What is borderline personality disorder (BPD)?

There is confusion around the diagnosis of BPD, known in the WHO classification (ICD-10) as Emotionally unstable personality disorder, borderline type. In order to understand the nature of the disorder, a word about personality disorders (PDs) in general is necessary, as BPD is in some ways unique among PDs.

Personality disorders are a group of mental health difficulties that are present throughout a persons life, and are part of their normal way of relating with other people, and thinking of themselves – and the actions that stem from this. They are disorders in that they cause suffering, either to the person themselves or (less commonly) those around them. Not everyone with a PD seeks help, in fact most probably do not; like most disorders, a PD can be more or less severe, and cause more problems at particular times of life, such as during transitions (leaving home, changing job, loss events). About 5% of the population of the UK would be diagnosed with a PD of some sort (there are 9 or 10 types depending on the classification system used) if they presented to a psychiatrist, which gives an indication of how few actually do. As a comparison, this is five times as many as suffer with schizophrenia, very few of whom do not receive a diagnosis and treatment at some point in their lives if they live in the developed world. There is debate about whether PDs should be classified with other mental illnesses, as they differ in important ways: they tend to be lifelong and consistent, or stable, throughout most of that time; in other words they seem more like a part of the way the person is constituted than an illness visited upon them. In this they may appear to resemble autistic spectrum disorder or differences in a continuous variable such as IQ more than for example schizophrenia or depression.

The ICD-10 lists the personality disorders as follows:

F60  Specific personality disorders

F60.0  Paranoid personality disorder
F60.1  Schizoid personality disorder
F60.2  Dissocial personality disorder
F60.3  Emotionally unstable personality disorder
.30 Impulsive type
.31 Borderline type
F60.4  Histrionic personality disorder
F60.5  Anankastic personality disorder
F60.6  Anxious [avoidant] personality disorder
F60.7  Dependent personality disorder
F60.8  Other specific personality disorders
F60.9  Personality disorder, unspecified

Borderline personality disorder differs from the other PDs in important ways. It is probably less stable and lifelong than other PDs, although this may be an artefact of the larger body of research devoted to BPD. It appears to be less pervasive, meaning people with BPD tend not to present in the same way in different situations. This is curious, as pervasiveness is a central element of the personality disorders. People with BPD are also more likely to seek treatment than people with other PD diagnoses; the majority of people receiving treatment in specialist centres suffer from BPD, often with one or more other PDs.

The most prominent features of BPD are self harm/suicidality, emotional instability (unpredictable variations in mood, both sad/happy and angry/irritable), impulsivity (doing things on impulse without due consideration of the consequences) and disordered attachment (stormy relationships, very strong feelings of abandonment when a close relationship ends). It is the first two of these that most commonly lead to people seeking help.

The International Classification of Diseases 10 of the World Health Organisation (ICD-10) includes the following description of emotional unstable personality disorder:

F60.3  Emotionally unstable personality disorder

A personality disorder in which there is a marked tendency to act impulsively without consideration of the consequences, together with affective instability. The ability to plan ahead may be minimal, and outbursts of intense anger may often lead to violence or “behavioural explosions”; these are easily precipitated when impulsive acts are criticised or thwarted by others. Two variants of this personality disorder are specified, and both share this general theme of impulsiveness and lack of self-control.

F60.30 Impulsive type
The predominant characteristics are emotional instability and lack of impulse control. Outbursts of violence or threatening behaviour are common, particularly in response to criticism by others.

F60.31 Borderline type
Several of the characteristics of emotional instability are present; in addition, the patient’s own self-image, aims, and internal preferences (including sexual) are often unclear or disturbed. There are usually chronic feelings of emptiness. A liability to become involved in intense and unstable relationships may cause repeated emotional crises and may be associated with excessive efforts to avoid abandonment and a series of suicidal threats or acts of self-harm (although these may occur without obvious precipitants).

The Diagnostic and Statistical Manual of the American Psychiatric Association (DSM 5) specifies 5 out of the following 9 symptoms must be present for the diagnosis to be made:

  1. Frantic efforts to avoid real or imagined abandonment. Note: Do not include suicidal or self-mutilating behavior covered in Criterion 5.
  2. A pattern of unstable and intense interpersonal relationships characterized by alternating between extremes of idealization and devaluation.
  3. Identity disturbance: markedly and persistently unstable self image or sense of self.
  4. Impulsivity in at least two areas that are potentially self- damaging (e.g., spending, sex, substance abuse, reckless driving, binge eating). Note: Do not include suicidal or self- mutilating behavior covered in Criterion 5.
  5. Recurrent suicidal behavior, gestures, or threats, or self- mutilating behavior.
  6. Affective instability due to a marked reactivity of mood (e.g., intense episodic dysphoria, irritability, or anxiety usually lasting a few hours and only rarely more than a few days).
  7. Chronic feelings of emptiness.
  8. Inappropriate, intense anger or difficulty controlling anger (e.g., frequent displays of temper, constant anger, recurrent physical fights).
  9. Transient, stress-related paranoid ideation or severe dissociative symptoms.

There is some debate about whether BPD should continue to be regarded as a single entity, as it can appear to be a collection of symptoms which happen to occur together in a group of people but perhaps as commonly occur separately, and that labelling them as a syndrome when occurring together does not add much to our understanding. A similar argument occurs about PDs as a whole, as comorbidity is so common (i.e. if you have one you are very likely to have more than one), and statistical experiments sometimes fail to identify the PDs (or indeed BPD) in the population (through for example cluster analyses). To widen matters further, following the publication of DSM 5, the usefulness of the term schizophrenia was called into question by the British Psychological Society. These debates are not uncommon in psychiatry.