Psychological resilience and mood disorders: a systematic review and meta-analysis

Abstract Objective This systematic review aims to describe the relationship between psychological resilience and mood disorders. Methods This is a systematic review and meta-analysis. The following databases were searched on November 6, 2020: PubMed, PsycINFO, and Embase. Results Twenty-three articles were included and the majority of the studies included (95.7%) showed that psychological resilience has a positive impact in mood disorders. Our meta-analysis showed that individuals with bipolar disorder presented significantly lower levels of psychological resilience compared to controls (standardized mean difference [SDM]: -0.99 [95% confidence interval {95%CI}: -1.13 to -0.85], p < 0.001). In addition, individuals with depression had significantly lower levels of psychological resilience compared to controls (SDM: -0.71 [95%CI -0.81 to -0.61], p < 0.001). Conclusion Our results showed that individuals with mood disorders are less resilient than individuals without mood disorders. Our findings reinforce the importance of investigating interventions that may help to improve psychological resilience considering its positive impact in the context of mood disorders.


Introduction
Mood disorders have high prevalence worldwide and are associated with increased rates of disability.The lifetime prevalence of major depressive disorder (MDD) in high-income countries is 14.6% 1 and the prevalence in low-to-middle-income countries is 11.1%, 1 while the lifetime prevalence of bipolar disorder (BD) worldwide is 2.4%. 2 Mood disorders are associated with reduced quality of life (QoL), 3 increased functional impairment, 4 and increased suicide risk, 5 even in a young adult population.Importantly, in a large population-based cohort study published in 2020, Frey et al. 6 showed that mood disorders were associated with elevated and early rates of receiving disability services.These data reinforce the negative impact of mood disorders on individuals' lives.Hence, it is necessary to evaluate strategies that can potentially limit this negative impact.
Current literature suggests a relationship between childhood adversity and mood disorders.Being a victim of bullying and emotional abuse or emotional neglect during childhood have been shown to be strong predictors of depression. 7Importantly, a recent study showed that resilience partly mediated the association of childhood trauma with both mood disorders and severity of depression, meaning that individuals who suffered from trauma but were more resilient were less likely to develop mood disorders. 8This reinforces the importance of studying resilience in the context of mood disorders.
Resilience is a complex multidimensional construct defined as the ability to adapt successfully in the face of stress and adversity, maintaining normal psychological and physical functioning. 9According to the American Association of Psychology (APA), psychological resilience is the ability to be able to "bounce back" from stressful times. 10Currently, to the best of our knowledge, there are only two systematic reviews that have assessed the relationship between mental health and resilience.In 2014, Siriwardhana et al. 11 examined the relationship between mental health and resilience in adults who were forced to migrate and showed a positive impact of resilience on the mental health of these individuals.In 2018, Färber et al. 12 examined the relationship between mental health and resilience in somatically ill adults and concluded that higher resilience led to better mental health when participants were suffering from a physical illness.It is important to point out that these reviews were focused on specific populations (individuals forced to migrate and individuals with somatic illness) and they did not specifically assess the impact of psychological resilience on mood disorders.Thus, the aim of our systematic review is to describe the impact of psychological resilience in mood disorders.

Methods
The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed for the present review.

Protocol registration
A protocol for this systematic review was registered prospectively with PROSPERO on November 23, 2020, under ID CRD42020214767.

Search strategy
A literature search with no year or language restrictions was conducted on November 6, 2020, using the following databases: PubMed, PsycINFO, and Embase.We searched for a combination of the following search items ("mood disorder" OR "mood disorders" OR "depression" OR "major depression" OR "major depressive disorder" OR "depressive episode" OR "dysthymia" OR "bipolar disorder" OR "bipolar disorders" OR "mania" OR "manic" OR "hypomanic") AND ("resilience" OR "Psychological Resilience" OR "Psychological Resiliences").The search yielded 15,749 articles (PubMed = 5,052, PsycINFO = 4,783, and Embase = 5,914), with 9,903 remaining after removal of duplicate (5,846 removed).We used the following inclusion criteria to determine whether an article was relevant to our study: (1) the study should present original data; (2)  The studies were assessed by two blinded raters (ST and AI), who determined whether the studies met the inclusion criteria.Each rater assessed manuscripts independently using the Rayyan platform and divergences were resolved in a meeting with a third researcher (TAC).The raters first screened articles by title and abstract and then by full text.All articles not fulfilling the search criteria were excluded.The details of the search strategy are illustrated in Figure 1.

Data extraction
Two researchers (ST and AI) conducted the data extraction process.They extracted authorship, year of publication, the country in which the study took place, study aims, characteristics of the population, confounding variables controlled, assessments, and main results.

Quality assessment
All 23 studies included were independently assessed by two blind researchers (ST and AI) using the Joanna Briggs Institute (JBI) critical appraisal tools.Disagreements were resolved during a meeting with a third researcher (TAC).

Statistical analysis
Meta-analyses were conducted using Review reported in the paper, we contacted the authors asking for additional information in order to include their paper in the meta-analysis.

Results
The literature search resulted in 15,749 articles from the three databases PubMed (

Psychological resilience and mood disorders in children
Elmore et al. 14 examined the association between adverse childhood experiences and positive childhood experiences on the outcome of depression.The study included 40,302 children 8 years or older who were divided into a currently depressed group (n = 2,174) and a not currently depressed group (n = 38,128).Depression was assessed using a self-report assessment, the National Survey of Children's Health (NSCH).The study found that child psychological resilience reduced the odds of depression four-fold and children who were currently depressed were less likely to report child psychological resilience.

Psychological resilience and mood disorders in adults
Seok et al. 15

Quality assessment for cross-sectional studies
The quality of all 17 cross-sectional studies was assessed using JBI Systematic Review's Checklist for Analytical Cross-Sectional Studies.However, we decided to omit question 4 because we were not assessing any specific condition.Hence, each article was scored out of a maximum possible score of 7. Our assessment showed that the total scores ranged from 4 to 7. The mean score for all 17 articles was 5.8 (Table 1).

Psychological resilience and mood disorders: evidence from longitudinal studies
Four cohort studies were included in the systematic review.All the studies showed that psychological resilience protects against the development of mood disorders.Wu et al. 29 examined the longitudinal effects of psychological resilience on depression in a Chinese sample of left-behind children.The prevalence rates of depression at baseline and 1-year follow-up were 12.7 and 8.5%, respectively.The study found that children with higher baseline psychological resilience (adjusted odds ratio [OR] = 0.97; 95%CI 0.95-0.99)were at a reduced risk for developing depression at the 1-year follow-up, adjusting for age, sex, and baseline depressive symptoms.Hiyoshi et al. 30

Quality assessment for longitudinal studies
The quality of all four cohort studies was assessed using JBI Systematic Review's Checklist for Cohort Studies.However, from the checklist, we decided to omit question 6 because our methodology did not necessarily require the subjects to be free of the outcome at the baseline.Hence, each article had a maximum possible score of 10.The total scores ranged from 3 to 9. The mean score for all four articles was 7 (Table 1).

Psychological resilience and mood disorders: evidence from interventional studies
Two interventional studies were included in the systematic review.One of the two studies (50%) found that the intervention increased the psychological resilience score and found that higher baseline weeks.These findings can probably be explained by the short follow-up period (5 weeks).

Quality assessment for interventional studies
The quality of the RCT study was assessed using JBI Systematic Review's Checklist for Randomized Controlled Trials.However, we decided to omit questions 4 and 5. Question 4 was omitted because it was not possible to blind participants to the treatment with psychotherapy.Similarly, question 5 was omitted because it was not possible to blind those delivering treatment.Hence, the maximum possible score was 11.
The RCT included in this systematic review had a score of 11 (Table 1).
The quality of the quasi-experimental study was assessed using JBI Systematic Review's Checklist for Quasi-Experimental studies.The maximum possible score was 9.The quasi-experimental study included in this systematic review had a score of 7 (Table 1).

Discussion
Our meta-analysis of the cross-sectional data showed that individuals suffering from mood disorders had lower psychological resilience scores than individuals without mood disorders.Moreover, results from our systematic review showed evidence from longitudinal studies suggested that higher psychological resilience protected against the development of mood disorders.Lastly, few interventional studies indicated that psychotherapy interventions may improve psychological resilience.One interventional study also showed that higher baseline psychological resilience indicated lower depressive symptoms at follow-up in individuals with MDD.
Psychological resilience is the ability to effectively cope with the stressors of life to maintain good mental health. 10Twenty-two of the 23 (95.7%) studies included in the present systematic review concluded either that individuals suffering from mood disorders had lower psychological resilience scores than individuals without mood disorders or that psychological resilience protected against the development of mood disorders.
These conclusions are in line with two other systematic reviews in the field demonstrating that psychological resilience positively impacts the mental health of individuals. 11,12However, it is important to highlight that those reviews were focused on specific populations (individuals forced to migrate and individuals with somatic illness) and they did not specifically assess the impact of psychological resilience on mood disorders.
There is no current gold standard assessment to measure psychological resilience.However, Windle et al. 35 systematically reviewed the psychometric rigor of resilience measurement scales developed for use in general and clinical populations.In the review, the CD-RISC, the Resilience Scale for Adults (RSA), and the Brief Resilience Scale (BRS) received the best psychometric ratings.In this sense, it is important to highlight that 12/23 (52%) studies included in our systematic review used one of the three aforementioned resilience scales.
It is known that mood disorders have multifactorial etiology.For instance, a recent study showed that childhood trauma partly mediated the impact of family history on mood disorder diagnosis in adulthood, which suggests that childhood trauma might act as an environmental trigger that, by interacting with a vulnerable genetic background, can lead to the onset of mood disorders. 36Psychological resilience has also been found to moderate the relationship between stress and childhood depression, 37 indicating that individuals who suffered from stress but were more resilient were less likely to develop depression.The same findings were replicated by Vieira et al., 8 who showed that psychological resilience mediated the relationship between childhood trauma and mood disorders in young adults.These data reinforce the importance of investigating psychological resilience in the context of mood disorders.
Importantly, interventions such as mindfulness show promise for increasing psychological resilience.
Galante et al. 38 conducted an RCT to assess whether mindfulness courses for university students would improve their resilience to stress.Their findings suggest that mindfulness courses effectively increased resilience to stress in university students.Moreover, a recent review found that interventions based on a combination of CBT and mindfulness techniques appear to impact individual resilience positively. 39We believe more research into mindfulness techniques and interventions can establish a more concrete understanding of the relationship between psychological resilience and mood disorders.
Our findings should be interpreted considering some limitations.First, the systematic review only included two interventional studies, which had conflicting results.
Hence, looking at more interventional studies would have strengthened the conclusions based on interventions.
Second, only four longitudinal studies were included and level of evidence for the causal relationship between psychological resilience and mood disorders is still weak.

Conclusion
To the best of our knowledge, this systematic review is the first in its field to look at the relationship between resilience and mood disorders through various circumstances endured by the individuals.Our results showed that individuals suffering from mood disorders had lower psychological resilience scores than individuals without mood disorders.In addition, higher psychological resilience scores may lead to reduced rates of mood disorders in the context of many adverse situations.In terms of future research into the impact of psychological resilience on mood disorders, we recommend more longitudinal studies to establish a causal relationship between psychological resilience and mood disorders.Also, more research is needed on interventions that can positively impact individuals with mood disorders.
cross-sectional studies should include individuals with depression or BD and compare their levels of resilience with individuals without depression or BD; and (3) prospective cohort studies and clinical trials should include individuals with depression or BD and assess the effect of resilience on mood symptoms over time.The exclusion criteria were (1) reviews and meta-analyses, (2) case reports or case series, and (3) conference abstracts.
examined the relationship between early-life stress, depression tendency, and psychological resilience in individuals with MDD.The sample included 52 individuals divided into a group with MDD (n = 26) and a group without MDD (n = 26).Depression was assessed using the Korean version of the Structured Clinical Interview for DSM-IV (SCID).The study concluded that psychological resilience scores were lower for the group with MDD than for the group without MDD.Cha et al. 16 examined the demographic and clinical factors related to psychological resilience in euthymic patients with BD.The sample included 124 individuals divided into a group with BD (n = 62) and a group without BD (n = 62).BD was diagnosed according to the DSM-IV-TR criteria.The study concluded that psychological resilience scores were lower in the group with BD than in the group without BD.Ozawa et al.

17
examined the degree and quality of psychological resilience in patients with depression in the context of remission status, spirituality/religiosity, and family members' psychological resilience levels, which had never been investigated prior to this study.The sample included 136 individuals divided into individuals without depression (n = 36) and individuals with depression (n = 100).Depression was assessed using the International Classification of Diseases (ICD) criteria.The study concluded that psychological resilience scores were lower in the depressed group compared to the control group.Deng et al. 18 examined the relationship between psychological resilience and cognitive functioning in individuals with schizophrenia and BD.The sample included 167 individuals divided into a group with schizophrenia (n = 81), a group with BD (n = 34), and a group with no mood disorders (n = 52).Mood disorders were diagnosed with a clinical interview.The study concluded that psychological resilience scores were lower in groups with schizophrenia and BD compared to the control group.Bozikas et al. 19 examined the association between resilience and social functioning in patients with BD.A sample of 80 individuals was divided into a group with BD (n = 40) and a group without BD (n = 40).BD was diagnosed according to the DSM-IV, and the diagnosis was confirmed using the Greek version of the Mini-International Neuropsychiatric Interview (MINI).The study concluded that psychological resilience scores were lower in the group with BD than in the control group.Post et al. 20 examined the impact of psychological resilience, internalized stigma, and psychopathology on QoL. 20The sample included 137 individuals divided into a group with BD (n = 60) and a group without BD (n = 77).BD was diagnosed following the DSM-IV-TR criteria.The study concluded that psychological resilience scores were lower in the group with BD compared to the group with no BD.Vieira et al. 8 examined the mediation effect of psychological resilience on the relationship between childhood trauma and mood disorders.The sample included 1,244 individuals who were divided into a group with MDD (n = 317), a group with BD (n = 90), and a group with no mood disorders (n = 837).Mood disorders were assessed using the MINI-PLUS.The study concluded that psychological resilience scores were lower in mood disorder groups than in the control group.Uygun et al. 21examined the association between psychological resilience and disease onset, QoL, and prognosis of BD in euthymic patients.The sample included 120 individuals divided into a group with BD (n = 90) and a group without BD (n = 30).BD was diagnosed using a clinical interview.The study concluded that psychological resilience scores were lower in the group with BD compared to the group without BD.Psychological resilience and mood disorders during stressful/traumatic situations Aroian et al. 22 examined the relationship between psychological resilience, demographic characteristics, immigration demands, and depression in a sample of 450 adult Russian immigrants to Israel between 1990 and 1995.The sample was divided into a group with depression (n = 241) and a group without depression (n = 209).Depression was assessed using a 13-item self-report Depression Scale (Russian language version of the Symptom Checklist 90-R [SCL-90-R]).The study concluded that individuals with high psychological resilience scores had a more than two-fold greater likelihood of not being depressed compared to individuals with a low psychological resilience score.Hsieh et al. 23 examined the relationship among recent workplace violence, depressive tendency, social support, and psychological resilience of victimized nurses.The sample was recruited from two hospitals in Taiwan.One hundred fifty-nine nurses met the inclusion criteria and were divided into a group with a depressive tendency (n = 74) and a group without a depressive tendency (n = 85).Depression was assessed using the self-report instrument CES-D, with a cut-off of 14 for depressive tendency.The study findings concluded that the group with a depressive tendency was significantly less resilient than the group without a depressive tendency.Blackmon et al. 24 examined the relationships between depression, psychological resilience, and other sociodemographic factors of individuals highly exposed to Hurricane Katrina in 2005 and the Deepwater Horizon Oil Spill in 2010.The sample included 294 Mississippi Gulf Coast residents living near the Gulf of Mexico and was divided into a group with depression and a group without depression.Twenty-one percent of the sample had depression.Depression was assessed using the self-report CES-D, with a cut-off for depression of 16.The study concluded the individuals with depression were significantly less resilient than individuals without depression.Simpkin et al. 25 examined how stress from uncertainty relates to psychological resilience among pediatric residents and whether these attributes are associated with depression and burnout.The sample included 86 residents and depression was assessed using the self-report instrument Harvard National Depression Screening Scale (HANDS).The study concluded that the pediatric residents with depression were significantly less resilient than the pediatric residents without depression.Poudel-Tandukar et al. 26 examined the association between psychological resilience and anxiety or depression in Bhutanese adults resettled in Western Massachusetts.The sample included 450 Bhutanese refugees aged 20-65 and residing in Massachusetts divided into refugees with depression (n = 54) and refugees without depression (n = 171).Depression was assessed using the Hopkins Symptom Checklist-25 (HSC-25) self-report scale with a mean cut-off of ≥ 1.75 for moderate to severe symptoms.The study concluded that refugees in the highest tertile by psychological resilience scores had a significantly decreased risk of depression.Yörük et al. 27 examined the relationship between psychological resilience, burnout, stress, and sociodemographic factors with depression in nurses and midwives during the coronavirus disease 2019 (COVID-19) pandemic.The sample included 377 midwives and nurses and was divided into a group with depression (n = 120) and a group without depression (n = 257).Depression was assessed using the self-report Beck Depression Inventory (BDI), with a cut-off of 17 for depression.The study concluded that the midwives and nurses with depression were significantly less resilient than the midwives and nurses without depression.Barzilay et al. 28 examined the role of psychological resilience for healthcare workers during the COVID-19 pandemic.The total sample size was 3,042 people and depression was assessed using the Patient Health Questionnaire-2 (PHQ-2) self-report scale.The study concluded that with every 1 SD increase in psychological resilience scores, there was a 69.3% decrease in the possibility of depression.
examined whether physical and psychological characteristics in late adolescence were associated with subsequent BD in adulthood.A total of 213,693 men born between 1952 and 1956 who participated in compulsory military conscription assessments in late adolescence were followed up to 2009, excluding men with any psychiatric diagnoses at baseline.Psychological resilience was measured using a semi-structured interview with a psychologist and was stratified into "low," "medium," and "high" psychological resilience.High resilience was protective against depression (adjusted OR = 0.61; 95%CI 0.56-0.66)and BD (adjusted OR = 0.83; 95%CI 0.70-0.98).The study adjusted for age, sex, body mass index, asthma, allergies, grip strength, cognitive ability, height, erythrocyte sedimentation rate, disease at conscription, region of residence, household crowding, and socioeconomic index in 1960.Hoorelbeke et al. 31 examined the cognitive risk and protective factors following remission from depression.The study utilized a 7-day experience sampling period in 85 patients with remitted depression and examined the interplay between five transdiagnostic vulnerabilities and protective factors (including psychological resilience) in daily life.The study suggests a significant role for positive affectivity as a key resilience factor.It positively impacted cognitive risk and protective factors over time in remitted patients with depression.Navrady et al. 32 assessed the moderating and mediating relationships between depression, polygenic risk score (PRS), neuroticism, resilience, and clinical and selfreport depression in a large, population-based cohort.Participants were screened for a clinical diagnosis of MDD at baseline using the SCID-I.During the reassessment visit, self-report MDD was assessed using a questionnaire developed by the World Health Organization (WHO): The Composite International Diagnostic Interview-Short Form (CIDI-SF).A total of 1,068 individuals in the mental health follow-up sample met the criteria for self-report MDD (26%), with 3,098 classified as non-MDD cases (74%).A strong inverse relationship was found between resilience and clinically diagnosed depression (adjusted OR = 0.44; 95%CI 0.40-0.48).A similar relation was found between resilience and self-report MDD (adjusted OR = 0.43; 95%CI 0.40-0.47).These findings were adjusted for age, sex, and PRS.

Figure 2 -
Figure 2 -Meta-analysis comparing the psychological resilience scores between individuals with bipolar disorder (BD) and controls (A) and individuals with depression and controls (B).SD = standard deviation; IV= interval variable; 95% CI = 95% confidence interval; MDD = major depressive disorder.
psychological resilience indicated lower depressive symptoms at follow-up among individuals diagnosed with MDD.Konradt et al. 33 conducted a randomized clinical trial including 91 young adults diagnosed with MDD and assessed the effects of psychological resilience on the severity of depressive symptoms after brief cognitive psychotherapy interventions (Cognitive Behavior Therapy [CBT] or Narrative Cognitive Therapy [NCT]) for depression.The study found a higher psychological resilience at post-intervention and at 6-month follow-up.Moreover, higher baseline psychological resilience indicated lower depressive symptoms at post-intervention and at 6-month followup.Seo et al. 34 conducted a quasi-experimental study and examined whether basic military training can strengthen psychological resilience in males with probable bipolar depression (PBD) and probable unipolar depression (PUD).The study population consisted of Korean conscripts admitted to a basic military training camp in 2015.All participants were men.There were 66 participants in the PUD group, 66 in the PBD group, and 66 in the control group.There were no differences in psychological resilience between the mood disorder groups and the control group at baseline and the intervention did not change resilience scores over 5

Finally, a
meta-analysis of interventional and longitudinal studies was not performed because of the heterogeneity of the studies included.Despite these limitations, our systematic review incorporated a diverse population, including children and adults who experienced several types of stressful situations (ex.: childhood trauma, immigration, pregnancy, dealing with the COVID-19 pandemic, etc.).This allowed us to describe the impact of psychological resilience in mood disorders in the context of various stressful situations individuals may face.

Table 1 -
Characteristics of the studies included