Psychological Flexibility in Borderline Personality Disorder: A Comparative Study with Healthy Controls

Zekeriya Temircan ^* 

1. Department of Psychology, Faculty of Humanities, Cappadocia University, Nevsehir, Türkiye

* Correspondence: Zekeriya Temircan 

Academic Editor: Yongxia Zhou

Special Issue: Multi-modal Neuroimaging Integration

Received: March 09, 2025 | Accepted: December 21, 2025 | Published: December 31, 2025

OBM Neurobiology 2025, Volume 9, Issue 4, doi:10.21926/obm.neurobiol.2504316

Recommended citation: Temircan Z. Psychological Flexibility in Borderline Personality Disorder: A Comparative Study with Healthy Controls. OBM Neurobiology 2025; 9(4): 316; doi:10.21926/obm.neurobiol.2504316.

© 2025 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

1. Introduction

Borderline personality disorder (BPD) is the most commonly diagnosed personality disorder, characterized by intense emotions, unstable interpersonal relationships, and disturbances in self-perception. Individuals with BPD often experience rapid mood shifts, including anger, depression, and anxiety, and may exhibit impulsive or self-injurious behaviors [1]. These affective instabilities frequently lead to difficulties in maintaining close and stable relationships. They are accompanied by a chronic sense of emptiness, transient stress-related psychotic states, and other maladaptive behaviors such as risky actions or disordered eating [2,3].

BPD affects approximately 2–5% of the general population, with higher rates in clinical settings (10–20%) [4]. Core diagnostic features include affective instability, impulsivity, unstable self-image, transient psychotic episodes, and excessive dependency in interpersonal relationships [5]. Emotional dysregulation is central to BPD and contributes to frequent crises, chaotic relationships, and maladaptive coping strategies.

This often leads to significant problems in developing close, stable, and meaningful interpersonal relationships with others [6]. In addition, weakness in self-integrity and a sense of emptiness also accompany the current situation. Transient psychotic states accompanied by hallucinations and delusions under stress have also been reported [7]. BPD cases are usually, but not always, preoccupied with recurrent self-injurious behaviors, suicidal and para-suicidal thoughts [8]. There are reasons behind self-injurious behaviors such as self-punishment, getting rid of painful emotions, using it as a means of relaxation, and feeling more alive [9]. This is consistent with a chronic sense of emptiness [10] and is frequently reported to be associated with other destructive behaviors such as gambling [11], eating disorders [12] and dangerous driving. BPD patients are often in emotional turmoil and crisis and, as a consequence, usually seek medical help [13].

It is observed that BPD cases give intense emotional reactions due to fluctuations in their moods. They may go from a depressed emotional state to an angry and argumentative state in an instant. Afterwards, they may describe a void where there is no emotion. This situation often leads borderline behaviors to be perceived as unpredictable [14]. Poor emotion regulation capacity leads to frequent self-injurious behavior, chaotic interpersonal difficulties associated with occasional emotional lability and volatility, and manipulative suicide attempts [15]. They may show dissociative and paranoid symptoms under intense stress [16].

Research indicates that cognitive flexibility is generally reduced in individuals with psychiatric disorders such as schizophrenia and major depressive disorder [17,18]. Belief flexibility, particularly in response to delusions, is notably impaired in schizophrenia compared to depression and healthy controls [19]. Different subtypes of psychological flexibility, such as affective instability and interpersonal flexibility are associated with distinct psychiatric disorders. Affective instability is linked to bipolar disorder, while less interpersonal flexibility is associated with depressive disorders [20]. Individuals with BPD often exhibit significant impairments in cognitive flexibility, which is the ability to adapt thinking and behavior in response to changing environments. These deficits are associated with poor social and occupational functioning and may worsen with the length of illness [21].

Psychological flexibility is an essential construct in the understanding and treatment of a wide range of psychiatric disorders. It refers to the ability to adapt to changing situational demands, to shift mental states, and to balance competing desires, needs, and domains of life. This concept is increasingly recognized as a key factor in mental health. It influences the development, maintenance, and treatment of psychiatric disorders. Observing negative internal experiences as they are, without judgment, allows these experiences to be experienced without accepting them as the absolute truth [21].

From this perspective, it has been proposed that individuals with greater psychological flexibility are less likely to engage in control- or avoidance-based behaviors in response to unwanted or harmful internal experiences and are more likely to respond in ways consistent with personally meaningful life domains. Many studies show that psychological flexibility is related to mental well-being and is negatively correlated with a wide range of psychopathological spectrums [5,7,14,20].

There are a limited number of studies in the literature on borderline personality disorder and psychological flexibility, and there is a significant gap in this area, especially in our country. The present study aims to examine specific components of psychological flexibility, namely cognitive fusion, experiential avoidance, mindfulness, valued living, and self-as-context in individuals diagnosed with borderline personality disorder, and to investigate how these components differ from those of healthy controls.

1.1 Research Questions

RQ1: Do individuals with BPD differ from healthy controls in psychological flexibility components (contextual self, cognitive fusion, mindfulness, valued living, and AAQ-II)?

RQ2: Which components of psychological flexibility show the most significant impairment in individuals with BPD?

RQ3: Are psychosocial factors such as loss experience, suicide attempts, and smoking associated with BPD?

1.2 Hypotheses

H1: Individuals with BPD will have lower contextual self and mindfulness, and lower valued living scores than controls.

H2: Individuals with BPD will show higher cognitive fusion compared to controls.

H3: Individuals with BPD will report higher rates of loss experience, suicide attempts, and smoking.

H4: Value importance (VLQ-1) will not differ between groups.

H5: Psychological flexibility components (CSS, CFS, VLQ, FMI, AAQ-II) will significantly correlate with each other.

2. Method

The study was conducted at the Psychiatry Outpatient Clinic of Erciyes University Research Hospital. Data collection took place over a six-month period, between January 2023 and June 2023. A total of 58 individuals diagnosed with borderline personality disorder (BPD) according to DSM-5 criteria and 62 healthy volunteer controls who met the inclusion and exclusion criteria were recruited. Patients in the BPD group were recruited consecutively from all eligible attendees of the outpatient clinic, while healthy controls were recruited using convenience sampling from the local community.

All clinical interviews and diagnostic evaluations for the BPD group were conducted by a senior psychiatrist working in the outpatient clinic. The administration of the self-report scales was conducted by a researcher trained in standardized test application procedures. To ensure standardization, all participants completed the questionnaires in a quiet room within the clinic, under the supervision of the same psychologist, following identical instructions.

Inclusion criteria for the BPD group were: being over 18 years old, being literate, receiving a DSM-5–based diagnosis of borderline personality disorder, voluntarily agreeing to participate, and signing the written informed consent. Exclusion criteria included having another psychiatric disorder (e.g., schizophrenia or other psychotic disorders) or intellectual disability.

For the control group, the inclusion criteria were being 18 years or older and not having any current or past psychiatric disorder, as confirmed through a brief structured interview conducted by the same clinician.

2.1 Power Analysis and Sample Size Justification

A post-hoc power analysis was conducted using G*Power, assuming a medium effect size (d = 0.5) and α = 0.05; the total sample of 120 participants (58 BPD, 62 controls) yielded a statistical power of 0.81, indicating that the sample size is sufficient to detect group differences in psychological constructs.

2.2 Data Collection Tools

The socio-demographic form, Borderline Personality Scale, Acceptance and Action Form II, Life with Values Scale, Cognitive Integration Scale, Freiburg Self Inventory, and Contextual Self Scale were applied to the participants.

2.2.1 Socio-Demographic Characteristics Form

It is a semi-structured form prepared by the researcher to determine the socio-demographic characteristics of the sample of the study. The form also includes questions about the participants' age, gender, marital status, education, and occupation.

2.2.2 Borderline Personality Scale (BPS)

The Borderline Personality Scale evaluates borderline personality traits based on DSM-5 criteria and is a self-report instrument. Initially developed by Poreh et al. [22], it includes 80 items divided into 9 subscales: impulsiveness, mood instability, abandonment, relationships, self-image, suicidal/self-injurious behavior, sense of emptiness, intense anger, and psychosis-like states. Items are scored as true/false. For positively keyed items, correct responses are scored 1 and incorrect responses 0; for negatively keyed items, scoring is reversed. The Turkish adaptation by Aydemir et al. [23] demonstrated acceptable psychometric properties. In this study, the scale was scored according to the original procedure. Cutoff scores are not specified; higher total scores indicate higher levels of borderline traits.

2.2.3 Acceptance and Action Questionnaire-II (AAQ-II)

The AAQ-II developed to [24] measures psychological flexibility, particularly experiential avoidance and psychological rigidity, using a single-dimension, 7-item scale scored on a 7-point Likert scale (1 = never true to 7 = always true). Higher scores indicate greater psychological rigidity and lower flexibility. The Turkish adaptation was done by the researchers [25] so that it showed good reliability (Cronbach's α = 0.84, test-retest r = 0.85); in the current study, Cronbach's α was 0.92.

2.2.4 Contextual Self Scale (CSS)

The This scale consists of 10 items rated on a 7-point Likert scale (1 = strongly disagree to 7 = strongly agree) and yields a total score as well as centering (4 items) and transcending (6 items) subscales, with all three exhibiting acceptable levels of internal consistency (α = 0.76-0.83 in the US sample) and testretest reliability [26]. Turkısh adaption was done by Aydın et al. [27] and this study Cronbach's α value was found 0.78.

2.2.5 Freiburg Mindfulness Inventory (FMI)

The FMI developed [28] to use a 14-item self-report mindfulness scale. Items are rated on a 4-point Likert scale (1 = rarely to 4 = always). Lower scores reflect higher psychological flexibility, whereas higher scores indicate greater rigidity. The Turkish adaptation was done [29] abd it demonstrates acceptable validity and reliability. The present study Cronbach’s alpha was found 0.87.

2.2.6 Cognitive Fusion Scale (CFS)

The CFS measures cognitive fusion, a key component of psychological rigidity, with 7 items rated on a 7-point Likert scale (1 = never true to 7 = always true). Higher scores indicate greater cognitive fusion. The 7-item Cognitive Fusion Questionnaire (CFQ-7) as developed by Gillanders et al. [30] has demonstrated good to excellent internal consistency in multiple validation studies, with Cronbach’s α typically in the range ≈ 0.88 to 0.93 across various samples and settings. In adapted versions of Turkish [31] studied in university students and the CFQ also demonstrated high reliability with Cronbach’s α = 0.92. The present study Cronbach’s alpha was found 0.91.

2.2.7 Valued Living Questionnaire (VLQ)

The VLQ is a two-part self-report instrument that addresses personal values and the extent to which individuals live according to these values [32]. In the first part, participants rate the importance of 10 value domains (1 = not at all important to 10 = extremely important). In the second part, they rate the consistency of their behaviors with these values over the past week (1 = not at all consistent to 10 = entirely consistent). Higher second-part scores indicate greater alignment between values and behavior. The Turkish adaptation is conducted and the Cronbach’s alpha was found α = 0.90, concurrently with this study [33]. The present study Cronbach’s alpha was found 0.89.

2.3 Ethical Statement

This study obtained ethical approval from the University Ethics Committee (approval number: 14672/2022), and Helsinki Declaration guidelines were followed during the study. Informed consent was obtained from all participants

3. Results

Table 1 presents the demographic characteristics of the borderline and control groups, including gender, marital status, and age distributions. For gender, the borderline group consists of 36 women and 22 men, while the control group includes 28 women and 34 men. The chi-square test result (χ² = 0.217) is above the significance level (p = 0.05), indicating no significant difference in gender distribution between the two groups. Regarding marital status, the borderline group has 20 single, 27 married, and 11 divorced individuals, whereas the control group consists of 26 single, 28 married, and 8 divorced participants. The chi-square test result (χ² = 0.254) is p > 0.05, suggesting no statistically significant difference between the two groups in terms of marital status. For age, the borderline group has a mean age of 36 years (SD = 8.02), while the control group has a mean age of 32 years (SD = 12.31). The chi-square test result (χ² = 0.462) indicates that the age difference between the two groups is not statistically significant. The control group has a higher standard deviation, indicating a wider age range compared to the borderline group. Since all chi-square test results are p > 0.05, there are no statistically significant differences between the borderline and control groups for gender, marital status, or age distribution. This suggests that the groups are demographically comparable, minimizing potential confounding effects from these variables.

Table 1 Comparison of Gender and Age Between Borderline and Control Groups.

Table 2 shows the Mann-Whitney U test results examining gender differences in psychological scales (CSS, CFS, VLQ-1, VLQ-2, FMI, AAQ-II) within the BPD and control groups. In both groups, all p-values exceeded 0.05, indicating no statistically significant gender differences. Although AAQ-II in the BPD group (p = 0.108) and VLQ-1 in the control group (p = 0.108) showed slight trends, these were not significant. Overall, gender did not significantly influence scores on any psychological measure in either group.

Table 2 Distribution of the Gender Variable According to Scales in the Borderline and Control Groups.

Sociodemographic data obtained from participants revealed significant differences between the borderline personality disorder (BPD) and control groups. Specifically, individuals with BPD were significantly more likely to have experienced loss compared to the control group (p = 0.035). Similarly, the frequency of suicide attempts was found to be much higher in the Borderline group. This difference was also significant (p = 0.001). This finding indicates that individuals with BPD are significantly more likely to attempt suicide compared to controls. A significant difference was also observed regarding smoking, with the borderline group smoking considerably more than the control group (p = 0). However, there was no statistically significant difference between the groups in terms of childhood exposure to violence (p = 0.623), alcohol use (p = 0.152), and drug use (p = 0.322). These results suggest that certain risk factors (experiencing loss, attempting suicide, smoking) differed between the borderline personality disorder and control groups. However, other behavioral variables, such as alcohol and substance use, were similar between the groups. These findings highlight the need to further investigate psychosocial factors associated with BPD.

In Table 3, the Mann-Whitney U test compares individuals with borderline personality traits and the control group across psychological variables. Overall, participants with borderline traits scored significantly lower on psychological flexibility (AAQ-II), mindfulness (FMI), value enactment (VLQ-2), and cognitive flexibility (CFS) compared to controls. In contrast, no significant difference was observed for value priorities (VLQ-1). These results suggest that borderline personality traits are associated with difficulties in psychological processes such as flexibility, mindfulness, and value enactment.

Table 3 Comparison of Psychological Variables Between Borderline Personality Disorder and the Control Groups: Mann-Whitney U Test Results.

In Table 4, psychological flexibility levels were compared between individuals with BPD and healthy controls using the Mann-Whitney U and Wilcoxon W tests. Significant differences were observed for CSS (U = 2737.5, W = 6474.5, p = 0.001), CFS (U = 2517.4, W = 5865.5, p = 0.002), VLQ-2 (U = 3715.5, W = 6778.5, p = 0.001), FMI (U = 3965.5, W = 8218.5, p = 0.004), and AAQ-II (U = 2445.5, W = 6525.5, p = 0.001), indicating that individuals with BPD scored lower across these measures. No significant difference was found for VLQ-1 (p = 0.382). These results demonstrate that BPD is associated with reduced psychological flexibility, underscoring the importance of interventions targeting flexibility enhancement in this population.

Table 4 Comparison of Psychological Flexibility Between Borderline Personality Disorder and Control Group.

Table 5 presents the Spearman correlation coefficients (r) and corresponding p-values for the relationships between various measures of psychological flexibility: Contextual Self Scale (CSS), Cognitive Fusion Scale (CFS), Values-Based Living Questionnaire-1 (VLQ-1), Values-Based Living Questionnaire-2 (VLQ-2), Freiburg Mindfulness Inventory (FMI), and Acceptance and Action Questionnaire-II (AAQ-II). There is a weak negative correlation between the CSS and CFS (r = -0.144, p = 0.001), suggesting that as contextual self-awareness increases, cognitive fusion tends to decrease. However, the relationship is weak. A moderate positive correlation is found between CSS and VLQ-2 (r = 0.328, p = 0.004), indicating that higher contextual self-awareness is associated with more values-based living. Additionally, a strong positive correlation exists between CSS and FMI (r = 0.652, p = 0.001), suggesting that individuals with higher self-awareness are also more mindful. On the other hand, a moderate negative correlation is observed between CSS and AAQ-II (r = -0.376, p = 0.001), implying that higher self-awareness is related to lower levels of acceptance and action.

Table 5 Correlations Results Between Psychological Flexibility Measures.

For the CFS, a significant moderate negative correlation is found with VLQ-1 (r = -0.274, p = 0.032), suggesting that greater cognitive fusion is associated with lower values-based living. However, CFS is positively correlated with VLQ-2 (r = 0.372, p = 0.001), indicating that greater cognitive fusion is linked with more values-based living. CFS is negatively correlated with FMI (r = -0.382, p = 0.001), indicating that higher cognitive fusion tends to decrease mindfulness. It also shows a moderate positive correlation with the AAQ-II (r = 0.554, p = 0.002), suggesting that increased cognitive fusion is associated with greater acceptance and action.

VLQ-1 and VLQ-2 show a strong positive correlation (r = 0.683, p = 0.001), meaning that individuals who engage in values-based living in one area tend to do so in other areas as well. VLQ-1 is moderately positively correlated with FMI (r = 0.274, p = 0.012), suggesting that those who live according to their values also tend to exhibit higher mindfulness. A weak negative correlation is found between VLQ-1 and AAQ-II (r = -0.236, p = 0.018), indicating a slight negative relationship between values-based living and acceptance/action. VLQ-2 shows a moderate positive correlation with FMI (r = 0.365, p = 0.001), suggesting that living according to one's values is associated with greater mindfulness. There is also a weak negative correlation between VLQ-2 and AAQ-II (r = -0.172, p = 0.007), indicating that values-based living in this domain is slightly negatively related to acceptance and action.

Finally, a weak positive correlation is found between FMI and AAQ-II (r = 0.248, p = 0.001), suggesting that mindfulness is somewhat positively related to acceptance and action. Overall, these findings imply that greater mindfulness, acceptance, and alignment with values tend to be associated with better psychological flexibility, which is essential for mental well-being.

4. Discussion

The study's findings show that gender does not have a determining effect on the differences observed in the psychological scales evaluated across both groups. Additionally, no significant differences were found between the BPD and control groups in age or marital status, suggesting that the groups were demographically comparable and minimizing potential confounding factors. Previous studies on BPD report higher prevalence in women, but male representation is also notable, particularly in clinical samples [34]. Similarly, while BPD is often associated with interpersonal instability, it occurs across marital statuses and adult age ranges, which aligns with the current findings [35].

Individuals diagnosed with BPD were found to exhibit significant differences in specific risk factors compared to the control group [36]. Specifically, individuals in the BPD group were more likely to experience loss, and the frequency of suicide attempts was significantly higher [37]. Smoking was also considerably more common in the BPD group. In contrast, no significant differences were found between the groups in terms of childhood exposure to violence, alcohol use, or substance use. These findings highlight the relevance of psychosocial factors in BPD [38,39].

Regarding psychological variables, individuals with BPD had significantly lower scores on psychological flexibility (AAQ-II), mindfulness (FMI), value-congruent living (VLQ-2), and cognitive flexibility (CFS) than the control group. This indicates that individuals with BPD may experience difficulties in psychological processes and suggests that psychological flexibility is an essential factor in understanding these difficulties.

Previous research has shown that low psychological flexibility is observed in various clinical populations, including individuals with depression and anxiety disorders, and is associated with experiential avoidance, cognitive rigidity, and reduced adaptive functioning [40,41]. While these studies provide a broader context, the present study did not directly measure depression severity, treatment outcomes, or prognosis in BPD. Therefore, although low psychological flexibility may relate to clinical challenges in BPD, causal or predictive conclusions regarding symptom severity or treatment response cannot be drawn from the current findings.

The present study contributes to the literature by demonstrating that individuals with BPD exhibit lower psychological flexibility, mindfulness, value-congruent living, and cognitive flexibility than healthy controls. These findings emphasize the potential importance of interventions to support psychological flexibility in BPD, while acknowledging that further research, including longitudinal and experimental designs, is needed to clarify the causal relationships and clinical implications.

5. Conclusion

This study demonstrates that individuals with BPD exhibit lower psychological flexibility, mindfulness, value-congruent living, and cognitive flexibility compared to healthy controls. The novel contribution of this research lies in examining multiple components of psychological flexibility, specifically in BPD, linking contextual self, cognitive fusion, and value-based living to the broader construct. Clinically, these findings highlight the potential value of interventions targeting psychological flexibility to support adaptive functioning in BPD. From a research perspective, the results underscore the need for longitudinal and experimental studies to clarify causal relationships and further explore how enhancing psychological flexibility may improve mental health outcomes in this population.

6. Limitations

This study has several limitations that should be considered when interpreting the findings. First, the sample size was relatively small (58 individuals with BPD and 62 healthy controls), which may limit the statistical power and generalizability of the results. Second, the study relied on self-report measures, which may be subject to response biases such as social desirability or inaccurate self-assessment. Third, some of the scales used, specifically the Turkish adaptations of the Contextual Self Scale (CSS) and the Valued Living Questionnaire (VLQ), are still undergoing ongoing validity and reliability analyses. While these scales were used cautiously and complemented by well-validated measures, the lack of fully established psychometric properties may affect the robustness of the findings. Finally, the cross-sectional design of the study prevents any causal inferences regarding the relationships between psychological flexibility and BPD characteristics. Future research with larger samples, longitudinal designs, and fully validated instruments is needed to confirm and extend these findings.

Author Contributions

The author did all the research work for this study.

Funding

The author declares that this research received neither internal nor external funding.

Competing Interests

The authors have declared that no competing interests exist.