Introduction

Borderline personality disorder (BPD) is characterized by a “pervasive pattern of instability of interpersonal relationships, self-image, and affects, and marked impulsivity that begins in early adulthood and is present in a variety of contexts” (American Psychiatric Association, 2000, p. 706). According to Zanarini (2009), individuals diagnosed with BPD make up 2-6% of American adults. However, even with psychiatric interventions, a large percentage will return for treatment and frequently require more mental health services than those with other psychiatric disorders (Lieb, Zanarini, Schmahl, Linehan, & Bohus, 2004; Piper & Ogrodniczuk, 2001).

Current literature on borderline personality disorder maintains a focus on exploring specific diagnostic criteria, including emotional dysregulation/affect instability (Tragesser, Solhan, Schwartz-Mette, & Trull, 2007), instability of interpersonal relationships (Berdahl, 2010), and poor attachment styles (Fonagy, 2000). Bohus, Schmahl, and Lieb (2004) stress the importance of a dimensional framework in the classification of diagnostic symptoms of BPD, explaining that “four core elements play a major role in the development and maintenance of BPD: 1) affective instability, 2) impulsivity and aggression, 3) cognitive features. . . and 4) identity problems” (p. 44).

Due to the complex diagnostic criteria of BPD, research in the field of neuropsychology has just begun to comprehensively explore the biological aspects of BPD. The purpose of this paper is to further examine the brain systems involved in emotional dysregulation and impulsivity, two key characteristics and diagnostic features of borderline personality disorder frequently reviewed in the literature.

According to Friedel (2004), core symptoms of borderline personality disorder seem to stem from “abnormalities in the neural systems that regulate emotional activity, impulse control, and thinking” (p. 88). Diagnostically, this can translate into affect instability or emotional dysregulation, impulsivity, and difficulties in cognitive processing (APA, 2000). Researchers believe that affective instability, which is also referred to in the literature as emotional dysregulation and will be referred to as such in this paper, is the cornerstone of the underlying features of BPD (Linehan, 1993). Emotional dysregulation can be defined as the “tendency for emotional states to gain momentum and become increasingly erratic and intense” (Tragesser et al., 2007, p. 604). Further, it has been argued that individuals diagnosed with BPD are likely to become emotionally overwhelmed and their cognitive processes might become impaired.

Friedel (2004) explains that challenges in cognitive processing could result in difficulty with reasoning and planning because of stress-related paranoid thinking, often resulting in high emotionality and low rational decision making skills. Difficulties in this process might also cause challenges in reasoning due to an inability to balance and resolve complex problems, which might increase impulsive behaviors. For many individuals suffering from borderline personality disorder, impulsivity can show up in a variety of symptoms. For example, increased aggression, suicide and parasuicidal behaviors, and intense interpersonal relationships can all be triggered by impulsive actions and behaviors (Soloff, Nutche, Goradia, & Diwadkar, 2008).

Emotional dysregulation and impulsivity can all be connected to certain structural components of the brain (Bohus, Schmahl, & Lieb, 2004; Donegan et al., 2003; Mauchnik, Schmahl, & Bohus, 2005; New et al., 2007). For example, research has shown an increased activation of the amygdala of individuals diagnosed with borderline personality disorder (Donegan et al., 2003).

Emotional Dysregulation

Linehan (1993) describes emotional dysregulation as an inability to regulate high emotional vulnerability and responses. The amygdala is part of the brain system that has been shown to be involved in the “generation of negative emotional states” and is frequently studied in behavioral neurobiology because of its role in generating fear and anxiety (Donegan et al., 2003, p. 1284). This part of the brain is located in the cerebellum and functions as an essential component in memory and emotion. The amygdala serves as a way in which individuals associate different sensory stimuli to memories of the past. The amygdala is also associated with fear and other intense emotions (Bernstein, Clarke-Stewart, Penner, Roy, & Wickens, 2000).

In a study by Donegan et al. (2003), researchers were interested in exploring the role of the amygdala in emotional regulation of individuals diagnosed with borderline personality disorder. Participants included a control group of fifteen right-handed subjects and fifteen right-handed subjects who were diagnosed with BPD and currently undergoing psychiatric treatment or had undergone treatment in the past six months. Participants with a diagnosis of BPD were required to meet five of the nine DSM-IV criteria of the disorder, based upon the Diagnostic Interview for Personality Disorders-IV (DIPD-IV; Zanarini, Frankenburg, Sickel, & Yong, 1996).

Researchers used functional magnetic resonance imaging (fMRI) lasting 4 minutes 20 seconds to assess for brain stimulation while participants were shown twenty pictures of a particular facial expressions, such as fear, sadness, happiness, or neutral. Researches used a “three-way repeated-measures analysis of variance (ANOVA)” (Donegan et al., 2003) to explore differences between participants (control vs. BPD), hemispheres affected (right vs. left amygdala), and facial expressions (happy, neutral, sad, fearful).
Results indicated that participants meeting criteria for borderline personality disorder exhibited “higher levels of left amygdala activation to the facial expressions” (Donegan et al. 2003, p. 1287). Specifically, a three-way ANOVA showed that participants with BPD had greater levels of left amygdala activation when presented neutral faces compared to the control group. This could indicate individuals with a diagnosis of borderline personality disorder are more sensitive and vigilant to emotional reactions of others because of hyperactivity in the amygdala. Limitations to this study might include confounding variables such as medication interaction with recognition and stimulation of the amygdala in addition to a unbalance representation of men and women in both the experimental and control sample.

Research in borderline personality disorder often connects a pattern of emotional dysregulation to previous child abuse or trauma (Bohus, Schmahl, & Lieb, 2004). The amygdala and hippocampus are involved in the retrieval of memories and therefore might be hypersensitive to past abuses and traumatic events, leading to an over-stimulation of response when triggered by emotional situations (Bohus, Schmahl, & Lieb, 2004). Research has found a decrease in volume of the hippocampus of individuals who survived a trauma and suffer from post-traumatic stress disorder (PTSD), frequently experienced by individuals diagnosed with BPD (Liotti & Pasquini, 2000). The hippocampus, like the amygdala, is part of the limbic system and services as an important brain structure for memory and frequently associated with PTSD and trauma research. Although it is beyond the scope of this paper to discuss the importance of PTSD as it relates to the hippocampus and borderline personality disorder, it should be noted that there is a variety of literature available for further review.

Impulse Control

Impulsivity in borderline personality disorder can be described at “physical aggression directed towards others, self-mutilation, suicide attempts, domestic violence, [and] substance abuse” (Goodman & New, 2000, p. 56). Often, this behavior leads to challenges in clinical settings and make therapy and treatment interventions difficult for bot the client and therapist.

Research has found that structures of the brain responsible for impulse control appear to be under-active (Friedel, 2004). Most specifically the orbitofrontal cortex, responsible for executive functions like thinking, planning, reasoning, and evaluating and “regulates the neural circuits that mediate impulsivity, response inhibition, and impulsive-aggressive behavior (Soloff, Meltzer, Becker, Greer, Kelly, & Constantine, 2003, p. 154). It is hypothesized that this particular part of the brain of individuals diagnosed with BPD might not function properly because of a disturbance in glucose metabolism. It is important to note that impulsivity in borderline personality disorder might be self-directed, as indicated by self-harm and self-mutilation (i.e.: cutting) or other-directed through violence and unstable interpersonal relationships (Soloff et al., 2003).

In a study to better understand glucose metabolism in the brain and its effects on controlling impulsive and aggressive behaviors, thirteen right-handed female subjects meeting BPD criteria (based upon the International Personality Disorder Examination; IPED and Diagnostic Interview for Borderline Patients; DIB) were compared with nine control subjects (Soloff et al., 2003). Of participants with a BPD diagnosis, 92.3% had made suicide attempts, while impulsivity (assessed on the Barratt Impulsiveness Scale; BIS) was higher than control participants.

Positron emission tomography (PET) scans were administered to all participants, after four mCi (estimated absorbed radiation doses) Fluorodeogyglucos-F18 (FDG) were “injected intravenously, followed by a 40-minute uptake during which the subjects rested quietly” (Soloff et al., 2003, p. 155). Results found “significant reduction in FDG uptake in BPD subjects relative to healthy controls were found in the medial orbital frontal cortex” (p. 156). This hypometabolism or reduction of uptake could inhibit the prefrontal cortex and thereby hinder executive functions from operating at a high level of functioning, inhibiting impulsive control.

Evidence Based Treatment: Dialectical Behavior Therapy

Dialectical Behavior Therapy (DBT; Linehan, 1993) was originally developed as a treatment for chronically suicidal individuals diagnosed with borderline personality disorder, specifically aimed at “improving affect regulation” (Schnell & Herpertz, 2006, p. 838). This manualized treatment is broken down into four modules: mindfulness, distress tolerance, emotion regulation, and interpersonal effectiveness which each teach clients positive coping skills to deal with adverse, stressful, and emotionally challenging situations.
Researchers were interested to explore whether or not behavioral changes from DBT treatment would affect the neural systems involved in affect (emotional) regulation. Specifically, that the amygdala would show the most change in arousal (Schnell & Herpertz, 2006). Six right-handed, medication free women meeting diagnostic criteria for BPD were selected to participate, while six control participants were matched by gender, age, and intellect. Those participants diagnosed with BPD participated in a 12-week DBT in-patient treatment program, attending ten group sessions per week and one individual therapy session per week. Participants were “examined with fMRI scans on days 0, 7, 35, 63, and 91.” (p. 839).
Participants were subject to viewing images from the Affective Picture System, which has been “consistently shown to reliably induce activation in the brain region involved in affective processing in normal subjects. . . as well as participants with a variety of psychiatric disorders” (Schnell & Herpertz, 2006, p. 839). Blood oxygenation level dependent (BOLD) images were acquired using a Philips Intera Scanner to explore the extent to which potentially triggering images might affect the brain’s response in both the control and experimental group.

Results indicated that differences in brain images between the control and experimental group were initially “greater before DBT-treatment than after treatment. . .[and] prior to DBT treatment patients displayed greater activation” in the brain (Schnell & Herpertz, 2007, p. 841). While the area of brain activation after DBT-treatment “revealed fewer areas of increased activation” when exposed to disturbing images in the group with a BPD diagnosis. These results might indicated that individuals who are currently diagnosed with BPD and in DBT treatment, undergoing specific therapy aimed at emotional regulation and increased coping skills during acutely stressful events, might have less stimulating reactions to such stimuli.

It can be speculated that one of the reasons DBT works so effectively with individuals diagnosed with borderline personality disorder is the use of mindfulness. It has been suggested that individuals diagnosed with borderline personality disorder have difficulties attending to their emotions in highly emotionally stimulating environments (Wupperman, Neumann, & Axelrod, 2008)
According to Robins (2002), mindfulness can be defined as “nonjudgmental awareness of one’s experience as it unfolds moment by moment [and] . . . that ability to nonjudgmentally focus one’s attention on a chosen object or event has clinically significant benefits” (p. 55). Siegal (2007) further explains that when the brain processes new information or experiences repeatedly, the brain will learn these experiences and create new neural pathways and create new memories associated with these experiences. Mindful experiences can create structural changes in the brain and “enables individuals to regulate their emotions in a more positive manner” (p. 32). Such practices are integral in the acceptance of vulnerabilities, in that they validate the feelings and emotions without requiring maladaptive or impulsive behaviors to take control.

Transpersonal Considerations: Mindfulness

Dialectical Behavior therapy “integrates cognitive-behavioral principles and strategies with Zen Buddhist principles and mindfulness practices (Robins, 2002, p. 51). The greater purpose of DBT is to promote an acceptance of where the client is at, focusing on validation instead of change. Linehan (1993) established DBT based upon several Zen Buddhist principles, which also views the world through a dialectic lens. Meaning, experiences are not independent from each other, but rather have “emergent properties that arise from the integration of diverse elements, constantly changing as they affect other things and are affected in turn by them” (Robins, 2002, p. 53).

Zen Buddhist principles are based upon the 4 Noble Truths, stating 1) life is suffering, 2) the cause of suffering is attachment, 3) it is possible to decrease suffering by letting go of attachment, and 4) the method for letting go of attachment is through practicing the Eight-Fold Path (Robins, 2002). Mindfulness in DBT calls attention to the tendency for individuals to grasp at and attach to aspects of life that ultimately cause suffering. This awareness of present, focused, attention directs the mind to the here and now and does not leave space for wandering into potentially emotionally triggering thoughts.

The principles of mindfulness as they relate to Dialectical Behavior Therapy and Zen Buddhism can be connected to transpersonal psychology through the awareness of something beyond the structure of the individual. Transpersonal psychology is viewed as a framework from which therapists understand and cultivate human transformation (Hartelius, Caplan & Rardin, 2007) whereas mindfulness can be used as a tool to connect individuals to their inner source of strength and agency. For individuals diagnosed with borderline personality disorder, this sense of agency and control over high emotional reactivity and impulsiveness can be quite transformative.

It is important to recognize that in working with an acute population, such as individuals diagnosed with borderline personality disorder, not one treatment method or theory of etiology will concretely define the entire construct of the diagnosis. Current literature maintains a focus on the importance of integrating neurobiological factors into a holistic view of development and treatment. Yet, even with available research, there is still much more required in the field to further understand the dynamic involvement of the brain, social, and environmental factors and their contribution to this diagnosis.

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