Distress tolerance moderates the relationship between negative affect intensity with borderline personality disorder levels

Abstract

A number of studies have suggested that negative emotionality and negative affect intensity play key roles in the development and maintenance of borderline personality disorder (BPD). However, more recent research indicates that one's response to affective discomfort may be an even more important variable in the pathogenesis of BPD than either negative emotionality or negative affect intensity per se. As such, the current study aimed to empirically test the moderating role of 2 well-validated laboratory measures of the ability to tolerate psychological distress (distress tolerance) in the relationship of negative emotionality and negative affect intensity with BPD levels. Results provide laboratory-based evidence for a moderating effect of distress tolerance on the relationship of negative emotionality and negative affect intensity with levels of BPD. Specifically, the 2 former variables were related to levels of BPD among those with low distress tolerance. The current results add support to existing developmental frameworks of BPD and suggest the importance of modifying one's response to affective distress along with levels of negative emotionality in treatment settings.

Introduction

Borderline personality disorder (BPD) is a severe and persistent mental illness characterized by pervasive affective, cognitive, interpersonal, and behavioral dysfunction, including emotional lability, interpersonal disturbances, and engagement in risky or impulsive behaviors [1], [2], [3], [4]. Epidemiological studies suggest that the rate of BPD in the general population ranges from 2% to 5% [5], [6], although Trull [7] has estimated that as many as 13% of nonclinical adults demonstrate symptoms consistent with a diagnosis of BPD. In line with clinical samples, subclinical levels of BPD are associated with significant social and occupational dysfunction as well as increased rates of mood, anxiety, and substance use disorders [8].

Given the degree of distress and impairment associated with BPD, theoretical conjecture and empirical work have focused on the understanding of risk and maintenance factors for the disorder. The dominant theory used to explain the pathogenesis of BPD is the diathesis-stress model, which suggests that BPD results from the combination of biologically-based temperamental vulnerabilities and adverse childhood experiences such as childhood sexual, physical, or emotional abuse or neglect [3], [9], [10]. Consistent with this model, a growing body of research has focused on temperamentally based emotional processes in BPD, including negative emotionality [4], [11], affective instability [4], affect intensity [12], [13], and emotion dysregulation [14].

The construct of negative emotionality (a heritable trait reflecting a tendency toward depression, anxiety, and poor reaction to stress) in particular has received a great deal of attention as a potential vulnerability for both the etiology and maintenance of BPD [4], [11], [15], [16], [17]. Theoretical work suggests that negative emotionality underlies many of the risky and impulsive behaviors associated with BPD (i.e., deliberate self-harm, interpersonal aggression, substance use) [18], [19], [20]. Empirically, several cross-sectional studies report higher rates of negative affect among those with BPD compared to these without the disorder [7], [21], [22]. Moreover, a recent prospective study of children reported that negative emotionality in both early childhood and early adolescence prospectively predicted BPD features [15]. Finally, a study of adult psychiatric patients reported that BPD traits predicted both the recurrence and new incidence of major depressive disorder [2].

Another variable, negative affect intensity, has also been implicated as a major risk factor for BPD. On the surface, negative affect intensity might seem quite similar to negative emotionality. However, conceptual and empirical research makes an important distinction. Affect intensity refers to how strong an individual's negative affect is, in general regardless of the frequency or exact content of said negative affect. In other words, negative emotionality refers to the what (frequency and content), whereas affect intensity refers to the how (stylistic aspects of behavior) [23], [24]. Follow-up empirical work also identifies negative emotionality and affect intensity as separate constructs. The correlation between affect intensity and negative emotionality is approximately .3 to .5 [23], [25], and the correlation of the former with negative affect frequency is approximately .2 [25]. Affect intensity predicts symptoms of psychopathology above and beyond negative emotionality [26]. Finally, extraversion and neuroticism together account for 42% of the variance in negative affect intensity, which suggests that affect intensity captures elements of emotional experience not accounted for by these personality dimensions [25], [27]. As such, negative affect intensity and negative emotionality can be thought of 2 correlated but distinct vulnerability factors.

The focus on negative affect intensity in BPD research is not surprising, as clinical lore describes individuals with BPD as “intense,” especially in relation to negative affective states. Preliminary empirical evidence also reports moderate relationships with BPD pathology. For instance, Flett and Hewitt [12] reported that high affect intensity was associated with self-reported BPD characteristics. Similarly, Levine et al [28] compared individuals with BPD to nonpsychiatric controls. Results indicated that the BPD group showed significantly greater intensity of negative emotions than controls. In 2 clinical samples, affect intensity has been found to be especially elevated in individuals with BPD relative to those with bipolar II disorder [29] and was predictive of BPD features beyond depressive symptomatology [30].

Yet, there are reasons to believe that the association between negative emotionality and BPD is more complex than previously believed. First, it is worth noting that negative emotionality is normally distributed in the population [31], which suggests that, at least in the middle ranges of the distribution, it cannot be inherently pathological. Consistent with this conceptualization, Rosenthal et al [32] reported that although negative emotionality was a stronger predictor of BPD than childhood sexual abuse, thought suppression fully mediated the relationship between negative emotionality and BPD. Similarly, Gratz et al [33] found that the relationship between negative emotionality and BPD was partially mediated by experiential avoidance.

A parallel problem applies to the relationship between negative affect intensity and BPD. Several studies suggest that an individual's response to intense affective distress may be as important as affect intensity per se in predicting BPD traits. In a study examining physiological correlates of emotion among those with BPD, Herpertz et al [13] examined affective responses to emotional stimuli using physiological and self-report measures. Results indicated that while individuals with BPD report elevated subjective reactions to emotional stimuli, they did not demonstrate increased physiological reactivity relative to individuals without BPD [13], [34]. These results may be interpreted as lower tolerance of emotional arousal rather than greater affect intensity among individuals with BPD [35]. Similarly, Cheavens et al [36] and Gratz et al [33] reported that the relationship between affect intensity and BPD symptoms was fully accounted for by (respectively) thought suppression and emotion dysregulation, that is, variables that encompass tolerance and acceptance of emotional distress in their definition [37]. Taken together, these findings suggest that it is not simply negative affect or negative affect intensity that is related to BPD traits, but how one responds to these vulnerability factors that may be critical in differentiating between those who develop BPD and those who do not.

The account of one's response to affective distress as a key variable in the development of BPD aligns this research with the larger literature focusing on the role of distress tolerance, or one's willingness and ability to persist in a positive behavior or to refrain from engagement in maladaptive behaviors during periods of physical or emotional distress [3], [38], [39] in BPD. Distress tolerance figures prominently in theoretical conceptualizations of BPD (eg, [3]), and recent experimental findings have provided further evidence for diminished distress tolerance among individuals with BPD compared to healthy controls [40], [41]. For instance, Bornovalova et al [40] examined emotional distress tolerance in a sample of inpatient substance users with and without BPD. Results indicated diminished willingness to tolerate distress among participants with BPD. Poor emotional distress tolerance explained 18% of the variance in BPD status above and beyond demographic variables and Axis I psychopathology, suggesting the centrality of emotional distress tolerance to BPD. These studies are consistent with the notion of emotional distress tolerance as a moderator between negative emotionality and/or affect intensity and levels of BPD.