Kynurenine and Tryptophan Levels in Patients With Schizophrenia and Elevated Antigliadin Immunoglobulin G Antibodies.

OBJECTIVE: Several studies have reported an association between nonceliac gluten sensitivity and schizophrenia. Immune and kynurenine (KYN) pathways have also been implicated in the pathophysiology of schizophrenia, and certain proinflammatory immune mediators may increase KYN and reduce tryptophan (TRP) levels. METHODS: We measured serum antigliadin immunoglobulin G (IgG), KYN, and TRP in 950 patients with schizophrenia. Patients with antibody level at the 90th percentile or higher of control participants (21.9% of all patients) were classified as having elevated antigliadin IgG. Independent t tests and linear regression models were used to compare TRP, KYN, and KYN-TRP ratio (indicator of TRP metabolism) between patients with and those without elevated antigliadin IgG. The correlation between antigliadin IgG and TRP, KYN, and the ratio was also evaluated in the patients. RESULTS: KYN and KYN-TRP ratio were higher in patients with elevated antigliadin IgG (geometric mean [standard deviation {SD}] = 2.65 [0.25] µmol/L versus 2.25 [0.23] µmol/L [p < .001] and 0.05 [0.26] versus 0.04 [0.25; p = .001] respectively), findings robust to adjustment for potential demographic and clinical confounders. Antigliadin IgG positively correlated with KYN and KYN-TRP ratio (r = 0.12, p < .001; r = 0.11, p = .002). TRP did not differ between the two groups and did not correlate with antigliadin IgG. CONCLUSIONS: Our results connect nonceliac gluten sensitivity with the KYN pathway of TRP metabolism in psychotic illness and hint toward potential individualized treatment targets.

Reciprocal moderation by Toxoplasma gondii seropositivity and blood phenylalanine - tyrosine ratio of their associations with trait aggression.

We previously reported that trait aggression, proposed as an endophenotype for suicidal behavior, is positively associated with Toxoplasma gondii (T. gondii) seropositivity in females, but not in males. Additionally, older males seropositive for T. gondii had lower scores on measures of trait aggression, including self-aggression. Trait aggression may be influenced by dopaminergic signaling, which is known to be moderated by gender and age, and potentially enhanced in T. gondii positives through the intrinsic production of dopamine by the microorganism. Therefore, we investigated associations between trait aggression and interactions between T. gondii enzyme-linked immunoabsorbant assay (ELISA) IgG titer-determined seropositivity and high-performance liquid chromatography- (HPLC-) measured blood levels of dopamine precursors phenylalanine (Phe), tyrosine (Tyr), and their ratio in a sample of 1000 psychiatrically healthy participants. Aggressive traits were assessed using the questionnaire for measuring factors of aggression (FAF), the German version of the Buss-Durkee hostility questionnaire. We found that 1) the decrease in trait aggression scores in T. gondii-positive older males was only present in individuals with a low Phe:Tyr ratio, and 2) that there was a positive correlation between Phe:Tyr ratio and total aggression and selected subscales of aggression in T. gondii-positive males, but not in T. gondii-negative males. These findings point toward a gender-specific reciprocal moderation by Phe:Tyr ratio and T. gondii seropositivity of their associations with aggression scores, and lead to experimental interventions geared to manipulating levels of dopamine precursors in selected T. gondii positive individuals with increased propensity for aggression.

Persistence of racial disparities in prescription of first-generation antipsychotics in the USA.

PURPOSE: The aim of this study was to estimate the prevalence of first-generation antipsychotics (FGA) prescribed for treatment of psychiatric and neurological conditions and use of benztropine to reduce extrapyramidal side effects (EPS) by patient race/ethnicity in a nationally representative sample of adult outpatient visits. METHODS: The study sample included all outpatient visits (N = 8154) among patients aged 18-69 years where a prescription for one or more antipsychotics was recorded across 6 years of the National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey (2005-2010). Use of FGA was compared by race/ethnicity using multiple logistic regression models accounting for patient and clinical characteristics stratified by neighborhood poverty rate. Frequency of EPS was determined by use of benztropine to reduce or prevent EPS. RESULTS: Black patients were significantly more likely than White patients to use FGA (odds ratio = 1.48, p = 0.040) accounting for psychiatric and neurological diagnoses, treatment setting, metabolic factors, neighborhood poverty, and payer source. Black patients were more than twice as likely as White patients to receive higher-potency FGA (haloperidol or fluphenazine), particularly in higher-poverty areas (odds ratio = 2.50, p < 0.001). Use of FGA, higher among Black than White patients, was positively associated with use of benztropine to reduce EPS. CONCLUSIONS: Racial disparities in the pharmacological treatment of severe mental disorders persist 30 years after the introduction of second-generation antipsychotics. The relatively high frequency of FGA of use among Black patients compared with White patients despite more Food and Drug Administration-approved indications and lower EPS risk for second-generation antipsychotics requires additional research.

Magnitude and causes of bias among family caregivers rating Alzheimer disease patients.

OBJECTIVE: Family caregivers generally underestimate the health and well-being of Alzheimer disease (AD) patients when compared to patients' self-assessments. The goals of this study were to identify caregiver, patient, and contextual factors associated with caregiver rating bias. METHODS: One hundred five patients with AD, along with their family caregivers, were assessed twice by trained interviewers 1-year apart. In separate interviews, caregivers were asked to rate the quality of life and suffering of their patient relative, and patients provided self-ratings using the same structured instruments. Multivariate cross-sectional and longitudinal analyses were used to identify predictors of caregiver-patient discrepancies. RESULTS: Caregivers consistently reported significantly higher levels of suffering and lower levels of quality of life than patients. Caregiver psychological well-being and health status accounted for a substantial portion of the difference in caregiver and patient ratings in both cross-sectional and longitudinal analyses. Caregiver depression and burden were consistently positively associated with the magnitude of caregiver-patient discrepancy, and caregiver health status was negatively associated with the size of the discrepancy. CONCLUSIONS: Caregiver assessments of dementia patients may determine the type and frequency of treatment received by the patient, and caregivers' ability to reliably detect change in patient status can play a critical role in evaluating the efficacy of therapeutic interventions and pharmacologic agents. Clinicians and researchers working with dementia patients who rely on caregiver reports of patient status should be sensitive to the health and well-being of the caregiver and recognize that caregiver assessments may be negatively biased when the caregiver's own well-being is compromised.

Predictors and consequences of perceived lack of choice in becoming an informal caregiver.

OBJECTIVES: Using data from a national sample of informal caregivers to older adults, we identify predictors of lack of choice and the consequences of lack of choice in taking on the caregiving role. METHODS: A national telephone survey with 1397 caregivers was carried out to assess whether respondents had a choice in taking on the caregiving role, their demographic characteristics, the nature and duration of their caregiving experience, and its impact on their physical and psychological well-being. We compare caregivers who felt they had no choice in taking on the caregiving role to those who did. RESULTS: In total, 44% of caregivers reported a lack of choice in taking on the caregiving role. Highly educated, older caregivers caring for a younger care recipient with emotional or behavioral problems were most likely to report that they had no choice in taking on the caregiving role. Lack of choice is associated with higher levels of emotional stress, physical strain, and negative health impacts, after controlling for multiple confounds including level of care provided, relationship type, primary health condition of the care recipient, and demographic characteristics. CONCLUSION: Lack of choice is an independent risk factor for the negative effects of caregiving, and clinicians should be vigilant to lack of choice as a marker of caregiver distress.

Moderation of the relationship between Toxoplasma gondii seropositivity and trait impulsivity in younger men by the phenylalanine-tyrosine ratio.

Previously, we reported that Toxoplasma gondii (T. gondii)-seropositivity is associated with higher impulsive sensation seeking in younger men. As dopaminergic and serotonergic signaling regulate impulsivity, and as T. gondii directly and indirectly affects dopaminergic signaling and induces activation of the kynurenine pathway leading to the diversion of tryptophan from serotonin production, we investigated if dopamine and serotonin precursors or the tryptophan metabolite kynurenine interact with the T. gondii-impulsivity association. In 950 psychiatrically healthy participants, trait impulsivity scores were related to T. gondii IgG seropositivity. Interactions were also identified between categorized levels of phenylalanine (Phe), tyrosine (Tyr), Phe:Tyr ratio, kynurenine (Kyn), tryptophan (Trp) and Kyn:Trp ratio, and age and gender. Only younger T. gondii-positive men with a high Phe:Tyr ratio, were found to have significantly higher impulsivity scores. There were no significant associations in other demographic groups, including women and older men. No significant effects or interactions were identified for Phe, Tyr, Kyn, Trp, or Kyn:Trp ratio. Phe:Tyr ratio, therefore, may play a moderating role in the association between T. gondii seropositivity and impulsivity in younger men. These results could potentially lead to individualized approaches to reduce impulsivity, based on combined demographic, biochemical and serological factors.

"Latent" infection with Toxoplasma gondii: association with trait aggression and impulsivity in healthy adults.

BACKGROUND: Latent chronic infection with Toxoplasma gondii (T. gondii), a common neurotropic pathogen, has been previously linked with suicidal self-directed violence (SSDV). We sought to determine if latent infection with T. gondii is associated with trait aggression and impulsivity, intermediate phenotypes for suicidal behavior, in psychiatrically healthy adults. METHODS: Traits of aggression and impulsivity were analyzed in relationship to IgG antibody seropositivity for T. gondii and two other latent neurotropic infections, herpes simplex virus 1 (HSV1) and cytomegalovirus (CMV). One thousand community-residing adults residing in the Munich metropolitan area with no Axis I or II conditions by SCID for DSM-IV (510 men, 490 women, mean age 53.6 ± 15.8, range 20-74). Plasma samples were tested for IgG antibodies to T. gondii, HSV-1 and CMV by ELISA. Self-reported ratings of trait aggression scores (Questionnaire for Measuring Factors of Aggression [FAF]) and trait impulsivity (Sensation-Seeking Scale-V [SSS-V]) were analyzed using linear multivariate methods. RESULTS: T. gondii IgG seropositivity was significantly associated with higher trait reactive aggression scores among women (p < .01), but not among men. T. gondii-positivity was also associated with higher impulsive sensation-seeking (SSS-V Disinhibition) among younger men (p < .01) aged 20-59 years old (median age = 60). All associations with HSV-1 and CMV were not significant. CONCLUSIONS: Aggression and impulsivity, personality traits considered as endophenotypes for SSDV, are associated with latent T. gondii infection in a gender and age-specific manner, and could be further investigated as prognostic and treatment targets in T. gondii-positive individuals at risk for SSDV.

Linguistic markers of emotion regulation and cardiovascular reactivity among older caregiving spouses.

This study examined linguistic markers of emotion regulation and cardiovascular stress reactivity in spousal caregivers. Fifty-three individuals were audiotaped while they privately disclosed an instance of partner suffering and a typical partner interaction (i.e., a meal together). Systolic blood pressure, diastolic blood pressure, and heart rate (HR) were measured. Linguistic analysis determined emotion and cognitive processing word use. Results revealed that using more positive emotion words was associated with lower HR reactivity in each verbal account. Caregivers who used fewer cognitive processing words (e.g., think, realize, because) overall had the highest HR reactivity to talking about the partner's suffering. These findings have implications for interventions for all caregivers as well as distinguishing more resilient caregivers from those who may be at a higher risk for caregiver burden.

Attachment Insecurity and Perceived Partner Suffering as Predictors of Personal Distress.

This study examined the extent to which perceptions of partner suffering mediate the association between attachment insecurity (anxiety and avoidance) and personal distress among spouses of older adults with osteoarthritis. Fifty-three spouses watched two videos of targets (their partner and an opposite sex stranger) perform a pain-eliciting household task, and spouses were asked to rate their own distress and perceptions of the targets' pain. Spouses also completed self-report measures of trait attachment. Results revealed that attachment anxiety was associated with greater personal distress in reaction to the partner's suffering, and heightened perceptions of partner pain mediated this association. Avoidant attachment was associated with less distress in reaction to the partner's suffering, but not with less perceived pain. The results of this study identify an important mechanism linking attachment insecurity and heightened distress responses when observing the suffering of a significant other.

Measuring the experience and perception of suffering.

PURPOSE: assess psychometric properties of scales developed to assess experience and perception of physical, psychological, and existential suffering in older individuals. DESIGN AND METHODS: scales were administered to 3 populations of older persons and/or their family caregivers: individuals with Alzheimer's disease (AD) and their family caregivers (N = 105 dyads), married couples in whom 1 partner had osteoarthritis (N = 53 dyads), and African American and Hispanic caregivers of care recipients with AD (N = 121). Care recipients rated their own suffering, whereas caregivers provided ratings of perceived suffering of their respective care recipients. In addition, quality of life, health, and functional status data were collected from all respondents via structured in-person interviews. RESULTS: three scales showed high levels of internal consistency, test-retest reliability, and convergent and discriminant validity. The scales were able to discriminate differences in suffering as a function of type of disease, demonstrated high intra-person correlations and moderately high inter-person correlations and exhibited predicted patterns of association between each type of suffering and indicators of quality of life, health status, and caregiver outcomes of depression and burden. IMPLICATIONS: suffering is an important but understudied domain. This article provides valuable tools for assessing the experience and perception of suffering in humans.