The association between posttraumatic disorder symptoms and addictive behaviours in Macao within a sample of female Filipino migrant workers: a network analysis

ABSTRACT

Background: Filipino migrant workers in Macao are vulnerable to posttraumatic stress disorder (PTSD) symptoms and addictive behaviours due to trauma histories, postmigration stressors, and access to alcohol and gambling venues. While PTSD addiction comorbidity is well-established in the existing literature, such research among migrant workers is lacking.

Objective: The current study investigated differential relations between PTSD symptoms and addictive behaviours in a polytrauma exposed sample of Filipino domestic workers in Macao (SAR), China.

Methods: Data were collected from 1375 Filipino migrant workers; data from a subsample of 1200 participants who reported an index traumatic event and PTSD symptoms were used in the analyses. Participants responded to the PTSD Checklist for DSM-5, gambling disorder symptoms checklist from DSM-5, and The Alcohol Use Disorders Identification Test. We estimated a regularized partial correlation network structure of PTSD symptoms and addictive behaviours employing graphical LASSO and extended Bayesian information criterion.

Results: PTSD symptoms of arousal and negative emotions had bridge connections with gambling disorder symptoms; while PTSD symptoms of arousal, restricted affect, negative emotions, and emotional reactivity had bridge connections with alcohol misuse.

Conclusions: PTSD's arousal and negative emotion symptoms were common in the networks of PTSD and addictive behaviours, while PTSD's restricted affect and emotional reactivity symptoms were unique to the network of PTSD and alcohol misuse. Treatment of the comorbidity of PTSD and addictive behaviours may yield optimal effects when tailored to these symptoms.

HIGHLIGHTS

• A network analytic study was conducted to explore patterns of comorbidity among international migrants.

• Post-traumatic stress disorder symptoms are associated with addiction symptoms among female Filipino migrant workers in Macau.

• Negative emotions symptoms of post-traumatic stress disorder are associated with both gambling disorder and alcohol misuse.

• Restricted affect and emotional reactivity are associated with alcohol misuse only.

Antecedentes: Las trabajadoras migrantes de origen filipino en Macao son vulnerables a síntomas del trastorno de estrés postraumático (TEPT) y a conductas adictivas debido a antecedentes traumáticos, a factores estresantes luego de la migración y al acceso a alcohol y a locales de apuestas. Si bien la comorbilidad entre el TEPT y las adicciones está bien documentada en la literatura existente, la investigación es insuficiente en trabajadoras migrantes.

Objetivo: Este estudio investigó las diferentes relaciones entre los síntomas del TEPT y las conductas adictivas en una muestra de trabajadoras del hogar de origen filipino con antecedente de múltiples traumas en Macao (SAR), China.

Métodos: Se recolectó información de 1375 trabajadoras migrantes filipinas; se empleó en el análisis la información de una submuestra de 1200 participantes que reportaron una experiencia traumática primigenia y síntomas de estrés traumático. Las participantes respondieron a la Lista de Chequeo del TEPT para el DSM-5, la lista de chequeo para el trastorno por juego de apuestas del DSM-5 y el Cuestionario de Identificación de los Trastornos debidos al Consumo de Alcohol (AUDIT por sus siglas en inglés). Se estimó una estructura de red con correlación parcial regularizada de los síntomas del TEPT y las conductas adictivas empleando la regularización Lasso y los criterios extendidos de información bayesiana.

Resultados: Los síntomas de hiperactivación y los de emociones negativas del TEPT presentaron conexiones en puente con los síntomas del trastorno por juegos de apuesta; por otro lado, los síntomas de hiperactivacion, afecto restringido, emociones negativas y reactividad emocional del TEPT presentaron conexiones en puente con el abuso de alcohol.

Conclusiones: Los síntomas de hiperactivación y de emociones negativas del TEPT fueron comunes en la red del TEPT y de las conductas adictivas, mientras que los síntomas de afecto restringido y reactividad emocional fueron exclusivos a la red del TEPT y del abuso de alcohol. El tratamiento de la comorbilidad del TEPT con las conductas adictivas podría brindar efectos beneficiosos al ser adaptado específicamente a estos síntomas.

背景：由于创伤史、移民后应激源以及酗酒和赌博场所，澳门的菲律宾移民工人容易出现创伤后应激障碍 (PTSD) 症状和成瘾行为。 虽然 PTSD 成瘾共病在现有文献中已得到证实，但缺乏针对移民工人的研究。

目的：本研究在一个中国澳门（特别行政区）菲律宾家庭佣工的多重创伤暴露样本中考查了 PTSD 症状与成瘾行为之间的不同关系。

方法：数据收集自 1375 名菲律宾移民工人； 分析中使用了 1200名报告了指数创伤事件和 PTSD 症状的参与者子样本数据。 参与者对 DSM-5 PTSD 检查表、DSM-5 赌博障碍症状检查表和酒精使用障碍识别测试做出了回应。 我们使用图形 LASSO 和扩展贝叶斯信息准则估计了 PTSD 症状和成瘾行为的正则化偏相关网络结构。

结果：PTSD症状的唤起和负性情绪与赌博障碍症状有桥连接； 而 PTSD 症状的唤起、受限情感、负性情绪和情绪反应与酒精滥用有桥连接。

结论：PTSD的唤起和负性情绪症状在PTSD和成瘾行为网络中普遍存在，而PTSD的受限情感和情绪反应症状是PTSD和酒精滥用网络所特有的。 当针对这些症状对PTSD 和成瘾行为共病的特定治疗可能会产生最佳效果。

KEYWORDS:

• PTSD
• addictive behaviours
• alcohol misuse
• gambling
• migrant workers

PALABRAS CLAVE:

• TEPT
• conductas adictivas
• abuso de alcohol
• apuestas
• trabajadoras migrantes

关键词:

• PTSD
• 成瘾行为
• 酒精滥用
• 赌博
• 移民工人

1. Introduction

Posttraumatic stress disorder is a mental disorder with a lifetime prevalence of 8% in US adults, and a prevalence between 6% and 59% in individuals that have been exposed to trauma (Kilpatrick et al., 2013; Terhakopian et al., 2008). PTSD may develop after exposure to potentially traumatic events (PTE) and, according to the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) definition, has four symptom clusters: instrusive memories, avoidance, negative alterations in cognitions and mood, and arousal (American Psychiatric Association, 2013). Research has provided theoretical and empirical evidence of comorbidity of PTSD and addictive behaviours (Debell et al., 2014; Fareed et al., 2013; Hildebrand et al., 2015 Strom et al., 2012; Ullman et al., 2013). For example, 36% to 50% of individuals seeking treatment for substance use disorders meet the diagnostic criteria for PTSD (Brady et al., 2004). In Ledgerwood and Pertry’s research (2006), among one-third of individuals who were seeking treatment for gambling disorders reported a higher frequency of PTSD symptoms. Individuals with PTSD are more likely to have a lifetime gambling disorder (Ledgerwood & Petry, 2006). Such findings have contributed to the expansion of the DSM-5 PTSD diagnostic conceptualization to include a reckless and self-destructive behaviour symptom criterion (E2; American Psychiatric Association, 2013). Reckless and self-destructive behaviour is defined as deliberate acts that lead to potentially negative consequences (Ben-Zur & Zeidner, 2009), with examples being excessive alcohol or drug misuse, suicidal behaviour, and risky sexual behaviour. Indeed, several studies on the E2 criterion have affirmed its role and utility in PTSD's conceptualization. For example, Contractor and colleagues (2017) found that higher E2 severity endorsement was associated with higher severity of PTSD subscales within an adult poly-trauma exposed sample.

Researchers have proposed several explanations for the association between PTSD and addictive behaviours: self-medication, emotion regulation, cognitive appraisal theory, and the compulsive re-exposure hypothesis. According to the self-medication hypothesis, individuals with PTSD symptoms resort to addictive behaviours such as substance use to relieve PTSD symptoms (Leeies et al., 2010). From an emotion regulation perspective, individuals with greater PTSD symptom severity engage in addictive behaviours due to maladaptive ways of responding to emotional distress (Weiss et al., 2013). In support of this perspective, Radomski and Read (2016) found that individuals with clinically significant PTSD symptoms had difficulties inhibiting impulses when feeling distressed, and this deficit mediated the relationship between PTSD symptoms and alcohol consumption. As another example, Currie et al. (2013) found that among individuals who experienced racial discrimination, PTSD's avoidance/numbing symptoms mediated the relationship between discrimination and gambling to escape negative emotions associated with racial trauma. Relatedly, Weiss et al. (2018) found that difficulties regulating positive emotions are associated with alcohol misuse and drug abuse. From a cognitive perspective, individuals with PTSD symptoms may have difficulties appraising risky situations, aligning with cognitive appraisal theory (Ben-Zur & Zeidner, 2009). Trauma survivors are more likely than non-survivors to perceive lower risk associated with addictive behaviours such as substance use (Smith et al., 2004). Finally, the compulsive re-exposure hypothesis suggests that individuals with PTSD may seek out risky situations (that may include addictive behaviours) to mimic the biological arousal experienced during the original trauma (Joseph et al., 1997).

Critically, the literature on comorbidity between PTSD and addictive behaviours has some limitations. First, fewer studies have examined the comorbidity of PTSD and addictive behaviours in Asian cultures (Li et al., 2021; Yuan et al., 2022) compared to Western cultures. Second, empirical data exploring PTSD and addictive behaviour comorbidity among vulnerable migrants generate contradicting results (Brune et al., 2003; Harris et al., 2019; Maremmani et al., 2021). For instance, Harris et al. (2019) have discovered that Sweden-born individuals had 2 times higher PTSD symptom severity compared to migrants and refugees with any substance use disorders. As a potential explanation for their findings, they suggested that individuals who chose to migrate may be younger and healthier. However, Maremmani et al.’s (2021) research suggested that migrants reported greater PTSD symptom severity than Italian patients. Lastly, very few studies have examined nuanced item-level associations between PTSD symptoms and addictive behaviours (Armour et al., 2020; Yuan et al., 2022).

To address these limitations, the current study aimed to understand such comorbidity by investigating the nuanced associations between PTSD symptoms and addictive behaviours in the female Filipino migrant workers population, which is vulnerable to both trauma exposure and addictive behaviours (Hall et al., 2019a; Yi et al., 2019). Regarding the study's sample, we note that being a domestic worker is a highly gender segregated occupation (Cheng, 1996), and Filipino domestic workers are overwhelmingly female (>90%). Men who are classified as domestic workers often engage in different aspects of domestic work such as being employed as security guards (Parreñas, 2000; Research Office Legislative Council Secretariat, 2017; Sayres, 2007). Using a female only sample is representative of experiences of a large majority of Filipino domestic workers in Macau. According to the Philippine Statistics Authority's latest data in 2020, there were 2.2 million Filipino migrant workers globally during April to September in 2019. Most of them (39.6%) worked in low skilled occupations, including as domestic workers (Philippine statistics authority, 2020). During the same period (September of 2019), there were 16,332 Filipino domestic workers which comprised more than half of the total Filipino migrant worker population (Labour Affairs Bureau, 2019). Domestic workers experience greater hardships when compared to Filipinos who migrate to work in other employment sectors (Garabiles et al., 2017). A qualitative needs assessment indicated that this population was exposed to trauma at various stages of migration, and that due to their precarious working conditions, long separation from family members (Garabiles et al., 2017; Vargas et al., 2020), and stress to provide economically for their families, they were vulnerable to experiencing mental disorders, including gambling disorder (Yi et al., 2019), depression, anxiety (Garabiles et al., 2020), and alcohol misuse (Hall et al., 2019b). Moreover, gambling disorder was associated with lower perceived social support, greater number of dependents upon monthly remittances, and increased depression severity (Yi et al., 2019). According to the research conducted by Garabiles and colleagues (2020), 27.2% of Filipino migrant workers in Macao had diagnostic PTSD. This evidence suggests that PTSD and addictive behaviours, including gambling disorder and alcohol misuse, are likely to occur among Filipino domestic workers and highlight the need to investigate this comorbidity.

Further, to evaluate nuanced associations between PTSD symptoms and addictive behaviours, the present study utilized a psychopathology network analytic approach to examine nuanced relationships between PTSD symptoms and addictive behaviours in gambling disorder and alcohol misuse. Within a network analysis framework, each variable is known as “nodes” and the associations between two variables are “edges”. The edge weights between nodes are either positive or negative to represent their association. The associations between variables belonging to different symptom communities are ‘bridge connections.’ Compared to traditional factor analytic approach which assumes psychological disorder resulting from a latent factor (e.g. PTSD) and that symptoms do not interact with each other, psychopathology networks provide greater clarity about patterns of comorbidity at the symptom level as it assumes that disorder is manifested through symptom interactions, thus it can provide insights on which symptoms are most central in explaining overlap/comorbidity between disorders (Borsboom & Cramer, 2013).

Relevant to the current study, limited research has adapted a network analysis approach to examine the comorbidity of PTSD and addictive behaviours. Afzali et al. (2017) and McGlinchey et al. (2021) have examined the networks of PTSD and alcohol misuse. Both of these studies discovered that the PTSD E2 criteria is a bridge between PTSD and alcohol misuse. In McGlinchey’s study, the E2 criteria had the highest bridge centrality in the PTSD and alcohol misuse networks. In addition, “not being able to stop drinking” and “number of drinks” items had the strongest bridge connections to PTSD items (McGlinchey et al., 2021). In contrast, according to Afzali's study, the bridge connecting symptoms were PTSD's reckless behaviour (E2), loss of interest, alcohol misuse causing physical and mental issues, and alcohol misuse in dangerous situations (Afzali et al., 2017). Research on network analysis of PTSD symptoms and behavioural addictions (including gambling disorder as relevant to this study) is scarce. Yuan and colleagues (2022) found that ‘difficulty concentrating’ was a PTSD symptom that had a bridge connection with an internet gaming disorder symptom in a sample of disaster-exposed Chinese adults. Further, Armour et al. (2020) examined networks associating PTSD and a broader range of addictive behaviours such as problematic use of technology (i.e. overuse of mobile phones or other devices; Elhai et al., 2019), reckless spending, alcohol misuse, substance use, and gambling disorders. Authors reported that the strongest bridge connections were PTSD's arousal symptoms and problematic use of technology (edge weight = 0.08) and the strongest adjusted bridge strength was reckless spending = 0.16.

However, except Yuan et al.’s study (2022) these studies had relatively smaller sample sizes, which did not allow them to model item-level relations between PTSD and addictive behaviour in the data. Relevant to the current study, non-network studies have found that substance use and gambling disorder are related to PTSD's arousal symptom cluster (Green et al., 2016; Shipherd et al., 2005). In another study using a treatment-seeking sample, PTSD's arousal symptoms were more severe among individuals with substance use disorder, and PTSD's avoidance symptoms were stronger in those with alcohol misuse (Dworkin et al., 2018). A systematic review also found support for associations between alcohol misuse and PTSD's avoidance/numbing symptoms and arousal symptoms (Debell et al., 2014).

Given the aforementioned literature, the current study examined the network structure of PTSD symptoms and addictive behaviours in a poly-trauma exposed sample of female Filipino domestic workers. Based on previous theoretical (Ben-Zur & Zeidner, 2009; Leeies et al., 2010; Weiss et al., 2013) and empirical (Afzali et al., 2017; Armour et al., 2020) literature, we expected that PTSD symptoms of arousal, negative affect, and anhedonia will have bridge connections with addictive behaviours symptoms.

2. Methods

2.1. Participants

Participants were selected from a cross-sectional study conducted between November 2016 and August 2017. This was part of the population research initiative for domestic employees (PRIDE) study, which was conducted among Filipino migrant domestic workers living and working in Macao. Eligibility criteria for the original study were: 1) being a female Filipino domestic worker, 2) being at least 18 years old, 3) being able to provide informed consent, and 4) holding a valid work visa or a residence ID card for Macao.

2.2. Procedure

The study was approved by the ethics committee of University of Macau. The purpose and procedure of the study was explained to all participants, and they were assured all information shared in the survey would be confidential. Informed consent was obtained from all participants. Of 1,375 Filipino domestic workers recruited through respondent-driven sampling, a majority (>90%) were exposed to at least one type of PTE. 1258 participants who reported any index trauma were included in the current analysis. A listwise deletion excluded 58 participants who had missing values on any measures of PTSD, gambling disorder, and alcohol misuse. The final sample included 1200 participants.

2.3. Measures

All measures were translated, back translated, and checked for cultural appropriateness, relevance, and clarity. The latter was done by one of the authors (BJH), with the assistance of a Filipino research assistant, by administering the questionnaires to a small representative sample of members from the target population and assessing each item using think aloud cognitive interviews.

2.3.1. The life events checklist for DSM-5 (LEC-5)

A 24-item adaptation of the 17-item LEC (Weathers et al., 2013a) was used in this study to assess PTE exposure. The LEC-5 is based on DSM-5 Criterion A of PTEs which are defined as: individuals personally experienced, witnessed, learned about, or experienced the event it as part of their occupation that caused serious injury, threatened death, actual death, or sexual violence (American Psychiatric Association, 2013). The adaptation added seven items that cover PTEs relevant to Filipino migrant workers based on a qualitative study (Hall et al., 2019a). Participants responded on a 5-point scale: having personally experienced, witnessed, learned about the event, experienced it as part of their occupation, or never exposed. The last item asked participants to indicate their worst PTE, and subsequent PTSD assessment was completed in reference to this index trauma.

2.3.2. PCL-5

PTSD symptoms were assessed by the Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5) (Weathers et al., 2013b). The PCL-5 has 20 items, and each item is rated on a 5-point Likert scale from 0 = ‘not at all’ to 4 = ‘extremely.’ Higher scores indicate higher PTSD symptom severity. A sample item is ‘Feeling distant or cut-off from other people.’ The PCL-5 was previously validated for use among Filipino domestic workers (Hall et al., 2019c). In this study, the PCL-5 score had excellent reliability (alpha = .96).

2.4. Addictive behaviours

2.4.1. Gambling disorder

Gambling disorder was assessed by nine items measuring gambling disorder symptoms from the DSM-5 (American Psychiatric Association, 2013). These nine items were forward and backward translated by bilingual Filipino researchers, and cognitive interviewing was conducted to ensure clarity of the items. Participants self-reported whether they had experienced each of the symptoms in the past 12 months on a 4-point Likert type scale from 0 = ‘never’ to 3 = ‘almost always.’ A sample item is ‘Has made repeated unsuccessful efforts to control, cut back, or stop gambling.’ The prevalence of gambling disorder in the population of female Filipino migrant workers in Macao was 5.1% (Yi et al., 2019), while the prevalence in the total Macau population was 2.1% (Wu et al., 2014). Cronbach's alpha for the total score was .91.

2.4.2. Alcohol use

Alcohol misuse was assessed by The Alcohol Use Disorders

Identification Test (AUDIT) (Saunders et al., 1993). AUDIT has 10 items. Participants responded to items 1 to 8 on a 5-point Likert scale from 0 = ‘never’ to 4 = ‘daily or almost daily.’ Participants responded to items 9 and 10 on a 3-point Likert scale with the options 0 = ‘no,’ 2 = ‘yes, but not in the last year’, and 4 = ‘yes, during the last year.’ The Cronbach's alpha for the total score was .86.

2.5. Analyses

Descriptive statistics were used to outline participant characteristics, index trauma, alcohol misuse, and gambling behaviours. A regularized partial correlation network structure was used to estimate two networks, which included PTSD symptoms and each addictive behaviour respectively. In a partial correlation network, the connection between two nodes is only established after controlling the effects of other nodes. In the current study, nodes in the two networks were PTSD symptoms and items measuring addictive behaviours. Using a cutoff of skewness>2 and/or kurtosis>7 (Curran et al., 1996), items of PTSD symptoms did not violate normality but items of the addictive behaviours both exceeded the cutoff. Thus, a Spearman correlation was computed to accommodate this skewed distribution. Moreover, we employed graphical LASSO, which will produce the network without noisy edges and extended Bayesian information criterion is suitable for the sparse graphical models and multivariate data. To identify bridge connections between PTSD symptoms and addictive behaviours, we used the ‘networktools’ package to calculate the bridge strength for these networks. The bridge strength of a node is the sum of absolute edge weights of all the intercommunity connections this node has. We adjusted the bridge strength of the two networks. Because PTSD symptoms have 19 nodes, and the two addictive behaviours have 9 (gambling) and 10 (alcohol misuse) nodes respectively, PTSD items have more potential bridge connections with addictive behaviours than the reverse. Thus, we adjusted the bridge strength values for PTSD symptoms nodes in each network by multiplying them by 9/19 and 10/19, consistent with previous research (Armour et al., 2020). We used the ‘qgraph’ package to plot the estimated network. Thicker lines indicate stronger connections between nodes. Finally, we used the ‘bootnet’ package to estimate network accuracy and stability. We did not include the PTSD symptom of ‘reckless behaviors’ because it conceptually overlaps with the addictive behaviour items and their associations would not provide more clarity regarding the comorbidity beyond their conceptual overlap. We used the R software for all analyses.

3. Results

Table 1 shows the characteristics of the sample. Ages ranged from 18 to 65, with half the sample being between 35-47 years old. The majority (35.4%, 425) had a high school education level. The largest proportion (44.4%, 533) of the sample was married, followed by single or never married (24.9%, 299). With regard to PTEs, the highest proportion of participants experienced a disaster (43.4%), followed by sudden death of loved one back home (24.7%), and a serious illness of loved one back home (7.4%).

Table 1. Sample characteristics (N = 1200).

Variable	M (Mdn)	SD	n	%
Age (years)	41.04	8.83
PCL-5 score	18.59	14.31
Gambling score	.78 (0)	2.73
Alcohol misuse score	2.27 (0)	4.34
Marital status
Single, never married			299	24.9
Married			533	44.4
Partnered but not married			88	7.3
Separated			197	16.5
Widowed			83	6.9
Educational attainment
Elementary			15	1.3
High school			425	35.4
Technical/Vocational			132	11.0
Two-year associate degree			175	14.6
Some college			214	17.8
Bachelor's degree or higher			239	19.9
PTE types
Natural disaster			521	43.4
Death of loved one back home			296	24.7
Serious illness of loved one back home			89	7.4
Severe human suffering			42	3.5
Fire or explosion			38	3.2
Others			214	17.8

Figures 1 and 2 show the estimated networks of PTSD symptoms and addictive behaviours. Figures 3 and 4 show the networks with bridge connections only. Figure 5 shows the adjusted bridge strength values of the two networks. Many bridge connections exist in the networks, and some of them are unique to one type of addictive behaviour. For example, restricted affect and emotional reactivity only had bridge connections with symptoms of alcohol misuse, but not with symptoms of gambling disorder.

Figure 1. Network of PTSD and gambling disorder symptoms.

Figure 2. Network of PTSD symptoms and alcohol misuse.

Figure 3. Network of PTSD and gambling disorder symptoms depicting only bridge connections. Solid lines represent positive associations, and dashed lines represent negative associations. Line thickness represents association strength.

Figure 4. Network of PTSD symptoms and Alcohol Misuse depicting only bridge connections. Solid lines represent positive associations, and dashed lines represent negative associations. Line thickness represents association strength.

Figure 5. Adjusted bridge strength for networks of PTSD with gambling disorder and of PTSD with alcohol misuse.

For the network of PTSD symptoms and gambling disorder, the strongest bridge connections were: ‘jumpy’ and ‘preoccupation’ (edge weight = 0.04); ‘sleep disturbance’ and ‘irritability/restlessness’ (edge weight = 0.02); as well as ‘negative emotions’ and ‘using gambling to escape’ (edge weight = 0.01). These results suggest that these pairs of symptoms were more likely to co-occur when referencing PTSD-gambling disorder comorbidity. For the network of PTSD symptoms and alcohol misuse, the strongest bridge connections were: ‘difficulty concentrating’ and ‘guilt’ (edge weight = 0.03); and ‘emotional reactivity’ and ‘drinks per day’ (edge weight = -0.03). This suggests that a person reporting ‘difficulty concentrating’ or ‘guilt’ is most likely to also have the other symptom; while a person reporting ‘emotional reactivity’ or ‘drinks more alcohol’ is least likely to report the other symptom.

As Figure 5 displays, among addictive behaviours, nodes with the strongest adjusted bridge strength (ABS) were: ‘drinks per day’ (ABS = 0.04); ‘injury’ (ABS = 0.02); ‘blackouts’ (ABS = 0.02); ‘preoccupation’ (ABS = 0.02); ‘irritability/restlessness’ (ABS = 0.02); and ‘unable to stop’ (ABS = 0.02). PTSD symptoms that have the strongest ABS in the network with gambling disorder were: ‘jumpy’ (ABS = 0.04); ‘sleep disturbance’ (ABS = 0.03); and ‘negative emotions’ (ABS = 0.01). PTSD symptoms that had the strongest ABS in the network with alcohol misuse were: ‘restricted affect’ (ABS = 0.08); ‘difficulty concentrating’ (ABS = 0.04); and ‘emotional reactivity’ (ABS = 0.04).

4. Discussion

Uniquely, the current study estimated nuanced associations between two types of addictive behaviours and PTSD symptoms utilizing network analytic models in a poly-trauma exposed sample of female Filipino domestic workers. Study findings provide insight on the comorbidity of PTSD and addictive behaviours among female Filipino domestic workers.

Due to the potential underlying mechanisms of addictive behaviour among individuals with PTSD (involving distress, impulse control, and difficulty appraising risky situations; Ben-Zur & Zeidner, 2009; Leeies et al., 2010; Weiss et al., 2013), individuals with experiences of multiple PTE types (interpersonal or not) may exhibit the same tendencies for addictive behaviours, and the type of addictive behaviour may not be limited to one kind (e.g. gambling), since addictive behaviours are linked to a common PTSD construct (e.g. E2; Afzali et al., 2017; McGlinchey et al., 2021). However, the pattern of specific PTSD symptoms and types of addictive behaviours may be different for individuals exposed to different trauma types (Levin et al., 2021). In this regard, in our poly-trauma sample, each of the examined addictive behaviours had at least one bridge connection with a PTSD symptom, and each type of addictive behaviour had bridge connections with different PTSD symptoms, though some PTSD symptoms had connections in both networks.

Bridge connections with PTSD's arousal and negative emotion symptoms were common in both networks of PTSD and addictive behaviours, while bridge connections with PTSD's restricted affect and emotional reactivity symptoms were unique to the network of PTSD and alcohol misuse. For the gambling disorder network, PTSD's arousal symptoms (jumpy, sleep disturbance, irritability/restlessness) and negative emotions had bridge connections with several nodes associated with gambling disorder (preoccupation, irritability/restlessness, using gambling to escape). For the alcohol misuse network, PTSD's arousal symptoms (difficulty concentrating, irritability, hypervigilance), restricted affect, negative emotions, and emotional reactivity had bridge connections with several nodes associated alcohol misuse (guilt, injury, peer concern, blackouts, failing responsibilities, drinks per day). Such findings suggest that several PTSD symptoms are uniquely associated with a certain type of addictive behaviour (PTSD's restricted affect and emotional reactivity symptoms associated with alcohol misuse), while some PTSD symptoms are associated with many types of addictive behaviours (e.g. PTSD's arousal symptoms and negative symptoms). These findings also provide potential research directions for PTSD treatments tailored to individuals with co-occurring addictive behaviours. In Rodebaugh's simulation network research, changing one central symptom affecting the whole network is well-documented (Rodebaugh et al., 2018). However, whether changing one symptom is sufficient to make changes to the entire network or address comorbidity still needs further evidence. Moreover, the individual network representation may be different from the generated network for the entire population. Furthermore, clinicians may not be able to target a specific symptom without changing others, also called ‘fat finger effect,’ which may provide difficulties in researching the specificity of treatment effectiveness.

Our results were consistent with Debell et al.’s (2014) review on associations between PTSD symptoms clusters and alcohol misuse, in which they found that PTSD's avoidance/numbing and arousal symptoms were linked with alcohol misuse. Our results showed PTSD symptoms with the strongest bridge connections in the network with alcohol misuse were avoidance/numbing symptoms and arousal symptoms. The association of arousal symptoms and addictive behaviours (which was present in all networks analyzed in this study) is also consistent with the self-medication hypothesis (Leeies et al., 2010), as it aligns with previous findings that PTSD arousal symptoms were longitudinally associated with more drug use in a sample of veterans (Shipherd et al., 2005).

We also identified two bridge connections between negative emotions and addictive behaviours. In the network with gambling disorder, ‘negative emotions’ had a bridge connection with ‘using gambling to escape.’ In the network with alcohol misuse, ‘negative emotions’ had a bridge connection with ‘drinks per day.’ These results support the emotion dysregulation theory, which suggests individuals engage in risky and potentially addictive behaviours to alleviate distress (Weiss et al., 2013). Our results also provide evidence for cognitive appraisal theory (Ben-Zur & Zeidner, 2009). We found a bridge connection between ‘difficulty concentrating’ and ‘guilt’, and ‘difficulty concentrating’ had the second highest inter-community bridge strength in the network with alcohol misuse. These findings suggest that ‘difficulty concentrating’ might be an influential symptom in the comorbidity of PTSD and alcohol misuse.’ When individuals fail to concentrate on situational, personal, and contextual aspects, it is difficult for them to assess accurately the risk associated with their actions. Alternatively, the bridge connection between ‘difficulty concentrating’ and ‘guilt’ could be the symptoms of depression, suggesting the comorbidity of PTSD, alcohol misuse, and depression.

Regarding problematic gambling, there is relatively scant research on its relationship with PTSD symptoms. Using diagnostic criteria from DSM-IV, Currie et al.’s (2013) findings in a sample of Aboriginal adults in Canada showed that PTSD's avoidance/numbing symptom severity predicted problematic gambling. PTSD's avoidance/numbing symptoms cluster was separated into avoidance and negative alterations in cognitions and mood in the DSM-5, and negative emotions was added to the negative alterations in cognition and mood cluster (American Psychiatric Association, 2013). Our finding of the association between negative emotions and gambling disorder may be partially consistent with Currie et al.'s finding. This calls for more studies directly examining nuanced PTSD symptoms and specific addictive behaviours instead of using aggregate symptom clusters or disorders. We additionally found that PTSD's arousal symptoms (e.g. ‘jumpy’) were associated with problematic gambling; these symptoms also had the highest bridge strength in the network with alcohol misuse. Perhaps, besides reckless and self-destructive behaviour symptoms, some addictive behaviours are linked to PTSD through arousal symptoms.

Another noteworthy finding is the negative bridge connection between ‘emotional reactivity’ and ‘drinks per day’ in the network of PTSD and alcohol misuse. This finding contrasts with Debell et al.’s (2014) review, in which they concluded there was limited evidence for associations between re-experiencing symptoms (including the emotional reactivity symptoms) and alcohol misuse. This result contradicts the self-medication theory suggested in previous literature (Leeies et al., 2010). The discrepancy may be in part related to Debell's differential categorization of PTSD symptom clusters using the International Classification of Diseases – 11 (ICD-11) definition, with DSM intrusion symptoms falling under the ICD re-experiencing category. The negative bridge connection between ‘emotional reactivity’ and ‘drinks per day’ could also be related to emotion regulation deficits associated with comorbid PTSD and substance use (Tull et al., 2018). The novel finding of this negative connection calls for future research to explore its mechanism.

Our findings also suggest the possibility of bidirectional influences of PTSD symptoms and addictive behaviours. For example, we found bridge connections between ‘jumpy’ and ‘preoccupation,’ as well as between ‘sleep disturbance’ and ‘irritability/restlessness.’ It is possible that individuals who are preoccupied with gambling thoughts can be easily startled as they invest most attention into thinking about gambling. Individuals who feel restless or irritable when they stop gambling may have difficulty sleeping. Further research using intensive longitudinal designs to unpack this potential directionality is needed.

The current study focused on a poly-trauma exposed sample, but due to uneven sample size of different index traumas, direct comparisons were not possible between various trauma types. Future research may be able to compare symptom networks across individuals reporting index interpersonal vs. non-interpersonal traumas. Second, we used cross-sectional data which did not allow us to test potential causal relations. Finally, we used self-report measures to collect data, which have certain well-established biases. Because trauma memory is dynamic and resilient individuals often create a more benign memory of traumatic events over time, self-report measures may have contributed to under-reporting of PTE exposure among this sample (Dekel & Bonanno, 2013). The sample was not randomly recruited. Although the sample represented more than 10% of the Filipino domestic workers living and working in Macao at the time of the study, our results may not be representative of PTSD or addictive behaviour prevalence among this population due to the sampling methods (Heckathorn, 1997).

5. Conclusion

The current study highlights the vulnerability of migrant workers to experience comorbid PTSD and addictive behaviours. Migrant workers are vulnerable to PTE exposure before, during, and after migration (Zimmerman et al., 2011), with common stressors including exploitation and abuse associated with precarious working conditions, as well as long separation from family members and difficulty to provide economically (Garabiles et al., 2017; Vargas et al., 2020).) As evidence supports a link between PTSD and addictive behaviours (Debell et al., 2014; Fareed et al., 2013; Li et al., 2021; Yuan et al., 2022), this increased vulnerability to PTE exposure and PTSD among migrant workers may also contribute to their increased engagement in addictive behaviours. The bridge connections were found between PTSD symptoms and addictive behaviours: PTSD's arousal and negative emotions symptoms had bridge connections with both gambling disorder and alcohol misuse, while PTSD's restricted affect and emotional reactivity symptoms were unique to PTSD and alcohol misuse. Findings are consistent with the emotion dysregulation theory but contradicted the self-medication theory. For PTSD treatments tailored to individuals with co-occurring addictive behaviours, clinicians may need further research on whether addressing connected symptoms may influence comorbidity patterns. For the similarity across networks, future research can assess whether it is due to a shared mechanism, such as emotion dysregulation and investigate such associations between different mental disorders and addictive behaviours. Additional work comparing the differences between the network structures of PTSD and addictive behaviours in different populations to evaluate the robustness of these associations, which can further aid in the design of interventions for patients reporting co-occurring PTSD symptoms and addictive behaviours.

The data that support the findings of this study are available on request from the corresponding author, B.J.H. The data are not publicly available due to their containing information that could compromise the privacy of research participants.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by a grant from the Macao (SAR) Government under Grant MYRG2015-00109-FSS.