The Relationship Between Dyadic Adjustment,Internalized Stigma,Psychological Inflexibility,and Playfulness in Bipolar Disorder: A Mediation Model

Abstract

Background and objectives:

The study investigates the influence of patients’ levels of psychological inflexibility, internalized stigma, and couple playfulness on their dyadic adjustment and proposes a novel model elucidating the interrelationships among these factors.

Methods:

The study included 99 patients diagnosed with bipolar disorder who were in remission and receiving follow-up care. The interviewer filled out the Socio-demographic Data Form, Hamilton Depression Scale, and Young Mania Rating Scale. Afterward, the participants filled out the Revised Dyadic Adjustment Scale (RDAS), Internalized Stigma of Mental Illness Scale (ISMI), Acceptance and Action Questionnaire-II (AAQ-II), and Play Questionnaire II (PQ-II).

Results:

The data from a total of 99 married participants diagnosed with bipolar disorder, including 41 men and 58 women, were examined in our study. Psychological inflexibility, internalized stigma, couple playfulness, and dyadic adjustment were all significantly correlated. Mediation analysis revealed that internalized stigma indirectly predicted dyadic adjustment negatively and that couple playfulness played a mediating role in this relationship.

Conclusion:

The hypothesis that couple playfulness mediates the effect of internalized stigma on dyadic adjustment was substantiated. However, psychological inflexibility did not mediate this relationship. These findings may inform the assessment of factors influencing dyadic adjustment in patients with bipolar disorder and the development of interventions to enhance it.

Keywords

internalized stigma psychological inflexibility playfulness bipolar disorder dyadic adjustment marital adjustment

Introduction

Although there is no universally agreed-upon definition, marital adjustment generally refers to the capacity of partners to communicate effectively, maintain positive affect toward each other, derive satisfaction from their shared experiences, and collaboratively resolve conflicts. The terms dyadic adjustment, marital adjustment, and relationship satisfaction are used interchangeably in the literature (Erbek et al., 2005). In psychiatric populations, dyadic adjustment and mental health exhibit bidirectional relationships: marriage can function as a stressor influencing illness course, while psychiatric disorders concurrently impact marital relationships (Grover et al., 2017). Understanding these reciprocal influences is essential for comprehensive treatment approaches.

Bipolar disorder significantly impacts dyadic adjustment and family dynamics, with research consistently showing adverse effects on marital harmony (Chaudhury et al., 2014; Lam et al., 2005). This relationship is particularly important given that psychosocial interventions, in conjunction with pharmacotherapy, play a crucial role in the treatment—demonstrating positive effects on adherence and mood regulation (Miklowitz, 2006). Dyadic adjustment both influences and is influenced by illness course, creating a bidirectional relationship central to treatment outcomes. The attitudes and support of family members serve as environmental facilitators or barriers influencing the patient’s functionality (Amato, 2000), underscoring the critical role of relationship quality in bipolar disorder management.

Despite the documented impact of bipolar disorder on relationships, studies on dyadic adjustment in bipolar disorder have mostly focused on symptom levels and sociodemographic correlates, largely neglecting the psychological processes through which illness-related factors influence couple outcomes (Chaudhury et al., 2014; Hançer et al., 2019; Lam et al., 2005). While mood symptoms, sexual dysfunction, and caregiver burden have been identified as correlates (Lam et al., 2005; Rowe & Morris, 2012; Sheets & Miller, 2010), proximal psychological mechanisms—particularly internalized stigma, psychological inflexibility, and relational engagement patterns—remain poorly understood (Namlı et al., 2023; Serravalle et al., 2020). This gap limits development of targeted interventions to enhance relationship quality in this population.

One psychological process examined in relation to dyadic adjustment in this patient group is internalized stigma (Hançer et al., 2019). As with numerous mental illnesses, internalized stigma is prevalent in bipolar disorder (Nilsson et al., 2016; Sarısoy et al., 2013). Individuals may experience stigma from their social environment or may themselves exhibit stigmatizing attitudes toward their illness. Internalized stigma involves accepting society’s negative beliefs/prejudices and the experience of distressing emotions, leading to avoidance behaviors (Corrigan, 1998). It is known that internalized stigma negatively impacts quality of life in individuals with mental illness (Miklowitz, 2006) and there is evidence indicating its impact on family functioning. Research demonstrates that higher internalized stigma in bipolar disorder is associated with lower dyadic adjustment, poorer family functioning (Hançer et al., 2019), and reduced relationship satisfaction (Sarısoy et al., 2013), suggesting that stigma-related shame and withdrawal may directly compromise intimate relationship quality.

Psychological inflexibility, closely related to both dyadic adjustment and internalized stigma, represents another potential mechanism (J. B. Luoma et al., 2013). Psychological inflexibility is defined as the fusion with one’s thoughts and feelings, a lack of conscious awareness of contextual factors, resulting in a restricted behavioral repertoire and a lack of steps toward a meaningful life. It includes six sub-dimensions: cognitive fusion, experiential avoidance, loss of flexible contact with the present moment, conceptualized self, avoidance-impulsivity, and disconnection from values (Yavuz et al., 2016). Research links psychological inflexibility to lower romantic and sexual satisfaction, increased conflict, physical violence, and insecure attachment patterns (Daks & Rogge, 2020). In a study implementing a mindfulness-based therapy program targeting a specific sub-dimension of psychological inflexibility, participants completed eight therapy sessions over 2 months. The intervention led to statistically significant improvement in marital satisfaction (Momeni & Radmehr, 2019).

Adult playfulness may serve as a protective factor enhancing dyadic adjustment. While play is predominantly associated with childhood, recent research examines playfulness in adulthood—defined as the tendency to reframe a situation to elicit pleasure, humor, and enjoyment (Barnett, 2007). Conceptualized as a personality trait rather than mere behavior, playfulness encompasses spontaneous interaction, pleasure-seeking, and reduced seriousness. Activities such as socializing, interactive games, dancing, and recreational sports exemplify play, whereas solitary activities like television watching do not (Van Vleet & Feeney, 2015).

Research consistently demonstrates that playfulness predicts higher relationship satisfaction and marital adjustment (Aune & Wong, 2002; Proyer, 2014; Saliba & Barden, 2021). Playfulness enhances dyadic quality through multiple mechanisms: generating positive affect, improving communication, facilitating adaptive conflict resolution (Betcher, 1981; Vanderbleek et al., 2011), indexing intimacy, reducing emotional jealousy, and fostering relational security (Brauer et al., 2023; Herrick, 2018). Beyond relationship benefits, playfulness contributes to overall quality of life and well-being in both community and clinical populations (Saliba & Barden, 2021), suggesting particular relevance for individuals managing chronic conditions like bipolar disorder.

This study investigates relationships among dyadic adjustment, internalized stigma, psychological inflexibility, and playfulness in married individuals with bipolar disorder, and examines these variables’ interplay through parallel mediation analysis. As an individual-level cognitive-emotional stressor, internalized stigma may influence dyadic adjustment through multiple pathways. Psychological inflexibility—characterized by experiential avoidance and cognitive fusion—may hinder the adaptive processing of stigma-related distress, leading to emotional unavailability and communication difficulties. Conversely, reduced playfulness may manifest behaviorally, as individuals experiencing internalized stigma often withdraw from spontaneous, joyful connections. While assessed at the individual level, these processes directly shape dyadic interactions, communication patterns, and relationship quality. In bipolar disorder, where illness-related stigma is prevalent and relationship strain common, understanding these individual-to-dyadic pathways is essential for developing effective couple-focused interventions.

We hypothesized playfulness and psychological inflexibility as parallel rather than sequential mediators, as these two constructs represent distinct psychological processes. Specifically, psychological inflexibility reflects cognitive-emotional rigidity, whereas playfulness represents behavioral engagement and relational spontaneity. Since these processes operate at different levels (cognitive-emotional vs. behavioral), they are treated as independent in the present model.

To our knowledge, this is the first study to simultaneously examine both psychological inflexibility and playfulness as mediators linking internalized stigma to relationship outcomes in bipolar disorder. This study makes three novel contributions. First, we test a theoretically-grounded mediation model integrating constructs from Acceptance and Commitment Therapy (ACT) and positive psychology frameworks, examining whether psychological inflexibility and couple playfulness mediate the stigma-dyadic adjustment relationship. This represents the first empirical test of these specific mechanisms in bipolar disorder. Second, by examining playfulness—a largely neglected construct in psychiatric populations—we extend research on positive relational processes beyond symptom-focused models. Playfulness may represent a modifiable target for couple-based interventions, offering a strengths-based complement to traditional deficit-focused approaches. Third, our findings have direct clinical implications: if playfulness mediates the stigma-dyadic adjustment relationship, interventions that reduce stigma-related shame while actively promoting playful engagement between partners may be particularly effective for enhancing relationship quality in bipolar disorder.

Based on the theoretical framework outlined above, we tested four hypotheses:

H1: Internalized stigma will be negatively associated with dyadic adjustment.

H2: Psychological inflexibility will mediate the stigma-dyadic adjustment relationship, such that higher internalized stigma predicts greater psychological inflexibility, which in turn predicts lower dyadic adjustment.

H3: Couple playfulness will mediate the stigma-dyadic adjustment relationship, such that higher internalized stigma predicts lower playfulness, which in turn predicts lower dyadic adjustment.

H4: In a combined model, both psychological inflexibility and playfulness will demonstrate significant indirect effects, reflecting parallel pathways through which internalized stigma influences dyadic adjustment.

Method

This cross-sectional, descriptive study was conducted at Bakirkoy Prof. Mazhar Osman Training and Research Hospital for Psychiatry, Neurology, and Neurosurgery (Istanbul, Turkey), from April 2022 to August 2022.

Participant

Patients who met the criteria and presented at the psychiatry outpatient clinic were included in the study through convenience sampling. The inclusion criteria for this study were as follows: being married, aged between 18 and 65, having and being followed up with a diagnosis of bipolar I disorder (diagnosed by a minimum of two clinicians), and being in remission for at least 6 months. The selection of this duration was based on prior literature indicating that a 6-month period is associated with a lower risk of relapse and allows for a more reliable establishment of clinical stability (Tohen et al., 2009). Remission was operationally defined as: (1) Hamilton Depression Rating Scale (HDRS) score ⩽7, indicating minimal depressive symptoms; (2) Young Mania Rating Scale (YMRS) score ⩽7, indicating minimal manic symptoms; and (3) clinician confirmation of euthymic status based on clinical interview and medical record review. Remission status was independently confirmed by two experienced psychiatrists. Exclusion criteria were substance-abuse disorder, mental retardation and severe somatic illness. Interviews were conducted with 352 patients. Of these, 23 were excluded because they were illiterate, 54 were over the age of 65, 28 did not meet the 6-month remission criterion, 17 had persistent additional psychotic symptoms, and 108 were unmarried. Among the 122 patients who met the criteria, 12 declined to participate in the study. The research battery was administered to 110 patients, but it was found that 11 of them had incomplete responses. As a result, the study was completed with 99 participants. The information about the participants of the study is summarized in Table 1.

Table 1.

Sociodemographic Characteristics of the Participants.

Variable	Mean	SD	Min–max
Age	44.85	7.26	28–65
Duration of illness	20.28	8.32	1–41
Duration of marriage	19.24	9.53	2–43
Age of onset of illness	24.57	7.46	13–45
Number of hospitalizations	2.28	3.2	0–17

SD. = standard deviation; min. = minimum; max. = maximum.

Based on established methodological recommendations for mediation analysis (Fritz & Mackinnon, 2007), a minimum sample of 85 participants was required to detect direct effects, assuming a medium effect size (f² = 0.15), α = .05, and power = 0.80.

While complex mediation models with multiple pathways typically necessitate larger samples—ranging from 150 to 200 participants—to adequately detect indirect effects (Schuler et al., 2025), the current study’s sample of 99 participants yielded an estimated power of approximately 0.65 to 0.70 for indirect pathways. Consequently, there is an increased risk of Type II error, as the study may have been underpowered to detect smaller indirect effects. This limitation is further addressed in the Discussion section.

Procedure

Ethical approval for this study was obtained from the Ethics Committee of Bakirkoy Prof. Mazhar Osman Training and Research Hospital for Psychiatry, Neurology, and Neurosurgery (Istanbul, Turkey) from April 2022 to August 2022 on 21.03.2022 with the decision number 2022-06-09. Patients who met the inclusion criteria were informed by the interviewer. Written informed consent was obtained from participants who volunteered to take part in the study. The Sociodemographic Data Form, the Hamilton Depression Rating Scale (HDRS), and the Young Mania Rating Scale (YMRS) were administered by the interviewer. Subsequently, the Revised Dyadic Adjustment Scale (RDAS), the Internalized Stigma of Mental Illness Scale (ISMI), the Acceptance and Action Questionnaire-II (AAQ-II), and the Playfulness Scale for Couples-II (PSC-II) were completed by the participants.

Measurement

Demographics

This semi-structured form, developed by the researchers, comprises items inquiring about participants’ age, education, sex, psychiatric disease history, and marital characteristics.

Acceptance and Action Questionnaire-II (AAQ-II)

Psychological flexibility/inflexibility was assessed using the Acceptance and Action Questionnaire-II (AAQ-II). Participants rate items on a seven-point Likert type scale, with higher scores on the AAQ-II indicating higher levels of psychological inflexibility. The Turkish validity and reliability study was conducted by Yavuz et al. (2016). Cronbach’s alpha coefficient was .84.

Revised Dyadic Adjustment Scale (RDAS)

The scale, originally developed in 1976 by Spanier to assess the quality of relationships between couples, was revised by Larson and Christensen in 1995 to include 14 items and 3 sub-dimensions. Turkish validity and reliability study was conducted by Bayraktaroğlu and Çakıcı (2017). The Cronbach’s alpha coefficient of the RDAS total score was .87.

The Internalized Stigma of Mental Illness Scale (ISMI)

The Internalized Stigma of Mental Illness Scale, developed by Ritsher in 2003, is a four-point Likert-type scale consisting of 29 items. The scale was designed to measure the subjective experience of stigma with sub-scales assessing alienation (six items), stereotype endorsement (seven items), perceived discrimination (five items), stigma resistance (five items), and social withdrawal (six items). Turkish validity and reliability study of the scale was conducted by Ersoy et al. Cronbach’s alpha coefficient was .8 (Ersoy & Varan, 2007).

The Play Questionnaire-II (PQ-II)

The Play Questionnaire II was developed in 1977 by Betcher to assess couple’s playfulness level and attitude toward the play in their relationships. The scale is a five-point Likert-type scale consisting of 28 items. Turkish validity and reliability study of the scale was conducted by Gör in her doctoral thesis (Gör, 2021). The Cronbach’s alpha coefficient of the scale total score was .86.

Statistical Analysis

Mean total scores and demographic data were calculated using descriptive statistics. The distribution of data, means, and standard deviations were determined. Skewness and Kurtosis values were used to examine whether the data met the assumption of normality. To test this study’s main hypothesis, Pearson correlation analysis conducted to determine the relationship between variables. Mediation analysis was applied to examine the mediating role of playfulness and psychological inflexibility on relationship between the dyadic adjustment and internalized stigma. All aforementioned analyses were conducted using IBM SPSS Statistics 26 and Jamovi 1.8.1, with the “medmod” module used for mediation analysis. Indirect effects were estimated using bias-corrected bootstrap confidence intervals with 5,000 bootstrap samples. We report unstandardized coefficients for all path estimates, as recommended for mediation analysis, along with 95% confidence intervals (Hayes, 2018). Effect sizes for indirect effects are reported as completely standardized indirect effects to facilitate interpretation.

Our analytical approach comprised two sequential stages. First, we conducted single-mediator models to examine whether each proposed mediator independently exerted a significant indirect effect on the outcome variable. This preliminary step served to empirically validate the individual viability of each mediating construct prior to evaluating more complex structural relationships. Second, we tested a combined mediation model incorporating both mediators simultaneously to assess their unique contributions while controlling for shared variance. This two-stage strategy ensures that the inclusion of multiple mediators is justified both theoretically (as detailed in the Introduction) and empirically, thereby enhancing the robustness and interpretability of our findings.

Result

Table 1 summarizes the demographic and clinical characteristics of the participants (Table 1). Of the participants, 58 (58.6%) were female and 41 (41.4%) were male. Mean age of participants was 41.85 years. The mean duration of marriage and duration of illness were 19.4 and 20.3 years, respectively.

According to skewness and kurtosis values, all scales exhibited a normal distribution.

As presented in Table 2, Pearson Correlation revealed that dyadic adjustment (RDAS) was positively correlated with playfulness (PQ-II) to a moderate degree and negatively correlated with psychological inflexibility (AAQ-II) and self-stigma (ISMI). PQ-II was negatively correlated with ISMI and AAQ-II . ISMI and AAQ-II exhibited a strong negative correlation (Table 2).

Table 2.

Relationships Between Scale Scores.

Variable	RDAS	AAQ-II	PQ-II	ISMI
RDAS	1
AAQ-II	−0.237*	1
PQ-II	0.447**	−0.262**	1
ISMI	−0.269**	0.652**	−0.283**	1

PQ-II = the play questionnaire-II; AAQ-2 = acceptance and action questionnaire; ISMI = internalized stigma of mental illness scale; RDAS = revised dyadic adjustment scale.

Bold values indicate statistical significance at* p < .05. **p < .01

Figure 1 illustrates the models depicting the mediating role of psychological inflexibility and playfulness in the influence of internalized stigma on dyadic adjustment. The relationships presented in the figure were examined using simple linear regression analysis. As summarized in Table 3, internalized stigma significantly predicted dyadic adjustment (c), and playfulness significantly predicted dyadic adjustment (b). When a simple regression analysis was conducted with internalized stigma as the independent variable and playfulness as the dependent variable (a), internalized stigma significantly predicted playfulness. In multiple linear regression analysis examining the relationship of internalized stigma and couple playfulness variables with dyadic adjustment, while couple playfulness positively predicted dyadic adjustment, the predictive effect of internalized stigma on dyadic adjustment became nonsignificant (c’). These findings indicate that playfulness functions as a mediating variable between internalized stigma and dyadic adjustment. Furthermore, simple linear regression analyses were conducted separately for relationships x and y. Internalized stigma significantly predicted psychological inflexibility (x), and psychological inflexibility significantly predicted dyadic adjustment (y). In multiple regression analysis with dyadic adjustment as the dependent variable; internalized stigma and psychological inflexibility as independent variables, the predictive effect of internalized stigma became nonsignificant (c’’). These findings suggest that psychological inflexibility as a mediating variable between internalized stigma and dyadic adjustment. Results of simple linear regression analyses are presented in Table 3.

Figure 1.

Illustration of the mediation model.

Table 3.

Results of Simple Linear Regression Analyses for Variables in the Mediation Model.

		Estimate	SD	95% C.I.		R ²	p
	Pathway	Estimate	SD	Lower	Upper	R ²	p
a	I.S.→ C.P.	−0.253	0.087	−0.425	−0.081	0.071	.004
b	C.P. → D.A.	0.353	0.072	0.211	0.496	0.200	<.001
c	I.S. → D.A.	−0.190	0.069	−0.327	−0.053	0.073	.007
x	I.S. → P.I.	0.486	0.057	0.373	0.600	0.426	<.001
y	P.I. → D.A.	−0.224	0.093	−0.409	−0.039	0.056	.018

Note. a, b, c, x, and y represent path coefficient in Figure 1. All path coefficients and indirect effects were estimated using bias-corrected bootstrap confidence intervals (5,000 resamples); I.S. = internalized stigma; C.P. = couple playfulness; D.A. = dyadic adjustment; P.I. = psychological inflexibility. Bold values indicate statistical significance.

The results of the mediation analysis testing the final model (the main hypothesis of this study) were presented in Table 4. Examination of the table revealed that the indirect effect, with playfulness as a mediating variable, was statistically significant. However, in the other pathway where psychological inflexibility functioned as the mediating variable, the indirect effect was found to be non-significant. Regarding direct relationships, internalized stigma significantly predicted both playfulness and psychological inflexibility, whereas dyadic adjustment was predicted solely by playfulness. The pathway estimates of the tested model are illustrated in Figure 2.

Table 4.

Results of Indirect and Direct Effects from the Mediation Analysis Model.

Model	Path	Estimate	SD	95% CI		β	Z	p
Model	Path	Estimate	SD	Lower	Upper	β	Z	p
Indirect effect	I.S. → C.P. → D.A	−0.080	0.029	−0.135	−0.023	−.113	−2.790	.0050
Indirect effect	I.S. → P.I. → D.A	−0.025	0.061	−0.146	0.094	−.035	−0.403	.687
Components	I.S. → C.P.	−0.253	0.076	−0.399	−0.102	−.284	−3.340	<.001
	C.P. → D.A	0.315	0.076	0.166	0.464	.399	4.141	<.001
	I.S. → P.I.	0.486	0.055	0.379	0.593	.652	9.908	<.001
	P.I. → D.A	−0.051	0.124	−0.296	0.190	−.054	−0.410	.682
Direct effect	I.S. → D.A	−0.086	0.089	−0.257	0.091	−.122	−0.962	.336
Total effect	I.S. → D.A	−0.190	0.069	−0.324	−0.055	−.269	−2.769	.006

Note. All path coefficients and indirect effects were estimated using bias-corrected bootstrap confidence intervals (5,000 resamples); I.S. = internalized stigma; C.P. = couple playfulness; D.A. = dyadic adjustment; P.I. = psychological inflexibility. Bold values indicate statistical significance.

Figure 2.

Final mediation model.

Discussion

The current study, to the best of our knowledge, represents the first examination of psychological factors that predict dyadic adjustment in individuals diagnosed with bipolar disorder and establishes a model for this relationship. As hypothesized, our findings indicate that internalized stigma and psychological inflexibility are negatively correlated with dyadic adjustment, while playfulness demonstrates a positive correlation. Regarding the primary hypothesis of our research, we found that playfulness mediated the relationship between internalized stigma and dyadic adjustment; however, psychological inflexibility did not mediate this relationship.

Consistent with the limited extant literature, our study found that high levels of internalized stigma are associated with low dyadic adjustment. A study comprising 200 married women diagnosed with bipolar disorder examined the relationship between marital adjustment and internalized stigma, revealing a negative and moderate correlation between the two variables (Hançer et al., 2019). Similarly, another study investigating patients diagnosed with depression found that internalized stigma negatively predicted marital adjustment, with spousal support serving as a mediating factor in this relationship (Nawaz et al., 2021). Furthermore, several studies in the literature explore the relationship between internalized stigma and various psychological processes, suggesting that internalized stigma may not exert a direct effect on primary outcomes. For instance, one study observed that despite stable levels of internalized stigma, psychological health improved (Seidman et al., 2018). González-Menéndez et al. interpreted these results by positing that other psychological processes might play a role in this relationship and that thoughts, feelings, and other internal events related to internalized stigma may not always be sufficient to shape behavior. They hypothesized that other psychological processes could function as mediating variables in psychopathology and investigated the mediating role of social functioning in the relationship between internalized stigma and the severity of psychosis (González-Menéndez et al., 2021). Similarly, other psychological variables might influence the relationship between internalized stigma and dyadic adjustment in patients with bipolar disorder. With the exception of one study demonstrating the mediating role of spousal support in patients diagnosed with depression (Nawaz et al., 2021), there is a paucity of research investigating the mechanism of the relationship between internalized stigma and dyadic adjustment in the literature.

Currently, there is no research in the literature that examining the relationship between internalized stigma and playfulness. The present study is the first to investigate this relationship, revealing a negative correlation between patients’ levels of playfulness and internalized stigma. The PQ2, which was used in our study as in most previous studies, measures the intensity of behaviors related to playfulness. Considering that high internalized stigma negatively affects overall functioning, social functioning, and the quality of close relationships (Cerit et al., 2012; Nawaz et al., 2021), it is reasonable to think that internalized stigma might also influence the intensity of behaviors related to playfulness. Additionally, self-esteem, which is highly negatively correlated with internalized stigma (Maharjan & Panthee, 2019), has been examined in relation to playfulness in one study. It is known that individuals with low self-esteem are more sensitive to feedback and therefore more likely to adjust their self-evaluation based on feedback (Campbell, 1990). A study examining playfulness, self-esteem, and relationship satisfaction found that self-esteem predicted playfulness, which in turn affected dyadic adjustment (Aune & Wong, 2002). The researchers interpreted these results by suggesting that individuals with low self-esteem might be less likely to engage in playful behaviors due to the potential for negative feedback. Given the relationship between high internalized stigma and low self-esteem, it can be hypothesized that increased levels of internalized stigma might reduce an individual’s tendency toward playfulness. This supports the finding that internalized stigma is negatively related to playfulness.

Research on the role of playfulness in close relationships is relatively limited. Studies have mainly involved healthy volunteers or couples seeking therapy for relationship issues. In these studies, playfulness has been found to be positively correlated with dyadic adjustment and relationship satisfaction (Aune & Wong, 2002; Proyer, 2014). A study involving individuals receiving sexual therapy, couples therapy, and healthy volunteers found that playfulness was lower in both therapy groups compared to the healthy group (Metz & Lutz, 1990). Our finding that high levels of playfulness are associated with high dyadic adjustment is consistent with the existing literature. Our study is the first to investigate the relationship between playfulness and dyadic adjustment in married individuals diagnosed with bipolar disorder. The similarity between the results of previous studies with healthy volunteers and our study with a psychiatric patient group suggests that playfulness is an important factor influencing relationship adjustment and that this effect can be observed independently of psychopathology.

Our study revealed a correlation between internalized stigma and psychological inflexibility. The key components of internalized stigma, such as holding negative stereotypes and acting according to these beliefs, are closely related to the subdimensions of psychological inflexibility, including attachment to the conceptualized self and cognitive fusion. The condition of being fused with one’s self-beliefs and acting in accordance with these beliefs is characterized as a state of psychological inflexibility (Yavuz et al., 2016). This phenomenon closely aligns with the conceptualization of internalized stigma. Existing research has demonstrated a relationship between internalized stigma and psychological inflexibility in patients with psychiatric disorders (K. K. S. Chan & Mak, 2017; J. Luoma et al., 2011; Rüsch et al., 2006). Our findings, together with existing literature, suggest that internalized stigma and psychological inflexibility are interrelated in chronic disorders such as bipolar disorder. Consequently, internalized stigma may be conceptualized as a transdiagnostic process that potentially accompanies various psychiatric disorders.

Given the robust correlation between internalized stigma and psychological inflexibility observed in our study, it would be advantageous to consider psychological inflexibility when developing interventions targeting internalized stigma in individuals diagnosed with bipolar disorder to achieve more efficacious outcomes.

In our study, we examined a model wherein playfulness and psychological inflexibility were designated as mediating variables to elucidate the relationship between internalized stigma and dyadic adjustment. Consistent with our hypothesis, playfulness was observed to mediate the relationship between internalized stigma and dyadic adjustment. However, contrary to our hypothesis, psychological inflexibility did not show a significant mediating effect, despite significant bivariate correlations among all variables.

Several considerations are relevant to interpreting the null finding for psychological inflexibility. First, post-hoc power analysis revealed that the current sample (N = 99) provided adequate power (73.7%) to detect the significant playfulness pathway but very low power (6.1%) for the psychological inflexibility pathway, reflecting its substantially smaller effect size (b₂ = −0.051 vs. b₁ = 0.315). This pattern suggests that psychological inflexibility, as measured by the general AAQ-II, may exert minimal direct influence on dyadic adjustment when controlling for other variables, rather than representing a power limitation per se (Schuler et al., 2025). Second, measurement specificity is critical: the AAQ-II assesses general experiential avoidance rather than relationship-specific inflexibility, and relationship-focused measures demonstrate stronger associations with dyadic outcomes (Rizzo et al., 2022). Third, in the parallel mediation structure, couple playfulness emerged as the significant pathway, possibly reflecting its role as a more proximal mechanism—directly capturing relationship interaction patterns—while psychological inflexibility may operate more distally or through alternative pathways not captured in the current model.

These findings should not be interpreted as establishing theoretical primacy of couple playfulness over psychological inflexibility. Cross-sectional designs preclude conclusions about temporal precedence or causal ordering, and the significant bivariate correlation between psychological inflexibility and dyadic adjustment (r = −.237, p < .05) indicates that inflexibility remains associated with relationship quality even when not emerging as a significant mediator (M. Chan et al., 2022). Rather, the current findings suggest that couple playfulness represents one empirically supported pathway linking internalized stigma to dyadic adjustment in individuals with bipolar disorder during remission. Future research employing larger samples, longitudinal designs, relationship-specific measures of psychological inflexibility, and theoretically-driven model specifications is needed to clarify the relative and interactive roles of these psychological processes across different illness phases.

The mediating role of couple playfulness may reflect psychological mechanisms particularly salient in bipolar disorder. Internalized stigma triggers social withdrawal and interpersonal guardedness, directly reducing opportunities for playful interaction (Livingston & Boyd, 2010). In bipolar disorder’s episodic context, partners experience heightened uncertainty regarding mood fluctuations (Perlick et al., 2007), creating interpersonal caution that constrains playful engagement. Playfulness counteracts these withdrawal tendencies by generating positive affect and signaling relational safety (Aune & Wong, 2002). Even during remission, individuals with bipolar disorder exhibit residual interpersonal sensitivity; playful interactions serve as behavioral markers of recovery and relational normalcy, reducing partner anxiety and reinforcing dyadic cohesion (Weinstock & Miller, 2008). Given that the spousal relationship represents a crucial domain for psychosocial intervention in bipolar disorder, these findings have important clinical implications. Interventions aimed at enhancing couple playfulness and reducing internalized stigma may prove beneficial for both relationship quality and individual functioning, with potential applicability beyond bipolar disorder to other clinical and non-clinical populations.

Limitations

Several important limitations must be considered when interpreting these findings. The cross-sectional design precludes causal inferences. True mediation requires temporal precedence and causal relationships, neither establishable with cross-sectional data (M. Chan et al., 2022). The observed indirect effects should be interpreted as associations consistent with mediation rather than causal evidence. Longitudinal designs are needed to establish temporal ordering and examine reciprocal influences between internalized stigma and relationship quality over time.

Sample size and power limitations are evident. Post-hoc analysis revealed adequate power (73.7%) for the playfulness pathway but very low power (6.1%) for the psychological inflexibility pathway. While this reflects the substantially smaller effect size of the latter, larger samples (N = 150–200) would enable detection of smaller effects and permit more complex modeling approaches (Schuler et al., 2025).

Measurement limitations include: (a) reliance on self-report from one partner, introducing shared method variance and precluding dyadic modeling; (b) use of general rather than relationship-specific psychological inflexibility assessment; and (c) lack of bipolar-specific measure validation (Rizzo et al., 2022). Multi-method assessment incorporating partner reports and behavioral observations would strengthen future research.

The analysis did not control for potentially confounding variables including illness severity (episode frequency, psychotic features, rapid cycling), treatment factors (medication type, adherence, psychotherapy), relationship history, socioeconomic status, and psychiatric comorbidities (Schuler et al., 2025). These unmeasured variables may account for some or all of the observed associations. For example, individuals with more severe illness courses may experience both greater internalized stigma and poorer dyadic adjustment due to illness burden rather than through the proposed mediating pathways. Additionally, detailed medication data were collected but not systematically analyzed in the current study due to sample size limitations and the complexity of medication regimens (many participants were on polypharmacy, making meaningful grouping difficult). Psychotropic medications may influence the study variables in complex ways—for example, by reducing emotional reactivity (potentially affecting psychological inflexibility), causing sedation (potentially reducing playfulness), or improving functioning (potentially reducing stigma). This represents a significant potential confound.

While the mediation model posits that internalized stigma influences dyadic adjustment through psychological processes, alternative directional relationships are plausible. For example, poor dyadic adjustment may increase internalized stigma (through partner criticism or relationship failure), or bidirectional relationships may exist. Only longitudinal or experimental designs can establish directionality.

Finally, the sample consisted of married individuals in remission engaged in psychiatric care, limiting generalizability to unmarried couples, acute episodes, untreated individuals, or diverse relationship structures. The model examined only two mediators; other mechanisms (communication patterns, emotional expression, sexual functioning, partner support) remain unexplored.

Despite these limitations, the study identifies couple playfulness as a significant mediator linking internalized stigma to dyadic adjustment in bipolar disorder, providing novel insights for intervention development.

Conclusion

This study examined psychological inflexibility and couple playfulness as potential mediators of the relationship between internalized stigma and dyadic adjustment in married individuals with bipolar disorder in remission. Couple playfulness demonstrated a significant indirect effect, suggesting that internalized stigma may be associated with reduced relationship playfulness, which in turn relates to poorer dyadic adjustment. However, psychological inflexibility did not demonstrate a significant mediating effect—a null finding that may reflect power limitations, measurement considerations (general vs. relationship-specific assessment), or genuine absence of this pathway during remission (Rizzo et al., 2022; Schuler et al., 2025).

The model accounts for 19% of variance in dyadic adjustment. While the cross-sectional design, limited sample size, and lack of covariate control necessitate cautious interpretation, the findings suggest that couple playfulness represents a potentially important target for interventions aimed at improving relationship quality in bipolar disorder. Clinicians working with couples affected by bipolar disorder may benefit from assessing and addressing playfulness and shared positive activities as part of comprehensive treatment. Future research should employ longitudinal designs, larger samples, relationship-specific measures, and comprehensive assessment of potential confounders to clarify the mechanisms linking internalized stigma to relationship functioning in this population.

Footnotes

Acknowledgements

We would like to express our gratitude to K. Fatih Yavuz for his valuable support in formulating the hypothesis of this study.

ORCID iDs

Veysel Güleç

Sevinç Ulusoy

Enver Denizhan Ramakan

Erhan Kurt

Ethical Considerations

Ethical approval for this study was obtained from the Ethics Committee of Bakırköy Dr. Sadi Konuk Training and Research Hospital on 21.03.2022 with the decision number 2022-06-09.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

The datasets generated during and/or analyzed during the current study are available from the corresponding author on request.*

Declaration of Generative AI and AI-Assisted Technologies in the Writing Process

During the preparation of this work, the authors used ChatGPT/OpenAI for the translation and refinement of the English language in the manuscript. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

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