger, the encounter may provoke reactions which feel unusually and surprisingly strong in the physician. This can be referred to in psychoanalytic terms as a countertransference reaction, and, if noticed by the physician, is postulated to provide data on the patient’s mental state.14 For example, a neurologist who fails to come up with a clear explanation for a patient’s medical symptoms may, following an appointment with the patient, end up feeling useless and powerless. Rather than reacting defensively, the doctor may wonder whether this feeling of uselessness tells him or her something about the patient’s feelings towards themselves—that is, that they are possibly connecting with the patient’s own feelings of powerlessness.

Maintaining appropriate boundaries

As part of their problems in interpersonal relationships, patients with BPD sometimes have difficulty understanding and observing the boundaries of others. The issue may manifest in the form of erratic appointment attendance, excessive contact between appointments or inappropriate requests for medication or hospital admission.32 While clearly demonstrating our wish to help, it is equally important to be clear about the limits of what can be offered. It can be containing for the patient if the doctor combines empathy with consistency, transparency and clarity about appropriate doctor–patient interaction, expectations and shared management goals.14

Clear limit-setting is also encouraged in the context of pharmacological management in patients with BPD. Examples relevant to the neurologist might include tackling medication overuse for patients with headaches,28 and treading the line between collaboration and firmness when reviewing antiepileptic medication in patients with dissociative (non-epileptic) seizures.32

When setting boundaries, it can help to adopt a mentalising approach with patients, to allow them to see the rationale for the limit-setting. People with BPD have been shown to have difficulties with mentalising, which has been defined by Bateman and Fonagy as:

“the process by which we make sense of each other and ourselves, implicitly and explicitly, in terms of subjective mental processes”.44

This can be as simple as letting the patient in on one’s thought process, as exemplified in figure 2.

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Figure 2

Suggestion on sharing a dilemma with the patient.

Responsibility and capacity

Some clinicians are quick to characterise behaviours of people with BPD such as self-harming as ‘manipulative’ in nature. In our experience, the most productive approach is finding a line between encouraging patients in their agency over their health and healthcare, while not blaming them for their situation. A feeling of disempowerment can already permeate the lives of many with BPD, so the aforementioned boundaries should not be held so strictly as to add to this feeling when it comes to treatment decisions. Whenever the opportunity presents itself, encouraging a patient’s sense of autonomy, competence and participation in healthcare decisions is recommended. However, in extreme situations, emotional dysregulation and the other psychological difficulties seen in BPD can sometimes cause substantial difficulties in using and weighing information.47 Thus, it is sometimes appropriate and necessary to use the Mental Capacity Act in order to enforce medical treatment in a patient’s ‘best interest’ if there are concerns about their mental capacity in relation to treatment refusal for a medical condition.47

Time and consistency

When psychiatrists urge neurologists to take more time in consultation with people with BPD, neurologists may the there is misunderstanding of the the challenges faced in their practice. Nevertheless, Stone encourages us to reflect that neurosurgeons do not allocate the same time slots for pituitary tumour removals as for carpal tunnel decompressions.33 In a similar vein, longer initial assessments for people with BPD and complex functional neurological problems are likely to be worthwhile in the long term, as trust is built more easily with less time constraint.

For example, some patients with BPD may find aspects of the neurological examination threatening or intrusive, depending in part on previous traumatic experiences. Being particularly clear about the process and purpose of the examination, though more time-consuming, is likely to help patients to feel safe and reduce the likelihood of them misconstruing the situation.

Insofar as possible, sticking to scheduled appointments and planning follow-up is particularly pertinent in this patient group. The trust which the neurologist may have worked hard to gain is likely to need continued authentication. For patients with BPD and dissociative (non-epileptic) seizures, for example, it is advisable to continue seeing the patient at scheduled intervals (even if sparse) once the diagnosis has been made.32 This prevents the receipt of medical attention becoming conditional on escalating illness behaviours.32 Moreover, after the establishment of a therapeutic alliance, discharges should be planned and gradually phased insofar as possible. People with BPD are characteristically highly sensitive to perceived rejection which may trigger decompensation and frantic help-seeking elsewhere if this is not thoughtfully managed.32 As such, careful planning will help both the patient and the health service as a whole.

Maintaining hope

The sense of shame, anxiety and hopelessness characteristically felt by people with BPD can engender a sense of hopelessness in the treating doctor, which may itself in turn be detected by these highly sensitive patients.32 The importance of reciprocal influence within the doctor–patient relationship has been demonstrated by the finding that either more positive or negative communication on one side elicits similar response styles from the other.48 Optimism and maintenance of hope on the part of the physician should therefore not be underestimated.

Moreover, this optimism is not misplaced. Though previously believed to be a treatment-resistant condition, there is now a growing body of evidence showing that patients with BPD can be effectively helped.44 As such, we believe that working with and advocating for these patients is an extremely rewarding experience.