Conceptual endophenotypes: A strategy to advance the impact of psychoneuroendocrinology in precision medicine

The cortisol switch between vulnerability and resilience

In concert with neuropeptides and transmitters, the end products of the hypothalamus-pituitary-adrenal (HPA) axis, the glucocorticoid hormones cortisol and corticosterone (CORT), promote resilience: i.e., the ability to cope with threats, adversity, and trauma. To exert this protective action, CORT activates mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) that operate in a complementary manner -as an on/off switch- to coordinate circadian events, stress-coping, and adaptation. The evolutionary older limbic MR facilitates contextual memory retrieval and supports an on-switch in the selection of stress-coping styles at a low cost. The rise in circulating CORT concentration after stress subsequently activates a GR-mediated off-switch underlying recovery of homeostasis by providing the energy for restraining the primary stress reactions and promoting cognitive control over emotional reactivity. GR activation facilitates contextual memory storage of the experience to enable future stress-coping. Such complementary MR-GR-mediated actions involve rapid non-genomic and slower gene-mediated mechanisms; they are time-dependent, conditional, and sexually dimorphic, and depend on genetic background and prior experience. If coping fails, GR activation impairs cognitive control and promotes emotional arousal which eventually may compromise resilience. Such breakdown of resilience involves a transition to a chronic stress construct, where information processing is crashed; it leads to an imbalanced MR-GR switch and hence increased vulnerability. Novel MR-GR modulators are becoming available that may reset a dysregulated stress response system to reinstate the cognitive flexibility required for resilience.

Can neurological soft signs and neurocognitive deficits serve as a combined endophenotype for Han Chinese with bipolar disorder?

BACKGROUND

Bipolar disorder's (BD) potential endophenotypes include neurological soft signs (NSS) and neurocognitive disorders (ND). Few research, meanwhile, has coupled NSS and ND as combined endophenotypes of BD.

OBJECT

This study intends to investigate NSS and ND and compare their differences in euthymic patients with bipolar disorder (EBP), their unaffected first-degree relatives (FDR), and healthy controls (HC). Additionally, search for potential endophenotypic subprojects of NSS and ND and construct and verify a composite endophenotypic.

METHODS

The subjects were all Han Chinese and consisted of 86 EBP, 81 FDR, and 81HC. Cambridge Neurological Inventory and MATRICSTM Consensus Cognitive Battery tested NSS and ND independently.

RESULTS

All three groups displayed a trapezoidal distribution of NSS levels and cognitive abnormalities, with EBP having the most severe NSS levels and cognitive deficits, followed by FDR and HC. Among them, motor coordination in NSS and Information processing speed (IPS), Verbal learning (VL), and Working memory (WM) in neurocognitive function are consistent with the traits of the endophenotype of BD. The accuracy in differentiating EBP and HC or FDRs and HC was higher when these items were combined as predictor factors than in differentiating EBP and FDR.

CONCLUSION

These results provide more evidence that motor coordination, IPS, VL, and WM may be internal characteristics of bipolar disease. When these characteristics are combined into a complex endophenotype, it may be possible to distinguish BD patients and high-risk groups from normal populations.

Brain-derived neurotrophic factor (BDNF) epigenomic modifications and brain-related phenotypes in humans: A systematic review

Epigenomic modifications of the brain-derived neurotrophic factor (BDNF) gene have been postulated to underlie the pathogenesis of neurodevelopmental, psychiatric, and neurological conditions. This systematic review summarizes current evidence investigating the association of BDNF epigenomic modifications (DNA methylation, non-coding RNA, histone modifications) with brain-related phenotypes in humans. A novel contribution is our creation of an open access web-based application, the BDNF DNA Methylation Map, to interactively visualize specific positions of CpG sites investigated across all studies for which relevant data were available. Our literature search of four databases through September 27, 2021 returned 1701 articles, of which 153 met inclusion criteria. Our review revealed exceptional heterogeneity in methodological approaches, hindering the identification of clear patterns of robust and/or replicated results. We summarize key findings and provide recommendations for future epigenomic research. The existing literature appears to remain in its infancy and requires additional rigorous research to fulfill its potential to explain BDNF-linked risk for brain-related conditions and improve our understanding of the molecular mechanisms underlying their pathogenesis.

Working Memory Performance Under Stress

Acute stress and chronic stress change the physiology and function of the individual. As one facet, stress and its neuroendocrine correlates - with glucocorticoids in particular - modulate memory in a concerted action. With respect to working memory, impairing effects of acute stress and increased levels of glucocorticoids could be expected, but empirical evidence on moderating effects of cortisol on working memory is ambiguous in human studies. In the current study, we thus aimed to investigate cortisol stress responses and memory performance. Older men and women (32 men, 43 women, aged 61-67 years) underwent the Trier Social Stress Test (TSST) and performed the 2-back task before and after exposure to acute stress. In line with theoretical assumptions, we found that higher cortisol stress responses led to a decline of working memory performance in men. However, the opposite was evident for women, who appeared to benefit from higher stress responses. This effect was evident for accuracy, but not for reaction time. In conclusion, cortisol might mediate working memory alterations with stress in a sex-specific manner in older people. Possible mechanisms and causes for these sex differences put a focus on endocrine changes in the aging population that might lead to differential effects across the lifespan.

Neurological soft signs and neurocognitive deficits in remitted patients with schizophrenia, their first-degree unaffected relatives, and healthy controls

Neurological soft signs (NSS) and neurocognitive deficits (ND) are highly prevalent in schizophrenia, and have been separately proposed as candidate endophenotypes of schizophrenia. However, few relevant studies focus on remitted patients with schizophrenia (RP) and integrate NSS and ND as a composite endophenotype. This study aimed to explore the NSS and ND and examine the comparative relationship between them in RP, their first-degree unaffected relatives (FDR), and healthy controls, furthermore, to seek potential endophenotypes subitems of NSS and ND and create a composite endophenotype. 86 RP, 86 FDR, and 86 healthy controls were included. NSS and ND were independently assessed with Cambridge Neurological Inventory and MATRICS^TM Consensus Cognitive Battery. RP had more NSS and ND than FDR in all subitems except disinhibition, information processing speed, working memory, and visual memory. Similarly, FDR presented poorer performance than controls in all subscales except disinhibition, sensory integration, working memory, and visual memory. Six subitems of NSS and ND met the criteria of endophenotype and the three groups were most accurately classified (71.2%) with these subitems working as a composite endophenotype. Moreover, information processing speed, attention, and social cognition were associated with sensory integration in RP and FDR. These findings add evidences that certain subitems of NSS and ND might be the endophenotypes of schizophrenia and integrating these endophenotypes may prove useful in identifying schizophrenia and high-risk individuals. Furthermore, sensory integration and specific cognitive domains covary, hence suggesting an overlap of compromised underlying neural systems.

Translating basic research knowledge on the biological embedding of early-life stress into novel approaches for the developmental programming of lifelong health

This review integrates scientific knowledge obtained over the past few decades on the biological mechanisms that contribute to the profound association between exposure to early adversity, including childhood trauma and prenatal stress, and the lifelong elevated risk to develop a broad range of diseases. We further discuss insights into gene-environment interactions moderating the association between early adversity and disease manifestation and we discuss the role of epigenetic and other molecular processes in the biological embedding of early adversity. Based on these findings, we propose potential mechanisms that may contribute to the intergenerational transmission of risk related to early adversity from the mother to the fetus. Finally, we argue that basic research knowledge on the biological embedding of early adversity must now be translated into novel intervention strategies that are mechanism-driven and sensitive to developmental timing. Indeed, to date, there are no diagnostic biomarkers of risk or mechanism-informed interventions that we can offer to victims of early adversity in order to efficiently prevent or reverse adverse health outcomes. Such translational efforts can be expected to have significant impact on both clinical practice and the public health system, and will promote precision medicine in pediatrics and across the lifespan.

The Trier Social Stress Test in first episode psychosis patients: Impact of perceived stress, protective factors and childhood trauma

Psychosis has been associated with abnormalities in hypothalamic-pituitary-adrenal axis functioning, which may emerge through heightened stress sensitivity following early life adversity - ultimately resulting in illness onset and progression. The present study assessed cortisol levels during an established psychosocial stress task and their association with current stress perception, putative protective factors and adverse childhood experiences in patients with a first episode of psychosis (FEP). A total of 100 volunteers participated in the study, 57 of whom were patients with a FEP (mean age 23.9 ± 3.8) and 43 healthy community controls (mean age 23.2 ± 3.9). Salivary cortisol, heart rate and blood pressure were measured at eight time points before and after the Trier Social Stress Test. Subjective stress and protective factors were assessed with the Perceived Stress Scale, the Self-Esteem Rating Scale and the Brief COPE. Early life adversity was assessed with the Childhood Trauma Questionnaire. Patients compared to controls showed significantly lower cortisol levels (F = 7.38; p = .008) throughout the afternoon testing period, but no difference in the cortisol response to the TSST. Heart rate was elevated and protective factors were lower in patients compared to controls. Attenuated cortisol levels were associated with higher levels of perceived stress, poor protective factors and more physical neglect during childhood. Our results suggest that attenuated baseline cortisol levels and not a blunted response during an acute stress task might be an indicator of heightened stress vulnerability and poor resilience in psychosis. The possible influence of childhood adversity and antipsychotic medication is discussed.

Genetic variation of the mineralocorticoid receptor gene (MR, NR3C2) is associated with a conceptual endophenotype of "CRF-hypoactivity"

Recently, the "conceptual endophenotype" approach has been proposed as a means to identify subgroups of patients affected by stress-related psychiatric disorders. Conceptual endophenotypes consist of patterns of psychological, biological, and symptomatic elements. We studied a sample of patients seeking help for psychosomatic and stress-related disorders (total N = 469), who were evaluated with a diagnostic instrument that integrates psychological and biological data to derive 13 endophenotypes, or Neuropattern. The goal of this study was to explore associations between common variations of the mineralocorticoid receptor gene (MR, NR3C2), and the 13 conceptual endophenotypes of Neuropattern, as well as with the respective biological and symptom measures. A common haplotype of the MR, comprised of two functional single nucleotide polymorphism (rs2070951 G/C & rs5522 A/G), was associated with the conceptual endophenotype CRF-hypoactivity, characterized by low cortisol levels at awakening and a symptom constellation often observed in atypical depression. Homozygous carriers of the G-A haplotype (haplotype 1), previously associated with reduced dispositional optimism, increased levels of rumination and higher risk for depression, more frequently endorsed this Neuropattern. In addition to the overall association between MR variation and CRF hypoactivity, we observed in the whole sample significant associations between MR haplotypes and cortisol awakening response patterns, as well as with symptoms that characterize the CRF hypoactivity endophenotype. If replicated, MR haplotype 1 might serve as a vulnerability marker for a disorder class characterized in biological terms by reduced cortisol levels, and in terms of symptom constellation by features often observed in atypical depression.

How to determine whether conceptual endophenotypes can improve clinical outcomes in patients suffering from major depression: An exploratory approach

Depression is a complex mental health disorder, resulting in a high degree of disability. Since symptom constellation, course, and outcome are heterogeneous in these patients, current research initiatives are striving to establish stratified diagnostic and treatment approaches. In the past two decades, Dirk Hellhammer and his team introduced Neuropattern, a new diagnostic concept, which is based on conceptual endophenotypes of the stress response network. We explore how to use this concept in clinical practice in order to ultimately determine whether it brings any value over standard care. In view of the novelty of the concept and the difficulties dealing with such a concept at a practical level, it was necessary to initiate an exploratory study to determine key factors for planning future clinical trials. We report results and knowledge gained from an exploratory single-site study investigating the use and potential benefits of Neuropattern in standard care. Inpatients (ICD-10 diagnosis F32, F33; Nö=ö178) were allocated to either treatment as usual (standard group, SG) or a novel Neuropattern oriented exploratory treatment (intervention group, IG). Symptom severity was assessed with psychometric tests at admission to hospital, during the first six weeks, and upon discharge from the hospital. In addition, direct and indirect costs were assessed for the 3-month-intervals prior to and after the hospital stay. Compared to the SG, depression scores of patients in the IG showed a faster decline once psychotherapeutic and pharmacological treatment were based on an individualized explanatory model. The patients in the IG with an F33 diagnosis showed a more pronounced reduction of depression severity during the stay in the hospital and a stronger and quicker reduction of general symptom severity. Comparing the average depression scores at the start of the study and after six weeks, symptom severity was reduced in all Neuropattern groups. Some limitations of the study have to be mentioned: The study was not blinded, was single-site, included highly depressed inpatients only, and was conducted for no longer than 8 months. The results highlight some important issues regarding taking the Neuropattern approach to the bedside and researching its efficacy and effectiveness to support personalized treatments in clinical care.

From serendipity to clinical relevance: How clinical psychology and neuroscience converged to illuminate psychoneuroendocrinology

Dirk Hellhammer and his colleagues have played a major role in creating the field of psychoneuroendocrinology from their roots in psychology. In this review, using examples from the history of the McEwen laboratory and neuroscience and neuroendocrinology colleagues, I summarize my own perspective as to how the fields of neuroscience and neuroendocrinology have contributed to psychoneuroendocrinology and how they converged with the contributions from Dirk Hellhammer and his colleagues.

The psychobiology of using automated driving systems: A systematic review and integrative model

Using vehicles with engaged automated driving systems (ADS) ('highly automated driving', HAD) will substantially impact on future society's mobility, yet the current understanding of human psychobiology related to HAD is still limited. Hence, we synthesized evidence on the psychobiology of subjects using HAD, informing an integrative model of the psychobiology of HAD, and providing guidance for reporting future research on this topic. We included (non-)randomized studies assessing human peripheral biology markers of in-vehicle-users in real or simulated driving environments, using vehicles with vs. without engaged ADS, published in English until April 2018. We systematically searched Web of Science, SCOPUS, and PubMed. The search consisted of a combination of terms describing HAD and psychobiological parameters. Risk of bias was assessed regarding randomization, blinding, incomplete outcome data, selective outcome reporting, and other potential causes. We extracted data using predefined data fields. Four out of five studies included in this review (N = 194 subjects) reported associations of use of vehicles with vs. without engaged ADS with various psychobiological parameters, including heart rate, respiratory sinus arrhythmia (RSA), indicators of electrodermal activity (EDA), and masseter electromyography (EMG). Heart rate tended to be reduced during HAD along with increased EDA and EMG, with no clear indication for changes in RSA. We cannot exclude substantial risk of bias, among others because the status of engagement of ADS was mostly non-randomized. Yet, findings suggest that HAD goes along with tractable changes in peripheral biology. Informed by the conceptual endophenotype approach (Hellhammer et al., 2018, Psychoneuroendocrinology), we propose the Embodied Driving (EMBODD) model that describes how HAD reshapes vehicle use experience, and highlight how to make future ADS equipped vehicles successful regarding user's health. Based on the review, we suggest reporting guidelines for future research on the psychobiology of HAD.

[The prognostic significance of biological rhythms assessment in depression]

AIM

To assess the prognostic significance of biological rhythms in depression on the example of the individual chronotype.

MATERIAL AND METHODS

One hundred patients (women 68%), aged 18-77 years, mean age 48±16, were examined before and after 8 weeks of treatment. The Morningness-Eveningness Questionnaire (MEQ) was used. Treatment response (a decrease of 50% in total MADRS scores to the 8^th week of treatment) and dynamics of depression severity (dMADRS; R) were assessed.

RESULTS AND CONCLUSION

Evening chronotype was found to be associated with poor prognosis. TCAs and SSRIs were more effective in eveningness, other antidepressants - in morningness. MEQ changes during and after treatment may reflect the resynchronizing activity of antidepressants.

Importance of the brain corticosteroid receptor balance in metaplasticity, cognitive performance and neuro-inflammation

Bruce McEwen's discovery of receptors for corticosterone in the rat hippocampus introduced higher brain circuits in the neuroendocrinology of stress. Subsequently, these receptors were identified as mineralocorticoid receptors (MRs) that are involved in appraisal processes, choice of coping style, encoding and retrieval. The MR-mediated actions on cognition are complemented by slower actions via glucocorticoid receptors (GRs) on contextualization, rationalization and memory storage of the experience. These sequential phases in cognitive performance depend on synaptic metaplasticity that is regulated by coordinate MR- and GR activation. The receptor activation includes recruitment of coregulators and transcription factors as determinants of context-dependent specificity in steroid action; they can be modulated by genetic variation and (early) experience. Interestingly, inflammatory responses to damage seem to be governed by a similarly balanced MR:GR-mediated action as the initiating, terminating and priming mechanisms involved in stress-adaptation. We conclude with five questions challenging the MR:GR balance hypothesis.