Patients with rheumatoid arthritis have a higher risk of bipolar disorder: A systematic review and meta-analysis

Assessment of Bidirectional Relationships between Mental Illness and Rheumatoid Arthritis: A Two-Sample Mendelian Randomization Study

A correlation between mental illness and systemic rheumatoid arthritis (RA) has been observed in several prior investigations. However, little is known about the causative relationship between them. The present study aimed to systematically investigate the potential association between genetically determined mental illness and RA. Two-sample bidirectional Mendelian randomization (MR) analysis was performed using publicly released genome-wide association studies (GWAS). We selected independent genetic variants associated with four mental illnesses (bipolar disorder, broad depression, major depression, and anxiety) as instrumental variables. The inverse variance weighted (IVW) method was used as the primary analysis to assess the causal relationship between mental illness and RA. Results of the IVW analysis suggested that genetic predisposition to bipolar disorder was associated with a decreased risk of RA (odds ratio [OR] = 0.825, 95% CI = 0.716 to 0.95, p = 0.007). Furthermore, we did not find a significant causal effect of RA on bipolar disorder in the reverse MR analysis (p > 0.05). In addition, our study found no evidence of a bidirectional causal relationship between genetically predicted broad depression, major depression, anxiety, and RA (p > 0.05). The genetically proxied bipolar disorder population has a lower RA risk, which may indicate that there is a hidden mechanism for inhibiting the pathogenesis of RA in bipolar disorder. However, results do not support a causal connection between depression, anxiety, and RA.

Low-grade inflammation as mediator between diet and behavioral disinhibition: A UK Biobank study

BACKGROUND

Dietary patterns have been associated with variations in behavior. However, evidence has been limited and mixed, and the underlying mechanism remains unclear.

OBJECTIVE

Extend a previous study reporting significant associations between food patterns and behavioral disinhibition and explore whether low-grade inflammation is linked to behaviors and mediates the association between diet and behavioral disinhibition.

DESIGN

Among participants of the UK Biobank (UKB) we extracted a single behavioral disinhibition principal component using the UKB touchscreen questionnaire, Mental Health Questionnaire (MHQ), and registered diagnoses. We identified four dietary patterns (prudent diet, elimination of wheat/dairy/eggs, meat-based diet, full-cream dairy consumption) by using the Food Frequency Questionnaire (FFQ). Immune biomarkers and an aggregated inflammation score (INFLA-score) were used to characterize low-grade inflammation. Associations between dietary patterns and immune biomarkers, between immune biomarkers and disinhibition were assessed, with adjustment for demographics, lifestyle factors, and somatic health conditions. Next, mediation analyses were run to examine whether the association between dietary patterns and disinhibition was partially explained by inflammatory levels. We also conducted subgroup analyses to explore whether associations and the mediation effect differed by sex, age, ethnicity/race, body-mass-index (BMI), and socioeconomic status (SES).

RESULTS

The prudent diet was negatively, and the meat-based diet was positively associated with several pro-inflammatory biomarkers. Most immune biomarkers were positively associated with disinhibition (numbers of lymphocytes (β_standardized = 0.082, p < 0.001), monocytes (β_standardized = 0.043, p < 0.001), neutrophils (β_standardized = 0.071, p < 0.001), platelets (β_standardized = 0.022, p < 0.001), leukocytes (β_standardized = 0.093, p < 0.001), C-reactive protein (β_standardized = 0.051, p < 0.001), and for INFLA-score (β_standardized = 0.074, p < 0.001). In the mediation model, the INFLA-score mediated the association between prudent diet and meat-based diet and disinhibition score, with a significant indirect effect of low-grade inflammation for the prudent diet-disinhibition association (β_standardized = -0.007, p < 0.001) and for meat-disinhibition association (β_standardized = 0.001, p < 0.001)). Although all effects were small, covariates and interaction term adjustments did not attenuate the effects, and neither did most subgroup-only analyses.

CONCLUSIONS

The prudent diet was associated with a lower disinhibition score and this effect was partially mediated by the lower inflammation. Reversely, the meat-based diet was linked to more inflammation, which was associated with more disinhibition. Our findings suggest mediating effects of immune function in the relationship between diet and behavioral disinhibition. However further alternative designs such as interventional trials are needed to establish causal effects.

A nationwide study of the risks of major mental disorders among the offspring of parents with rheumatoid arthritis

Rheumatoid arthritis (RA) may share genomic risks with certain mental disorders. This study aimed at investigating associations between parental RA and risks of mental disorders in offspring. Using the National Health Insurance Research Database (2001–2010), we conducted a matched cohort study involving two parent–child cohorts (i.e., RA-parent–child cohort and non-RA-parent–child cohort) between which risks of major mental disorders in offspring were compared. There were 23,981 parent–child pairs in the RA-parent–child cohort and 239,810 in the non-RA-parent–child cohort. Preliminary analysis demonstrated increased risks of autism spectrum disorders (ASDs) [Odds ratio (OR) 1.47; 95% confidence interval (CI) 1.05–2.07], attention-deficit/hyperactivity disorder (ADHD) [OR 1.34; (95% CI 1.17–1.54)], bipolar disorder [OR 1.41 (95% CI 1.17–1.70)], and major depressive disorder [OR 1.20 (95% CI 1.07–1.35)] associated with parental RA. Sub-group analysis further showed higher risks of the four disorders in children of mothers with RA but not those from fathers with RA. Higher risks of ASDs and ADHD were not noted in children of mothers with RA before childbirth. Maternal RA, but not paternal RA or mothers diagnosed with RA before childbirth, was associated with increased risks of multiple mental disorders in their offspring, suggesting potential contributions of maternal genetic factors to ASDs and ADHD development in offspring.

Inflammation, anxiety, and stress in bipolar disorder and borderline personality disorder: A narrative review

Bipolar disorder (BD) and borderline personality disorder (BPD) are serious and prevalent psychiatric diseases that share common phenomenological characteristics: symptoms (such as anxiety, affective lability or emotion dysregulation), neuroimaging features, risk factors and comorbidities. While several studies have focused on the link between stress and peripheral inflammation in other affective disorders such as anxiety or depression, fewer have explored this relationship in BD and BPD. This review reports on evidence showing an interplay between immune dysregulation, anxiety and stress, and how an altered acute neuroendocrine stress response may exist in these disorders. Moreover, we highlight limitations and confounding factors of these existing studies and discuss multidirectional hypotheses that either suggest inflammation or stress and anxiety as the primum movens in BD and BPD pathophysiology, or inflammation as a consequence of the pathophysiology of these diseases. Untangling these associations and implementing a transdiagnostic approach will have diagnostic, therapeutic and prognostic implications for BD and BPD patients.

Mental Comorbidity in Rheumatic Diseases

In this review, we summarise the most relevant studies in a PubMed Search term “mental disorders and rheumatic disease” in the last 15 years. Mental disorders such as depression and anxiety are common in people with rheumatic diseases. Treating these comorbidities can improve the patientʼs quality of life. The high prevalence of symptoms of psychiatric disorders is a challenge for rheumatologists, especially with regard to the differentiation of possible psychiatric components in rheumatological diseases. Screening for psychiatric problems in patients with rheumatic diseases should be evaluated as soon as possible, as these can have a major influence on the perception of pain and physical functioning status from the outset. Mental health disorders are seen as a risk factor for poor patient outcomes, as patients may not adhere to medical treatments. The potential side effects of biological agents can increase patient anxiety and affect adherence to therapy. Therefore, interdisciplinary care would be of great advantage in the treatment of rheumatic patients with psychological comorbidities.