Inflammation as a mediator between adverse childhood experiences and adult depression: A meta-analytic structural equation model.

Exposure to adverse childhood experiences (ACEs) confers a higher risk of developing depression in adulthood, yet the mediation of inflammation remains under debate. To test this model, we conducted a systematic review and two-stage structural equation modelling meta-analysis of studies reporting correlations between ACEs before age 18, inflammatory markers and depression severity in adulthood. Scopus, Pubmed, Medline, PsycInfo, and CINAHL were searched up to 2 October 2023. Twenty-two studies reporting data on C-reactive protein (CRP, n = 12,935), interleukin-6 (IL-6, n = 4108), tumour necrosis factor-α (TNF-α, n = 2256) and composite measures of inflammation (n = 1674) were included. Unadjusted models revealed that CRP (ß = 0.003, 95 % LBCI 0.0002 to 0.0068), IL-6 (ß = 0.003, 95 % LBCI 0.001 to 0.006), and composite inflammation (ß = 0.009, 95 % LBCI 0.004 to 0.018) significantly mediated the association between ACEs and adult depression. The mediation effects no longer survived after adjusting for BMI; however, a serial mediation model revealed that BMI and IL-6 sequentially mediated the association between ACEs and depression (ß = 0.002, 95 % LBCI 0.0005 to 0.0046), accounting for 14.59 % and 9.94 % of the variance of IL-6 and depressive symptoms, respectively. Due to the cross-sectional nature of assessment of inflammation and depression findings should be approached with caution; however, results suggest that complex interactions of psychoneuroimmunological and metabolic factors underlie the association between ACEs and adulthood depression.

Body shaming and internalized weight bias as potential precursors of eating disorders in adolescents.

Introduction: Body shaming (BS) is a growing phenomenon within the school context, especially among adolescents. Recently, it has been described as an unrepeated act in which a person expresses unsolicited, mostly negative comments about an individual's body. The targeted person perceives these comments as negative, offensive or body shame-inducing. Empirical evidence also suggests that body weight is the most common reason that youths are teased and bullied. Indeed, weight stigma, described as bias or discriminatory behaviors, attitudes, feelings, and thinking about individuals, because of their weight, can lead to weight-based discrimination and victimization. Preliminary evidence suggests that BS and weight stigma have negative effects on psychological health both in the short and long term. In the delicate stage of adolescence development and pubertal maturation, BS experiences can be highly prevalent and it can lead to adverse outcomes such as eating disorders (ED). However, prevalence data in the Italian context are still lacking. Methods: The study aims to estimate weight-related BS perceived by different sources (i.e., peers and family members) and their associations with public and internalized weight bias, body mass index (BMI), body dissatisfaction, and ED symptoms. A sample of 919 high school students (Mage = 15.97, SD = 1.58; 57.1% boys) completed a battery of self-report questionnaires assessing these variables. Results: One in four students reported experiences of weight-related BS by peers or family members. A total of 37% reported having at least one BS experience in a lifetime. Higher scores of ED symptoms, body dissatisfaction, and weight bias were reported by adolescents who experienced BS, especially females. Among overweight participants, results showed that internalized weight bias partially mediated the relationship between BS by family members and ED symptoms and fully mediated the relationship between BS by peers and ED symptoms, after controlling for age, sex and BMI. Discussion: These findings, despite their cross-sectional nature, add an important contribution to the creation of quantitative empirical evidence on the phenomenon of BS. Its role in explaining eating disorders, both alone and with the mediation of internalized weight stigma has been first proved and needs to be confirmed by longitudinal results.

The Short Version of the Italian Maastricht Vital Exhaustion Questionnaire (MVEQ): Psychometric Properties and Relationships with Anxiety, Depression, and Stress in a Community Sample of Older Adults.

Vital Exhaustion (VE) refers to a physical and mental state of excessive fatigue, feelings of demoralization, hopelessness, and increased irritability. The short form of the Maastricht Vital Exhaustion Questionnaire (MVEQ) is a widely used measure to assess VE. Despite its utility is broadly recognized, the validity and reliability of the scale have yet to be examined in the Italian context. The present study aimed to evaluate the psychometric properties of the shortened MVEQ in a community sample of Italian older adults. A total of 722 older adults (Mage = 72.97, SD = 7.71; 60.4% females) completed the MVEQ, as well as other self-report questionnaires assessing anxiety, depression and stress in order to evaluate the criterion-related validity of the scale. A confirmatory factor analysis (CFA) was conducted to examine the original MVEQ latent structure. Internal consistency was assessed through model-based omega coefficient. Test-retest reliability was examined by re-administering the MVEQ after three months to a subsample of 568 participants. Factorial invariance tests across gender were conducted by means of multi-group CFAs. The one-factor model showed an acceptable fit to the data. The MVEQ yielded a reliable total score (ω = 0.822) and showed moderate-to-large correlations with measures of anxiety, depression, and stress (r range 0.30 to 0.75, ps < 0.001). Test-retest reliability was supported by an Intraclass Correlation Coefficient (ICC) of 0.661. Lastly, the scale was factorially invariant across gender. Overall, the MVEQ provided evidence of reliability and criterion-related validity in a sample of Italian older adults and may be useful for both clinical and research practices.

Inflammation as an aetiological trigger for depressive symptoms in a prospective cohort of patients with inflammatory bowel disease.

OBJECTIVE: Inflammatory bowel disease (IBD) is often comorbid with mood disorders and depressive symptoms. The aetiology of depressive symptoms in IBD, however, remains largely unknown. Consistent with the inflammatory hypothesis of depression, the aim of this study was to explore the prospective associations between inflammatory biomarkers and depressive symptoms in a cohort of IBD patients with and without a previous clinical diagnosis of mood disorder. METHOD: IBD clinical activity was determined using the Harvey-Bradshaw Index for CD and the Partial Mayo score for UC; serum C-reactive protein (CRP) and faecal calprotectin (fCAL) were used as biomarkers of systemic and intestinal inflammation, respectively. Participants were administered the Hospital Anxiety and Depression Scale-depression (HADS-D) at baseline and 1-year follow-up. RESULTS: Eighty-four participants (50 ± 16 years; 75% UC and 25% CD) were included in the main analyses. Longitudinal moderated regression models showed that baseline CRP significantly predicted follow-up HADS-D scores among individuals with a previous mood disorder diagnosis (ß = 0.843, p < .001), but not among individuals without (ß = -0.013, p = .896), after controlling for baseline HADS-D scores, body mass index, IBD phenotype, sex, and perceived stress. Likely due to lower power, results on FCAL (n = 31) were not statistically significant. CONCLUSION: This study suggests that IBD patients with previous diagnosis of mood disorder may be at higher risk of inflammation-related depressive symptoms.

Parental quality of life, child adjustment and adult attachment in parents of children and adolescents with Autism Spectrum Disorder.

BACKGROUND: Parents of children and adolescents with Autism Spectrum Disorder (ASD) may experience a lower quality of life (QoL) than parents of offspring with typical development. However, factors associated with parental QoL are not yet fully understood. AIMS: This study aimed to investigate the relationships between parental QoL, child adjustment and adult attachment among parents of children and adolescents with ASD. METHODS AND PROCEDURES: One hundred and eighty-eight parents of children and adolescents diagnosed with ASD completed a group of self-report questionnaires on sociodemographic variables, QoL (i.e., overall QoL and ASD symptoms-related parental QoL), child adjustment (i.e., offspring's total problems and prosocial behaviors) and adult attachment. OUTCOMES AND RESULTS: Structural equation modeling revealed that the overall parental QoL was negatively related to children's total problems and positively associated with prosocial behaviors, as well as with higher levels of secure attachment and lower levels of fearful attachment styles. Additionally, ASD symptoms-related parental QoL was negatively associated with the offspring's total problems. CONCLUSIONS AND IMPLICATIONS: This suggests that child characteristics may interact with parental characteristics to either enhance or compromise the QoL of parents of children and adolescents with ASD. Implications of these findings for promoting parental QoL are discussed.

A close look at sociality in DSM criteria.

PURPOSE: The importance of sociality in psychology and psychotherapy is quite undisputed; however, this construct risks being underestimated in psychiatric nosography. The aim of the review was to assess the relevance of sociality in DSM 5 criteria. METHOD: Sociality-laden criteria of 192 selected DSM categories have been identified through a textual grid. Second, the criteria have been classified into 6 categories, i.e., (1) Affiliation and Attachment (AA), (2) Social Communication (SC), (3) Perception and Understanding of Others (PUO), (4) Culture, (5) Clinical Significance Criterion (CSC) (6), and No Specific Construct (NSC). RESULTS: 13% of all mental disorders mention AA in their criteria. 8.8% of all mental disorders mention SC; 8.8% of all mental disorders mention PUO in their criteria. 15% of all mental disorders mention culture in their criteria (exclusively ex negativo though). 40% of mental disorders mention non-specific sociality (NSC) in their criteria. CSC is mentioned in 85% of mental disorders. Personality disorders have the highest "concentration" of sociality mentions throughout the DSM categories. CONCLUSIONS: The overall results suggest that DSM criteria offer a confused account of sociality. We believe that the descriptive approach is the underlying reason. We suggest that in the long run a theory-laden approach to sociality, informed by evolutionary insights about motivations, could be of help.

Anxiety, Depression, Emotion Regulation, and Daytime Sleepiness: Are There Links Between These Factors? Network Analysis on an Italian Sample During the Covid-19 Pandemic.

Objective: The COVID-19 pandemic has contributed to the occurrence of psychological disturbances, such as depressive and anxiety symptomatology, thereby significantly impacting individuals' lifestyles by disrupting sleep patterns. This study aimed to elucidate the interconnections between emotion regulation, depression, anxiety, and daytime sleepiness. Method: We recruited 632 community adults who underwent an online survey of self-report questionnaires, including the Depression Anxiety Stress Scale (DASS-21), the Difficulties in Emotion Regulation Scale (DERS), and the Epworth Sleepiness Scale (ESS).A network analysis was performed to examine and visually represent the pattern of relationships between psychological distress, emotion regulation, and daytime sleepiness. Results: The DERS Strategy dimension showed high values across all centrality indices, indicating it as the most influential node in the network. In addition, the DASS Depression and DERS Goals dimensions exhibited high betweenness values, emerging as points of connection between the other nodes within the network structure. Conclusions: Our primary findings underscore the connection between psychological distress and emotion regulation, specifically between depressive symptoms, a lack of emotional clarity, and difficulty in the flexible use of emotional strategies. These specific constructs hold promising potential as valuable targets for both assessment and the development of effective interventions during highly challenging situations such as the COVID-19 pandemic.

Bullying Victimization and Adolescent Depression, Anxiety and Stress: The Mediation of Cognitive Emotion Regulation.

BACKGROUND: Existing research has revealed a robust association between bullying victimization and psychological distress, but less is known about the underlying mechanism of this link. cognitive emotion regulation (CER) strategies could be a potential mediator. The current study examined the role of functional and dysfunctional CER strategies as potential mediators of the association between bullying victimization and depression, anxiety, and stress symptoms among 638 high school students (53.9% boys; Mean age = 15.65, SD = 1.32). METHOD: Participants completed a series of questionnaires assessing bullying victimization (Olweus Bully/Victim Questionnaire), CER strategies (CERQ-18), and symptoms of depression, anxiety, and stress (DASS-21). The indirect relationships between bullying victimization and psychopathological symptoms via functional and dysfunctional CER strategies were tested through structural equation modeling. RESULTS: Dysfunctional CER strategies mediated the impact of bullying victimization on depression, anxiety, and stress. In contrast, bullying victimization did not significantly influence functional CER strategies. CONCLUSIONS: The findings provide additional support for the detrimental role of bullying victimization on mental distress, also suggesting that this effect is not only direct, but indirect is well. These results are particularly relevant in light of the absence of mediation by protective factors such as the use of positive emotion regulation strategies.

Poor sleep hygiene practices are associated with a higher increase in sleep problems during the COVID-19 pandemic: A latent change score model.

The Coronavirus 2019 (COVID-19) pandemic significantly influenced physical and mental health worldwide. The present study aimed to investigate changes in sleep problems across three waves of the COVID-19 pandemic, and to identify potential predictors of the inter-individual variability around these changes, with a particular focus on the role of detrimental sleep hygiene practices. A total of 352 participants completed an online survey of self-report questionnaires at three different waves of the COVID-19 pandemic: T1 (Spring 2020); T2 (Autumn-Winter 2020); and T3 (Spring 2021). The questionnaires collected information on socio-demographic and COVID-19-related variables, psychological distress (i.e. the Depression Anxiety Stress Scale-21), sleep hygiene (i.e. the Sleep Hygiene Index) and sleep problems (i.e. the Medical Outcomes Study-Sleep Scale). Latent change score modelling revealed an average increase in sleep problems between T1 and T2 with significant inter-individual variability. No substantial changes were observed on average between T2 and T3. Notably, poorer sleep hygiene practices were associated with a more pronounced increase in sleep problems between T1 and T2 (ß = 0.191, p = 0.013), even after controlling for relevant confounders such as demographic factors, COVID-19-related information and psychological distress. These findings expand on previous research regarding the detrimental effects of the pandemic on mental health, suggesting that interventions targeting sleep hygiene practices may be beneficial for mitigating its negative impact on sleep disruptions.

Psychological Counseling among University Students Worldwide: A Systematic Review.

University counseling services (UCSs) are actively involved in mental health assessment and in supplying interventions aimed at preventing, facing and possibly overcoming psychological problems. However, we do not have a global overview of psychological counseling among universities. This systematic review aims at reviewing the literature on university psychological counseling, including articles documenting: (1) mental health and attitudes regarding help-seeking behaviors and UCSs among university students or counselors, (2) the description of protocols/services among UCSs, (3) the efficacy of psychological counseling/interventions among university students (both face-to-face and internet-delivered interventions). The study followed PRISMA guidelines and was registered on PROSPERO. After defining inclusion and exclusion criteria, a literature search was conducted, identifying 7085 records. Finally, 152 articles met the review eligibility criteria and were included in the qualitative synthesis. Results are divided into seven thematic topics that emerged during the analysis of the literature. The results mainly showed that face-to-face and web-based counseling/psychological interventions improve university students' mental health. Cross-sectional studies showed that many biases exist toward help-seeking behaviors, especially among international students. Both students and counselors must strive to overcome cultural barriers. Available resources for UCSs are scarce and need to be strengthened, as well as efficacy studies through randomized clinical trials.

Cross-cultural adaptation and psychometric properties of the Italian version of the Orthorexia Nervosa Inventory (ONI).

BACKGROUND: Orthorexia Nervosa (ON) is an emerging clinical condition characterized by a pathological fixation with healthy eating. Recently, the Orthorexia Nervosa Inventory (ONI) has emerged as a promising tool for assessing orthorexic tendencies and behaviours, aiming to overcome the well-established limitations of existing measures for ON. The present study aimed to examine the psychometric properties of the Italian version of the ONI. METHODS: A total of 879 participants (Mage = 33.22 years, SD = 9.19; 56.9% females) completed the ONI along with the Düsseldorf Orthorexia Scale (DOS), measures of disordered eating, obsessive-compulsive symptoms (OCD), and psychosocial impairment. To establish the factorial validity of the ONI, a competing measurement modeling approach was employed by comparing standard confirmatory factor analytic (CFA) with exploratory structural equation modeling (ESEM) solutions. Model-based omega coefficients were computed to examine the internal consistency of the scale. Factorial invariance tests across gender were conducted within a multi-group framework. RESULTS: A three-factor first-order ESEM solution provided the best and most parsimonious representation of the data: χ2(207) = 558.641, p < .001, RMSEA = 0.044 (90% CI 0.040-0.048), CFI = 0.976, TLI = 0.968, SRMR = 0.036. The three latent dimensions, labelled behaviors, emotions, and impairments, showed excellent internal consistency (ω > 0.88). Furthermore, ONI scores were found to be positively correlated with DOS scores, disordered eating, OCD symptoms, and psychosocial impairment, supporting its convergent and criterion validity. Eventually, the ONI was factorially invariant across gender. CONCLUSIONS: Overall, the present study provides evidence for the satisfactory psychometric properties of the ONI in the Italian context, endorsing its use in both clinical and research settings.

Orthorexia Nervosa (ON) is a clinical condition characterized by a pathological fixation with healthy eating. The Orthorexia Nervosa Inventory (ONI) is a recently developed instrument to assess ON behaviours and tendencies. However, the scale has not yet been adapted for the Italian cultural context. To fill this gap, the present investigation aimed to translate the ONI into Italian and examine its psychometric properties on a community sample. The study involved 879 participants (M_age = 33.22 years, SD = 9.19; 56.9% females) who completed a series of self-report questionnaires. Findings revealed that the ONI items reflect  three latent dimensions: behaviours and preoccupation with healthy eating; physical and psychosocial impairments; and emotional distress. Importantly, the present study accrued substantial evidence for the internal consistency and criterion validity of the scale, the latter supported by significant correlations with measures of disordered eating, obsessive-compulsive symptoms, and psychosocial impairment. Overall, these findings endorse the use of the Italian version of the ONI for clinical and research practices.

The relationship between internalized weight stigma and physical and mental health-related quality of life in a large sample of women: a structural equation modeling analysis.

PURPOSE: Health-related quality of life (HRQOL) refers to an individual's perception of their physical and mental health status over time. Although emerging evidence has documented a negative association between weight stigma (i.e., negative weight-related attitudes and beliefs towards individuals with overweight or obesity) and mental HRQOL, its influence on physical HRQOL still needs to be fully clarified. This study aims to investigate the impact of internalized weight stigma on mental and physical HRQOL by employing a structural equation modeling (SEM) approach. METHODS: The Short Form Health Survey 36 (SF-36) and the Weight Bias Internalization Scale (WBIS) were administered to a sample of 4450 women aged 18-71 (Mage = 33.91 years, SD = 9.56) who self-identified in a condition of overweight or obesity (MBMI = 28.54 kg/m2; SD = 5.86). Confirmatory factor analysis (CFA) was conducted to assess the dimensionality of the scales before testing the proposed structural model. RESULTS: After establishing the adequacy of the measurement model, SEM results revealed that internalized weight stigma was significantly and negatively associated with both mental (ß = - 0.617; p < 0.001) and physical (ß = - 0.355, p < 0.001) HRQOL. CONCLUSION: These findings offer additional support to prior research by confirming the association between weight stigma and mental HRQOL. Moreover, this study contributes to the existing literature by strengthening and extending these associations to the physical HRQOL domain. Although this study is cross-sectional in nature, it benefits from a large sample of women and the use of SEM, which offers advantages over traditional multivariate techniques, e.g., by explicitly accounting for measurement error. LEVEL OF EVIDENCE: Level V, descriptive cross-sectional study.

Differential Associations of Cognitive Emotion Regulation Strategies with Depression, Anxiety, and Insomnia in Adolescence and Early Adulthood.

While difficulties with emotion regulation (ER) are consistently linked to poor mental health in adulthood, findings in adolescence have been more mixed. Cognitive ER strategies, which involve the ability to manage emotions through mental processes, may be particularly important during different stages of development due to age-specific adjustments. We conducted two exploratory and cross-sectional studies to examine the relationships between cognitive ER strategies and mental health (i.e., depressive, anxiety, and insomnia symptoms) in two samples: 431 young adults (Mage = 20.66 ± 2.21; 70% women and 30% men) and 271 adolescents (Mage = 14.80 ± 0.0.59; 44.6% girls and 55.4% boys). The participants completed a group of questionnaires, including the Cognitive Emotion Regulation Questionnaire, the Insomnia Severity Index, the Beck Depression Inventory-II, the State-Trait Anxiety Inventory, and the Youth Self Report. We employed hierarchical multiple regressions to assess the unique contribution of cognitive ER strategies to mental health outcomes. Maladaptive strategies (such as rumination and catastrophizing) were consistently associated with impaired mental health in both samples, while adaptive strategies (such as positive refocusing and positive reappraisal) were only associated with better mental health in young adults. These findings support the importance of cognitive ER strategies as potential risk factors for psychopathology and suggest that interventions aimed at improving emotion regulation may be beneficial. The age-specific differences in the relationship between cognitive ER strategies and mental health may reflect the refinement of emotion regulation abilities across the lifespan.

Comparative efficacy of psychological interventions on immune biomarkers: A systematic review and network meta-analysis (NMA).

Psychological interventions are viable, cost-effective strategies for improving clinical and psychological impact of inflammation-related conditions. However, their efficacy on immune system function remains controversial. We performed a systematic review and frequentist random-effects network meta-analysis of randomised controlled trials (RCTs) assessing the effects of psychological interventions, against a control condition, on biomarkers of innate and adaptive immunity in adults. PubMed, Scopus, PsycInfo, and Web of Science were searched from inception up to Oct 17, 2022. Cohen's d at 95% confidence interval (CI) was calculated to assess the effect sizes of each class of intervention against active control conditions at post-treatment. The study was registered in PROSPERO (CRD42022325508). Of the 5024 articles retrieved, we included 104 RCTs reporting on 7820 participants. Analyses were based on 13 types of clinical interventions. Compared with the control conditions, cognitive therapy (d =  - 0.95, 95% CI: -1.64 to - 0.27), lifestyle (d =  - 0.51, 95% CI: -0.99 to - 0.02), and mindfulness-based (d =  - 0.38, 95% CI: -0.66 to - 0.09) interventions were associated with post-treatment reduction of proinflammatory cytokines and markers. Mindfulness-based interventions were also significantly associated with post-treatment increase in anti-inflammatory cytokines (d = 0.69, 95% CI: 0.09 to 1.30), while cognitive therapy was associated also with post-treatment increase in white blood cell count (d = 1.89, 95% CI: 0.05 to 3.74). Results on natural killer cells activity were non-significant. Grade of evidence was moderate for mindfulness and low-to-moderate for cognitive therapy and lifestyle interventions; however, substantial overall heterogeneity was detected in most of the analyses.

Psychosocial and behavioural predictors of immune response to influenza vaccination: a systematic review and meta-analysis.

High variability of influenza vaccine efficacy requires the identification of modulators of immunisation that may be targeted as adjuvants in health psychology interventions. Psychosocial and behavioural variables such as psychological stress, greater negative and lower positive affectivity, poor sleep, loneliness, and lack of social support, have been associated with abnormal immune and inflammatory responses and negative health outcomes, yet their effects in modulating vaccine efficacy are yet to be fully understood. We conducted an updated systematic review of longitudinal and experimental studies examining the effects of such variables in predicting immune response to influenza vaccine. PubMed, Medline, PsycINFO, CINAHL and Scopus were searched up to November 2022. Twenty-five studies met the inclusion criteria for qualitative synthesis and 16 provided data for meta-analysis. Low positive and high negative affect were associated with low antibodies and weak cell-mediated immunity following vaccination in qualitative synthesis. Literature on sleep disturbance, loneliness and social support was limited and yielded inconsistent results. Psychological stress was associated with poorer antibody response in meta-analysis. In conclusion, findings from this review suggest a need for further longitudinal and experimental studies on these factors to support their inclusion as target variables in vaccine adjuvant interventions.

Perseverative Cognition and Psychotic-Like Experiences in Young Adults: A Cross-Lagged Panel Model.

Psychotic-like experiences (PLEs), including persecutory ideation, bizarre experiences, and perceptual abnormalities, are considered risk factors for psychotic disorders and mental distress in the general population. The cognitive-affective mechanisms associated with PLEs remain under-investigated. We aimed to longitudinally assess the reciprocal associations between perseverative cognition (PC), an emerging transdiagnostic factor of psychopathology, and PLEs facets in young adults. Participants (n = 160) from the general population completed measures of PC and PLEs at baseline and at 2-month follow-up. A two-wave, three-variable, cross-lagged panel model was implemented controlling for well-established correlates of PC and PLEs such as depression, anxiety, and symptoms of sleep disturbance. Both PLEs and PC exhibited substantive rank-order stability (ß ranged from 0.359 to 0.657, ps < 0.001). Cross-lagged effects revealed that baseline PC was associated with bizarre experiences at 2-month follow-up (ß = 0.317; p < 0.01). This effect overcame the well-established cut-off for practical significance. In contrast, no baseline PLEs were associated with PC at follow-up. Findings suggest the presence of a monodirectional, rather than bidirectional, association between PC and bizarre experiences in young adulthood. Results should be interpreted in light of the relatively small, non-clinical, and convenient sample.

Peripheral brain-derived neurotrophic factor (BDNF) in insomnia: A systematic review and meta-analysis.

The brain-derived neurotrophic factor (BDNF) is associated with emotional and cognitive functioning, and it is considered a transdiagnostic biomarker for mental disorders. Literature on insomnia related BDNF changes yielded contrasting results and it has never been synthetized using meta-analysis. To fill this gap, we conducted a systematic review and meta-analysis of case-control studies examining the levels of peripheric BDNF in individuals with insomnia and healthy controls using the PRISMA guidelines. PubMed, Scopus, Medline, PsycINFO and CINAHL were searched up to Nov 2022. Nine studies met the inclusion criteria and were assessed using the Newcastle-Ottawa Scale. Eight studies reported sufficient data for meta-analysis. Random-effects models showed lower BDNF in subjects with insomnia (n = 446) than in controls (n = 706) (Hedge's g = -0.86, 95% CI: -1.39 to -0.32, p = .002). Leave-one-out sensitivity analysis confirmed that the pooled effect size was robust and not driven by any single study. However, given the small sample size, the cross-sectional nature of the measurement, and the high heterogeneity of included data, the results should be cautiously interpreted. Progress in the study of BDNF in insomnia is clinically relevant to better understand the mechanisms that may explain the relationship between disturbed sleep and mental disorders.