Mental Health in Times of the COVID-19 Pandemic

The COVID-19 pandemic is one of the most serious health and economic crises of the 21st century. From a psychological point of view, the COVID-19 pandemic and its consequences can be conceptualized as a multidimensional and potentially toxic stressor for mental health in the general population. This selective literature review provides an overview of longitudinal studies published until June 2021 that have investigated the impact of the COVID-19 pandemic on mental health in the European population. Risk and protective factors identified in the studies are summarized. Forty-two studies that met inclusion and search criteria ( COVID-19, mental health, longitudinal, and Europe) in PubMed, PsycInfo, and Web of Science databases indicate differential effects of the pandemic on mental distress, depression, and anxiety, depending on samples and methods used. Age-specific (e.g., young age), social (e.g., female, ethnical minority, loneliness), as well as physical and mental health-related factors (e.g., pre-pandemic illness) were identified as risk factors for poor mental health. The studies point to several protective factors such as social support, higher cognitive ability, resilience, and self-efficacy. Increasing evidence supports the assumption of the pandemic being a multidimensional stressor on mental health, with some populations appearing more vulnerable than others, although inconsistencies arise. Whether the pandemic will lead to an increase in the prevalence of mental disorders is an open question. Further high-quality longitudinal and multi-national studies and meta-analyses are needed to draw the complete picture of the consequences of the pandemic on mental health.Peer Reviewe

Current Knowledge and Implications From a European Perspective

The COVID-19 pandemic is one of the most serious health and economic crises of the 21st century. From a psychological point of view, the COVID-19 pandemic and its consequences can be conceptualized as a multidimensional and potentially toxic stressor for mental health in the general population. This selective literature review provides an overview of longitudinal studies published until June 2021 that have investigated the impact of the COVID-19 pandemic on mental health in the European population. Risk and protective factors identified in the studies are summarized. Forty-two studies that met inclusion and search criteria (COVID-19, mental health, longitudinal, and Europe) in PubMed, PsycInfo, and Web of Science databases indicate differential effects of the pandemic on mental distress, depression, and anxiety, depending on samples and methods used. Age-specific (e.g., young age), social (e.g., female, ethnical minority, loneliness), as well as physical and mental health-related factors (e.g., pre-pandemic illness) were identified as risk factors for poor mental health. The studies point to several protective factors such as social support, higher cognitive ability, resilience, and self-efficacy. Increasing evidence supports the assumption of the pandemic being a multidimensional stressor on mental health, with some populations appearing more vulnerable than others, although inconsistencies arise. Whether the pandemic will lead to an increase in the prevalence of mental disorders is an open question. Further high-quality longitudinal and multi-national studies and meta-analyses are needed to draw the complete picture of the consequences of the pandemic on mental health

Modulating emotional memories: Influence of stress and interference learning on brain potentials during encoding and retrieval

There is multiple evidence that emotionally arousing events are preferentially processed, and better remembered than neutral events. In the present dissertation I investigated whether those strong emotional memories are affected by acute and chronic stress. Moreover, I was interested in whether already established emotional memories can be changed by behavioral intervention. According to the modulation hypothesis, emotionally arousing events promote attention and memory processes via noradrenergic and glucocorticoid actions. Recent models suggest that stress hormones differentially impact mnemonic processing, namely encoding, (re-) consolidation and memory retrieval, depending on timing and duration of the stressor relative to the learning experience. Acute stress around the time of encoding has been found to enhance memory, whereas chronic stress has been associated with memory impairments. Furthermore, consolidated memories are not resistant to modifications. Following reactivation, memories can turn into an unstable state and undergo a process called reconsolidated in order to persist. During this vulnerable state, memories are prone to modification, for instance by pharmacological blockade or interference learning. Here, the modulation of newly formed emotional and neutral memories as well as existing emotional and neutral memories was investigated in a well-established picture viewing and recognition memory paradigm using behavioral and neurophysiological measures (event-related potential, ERPs). More elaborative processing of emotional, relative to neutral stimuli has been related to the late positive potential (LPP). During encoding of emotional and neutral pictures, enhanced LPPs (starting at about 400 ms after stimulus onset) are usually observed for emotionally arousing relative to neutral pictures, indicating preferential attention allocation and processing. During recognition, correctly recognized old items evoke larger ERP amplitudes than correctly identified new items. This difference, the ERP old/new effect, was used to measure mnemonic processing during retrieval. The ERP old/new effect over centro-parietal sensor sites (400-800 ms) has been associated with recollection processes, and is enhanced for emotional, compared to neutral materials. Three studies are presented, that investigated 1) the influence of acute stress prior to encoding on long-term memory and its neural correlates, 2) the impact of chronic stress on encoding and memory, and 3) the influence of interference on already established memories (reconsolidation), always contrasting emotionally arousing and neutral scenes. Study 1 investigated subsequent recognition memory after encoding following acute stress using a socially evaluated cold pressure test, while study 2 tested the influence of chronic stress investigating breast cancer survivors about two years after cancer treatment. In study 3, one day after encoding, reconsolidation of the reactivated picture memory was targeted with an interfering learning task. In all three studies, recognition memory was tested one week later. High-density electroencephalograms (EEGs; 257 electrodes) were recorded to measure brain potentials. The results showed, in line with previous research, that emotionally arousing scenes were preferentially processed, as indicated by larger LPPs, and were better remembered than neutral scenes, as indicated by enhanced memory performance and larger ERP old/new differences. Experiencing acute stress prior to encoding enhanced the centro-parietal ERP old/new effect for emotionally arousing pictures at recognition, corroborating that acute stress facilitates memory for emotional scenes (Study 1). In contrast, attenuated LPPs for unpleasant pictures and impaired memory performance for arousing pictures were observed in breast cancer survivors (Study 2), indicating altered attention to emotion and subsequent emotional memory storage in chronically stressed individuals. When memory reactivation was followed by an interfering learning task, recognition memory and ERP old/new differences were attenuated for emotionally arousing scenes, selectively, showing the possibility that emotional memories might be modulated by behavioral interventions (Study 3). The results of all three studies are discussed and integrated into a model of memory modulation by stress and interference. The results highlight the importance of understanding the role of emotional arousal in the processes of memory formation, retrieval and reconsolidation. Moreover, shedding light on the differential effects of acute and chronic stress, interference and their possible interactions might help to prevent and even modify impairing memories that are one of the major concerns in stress- and fear-related mental disorders.Eine Vielzahl von Studien zeigt, dass emotional erregende Ereignisse mehr Aufmerksamkeit auf sich ziehen, dadurch bevorzugt verarbeitet und folglich auch besser erinnert werden, als neutrale Ereignisse. Die sogenannte Modulationshypothese postuliert, dass die Effekte von emotional erregenden Ereignissen auf Aufmerksamkeits- und Gedächtnisprozesse über eine Aktivierung von Noradrenalin und Glukokortikoiden vermittelt werden. Stresshormone beeinflussen Gedächtnisprozesse, also die Aufnahme, die (Re-)Konsolidierung und den Abruf, in unterschiedlicher Weise. Dieser Einfluss ist dabei abhängig vom zeitlichen Zusammenhang zwischen Stress und Lernerfahrung, sowie der Dauer des Stressors. Akuter Stress fördert die Informationsaufnahme und Gedächtniskonsolidierung, während chronischer Stress mit Gedächtniseinschränkungen in Verbindung gebracht wird. Werden einmal konsolidierte Inhalte reaktiviert, so erreichen sie erneut einen instabilen Zustand und müssen rekonsolidiert werden, um dauerhaft im Gedächtnis zu bleiben. In diesem instabilen Zustand sind die Inhalte beispielsweise durch eine pharmakologische Blockade oder eine neue, konkurrierende Lernaufgabe (Interferenzlernen) modifizierbar. In der vorliegenden Arbeit wurde die Modulation von emotionalen und neutralen Gedächtnisinhalten durch akuten und chronischen Stress sowie durch Blockade der Rekonsolidierung anhand eines gut etablierten Paradigmas (Bildbetrachtung und Wiedererkennenstest) untersucht. Neben Verhaltensmaßen für die Gedächtnisleistung wurden hochauflösende Ereigniskorrelierte Potentiale (EKPs) als ein neuronaler Indikator während des Gedächtnistests erhoben. Während der Einspeicherung emotionaler und neutraler Bilder werden üblicherweise erhöhte späte Positivierungen (Late Positive Potentials, LPPs; beginnend bei etwa 400 ms nach Stimulusbeginn) beim Betrachten emotionaler im Vergleich zu neutralen Bildern beobachtet, was für eine verstärkte Aufmerksamkeitszuwendung und Verarbeitung dieser Reize spricht. Während des Wiedererkennens evozieren korrekt wiedererkannte alte Items größere EKP-Amplituden als richtig eingestufte neue Items (Old/New Effekt). Der Old/New Effekt über zentroparietalen Sensoren (400-800 ms) wurde mit Aktivierungen im Hippocampus und exaktem Wiedererkennen in Verbindung gebracht. Er tritt verstärkt bei emotionalen Inhalten auf. Drei Studien werden vorgestellt, die 1) den Einfluss von akutem Stress während der Enkodierung auf das Langzeitgedächtnis und dessen neuronale Korrelate, 2) den Einfluss von chronischem Stress auf Enkodierung und Gedächtnis und 3) den Einfluss von Interferenz auf die Rekonsoliderung bereits gespeicherter Gedächtnisinhalte untersuchen. Dabei wurden jeweils emotionale und neutrale Reize gegenübergestellt. Studie 1 untersuchte das Wiedererkennen von Reizen, die in Folge des sozial evaluierten Kaltwassertests unter Stress enkodiert wurden, während Studie 2 den Einfluss von chronischem Stress in einer Gruppe Brustkrebsüberlebender ca. zwei Jahre nach der Krebsbehandlung untersuchte. In Studie 2 wurden die 24 Stunden zuvor bereits gesehenen Bilder erneut präsentiert, um die Gedächtnisspur zu reaktivieren. Interferenzlernen zielte hier auf eine Blockade der Rekonsolidierung ab. In allen drei Studien erfolgte nach einer Woche ein unerwarteter Wiedererkennenstest. Ein hochauflösendes Elektroenzephalogramm (EEG; 257 Sensoren) wurde in den Untersuchungen abgeleitet. Im Einklang mit früheren Untersuchungen wurden emotional erregende Bilder bevorzugt verarbeitet. Dies spiegelte sich in größeren LPPs wider. Emotional erregende Bilder wurden besser wiedererkannt als neutrale Bilder, was mit einem stärkeren Old/New Effekt verbunden war. Akuter Stress vor Enkodierung ging mit einem größeren zentroparietalen Old/New Effekt für emotional erregende Bilder einher, was dafür spricht, dass akuter Stress die Gedächtnisspeicherung für emotionale Erlebnisse fördert (Studie 1). Im Gegensatz dazu wurden geringere LPPs für unangenehme Bilder und eine eingeschränkte Gedächtnisleistung für emotional erregende Bilder bei Brustkrebsüberlebenden beobachtet (Studie 2), was auf eine veränderte Verarbeitung in chronisch gestressten Personengruppen hinweist. Interessanterweise (Studie 3) führte Interferenzlernen nach Reaktivierung zu selektiven Einschränkungen in der Gedächtnisleistung und dem Old/New Effekt für emotionale Bilder. Dies weist auf die Möglichkeit hin, dass etablierte emotionale Erinnerungen durch Verhaltensinterventionen beeinflusst werden können

Effects of pre-encoding stress on brain correlates associated with the long-term memory for emotional scenes.

Recent animal and human research indicates that stress around the time of encoding enhances long-term memory for emotionally arousing events but neural evidence remains unclear. In the present study we used the ERP old/new effect to investigate brain dynamics underlying the long-term effects of acute pre-encoding stress on memory for emotional and neutral scenes. Participants were exposed either to the Socially Evaluated Cold Pressure Test (SECPT) or a warm water control procedure before viewing 30 unpleasant, 30 neutral and 30 pleasant pictures. Two weeks after encoding, recognition memory was tested using 90 old and 90 new pictures. Emotional pictures were better recognized than neutral pictures in both groups and related to an enhanced centro-parietal ERP old/new difference (400-800 ms) during recognition, which suggests better recollection. Most interestingly, pre-encoding stress exposure specifically increased the ERP old/new-effect for emotional (unpleasant) pictures, but not for neutral pictures. These enhanced ERP/old new differences for emotional (unpleasant) scenes were particularly pronounced for those participants who reported high levels of stress during the SECPT. The results suggest that acute pre-encoding stress specifically strengthens brain signals of emotional memories, substantiating a facilitating role of stress on memory for emotional scenes

Effects of Transcutaneous Vagus Nerve Stimulation (tVNS) on the P300 and Alpha-Amylase Level: A Pilot Study

Recent research suggests that the P3b may be closely related to the activation of the locus coeruleus-norepinephrine (LC-NE) system. To further study the potential association, we applied a novel technique, the non-invasive transcutaneous vagus nerve stimulation (tVNS), which is speculated to increase noradrenaline levels. Using a within-subject cross-over design, 20 healthy participants received continuous tVNS and sham stimulation on two consecutive days (stimulation counterbalanced across participants) while performing a visual oddball task. During stimulation, oval non-targets (standard), normal-head (easy) and rotated-head (difficult) targets, as well as novel stimuli (scenes) were presented. As an indirect marker of noradrenergic activation we also collected salivary alpha-amylase (sAA) before and after stimulation. Results showed larger P3b amplitudes for target, relative to standard stimuli, irrespective of stimulation condition. Exploratory post hoc analyses, however, revealed that, in comparison to standard stimuli, easy (but not difficult) targets produced larger P3b (but not P3a) amplitudes during active tVNS, compared to sham stimulation. For sAA levels, although main analyses did not show differential effects of stimulation, direct testing revealed that tVNS (but not sham stimulation) increased sAA levels after stimulation. Additionally, larger differences between tVNS and sham stimulation in P3b magnitudes for easy targets were associated with larger increase in sAA levels after tVNS, but not after sham stimulation. Despite preliminary evidence for a modulatory influence of tVNS on the P3b, which may be partly mediated by activation of the noradrenergic system, additional research in this field is clearly warranted. Future studies need to clarify whether tVNS also facilitates other processes, such as learning and memory, and whether tVNS can be used as therapeutic tool

Subjective stress and centro-parietal ERP old/new effect.

<p>A. Experienced stress predicts enhanced centro-parietal ERP old/new difference for emotional pictures (400–800 ms) in the stress group. Correlations between (averaged) subjective stress ratings and centro-parietal ERP old/new effect (400–800 ms) for emotional pictures in both experimental groups (stress vs. controls). B. ERP old/new differences averaged over centroparietal sensors (400–800 ms) for unpleasant, neutral and pleasant pictures in high and low stressed participants and control group. Error bars indicate SEM. C. ERP difference waveforms (old-new) averaged over centroparietal sensors for emotional pictures in high stressed (black line), low stressed (dotted line) and control (grey line) participants. The lower section displays the corresponding scalp topographies of the ERP difference separately for the three groups.</p

Grand average ERPs waveforms at frontal (A) and centro-parietal (B) sensor clusters for old (thick line) and new (dotted line) unpleasant, neutral and pleasant pictures in stressed (black lines) and control (grey lines) participants.

<p>Grand average ERPs waveforms at frontal (A) and centro-parietal (B) sensor clusters for old (thick line) and new (dotted line) unpleasant, neutral and pleasant pictures in stressed (black lines) and control (grey lines) participants.</p

Subjective stress ratings and autonomic measures during and after the SECPT/warm water control condition.

<p>Subjective assessments were measured using a scale from 0 (“not at all”) to 100 (“very much”). Data represent means (SEM). Bold indicates significantly higher values in stress compared to control group (*p<.05, **p<.001).</p

ERPs for correctly classified old and new pictures averaged over centro-parietal sensors (400–800 ms).

<p>Data represent means in µV (SEM).</p