Tobacco smoking related to childhood trauma mediated by cognitive control and impulsiveness in severe mental disorders.

BACKGROUND: People with severe mental disorders (SMDs) show an increased prevalence of tobacco smoking compared to the general population. Tobacco smoking and other adult adverse health behaviors have been associated with traumatic experiences in childhood. In the present study we investigated the relationship between childhood trauma and tobacco smoking in people with SMDs, including the possible mediating role of cognitive- and personality characteristics, i.e. cognitive control, impulsiveness, affective lability and self-esteem. METHODS: Enrolled in the study were 871 participants with schizophrenia (SCZ, N = 484) and bipolar (BD, N = 387) spectrum disorders. We assessed tobacco smoking behavior (yes/no and amount), and history of childhood trauma with the Childhood Trauma Questionnaire. Data on cognitive control, impulsiveness, affective lability, and self-esteem were available in subsamples. We performed linear and logistic regressions, and conducted mediation analyses in PROCESS. All analyses were as standard adjusted for age, sex, and diagnostic group. RESULTS: Experience of one or more subtypes of childhood trauma was significantly associated with smoking tobacco in SMDs (p = 0.002). There were no significant associations between childhood trauma and amount of tobacco smoking. Cognitive control and impulsiveness were significant mediators between childhood trauma and tobacco smoking. CONCLUSIONS: These findings indicate the experience of childhood trauma as a predisposing factor for tobacco smoking in SMDs. Cognitive control and impulsiveness were suggested as mediating mechanisms, indicating the importance of considering inhibition related self-regulatory aspects in efforts to improve health behavior in individuals with SMDs and childhood trauma.

Impulsivity across severe mental disorders: a cross-sectional study of immune markers and psychopharmacotherapy.

BACKGROUND: Impulsivity is a transdiagnostic feature linked to severe clinical expression and a potential target for psychopharmacological strategies. Biological underpinnings are largely unknown, but involvement of immune dysregulation has been indicated, and the effects of psychopharmacological agents vary. We investigated if impulsivity was associated with circulating immune marker levels and with a range of psychopharmacological treatment regimens in severe mental disorders. METHODS: Impulsivity was assessed in a sample (N = 657) of patients with schizophrenia or schizophreniform disorder (SCZ) (N = 116) or bipolar disorder (BD) (N = 159) and healthy participants (N = 382) using the Barratt Impulsiveness Scale (BIS-11) questionnaire. Plasma levels of systemic immune markers (RANTES, IL-1RA, IL-18, IL-18BP, sTNFR-1) were measured by enzyme immunoassays. Patients underwent thorough clinical assessment, including evaluation of psychotropic medication. Associations were assessed using linear regressions. RESULTS: Impulsivity  was positively associated with SCZ (p < 0.001) and BD (p < 0.001) diagnosis and negatively associated with age (p < 0.05), but not significantly associated with any of the circulating immune markers independently of diagnostic status. Among patients, impulsivity was negatively associated with lithium treatment (p = 0.003) and positively associated with antidepressant treatment (p = 0.011) after controlling for diagnosis, psychotropic co-medications, manic symptoms, and depressive symptoms. CONCLUSIONS: We report elevated impulsivity across SCZ and BD but no associations to systemic immune dysregulation based on the current immune marker selection. The present study reveals associations between impulsivity in severe mental disorders and treatment with lithium and antidepressants, with opposite directions. Future studies are warranted to determine the causal directionality of the observed associations with psychopharmacotherapy.

Interleukin-18 signaling system links to agitation in severe mental disorders.

OBJECTIVE: Agitation is a challenging clinical feature in severe mental disorders, but its biological correlates are largely unknown. Inflammasome-related abnormalities have been linked to severe mental disorders and implicated in animal models of agitation. We investigated if levels of circulating inflammasome-related immune markers were associated with agitation in severe mental disorders. METHODS: Individuals with a psychotic or affective disorder (N = 660) underwent blood sampling and clinical characterization. Plasma levels of interleukin (IL)-18, IL-18 binding protein (IL-18BP), IL-18 receptor 1 (IL-18R1), IL-18 receptor accessory protein (IL-18RAP), and IL-1 receptor antagonist (IL-1RA) were measured. Agitation levels were estimated with the Positive and Negative Syndrome Scale Excited Component. Multiple linear- and logistic regression were used to investigate the associations between agitation and the immune markers, while controlling for confounders. The influence of psychotic and affective symptoms was assessed in follow-up analyses. RESULTS: Agitation was positively associated with IL-18BP (ß = 0.13, t = 3.41, p = 0.0007) after controlling for multiple confounders, including BMI, smoking, medication, and substance use. Adjustment for psychotic, manic, and depressive symptoms did not affect the results. There were no significant associations between agitation and the other investigated immune markers (IL-1RA (ß = 0.06, t = 1.27, p = 0.20), IL-18 (ß = 0.05, t = 1.25, p = 0.21), IL-18R1 (ß = 0.04, t = 1.01, p = 0.31), IL-18RAP (odds ratio = 0.96, p = 0.30)). In a subsample (N = 463), we also adjusted for cortisol levels, which yielded unaltered results. CONCLUSION: Our findings add to the accumulating evidence of immune system disturbances in severe mental disorders and suggest the IL-18 system as a part of the biological correlate of agitation independent of affective and psychotic symptoms.

Limited association between infections, autoimmune disease and genetic risk and immune activation in severe mental disorders.

BACKGROUND: Low-grade inflammation may be part of the underlying mechanism of schizophrenia and bipolar disorder. We investigated if genetic susceptibility, infections or autoimmunity could explain the immune activation. METHODS: Seven immune markers were selected based on indicated associations to severe mental disorders (IL-1Ra, sIL-2R, IL-18, sgp130, sTNFR-1, APRIL, ICAM-1) and measured in plasma of patients with schizophrenia (SCZ, N = 732) and bipolar spectrum disorders (BD, N = 460) and healthy controls (HC, N = 938). Information on rate of infections and autoimmune diseases were obtained from Norwegian national health registries for a twelve-year period. Polygenic risk scores (PRS) of SCZ and BD were calculated from genome-wide association studies. Analysis of covariance were used to test effects of infection rate, autoimmune disease and PRS on differences in immune markers between patients and HC. RESULTS: Infection rate differed between all groups (BD > HC > SCZ, all p < 0.001) whereas autoimmune disease was more frequent in BD compared to SCZ (p = 0.004) and HC (p = 0.003). sIL-2R was positively associated with autoimmune disease (p = 0.001) and negatively associated with PRS of SCZ (p = 0.006) across SCZ and HC; however, associations represented only small changes in the difference of sIL-2R levels between SCZ and HC. CONCLUSION: There were few significant associations between rate of infections, autoimmune disease or PRS and altered immune markers in SCZ and BD, and the detected associations represented only small changes in the immune aberrations. The findings suggest that most of the low-grade inflammation in SCZ and BD is explained by other factors than the underlying PRS, autoimmunity and infection rates.

Immune marker levels in severe mental disorders: associations with polygenic risk scores of related mental phenotypes and psoriasis.

Several lines of evidence implicate immune abnormalities in the pathophysiology of severe mental disorders (SMD) and comorbid mental disorders. Here, we use the data from genome-wide association studies (GWAS) of autoimmune diseases and mental phenotypes associated with SMD to disentangle genetic susceptibilities of immune abnormalities in SMD. We included 1004 patients with SMD and 947 healthy controls (HC) and measured plasma levels of IL-1Ra, sIL-2R, gp130, sTNFR-1, IL-18, APRIL, and ICAM-1. Polygenic risk scores (PRS) of six autoimmune disorders, CRP, and 10 SMD-related mental phenotypes were calculated from GWAS. General linear models were applied to assess the association of PRS with immune marker abnormalities. We found negative associations between PRS of educational attainment and IL-1Ra (P = 0.01) and IL-18 (P = 0.01). There were nominal positive associations between PRS of psoriasis and sgp130 (P = 0.02) and PRS of anxiety and IL-18 (P = 0.03), and nominal negative associations between PRS of anxiety and sIL-2R (P = 0.02) and PRS of educational attainment and sIL-2R (P = 0.03). Associations explained minor amounts of the immune marker plasma-level difference between SMD and HC. Different PRS and immune marker associations in the SMD group compared to HC were shown for PRS of extraversion and IL-1Ra ([interaction effect (IE), P = 0.002), and nominally for PRS of openness and IL-1Ra (IE, P = 0.02) and sTNFR-1 (IE, P = 0.04). Our findings indicate polygenic susceptibilities to immune abnormalities in SMD involving genetic overlap with SMD-related mental phenotypes and psoriasis. Associations might suggest immune genetic factors of SMD subgroups characterized by autoimmune or specific mental features.

Childhood trauma and cardiometabolic risk in severe mental disorders: The mediating role of cognitive control.

BACKGROUND: Cardiometabolic risk is increased in severe mental disorders (SMDs), and there appears to be a relationship between childhood trauma and cardiometabolic risk, possibly related to adverse health behavior. The current study examined the association between childhood trauma and serum lipids and adiposity in SMDs and the potential mediating role of cognitive and personality characteristics. METHODS: Participants with schizophrenia and bipolar spectrum disorders (N = 819) were included, cardiometabolic risk factors (serum lipids, body mass index, and waist circumference) were measured, and history of childhood trauma was assessed by the Childhood Trauma Questionnaire. Cognitive and personality characteristics were available in subsamples, with assessments of cognitive control, impulsiveness, self-esteem, and affective lability. Linear regressions and mediation analyses with Hayes' PROCESS were performed, adjusting for age, sex, antipsychotic agent propensity of metabolic side-effect, and diagnostic group. RESULTS: Experience of three or more subtypes of childhood trauma was positively associated with waist circumference in patients with SMDs (p = 0.014). There were no other significant associations between trauma variables and lipid or adiposity measures in the total sample. Cognitive control was a significant mediator between experience of one or two subtypes of childhood trauma and waist circumference. CONCLUSIONS: The results indicate childhood trauma as a predisposing factor for increased waist circumference in individuals with SMDs. Poorer cognitive control, suggestive of adverse health behavior, might be a mediating factor of the association, and the findings indicate the potential importance of increased focus on these factors in prevention and treatment regimens targeting cardiometabolic health.

Disentangling the relationship between cholesterol, aggression, and impulsivity in severe mental disorders.

OBJECTIVE: Low total cholesterol has been linked with adverse mental symptoms such as aggression and impulsivity in severe mental disorders (SMDs). This putative association may affect the clinician's decision making about cholesterol lowering in this patient group. Here, we investigated the associations between cholesterol levels, aggression, and impulsivity in a large representative sample of in- and outpatients with SMD. METHODS: Patients with schizophrenia- or bipolar spectrum disorders (N = 1 001) underwent thorough clinical characterization and blood sampling (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol). Aggression was characterized by the Positive and Negative Syndrome Scale Excited Component. Impulsivity was measured with the Barratt Impulsiveness Scale in a subsample of patients (N = 288). We used a multinomial logistic regression model to analyze the association between cholesterol and aggression and a multiple linear regression model to analyze the association between cholesterol and impulsivity, while controlling for confounders. RESULTS: We found no significant associations between cholesterol levels and aggression or impulsivity. There were no significant interactions between cholesterol and diagnostic group or inpatient versus outpatient status. Controlling for medication use, body mass index, alcohol or illicit substance use did not affect the results. CONCLUSION: In this large sample of patients with schizophrenia- and bipolar spectrum disorders, we found no associations between cholesterol levels and aggression or impulsivity. This has clinical implications as patients with SMD are at increased CVD risk and currently undertreated with statins.

Indicated association between polygenic risk score and treatment-resistance in a naturalistic sample of patients with schizophrenia spectrum disorders.

BACKGROUND: One third of people diagnosed with schizophrenia fail to respond adequately to antipsychotic medication, resulting in persisting disabling symptoms, higher rates of hospitalization and higher costs for society. In an effort to better understand the mechanisms behind resistance to antipsychotic treatment in schizophrenia, we investigated its potential relationship to the genetic architecture of the disorder. METHODS: Patients diagnosed with a schizophrenia spectrum disorder (N = 321) were classified as either being treatment-resistant (N = 108) or non-treatment-resistant (N = 213) to antipsychotic medication using defined consensus criteria. A schizophrenia polygenic risk score based on genome-wide association studies (GWAS) was calculated for each patient and binary logistic regression was performed to investigate the association between polygenetic risk and treatment resistance. We adjusted for principal components, batch number, age and sex. Additional analyses were performed to investigate associations with demographic and clinical variables. RESULTS: High levels of polygenic risk score for schizophrenia significantly predicted treatment resistance (p = 0.003). The positive predictive value of the model was 61.5% and the negative predictive value was 71.7%. The association was significant for one (p = 0.01) out of five tested SNP significance thresholds. Season of birth was able to predict treatment-resistance in the regression model (p = 0.05). CONCLUSIONS: The study indicates that treatment-resistance to antipsychotic medication is associated with higher polygenetic risk of schizophrenia, suggesting a link between antipsychotics mechanism of action and the genetic underpinnings of the disorder.