Mental well-being during the first months of Covid-19 in adults and children: behavioral evidence and neural precursors

Pandemics such as the Covid-19 pandemic have shown to impact our physical and mental well-being, with particular challenges for children and families. We describe data from 43 adults (31♀, ages = 22–51; 21 mothers) and 26 children (10♀, ages = 7–17 years) including pre-pandemic brain function and seven assessment points during the first months of the pandemic. We investigated (1) changes in child and adult well-being, (2) mother–child associations of mental well-being, and (3) associations between pre-pandemic brain activation during mentalizing and later fears or burden. In adults the prevalence of clinically significant anxiety-levels was 34.88% and subthreshold depression 32.56%. Caregiver burden in parents was moderately elevated. Overall, scores of depression, anxiety, and caregiver burden decreased across the 11 weeks after Covid-19-onset. Children’s behavioral and emotional problems during Covid-19 did not significantly differ from pre-pandemic levels and decreased during restrictions. Mothers’ subjective burden of care was associated with children’s emotional and behavioral problems, while depression levels in mothers were related to children’s mood. Furthermore, meeting friends was a significant predictor of children’s mood during early restrictions. Pre-pandemic neural correlates of mentalizing in prefrontal regions preceded later development of fear of illnesses and viruses in all participants, while temporoparietal activation preceded higher subjective burden in mothers.

www.nature.com/scientificreports/ Notably, reports on increases in emotional distress are complemented by reports of a smaller, but significant, proportion of individuals who describe no changes or increases in well-being during restrictions. Such data indicates that interindividual differences in the effect of restrictions on mental health should be considered 2 . For example, restrictions may bring some families closer together, increase parent-child bonding and joint experiences 7 . An increased understanding of interindividual differences that protect or increase risk for psychopathologies holds the potential to inform personalized support associated with pandemics.
The identification of potential precursors for psychosocial functioning during challenging life events is crucial for the development and implementation of prevention and intervention measures. Socioemotional abilities represent different skill sets of social and emotional functioning 16 which may serve as potential antecedents of psychosocial functioning during challenging life events 17 . Successful socioemotional skill development in children is positively linked to present and future well-being 18 and a disruption of these has been linked to externalizing and internalizing problems 19 . Furthermore, socioemotional skill development strongly relies on caregiver-child relationships and dyadic learning 20 .
A fundamental ability for many later-emerging socioemotional abilities is mentalizing, a sociocognitive skill enabling the understanding of emotions, thoughts or motives of others and oneself (enabled by our so-called Theory of Mind and impacted by parenting behaviors 21 ). Having a well-developed Theory of Mind has been associated with higher social competences, psychological and physiological functioning 22 . Contrariwise, impaired mentalizing abilities have been linked to stress and depression 23 , potentially serving as a predictor of these 17 . On a neural level, the functional brain network associated with mentalizing typically includes areas such as the bilateral temporoparietal junction, precuneus, medial prefrontal cortex and right superior temporal sulcus 24 , with the temporoparietal junction and prefrontal cortex particularly relevant when thinking about others' and one's own mental states 10 . The right temporoparietal junction has been the area most consistently activated during different types of fMRI mentalizing tasks 24 . The right dorsolateral prefrontal cortex is similarly involved during mentalization and perspective taking, but also plays a key role in emotion regulation, which is strongly associated with mental well-being 25,26 . A disrupted ability to mentalize, including associated neural alterations, can be found in clinical disorders, such as borderline personality disorder, conduct disorder or alexithymia 27,28 .
Increasing evidence highlights the urgent need to consider the indirect consequences of the pandemic on physical and psychological well-being. Children's, parents' , or families' lives may be particularly affected, and parental well-being is suggested to be intertwined with that of children. Past evidence further indicates that well-being and stress are moderated by sociocognitive skills. In this study, we aimed (1) to investigate the effects of Covid-19 and associated restrictions on child and adult well-being as measured repeatedly during the first months after Covid-19 onset; (2) to assess associations of mental well-being (e.g., anxiety, depression, caregiver burden) in mothers with children's emotional and behavioral problems or mood; (3) to examine the association between the neural correlates of mentalizing as measured prior to Covid-19 and later development of fear of contamination and illnesses in all participants, or caregiver burden in mothers. In line with prior work 2,29 , we expect reports of negative effects on mental well-being (e.g., general health, anxiety, distress, depression), with possible changes over time. Emotional and behavioral problems in children may vary over time. Furthermore, we suggest that variations in emotional and behavioral problems or mood in children are positively associated with variables of mental well-being of their mothers. In everyday life, increased mentalizing skills are linked to improved socioemotional functioning 22 . However, studies have shown that particularly during challenging life circumstances an elevated tendency to mentalize may also be negatively associated with our well-being (e.g., higher anxiety in those with better mentalization skills 17 ). In line with this observation, we suggest that neural correlates of mentalizing are positively associated with later caregiver burden or the development of higher anxiety and fears associated with viruses.

Methods
Participants. Ninety-eight European participants (60 adults and 38 children) of a previous cross-sectional neuroimaging study investigating socioemotional development between 2018 and 2020 were asked to participate in the Covid-19 online follow-up assessments. Pre-pandemic assessments included behavioral tests and functional magnetic resonance imaging (fMRI) during mentalizing; see study description in 30 . We here describe data from the first 3 months after the first implementation of stringent restrictions following Covid-19 onset in Switzerland and include seven assessments time points across this time period (Fig. 1 All adults and children were previously recruited from the general community and schools for a study on the behavioral and neural correlates of socioemotional skill development. More specifically, participants took part in an evaluation study for a novel cognitive and affective Theory of Mind cartoon task (specifics may be found in 30 ). Furthermore, 21 women and 26 children were related (mother-child dyads). Parents of the children reported no known clinical diagnosis for 23 of the children, for three children a clinical diagnosis of ADHD was indicated and for one of these three children the parents further noted a possible developmental delay. In line with guidelines and approval by the local ethics board (Ethikkomission Nordwest-und Zentralschweiz) all participants signed an informed consent form. Additionally, in case of children, verbal assent of the child and written informed consent from a parent and/or legal guardian was collected. All research presented here was performed in accordance with the relevant guidelines and regulations of the Ethikkomission Nordwest-und Zentralschweiz.  Fig. 1). For adults, these targeted anxiety (State-Trait Anxiety Inventory or STAI-6; a self-report questionnaire to assess anxiety level as state 31 ), depression (Center for Epidemiologic Studies Depression Scale or CESD-R, German version 32 ; assessing symptoms in the last 1-2 weeks relating dysphoria, anhedonia, appetite, sleep, thinking, guilt, fatigue, movement and suicidal ideation), general health (General Health Questionnaire or GHQ-12, German version; a self-report instrument to screen for psychosocial well-being 33 ), distress (questionnaire adapted from the Kessler Psychological Distress Scale, but answer format was modified allowing participants to indicate their emotional state in relation to their usual emotional state 34 ) and subjective burden of caregiving for mothers (the Burden Scale for Family Caregivers or BSFC-s 35 ; a self-report questionnaire assessing subjective burden of family caregivers, which was adapted to capture increased burden in parental responsibilities during restrictions). In children emotional and behavioral problems were assessed using the Strengths and Difficulties Questionnaire (SDQ 36 ) and subjective mood ratings (children had to choose between 5 different smileys in order to indicate their mood in the last days. Ratings included 1: very happy, 2: happy, 3: unsure, 4: unhappy, 5: very sad). Children were further asked whether they had met any friends in the previous week. News consumption (adults only) and time spent outside (all participants) were assessed by asking participants to indicate the amount of time spent on these activities on a 5-point Likert scale. Adults reported their daily news consumption across all forms of media through the following scale: 1: no time, 2: approximately 15 min, 3: approximately 30 min, 4: approximately 1 h, 5: more than an hour of time spent consuming news). Adults and children indicated the average duration of spending time outside per day in the past week (1: no time, 2: half an hour, 3: 1 h, 4: 1-2 h, 5: more than 2 h of time spent outside).
One extra questionnaire (T E , between T4 and T5) was added before a first ease in restrictions was introduced by the government. This extra testing consisted of the Child Behavior Checklist (CBCL 37 ) evaluating child behavior and the Fear of Illness and Virus Evaluation (developed by Professor Jill Ehrenreich-May, https:// adaa. org/ node/ 5168). CBCL was also acquired at T0 allowing a pre-/post-comparison. Of the six biweekly assessments, the last two (T5, T6) were conducted after schools reopened.
Behavioral data analyses. Mental well-being during Covid-19-related restrictions. First, adults' scores in anxiety depression, and caregiver burden were screened. STAI-6 total scores above 40 were considered as an indicator of clinically significant levels of anxiety, according to 38 . Depression scores were screened to detect subthreshold depression symptoms according to the CESD total score (CESD total ≥ 16) or meeting criteria for a major depressive episode (description of the algorithm for calculation may be found at: https:// cesd-r. com/ cesdr/). Next, we calculated the 11-week prevalence of clinically significant anxiety, subthreshold depression and major depression (i.e., the proportion of participants surpassing relevant cut-off scores and fulfilling criteria at least once during the assessment period). Finally, parental burden was classified as "low", "moderate" or "high" according to the classification suggested by Pendergrass and colleagues 39 (BSFC-s scores of 0-4 are considered as low; 5-14 as moderate; 15-30 as high). www.nature.com/scientificreports/ We investigated the effect of Covid-19 and related restrictions on mental well-being using linear mixed-effect models in R (https:// www.r-proje ct. org/). As a first step, missing data points were evaluated to assess whether these were missing at random (MAR). In case of no violation of MAR assumption missing data was replaced by Multivariate Imputation by Chained Equations MICE package in R 40 employing the predictive mean matching method. Overall, 14.41% of the testing time points reported in the present analyses were imputed (12.79% in adults, 16.03% in children).
Linear mixed-effects models were employed to analyze the relationship between length since Covid-19 onset and continuous outcome measures (depression, anxiety, general health, distress, caregiver burden, and emotional and behavioral problems in children) using lme4 41 . Duration (in weeks) was entered as a fixed effect. Subjects were entered as a random effect and the model allowed for random intercepts and random slopes accounting for non-independence of datapoints (same person answering multiple times). Furthermore, a different response of the subjects was expected (each person might react differently to duration of restrictions). P values were obtained by the Satterthwaite approximation as recommended by Luke et al. 42 for small group sizes using the lmerTest package 43 . This pipeline was adjusted for the analysis of depression, caregiver burden and emotional and behavioral problems in children for the following reasons: Depression scores (CESD-R) and children's emotional problems, conduct problems, hyperactivity, peer problems and total scores (SDQ) were log-transformed after a visual inspection of the data revealing a right skew. For caregiving burden (BSFC-s), and children's peer problems and total score of emotional and behavioral problems (SDQ), the full model (including random intercepts and slopes for each subject) indicated an overfit. Consequently, a simplified model excluding random slopes by subject was implemented.
For the analysis of categorical, non-parametric data (i.e., clinically relevant threshold for depression reached [yes/no], time spent outside, news consumption and mood in children), Friedman tests were used. Significant main effects were followed up using post-hoc pairwise comparisons and adjusted using Holm-Bonferroni correction. Finally, one-way analysis of variance was employed to test whether emotional and behavioral problems (SDQ and CBCL) in children differed prior to and during Covid-19-related restrictions. For the score during Covid-19 all time points of SDQ were averaged to build one score (average of five online assessments). CBCL was only assessed once at T E .
Mother-child associations. To test whether mental well-being in mothers (anxiety, depression, and caregiver burden) explained variability in children's emotional or behavioral problems a multiple regression analysis was implemented corrected for children's age and sex. Since emotional and behavioral problems in children were assessed through parental reports, parental bias may impact findings. Therefore, we repeated the multiple regression analysis by using mood scores provided by the children as a dependent variable.
Post-hoc follow-up assessment. Mental well-being and the development of negative symptoms during stressful life events have been suggested to be influenced by further variables of interest, including sex and parenting 44 , news exposure 2 or time spent outside 45 . For adult participants, multiple regression analysis controlling for age was conducted to assess whether variation in mental well-being (i.e., anxiety, depression, or distress) were explained by sex, news consumption, time spent outside or parenthood. For children, we assessed whether children's well-being (self-report for mood) during restrictions was explained by time spent outside or meeting friends (yes/no) using multiple regression analyses, controlling for age and sex of the children.
Children's subjective reports. Children were asked two open-ended questions: At T1-T4, these were "What do you like about spending more time at home now?" and "What do you like less about spending more time at home now?". At T5 (after the first week of school opening) and T6 (3 weeks after school reopened) these were changed to "What do you like about going back to school?" and "What do you like less or think, is a bit annoying, about going back to school?" Subcategories based on topics mentioned were built and coded by two independent reviewers (Supplementary Methods). fMRI data analyses. fMRI data was analyzed using SPM12 running on MATLAB R2020b (www. fil. ion. ucl. ac. uk/ spm). Neural correlates of mentalizing were tested using the CAToon task 30 (see 30 and Supplementary Methods). fMRI was acquired for all participants between 2018 and 2020. In short, fMRI during mentalization was acquired using a cartoon-based Theory of Mind task [experimental condition: affective (AT) and cognitive (CT) Theory of Mind; control condition: physical causality (PC)]. The neural correlates of mentalizing were based on a regressor of interest including both cognitive and affective Theory of Mind as compared to physical causality ((AT|CT) > PC). Whole-brain T2-weighted echo-planar images were collected using a 20-channel head coil on a Siemens 3T Prisma MR scanner (specifics in Supplementary Methods). Group analyses included age and sex as covariates and all findings were corrected for multiple comparisons using whole brain family-wise error correction (FWE).
For the present purpose mean parameter estimates were extracted for areas of interest consistently recruited during mentalizing 24 , including right temporoparietal junction (TPJ) and dorsolateral prefrontal cortex (dlPFC), using the MarsBar toolbox 46 . More specifically, right TPJ was selected as a region of interest since it is most consistently recruited during mentalizing tasks and perspective taking in both children and adults 47 . A 7 mm sphere was extracted for the right TPJ, because the group activation cluster extended beyond the area of interest (spanning over 5860 voxels reaching from temporal pole to occipital areas). The right dlPFC was selected as a region of interest, because of its involvement during mentalization and perspective taking, but also because of its key role in emotion regulation, which is in turn strongly associated with mental well-being 25 , including the development of stress-related burden, depression and anxiety 26,48 . To test whether these regions were significant www.nature.com/scientificreports/ predictors of fears about contamination and illness, or caregiver burden, we employed multiple regression analyses controlling for age and sex when applicable. For the multiple regression analysis including caregiver burden we calculated one score averaging all BSFC total scores. In-scanner data collection was only evaluated to assure task compliance (i.e., no more than 10% missing in all trials; Supplementary Table S1).

Results
Behavioral findings. Descriptive statistics. A summary of the behavioral data collected prior to and during the early weeks following Covid-19 onset is included in Table 1 (in children scores prior to and scores averaged over the 11-weeks online assessment are reported. For adults only averaged scores are reported; Fig. 2). In mothers only. c Distress: 1-much less than usual, 2-quite less than usual, 3-a little less than usual, 4-as much as usual, 5-a little more than usual, 6-quite a bit more than usual, 7-much more than usual. d N = 25 (out of a total N pre-/during confinement of 26).  39 ) throughout the whole assessment period (Fig. 3).
When estimating the effect of restrictions on mental health longitudinally, linear mixed-effect models revealed a small but significant decrease in depression (β = − 0.04), anxiety (β = − 0.61), and burden of caregiving (β = − 0.26) scores with each week passing by. There was a non-significant decrease in general health (β = − 0.06) and distress (β = − 0.02) scores. A detailed summary of all models is included in Table 2. Follow-up Bonferroni-corrected pairwise comparisons showed no significant differences for time spent outside between timepoints. For news consumption, follow-up pairwise comparisons showed significant differences between timepoints T2 and T6 (Fig. 2).  Linear mixed-effects models indicated a significant decrease in children's scores of conduct problems (β = − 0.04), hyperactivity (β = − 0.03), peer problems (β = − 0.03) and overall emotional and behavioral problems (β = − 0.04; total score of SDQ), whereas there was a non-significant decrease in emotional problems (β = − 0.003) and increase in prosocial behavior (β = 0.08). A detailed summary of all models is included in Table 3. Friedman test revealed a significant variation in time spent outside (χ 2 = 21.002, p < 0.001), with significant differences between timepoints T1 and T3. A significant variation over time was also revealed in mood ratings (χ 2 = 13.425, p = 0.020), however, post-hoc pairwise comparisons remained non-significant. One-way analysis of variance indicated no significant difference in behavioral and emotional problems in children when comparing pre-Covid-19 scores with average scores obtained during Covid-19 (Supplementary  Table S2).

Discussion
We describe data on a small, but extensively characterized group of children and adults (N = 69, 41♀, age range = 7-51 years, including 26 children and their mothers), with reports across eight waves of testing, including seven assessment timepoints during the early months after Covid-19 onset in Switzerland and one assessment prior to the pandemic onset. Our findings report on mental well-being and psychosocial functioning in children and adults. The prevalence of clinically significant anxiety was 34.88%, and a 32.56% prevalence of subthreshold depression symptoms was observed across the 11 weeks. Caregiver burden was in the moderate ranges. Overall, scores of depression, anxiety and caregiver burden decreased over the course of the 11 weeks investigated. In Table 3. Linear mixed models estimating the effect of time after Covid-19 onset on children's behavioral and emotion problems. SE standard error, CI confidence interval, Duration (weeks) fixed effect, weeks passed since restrictions have been introduced, ICC intraclass correlation coefficient, N (number of observations)/(number of participants), p values have been estimated using Satterthwaite approximation, significant effects in bold.

Predictors
Conduct problems (log) Emotional problems (log) Hyperactivity (log) Peer problems (log) Prosocial behavior Total (log) www.nature.com/scientificreports/ children pre-pandemic levels of emotional and behavioral problems did not differ significantly from the average of the 11-week period during restrictions. Scores of conduct problem, hyperactivity, peer problems and overall emotional and behavioral problems in children decreased across time after Covid-19 onset. Well-being in mothers predicted mood and emotional and behavioral problems in children. In children meeting friends was a significant predictor of mood during restrictions. Additionally, neural correlates of mentalizing in prefrontal, but not temporoparietal regions, preceded the development of fear about contamination and illness across all participants. In mothers, higher neural activation in temporoparietal, but not frontal, regions during mentalizing preceded higher reports of subjective burden of care during restrictions. This may indicate that higher tendency to mentalize, usually considered beneficial for social interactions 49 and favorable when present in mother-child dyads 50 , can be negatively associated with socioemotional functioning during prolonged stress. Child behavior as measured by the SDQ or CBCL showed no difference when comparing pre-pandemic scores to those during restrictions, which is in line with longitudinal reports 7 observing a relatively stable level of problem behaviors after Covid-19 onset. Based on parental reports conduct problems, hyperactivity, peer problems and the overall level of emotional and behavioral problems decreased across time in the child group studied here. Emotional problems and prosocial behavior showed no significant changes during the 11-weeks assessment period. Additionally, children's time spent outside, and mood varied significantly. Variations in mood www.nature.com/scientificreports/ scores may be explained by several public holidays (Easter) around mid-restrictions. It may be possible that time spent outside during vacation allowed the meeting of friends, which was a relevant variable for increases in mood in children. Prior evidence highlights that prolonged school closure or restrictive measures are detrimental to children's physical and mental health and can have long-lasting consequences 14 . Conversely, the present study did not identify significant changes for emotional and behavioral problems of the children comparing pre-and post-pandemic onset levels. Our findings further indicate that meeting friends predicted better mood, which is in line with prior evidence emphasizing the importance of friendships and peer relationships in developmental groups 11,45 . Quantitative measures obtained were further supported by qualitative reports, which provide a unique insight into children's values and further highlight sources of resilience. More specifically, children mentioned more time for leisure, sleep, family, and friends or less stress or exams as positive attributes of school closure. Negative mentions centered around restrictions affecting social contacts, prohibiting hobbies or sports, or increased stress and conflict. Interestingly, across two time points, positive mentions about returning to schools across all children solely focused on social domains (e.g., meeting friends, class, teachers again or in-person schooling), whereas negative mentions included less sleep, less free time or increased stress and homework, or restrictions. Themes reported were in line with findings of qualitative reports during Covid-19 11,45 .
Anxiety, depression and caregiver burden was high amongst adults with scores decreasing across the 11-week assessment period. Clinically significant levels of anxiety were reached at the beginning and after 7 weeks of restrictions. Furthermore, the 11-week prevalence of anxiety was 34.88%. An increase in anxiety due to Covid-19 and related restrictions has been reported previously 2,5,8,51 , however, missing pre-pandemic scores hindered a www.nature.com/scientificreports/ direct investigation in the present group. Mixed-effects models reflected a decrease of anxiety scores across the first months after Covid-19 onset, which is in line with similar longitudinal studies indicating a decrease following a significant early impact in affect 2,51 . Similarly, a decrease in depressive symptomatology was observed. While group average scores of depression were in the normal range, it is notable that 32.56% of all adults reported heightened depressive symptoms and 4.65% qualified for a major depressive episode at least once. These observations mirror reports of heightened depression scores in the general population during Covid-19 (e.g., retrospective reports 2 or longitudinal data 6 ). Mothers reported elevated levels of subjective burden of care (in the moderate range), which is in line with similar studies investigating parental burden during Covid-19 52 . Notably, a moderate burden of care has been associated with elevated risk for physical, psychosomatic, or mental health problems 39,52 , indicating the need for parental programs mitigating possible stress-related health consequences. The experienced subjective burden of care decreased across the early months of investigation. Distress and general health, however, did not significantly change. Longitudinal studies to date have either reported a decrease or stagnation of depression or anxiety levels for the early months following Covid-19 onset across different countries 2,29,53 . Loosen et al. 29 for example suggest that such decreases in stress-related symptoms can partly be explained by adaptation, a phenomenon well-described in stress research 54 . Overall, first meta-analyses of studies compiling pre-/post mental health data report significant, but only small effects on anxiety and depression in adults 55 . Participant reports reflected significant changes in news consumption, reporting a higher amount of news consumed at the beginning and lower scores towards the end of the assessment period. Sex, news consumption, time spent outside or parenthood were not associated with variations in scores of anxiety, depression or distress in adults. This is somewhat surprising given prior evidence of the impact of each of these variables on mental well-being during Covid-19 (gender and parenting 44 ; news consumption 2 ; time spent outside 45 ).
In the present study, mother-child variables were positively associated. Subjective burden of caregiving in mothers predicted emotional and behavioral problems in children, while anxiety and depression did not. This indicates that higher burden in mothers was linked to more problem behaviors in children. It is important to mention though that emotional and behavioral problems in the child were reported by the mother, thus reporting bias can't be excluded. We further investigated the effect of the mothers' well-being on children's self-reported mood, demonstrating that elevated depression in mothers was associated with children's mood ratings. Dyadic relationships are a primary vehicle for children's learning 9 . While commonly a driver of positive effects, it may also lead to negative consequences, as demonstrated in the example of vicarious conditioned fear learning in parent-child dyads 56 . We thus hypothesize, that negative mental health in adults may negatively impact children's well-being, possibly through learnt maladaptive coping or contagion. Increased parental stress and anxiety may lead to parental burnout 13 or increased aggression 15 . Intergenerational care during early years lays the foundation for healthy social skill development 57 and systemic mental health intervention programs commonly draw from this relationship 58 . Our data point towards a support of programs investing in increased parental support, which are expected to influence children's well-being positively.
The neural correlates of mentalizing as measured prior to the pandemic in prefrontal, but not temporoparietal brain regions, preceded the development of fear about contamination and illness in all participants. In mothers, higher neural activation during mentalizing in temporoparietal, but not frontal regions was associated with higher burden of caregiving during restrictions. Activation increases in the right temporoparietal junction are commonly reported as a response to tasks of mentalizing, as this area selectively responds to observed social interactions 59 and is part of the so-called paternal caregiver brain network 60 . Prefrontal areas are similarly engaged during tasks of mentalizing and are crucial for cognitive control processes 10 . Our data indicate that neural activation during mentalization in prefrontal cortex prior to Covid-19 may precede the development of fear of contamination and illnesses in both children and adults. The assessment of fear about contamination and illness required participants to make statements relating to the likelihood of oneself, a parent, a pet, or someone else in the world becoming sick and/or dying because of a virus or illness. Activation increases in prefrontal cortex have been linked to psychological state attributions, independent of whether they affect oneself, a relative, imagined people or animals 61 or cognitive control (i.e., emotion regulation). A higher tendency to think about other people's well-being, as reflected by higher mentalization-related activation in the prefrontal cortex, may thus be linked to the likelihood of developing fear about contamination and illness affecting ourselves and others.
Overall, better mentalizing has been associated with higher social competence, psychological and physiological functioning 22 , while impairments have been associated with stress and depression 23 . Increased mentalizing skills in caregivers are beneficial for child development. For example, parental mentalization has been positively associated with regulatory skills in children 62,63 , which may be protective during stressful life events 43 . However, the opposite effect may occur during stressful situations 17 . Higher levels of empathy in parents have for example been linked to better psychological and physiological health of their children, but also higher levels of inflammatory markers in the parents 63 . Moreover, higher levels of mentalizing abilities were shown to be associated with higher cortisol and heart rate reactivity in stressful situations 64 . This may temporarily be beneficial but may have a long-term negative impact depending on the intensity and duration of negative events. Our data indicate that mentalization can be negatively associated with increased burden and fear development in prolonged stressful situations.
In the present example, extensive phenotyping within individuals allow a comprehensive view and an opportunity to assess effects of time within individuals. Although the presented findings mostly align with Covid-19 literature they should be considered with caution due to the relatively small group size and less comprehensive pre-pandemic health measures. Research on the existence of potential subgroups will have to be further examined using larger and more diverse populations. An indication for possible subgroups reacting differently to stressful life events as associated with pandemics include reports of children that may in fact benefit or even thrive during restrictions 7 . A more detailed understanding of subgroups of individuals that are differently affected may increase opportunities to select the best fitting individualized treatments or prevention. Assessing direct www.nature.com/scientificreports/ subjective experience of the severity of impact by Covid-19 and associated restrictions would have been a valuable addition. Moreover, as the pre-pandemic assessment did not include comparable measures of mental health in the adult group, it is difficult to disentangle the effect of Covid-19 and related restrictions from pre-existing mental health symptoms. It remains to be investigated how far-reaching the herein observed negative effects on wellbeing are. Past work has indicated that early adversities can have an impact for life, with effects potentially being most significant in younger age and depending on the intensity of the experience 65 . An increased understanding of protective and/or risk factors and mechanisms leading to the development of stress-related psychopathologies may ultimately hold the potential to facilitate more personalized prevention and treatment strategies.

Data availability
Behavioral mean scores are included in the manuscript and neuroimaging data is provided through NeuroVault (https:// ident ifiers. org/ neuro vault. colle ction: 9780). Further information or data may be obtained from the corresponding author.