Coronavirus-related conspiracy theories (CT) have been found to be associated with fewer pandemic containment-focused behaviors. It is therefore important to evaluate associated cognitive factors. We aimed to obtain first endorsement rate estimates of coronavirus-related conspiracy beliefs in a German-speaking general population sample and investigate whether delusion-related reasoning biases and paranoid ideation are associated with such beliefs.

We conducted a cross-sectional non-probability online study, quota-sampled for age and gender, with 1684 adults from Germany and German-speaking Switzerland. We assessed general and specific coronavirus conspiracy beliefs, reasoning biases [jumping-to-conclusions bias (JTC), liberal acceptance bias (LA), bias against disconfirmatory evidence (BADE), possibility of being mistaken (PM)], and paranoid ideation, using established experimental paradigms and self-report questionnaires.

Around 10% of our sample endorsed coronavirus-related CT beliefs at least strongly, and another 20% to some degree. Overall endorsement was similar to levels observed in a UK-based study (Freeman et al., 2020b). Higher levels of conspiracy belief endorsement were associated with greater JTC, greater LA, greater BADE, higher PM, and greater paranoid ideation. Associations were mostly small to moderate and best described by non-linear relationships.

A noticeable proportion of our sample recruited in Germany and German-speaking Switzerland endorsed coronavirus conspiracy beliefs strongly or to some degree. These beliefs are associated with reasoning biases studied in delusion research. The non-probability sampling approach limits the generalizability of findings. Future longitudinal and experimental studies investigating conspiracy beliefs along the lines of reasoning are encouraged to validate reasoning aberrations as risk factors.

Borderline personality disorder (BPD) is characterized by instability in affective regulation that can result in a loss of cognitive control. Triggers may be neuronal responses to emotionally valenced context and/or stimuli. ‘Neuronal priming’ indexes the familiarity of stimuli, and may capture the obligatory effects of affective valence on the brain's processing system, and how such valence mediates responses to the repeated presentation of stimuli. We investigated the effects of affective valence of stimuli on neuronal priming (i.e. changes in activation to repeated presentation of stimuli), and if these effects distinguished BPD patients from controls.

Forty BPD subjects and 25 control subjects (age range: 18–44) participated in an episodic memory task during fMRI. Stimuli were presented in alternating epochs of encoding (six images of positive, negative, and neutral valence) and recognition (six images for ‘old’ v. ‘new’ recognition). Analyses focused on inter-group differences in the change in activation to repeated stimuli (presented during Encoding and Recognition).

Relative to controls, BPD showed greater priming (generally greater decrease from encoding to recognition) for negatively valenced stimuli. Conversely, BPD showed less priming for positively valenced stimuli (generally greater increase from encoding to recognition).

Plausibly, the relative familiarity of negative valence to patients with BPD exerts an influence on obligatory responses to repeated stimuli leading to repetition priming of neuronal profiles. The specific effects of valence on memory and/or attention, and consequently on priming can inform the understanding of mechanisms of altered salience for affective stimuli in BPD.

The aim of this study was to examine whether exposure to previous traumatic events is a risk factor for stress reactions during this pandemic. Capitalizing on a 29-year longitudinal study of Israeli ex-prisoners of war (ex-POWs) and combat veterans, we examined whether captivity is a risk factor for fear of coronavirus disease 2019 (COVID-19) and COVID-19-induced acute stress disorder (COVID-19 ASD) beyond the effects of combat exposure and other stressful life events. In addition, we examined the contribution of captivity experiences (severity of captivity, experience of solitary confinement, and suffering during captivity) and veterans' appraisal of the impact of their war-related experiences on adjustment to the current quarantine and isolation to fear of COVID-19 and COVID-19 ASD.

One-hundred-and-twenty Israeli ex-POWs from 1973 Yom Kippur War and 65 matched controls (combat veterans from the same war) filled out self-report questionnaires 18 (T1), 35 (T2), 42 (T3), and 47 (T4) years after the war.

Findings revealed that although ex-POWs and controls did not differ in their level of exposure to COVID-19, ex-POWS reported higher levels of fear of COVID-19 and COVID-19 ASD than controls. Suffering during captivity, measured at 1991, and participants' appraisal of the extent to which their war-related experiences affected adjustment to COVID-19 were significantly associated with fear of COVID-19 and COVID-19 ASD.

The findings of the study demonstrate the long-term effects of exposure to traumatic experiences (captivity) during young adulthood on adjustment to an unrelated collective stress, such as COVID-19, 40 years later.

Animal studies have shown beneficial effects of probiotic supplementation on the hippocampus (HC) and cognitive performance. Evidence in humans is scarce. It was hypothesised that probiotic supplementation is associated with enhanced hippocampal (HC) regional grey matter volume (rGMV), as well as HC functional connectivity (FC). Relatedly improvements in mnestic and navigational performance, or emotional well-being, were expected to be observed in healthy human volunteers.

A randomised-controlled, double-blind trial (RCT) was conducted in N = 59 volunteers (age Mean = 27.1, s.d. = 6.7), applying a multi-strain probiotic (Vivomixx®) v. non-probiotic milk-powder placebo, each with 4.4 g/day, for 4 weeks. Volumetric data was extracted from 3T structural magnetic resonance images of total HC and -subfields. Voxel-based morphometry (VBM) and FreeSurfer-based analyses were performed. Potential neuroplastic change beyond HC was explored using whole-brain-VBM for white- and GMV. Seed-based FC was calculated based on HC. Cognitive tests included visual, map-based, object-location, and verbal memory, and spatial navigation. Mental health status (stress, anxiety, depression, and emotion-regulation) was assessed using self-reports.

There were no changes in HC-total, -subfield GMV, or FC, through probiotics. VBM revealed no changes at a whole-brain-level. There were no effects on cognitive performance or mental health. Evidence in favor of the null-hypothesis, using Bayesian statistics, was consistent.

The applied multi-strain probiotic did not elicit any effects concerning hippocampal structural plasticity, cognition, or mental well-being in young, healthy adults. For future studies, longer application/observation RCTs, perhaps in stressed, otherwise psychologically/ cognitively vulnerable, or ageing groups, with well-founded strain selection and investigation of mechanism, are advised.