An integrative study of the microbiome gut-brain-axis and hippocampal inflammation in psychosis: Persistent effects from mode of birth.

The mechanism producing psychosis appears to include hippocampal inflammation, which could be associated with the microbiome-gut-brain-axis (MGBS). To test this hypothesis we are conducting a multidisciplinary study, herein described. The procedures are illustrated with testing of a single subject and group level information on the impact of C-section birth are presented. METHOD: Study subjects undergo research diagnostic interviews and symptom assessments to be categorized into one of 3 study groups: psychosis, nonpsychotic affective disorder or healthy control. Hippocampal volume and metabolite concentrations are assessed using 3-dimensional, multi-voxel H1 Magnetic Resonance Imaging (MRSI) encompassing all gray matter in the entire hippocampal volume. Rich self-report information is obtained with the PROMIS interview, which was developed by the NIH Commons for research in chronic conditions. Early trauma is assessed and cognition is quantitated using the MATRICS. The method also includes the most comprehensive autonomic nervous system (ANS) battery used to date in psychiatric research. Stool and oral samples are obtained for microbiome assessments and cytokines and other substances are measured in blood samples. RESULTS: Group level preliminary data shows that C-section birth is associated with higher concentrations of GLX, a glutamate related hippocampal neurotransmitter in psychotic cases, worse symptoms in affective disorder cases and smaller hippocampal volume in controls. CONCLUSION: Mode of birth appears to have persistent influences through adulthood. The methodology described for this study will define pathways through which the MGBA may influence the risk for psychiatric disorders.

Cross-Domain Association in Metacognitive Efficiency Depends on First-Order Task Types.

An important yet unresolved question is whether or not metacognition consists of domain-general or domain-specific mechanisms. While most studies on this topic suggest a dissociation between metacognitive abilities at the neural level, there are inconsistent reports at the behavioral level. Specifically, while McCurdy et al. (2013) found a positive correlation between metacognitive efficiency for visual perception and memory, such correlation was not observed in Baird et al. (2013). One possible explanation for this discrepancy is that the former included two-alternative-forced choice (2AFC) judgments in both their visual and memory tasks, whereas the latter used 2AFC for one task and yes/no (YN) judgments for the other. To test the effect of task on cross-domain association in metacognitive efficiency, we conducted two online experiments to mirror McCurdy et al. (2013) and Baird et al. (2013) with considerable statistical power (n = 100), and replicated the main findings of both studies. The results suggest that the use of task could affect cross-domain association in metacognitive efficiency. In the third experiment with the same sample size, we used YN judgments for both tasks and did not find a significant cross-domain correlation in metacognitive efficiency. This suggests that the cross-domain correlation found in McCurdy et al. (2013) was not simply due to the same task being used for both domains, and the absence of cross-domain correlation in Baird et al. (2013) might be due to the use of YN judgments. Our results highlight the importance of avoiding confusion between 2AFC and YN judgments in behavioral tasks for metacognitive research, which is a common problem in many behavioral studies.

On a 'failed' attempt to manipulate visual metacognition with transcranial magnetic stimulation to prefrontal cortex.

Rounis, Maniscalco, Rothwell, Passingham, and Lau (2010) reported that stimulation of prefrontal cortex impairs visual metacognition. Bor, Schwartzman, Barrett, and Seth (2017) attempted to replicate this result, but adopted an experimental design that reduced their chanceof obtaining positive findings. Despite that, their results appeared initially consistent with those of Rounis et al., but they subsequently claimed it was necessary to discard ∼30% of their subjects, after which they reported a null result. Using computer simulations, we found that, contrary to their supposed purpose, excluding subjects by Bor et al.'s criteria does not reduce false positive rates. Including both their positive and negative result in a Bayesian framework, we show the correct interpretation is that PFC stimulation likely impaired visual metacognition, exactly contradicting Bor et al.'s claims. That lesion and inactivation studies demonstrate similar positive effects further suggests that Bor et al.'s reported negative finding isn't evidence against the role of prefrontal cortex in metacognition.

Telomere length and early trauma in schizophrenia.

BACKGROUND: Childhood trauma is emerging as a risk factor for schizophrenia, but its mechanism with respect to etiology is unknown. One possible pathway is through leucocyte telomere length (LTL) shortening, a measure of cellular aging associated with trauma. This study examined early trauma and LTL shortening in schizophrenia and considered sex effects. METHODS: The early trauma inventory (ETI) was administered to 48 adults with DSM-5 schizophrenia and 18 comparison participants. LTL was measured using qPCR. OUTCOMES: Cases had significantly more global trauma (F=4.10, p<0.01) and traumatic events (F=11.23, p<0.001), but case and control groups had similar LTL (1.91±0.74 and 1.83±0.62: p=0.68). The association of early trauma and LTL differed by sex in cases and controls (Fisher's R: Z<0.05). Significant negative associations were shown in male cases and, conversely, in female controls. For example, physical punishment was associated LTL shortening in males' cases (r=-0.429, p<01). Only female controls showed significant telomere shortening in association with early trauma. INTERPRETATION: This data confirms the substantial excess of early trauma among schizophrenia cases. There were significant sex-differences in the relationship of the trauma to LTL, with only male cases showing the expected shortening. There were converse sex effects in the control group. Mean LTL was notably similar in cases and controls, despite the trauma-related shortening in male cases, cigarette smoking, older age and chronic illness of the cases. Factors may lengthen LTL in some schizophrenia cases. The converse sex differences in the cases are consistent with findings defective sexual differentiation in schizophrenia, consistent with other findings in the field.

Influence of early trauma on features of schizophrenia.

AIM: This proof-of-concept study examined if early trauma influences features of schizophrenia, consistent with hypothalamic-pituitary-adrenal (HPA) axis activation. METHODS: Early trauma and current perceived stress were assessed in 28 treated schizophrenia cases, along with salivary cortisol, brain volumes, cognition and symptoms. RESULTS: Early trauma predicted more positive (r = .66, P = .005) and dysthymia symptoms (r -.65, P = .007), but less negative symptoms (r = -.56, P = .023), as well as reduced whole brain volumes (r = .50, P = .040) and increased amygdala to whole brain volume ratios (r = .56, P = .018). Larger volume reductions accompanied cortisol levels: evening values predicted smaller whole brain and hippocampal volumes whereas afternoon levels only significantly predicted smaller brain volumes in women. Sex differences were demonstrated between early trauma and cognition, with better cognition in traumatized women than other women and no male effects. Current perceived stress was related to dysthymia (especially in women) and diminished sense of purpose and social drive (especially in men). CONCLUSIONS: These results suggest that early trauma and current stress impact features of schizophrenia, consistent with stress sensitization and increased dopamine activity for treatment refractory positive symptoms, as well as the cascade of increased morning cortisol, reduced brain volumes, and depressive and deficit symptoms. Conversely, cognitive deficits and negative symptoms may arise from a distinct diathesis. The sex differences accord with the literature on human HPA function and stress responses. Early trauma may be a stressor in the aetiopathophysiology of schizophrenia, particularly for cases with treatment refractory positive symptoms, and may guide future treatment development.

Pathways Associating Childhood Trauma to the Neurobiology of Schizophrenia.

While researchers have for decades considered the role of social factors, endocrinology, neural function, hippocampal integrity, and cognition in the development of schizophrenia, there has been a relative paucity of studies considering the participation of the stress cascade in the interplay of these elements. As described in this review, stressful exposures and stress sensitivity may plausibly be argued to play a role in the etiology, neurobiology, and course of schizophrenia and related psychotic disorders. Notably, research conducted over the last decade has made it increasingly clear that childhood traumatic experiences represent a prominent risk factor for the development of psychotic disorders, including schizophrenia. Accumulating evidence suggests that this relationship is mediated by the development of a neuropathological stress response, involving HPA axis dysregulation, aberrant functioning of different neurotransmitter systems, hippocampal damage, and memory deficits. However, it remains difficult to identify exact causal pathways linking early trauma to schizophrenia, including to the individual symptoms associated with the disorder. In addition to the strong association among early trauma, stress sensitization, and positive symptoms in schizophrenia, there is also evidence indicating that the negative and cognitive symptoms are related to these factors. However, the emergence of these symptoms may lie on a distinct and non-interacting pathway in relation to the development of the positive symptoms. The natural increases in stress sensitivity and HPA axis activity during adolescence may act on already maladaptive stress circuitry resulting from early trauma and/or a genetic predisposition to produce full blown stress sensitization and cause epigenetic effects, such as the altered methylation of different genes, that lead to schizophrenia or other psychiatric illnesses.

Prevention of suicidal behavior in adolescents with post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is significantly associated with an increased risk for suicidal behavior among adolescents. Suicide is one of the top three causes of adolescent deaths worldwide. Despite the strong relationship between PTSD and suicidal behavior, precise causal pathways linking PTSD to suicide in adolescents remains unclear. A slew of mediating factors and variables commonly present themselves with both suicide and PTSD, including co-morbid psychiatric disorders, exposure to different forms of trauma and stressful life events, core neurobiological changes, and mental, emotional, and physiological states such as hyperarousal, impulsivity, and aggression. Because youth is such a critical stage of development, it is very important that at-risk adolescents are identified and referred for treatment. With many treatment challenges in these populations, effective implementation and use of prevention methods are of increasing importance. The most proven prevention methods include physician education, means restriction, and gatekeeper training. Other strategies that have received empirical support are public education campaigns and implementing guidelines for the media, including those for television, print media, and the Internet.