Mother-infant interaction characteristics associate with infant falling reactivity and child peer problems at pre-school age.

This longitudinal study investigated the associations between mother-infant interaction characteristics at 9 months of age, maternal mental health, infant temperament in the first year postpartum, and child behaviour at 3 years of age. The infants (N = 54, 22 females) mainly had White British ethnic backgrounds (85.7%). Results showed that i) mother-infant dyadic affective mutuality positively correlated with infant falling reactivity, suggesting that better infant regulatory skills are associated with the dyad's ability to share and understand each other's emotions; and ii) maternal respect for infant autonomy predicted fewer child peer problems at 3 years of age, suggesting that maternal respect for the validity of the infant's individuality promotes better social and emotional development in early childhood.

Visualizing the invisible tie: Linking parent-child neural synchrony to parents' and children's attachment representations.

It is a central tenet of attachment theory that individual differences in attachment representations organize behavior during social interactions. Secure attachment representations also facilitate behavioral synchrony, a key component of adaptive parent-child interactions. Yet, the dynamic neural processes underlying these interactions and the potential role of attachment representations remain largely unknown. A growing body of research indicates that interpersonal neural synchrony (INS) could be a potential neurobiological correlate of high interaction and relationship quality. In this study, we examined whether interpersonal neural and behavioral synchrony during parent-child interaction is associated with parent and child attachment representations. In total, 140 parents (74 mothers and 66 fathers) and their children (age 5-6 years; 60 girls and 80 boys) engaged in cooperative versus individual problem-solving. INS in frontal and temporal regions was assessed with functional near-infrared spectroscopy hyperscanning. Attachment representations were ascertained by means of the Adult Attachment Interview in parents and a story-completion task in children, alongside video-coded behavioral synchrony. Findings revealed increased INS during cooperative versus individual problem solving across all dyads (𝛸2(2) = 9.37, p = 0.009). Remarkably, individual differences in attachment representations were associated with INS but not behavioral synchrony (p > 0.159) during cooperation. More specifically, insecure maternal attachment representations were related to higher mother-child INS in frontal regions (𝛸2(3) = 9.18, p = 0.027). Conversely, secure daughter attachment representations were related to higher daughter-parent INS within temporal regions (𝛸2(3) = 12.58, p = 0.006). Our data thus provide further indication for INS as a promising correlate to probe the neurobiological underpinnings of attachment representations in the context of early parent-child interactions. RESEARCH HIGHLIGHTS: We assessed attachment representations using narrative measures and interpersonal neural synchrony (INS) during parent-child problem-solving. Dyads including mothers with insecure attachment representations showed higher INS in left prefrontal regions. Dyads including daughters with secure attachment representations showed higher INS in right temporo-parietal regions. INS is a promising correlate to probe the neurobiological underpinnings of attachment representations in the context of parent-child interactions, especially within the mutual prediction framework.

Precursors and Effects of Self-reported Parental Reflective Functioning: Links to Parental Attachment Representations and Behavioral Sensitivity.

Parental reflective functioning is thought to provide a missing link between caregivers' own attachment histories and their ensuing parenting behaviors. The current study sought to extend research on this association involving 115 parents, both mothers and fathers, of 5-to-6-year-old preschoolers using the German version of the Parental Reflective Functioning Questionnaire (PRFQ). Our study was the first to combine Adult Attachment Interview classifications of parental attachment, behavioral observations of parental sensitivity and PRFQ ratings while drawing on a sizable father subsample. We found theoretically consistent significant relations between all measures, while our results particularly highlighted the role of dismissing attachment for decreases in parenting quality on both cognitive and behavioral levels as the dismissing status differentially affected specific components of self-reported parental reflective functioning and observed sensitivity. Interestingly, these patterns were largely comparable in mothers and fathers. Exploratory mediation analyses further suggested that decreased parental reflective functioning may partially mediate the relationship between parents' dismissing attachment and decreased parental sensitivity. Thus, for prevention and intervention programs targeting parental sensitivity and thus children's long term healthy mental development, the interplay between parental reflective functioning and parents' own attachment history emerges as a key mechanism. Finally, our study served as a further validation of the PRFQ given the caveat that the pre-mentalizing subscale may need further revision in the German version.

Charting the social neuroscience of human attachment (SoNeAt).

This introduction aims to set out the potential as well as some of the pitfalls of the newly emerging area of the Social Neuroscience of Human Attachment (SoNeAt). To organize and interconnect the burgeoning empirical studies in this line of research, including those in this special issue, we outline a programmatic framework including an extension of our conceptual proposals NAMA and NAMDA to guide future research. We hope that this special issue will act as a stimulus for redoubling our efforts advancing the newly emerging SoNeAt area bridging attachment theory and social neuroscience.

Longitudinal associations between self-reported attachment dimensions and neurostructural development from adolescence to early adulthood.

The existing literature suggests that individual differences in attachment may be associated with differential trajectories of structural brain development. In addition to maturation during infancy and childhood, developmental trajectories are characteristic of adolescence, a period marked by increasingly complex interpersonal relationships and significant neurostructural and functional plasticity. It remains to be examined whether attachment prospectively relates to neurostructural developmental trajectories during adolescence. In this longitudinal study, we investigated whether self-reported attachment dimensions of anxiety (AX) and avoidance (AV) could predict elements of cortical thickness (CT) and subcortical volume (SV) trajectories in 95 typically developing adolescents (12-19 years old at study baseline). Self-reported scores of AX and AV were obtained at study baseline, and neurostructural development was assessed at baseline and three timepoints over the four following years. Self-reported AX and AV were associated with steeper CT decreases in prefrontal cortical and cortical midline structures as well as anterior temporal cortex, particularly in participants younger at study baseline. Regarding SV, preliminary differential associations were observed between developmental trajectories and attachment dimensions. Our study suggests that interindividual differences in attachment contribute to shaping neurodevelopmental trajectories for several cortical and subcortical structures during adolescence and young adulthood.

Deactivating attachment strategies associate with early processing of facial emotion and familiarity in middle childhood: an ERP study.

Neurophysiological evidence suggests associations between attachment and the neural processing of emotion expressions. This study asks whether this relationship is also evident in middle childhood, and how it is affected by facial familiarity. Attachment strategies (deactivation, hyperactivation) were assessed in 51 children (9 - 11 years) using a story stem completion task. Event-related potentials (ERPs) were recorded during children's passive viewing of mother and stranger emotional faces (angry/happy). At the stage of facial information encoding (N250), attachment deactivation was associated with a pattern pointing to increased vigilance towards angry faces. Further, the attention-driven LPP was increased to happy mother faces as highly salient stimuli overall, but not in children scoring high on deactivation. These children did not discriminate between mothers' facial emotions and showed a general attentional withdrawal from facial stimuli. While our results on attachment deactivation support a two-stage processing model, no effect of hyperactivation was found.

Association between attachment anxiety and the gaze direction-related N170.

Attachment theory suggests that interindividual differences in attachment security versus insecurity (anxiety and avoidance) contribute to the ways in which people perceive social emotional signals, particularly from the human face. Among different facial features, eye gaze conveys crucial information for social interaction, with a straight gaze triggering different cognitive and emotional processes as compared to an averted gaze. It remains unknown, however, how interindividual differences in attachment associate with early face encoding in the context of a straight versus averted gaze. Using electroencephalography (EEG) and recording event-related potentials (ERPs), specifically the N170 component, the present study (N = 50 healthy adults) measured how the characteristics of attachment anxiety and avoidance relate to the encoding of faces with respect to gaze direction and head orientation. Our findings reveal a significant relationship between gaze direction (irrespective of head orientation) and attachment anxiety on the interhemispheric (i.e. right) asymmetry of the N170 and thus provide evidence for an association between attachment anxiety and eye gaze processing during early visual face encoding.

Plasma oxytocin is modulated by mental training, but does not mediate its stress-buffering effect.

Based on its role in social processing and stress, oxytocin has been suggested to mediate stress reduction of socio-affective, compassion-based mental training. We tested this hypothesis in the ReSource Project, a 9-month longitudinal mental training study. Participants practiced three different types of mental training, targeting either attentional abilities (Presence Module), socio-affective or socio-cognitive abilities (Affect and Perspective Modules). We investigated plasma oxytocin levels, and their link to cortisol and subjective reactivity to acute psychosocial stress as a function of previous mental training (n = 313). In a subsample (n = 113), to better understand oxytocin's involvement in the effects of socio-affective training, we explored oxytocin, cortisol and subjective experiential responses to a single Loving-kindness Meditation (LKM) conducted after three months of Affect training (versus rest without prior training). We found that, independent of mental training, stress triggered acute oxytocin release. Following a single LKM, however, acute oxytocin release was unaffected. Training effects were only found in overall oxytocin release during both, stress and LKM. Compared to no training, 3-month compassion-based Affect training decreased overall oxytocin levels in the context of psychosocial stress, but increased overall oxytocin levels during LKM. Training-induced changes in overall oxytocin were unrelated to cortisol and subjective stress reactivity. Based on Quintana and Guastella's (2020) theory of oxytocin as an allostatic hormone with anticipatory properties, we interpret training-induced changes in overall oxytocin levels as alterations in the anticipated emotional relevance of specific events. After training socio-affective skills for three months, the stressful situation may have lost its emotional saliency, whereas the meditation technique itself gained emotional relevance. We conclude that changes in peripheral oxytocin release do not mediate stress reduction after mental training, and encourage the investigation of an allostatic concept of oxytocin in future research.

Emotional maltreatment and neglect impact neural activation upon exclusion in early and mid-adolescence: An event-related fMRI study.

Child maltreatment gives rise to atypical patterns of social functioning with peers which might be particularly pronounced in early adolescence when peer influence typically peaks. Yet, few neuroimaging studies in adolescents use peer interaction paradigms to parse neural correlates of distinct maltreatment exposures. This fMRI study examines effects of abuse, neglect, and emotional maltreatment (EM) among 98 youth (n = 58 maltreated; n = 40 matched controls) using an event-related Cyberball paradigm affording assessment of both social exclusion and inclusion across early and mid-adolescence (≤13.5 years, n = 50; >13.5 years, n = 48). Younger adolescents showed increased activation to social exclusion versus inclusion in regions implicated in mentalizing (e.g., superior temporal gyrus). Individual exposure-specific analyses suggested that neglect and EM coincided with less reduction of activation to social exclusion relative to inclusion in the dorsal anterior cingulate cortex/pre-supplementary motor area (dACC/pre-SMA) among younger versus older adolescents. Integrative follow-up analyses showed that EM accounted for this dACC/pre-SMA activation pattern over and above other exposures. Moreover, age-independent results within respective exposure groups revealed that greater magnitude of neglect predicted blunted exclusion-related activity in the parahippocampal gyrus, while EM predicted increased activation to social exclusion in the precuneus/posterior cingulate cortex.

Contemplative Mental Training Reduces Hair Glucocorticoid Levels in a Randomized Clinical Trial.

OBJECTIVE: This study aimed to investigate the effect of regular contemplative mental training on endocrine and psychological indices of long-term stress. METHODS: An open-label efficacy trial that comprised three distinct 3-month long modules targeting attention and interoception, socioaffective, or sociocognitive abilities through dyadic exercises and secularized meditation practices was conducted with healthy adults. Participants underwent the training for 3 or 9 months, or were assigned to a retest control cohort. Chronic stress indices were assayed at four time points: pretraining and after 3, 6, and 9 months. The main outcome measures were cortisol (HC) and cortisone (HE) concentration in hair and self-reported long-term stress. RESULTS: Of 362 initially randomized individuals, 30 dropped out before study initiation (n = 332; mean [SD] age = 40.7 [9.2] years; 197 women). Hair-based glucocorticoid assays were available from n = 227, and questionnaire data from n = 326. Results from three separate training cohorts (TC1-3) revealed consistent decreases in HC and HE levels over the first three (TC3) to 6 months (TC1 and TC2) of training, with no further reduction at the final 9-month mark (baseline to end of training differences, HC, TC1: t(355) = 2.59, p = .010, contrast estimate (est.) [SE] = 0.35 [0.14]; HC, TC2: t(363) = 4.06, p < .001, est. = 0.48 [0.12]; HC, TC3: t(368) = 3.18, p = .002, est. = 0.41 [0.13]; HE, TC1: t(435) = 3.23, p = .001, est. = 0.45 [0.14]; HE, TC2: t(442) = 2.60, p = .010, est. = 0.33 [0.13]; HE, TC3: t(446) = 4.18, p < .001, est. = 0.57 [0.14]). Training effects on HC increased with individual compliance (practice frequency), and effects on both HC and HE were independent of training content and unrelated to change in self-reported chronic stress. Self-reported stress, and cortisol-to-dehydroepiandrosterone ratios as an exploratory endpoint, were also reduced, albeit less consistently. CONCLUSIONS: Our results point to the reduction of long-term cortisol exposure as a mechanism through which meditation-based mental training may exert positive effects on practitioners' health.Trial Registration: ClinicalTrials.gov identifier: NCT01833104.

A Guide to Parent-Child fNIRS Hyperscanning Data Processing and Analysis.

The use of functional near-infrared spectroscopy (fNIRS) hyperscanning during naturalistic interactions in parent-child dyads has substantially advanced our understanding of the neurobiological underpinnings of human social interaction. However, despite the rise of developmental hyperscanning studies over the last years, analysis procedures have not yet been standardized and are often individually developed by each research team. This article offers a guide on parent-child fNIRS hyperscanning data analysis in MATLAB and R. We provide an example dataset of 20 dyads assessed during a cooperative versus individual problem-solving task, with brain signal acquired using 16 channels located over bilateral frontal and temporo-parietal areas. We use MATLAB toolboxes Homer2 and SPM for fNIRS to preprocess the acquired brain signal data and suggest a standardized procedure. Next, we calculate interpersonal neural synchrony between dyads using Wavelet Transform Coherence (WTC) and illustrate how to run a random pair analysis to control for spurious correlations in the signal. We then use RStudio to estimate Generalized Linear Mixed Models (GLMM) to account for the bounded distribution of coherence values for interpersonal neural synchrony analyses. With this guide, we hope to offer advice for future parent-child fNIRS hyperscanning investigations and to enhance replicability within the field.

Interpersonal Neural Synchrony During Father-Child Problem Solving: An fNIRS Hyperscanning Study.

Interpersonal neural synchrony (INS) has been previously evidenced in mother-child interactions, yet findings concerning father-child interaction are wanting. The current experiment examined whether fathers and their 5- to 6-year-old children (N = 66) synchronize their brain activity during a naturalistic interaction, and addressed paternal and child factors related to INS. Compared to individual problem solving and rest, father-child dyads showed increased INS in bilateral dorsolateral prefrontal cortex and left temporo-parietal junction during cooperative problem solving. Furthermore, the father's attitude toward his role as a parent was positively related to INS during the cooperation condition. These results highlight the implication of the father's attitude to parenting in INS processes for the first time.

Exclusion Expected? Cardiac Slowing Upon Peer Exclusion Links Preschool Parent Representations to School-Age Peer Relationships.

Attachment theory proposes that children's representations of interactions with caregivers guide information-processing about others, bridging interpersonal domains. In a longitudinal study (N = 165), preschoolers (Mage  = 5.19 years) completed the MacArthur Story Stem Battery to assess parent representations. At school-age (Mage  = 8.42 years), children played a virtual ballgame with peers who eventually excluded them to track event-related cardiac slowing, a physiological correlate of rejection, especially when unexpected. At both ages, parents and teachers reported on peer and emotional problems. During exclusion versus inclusion-related events, cardiac slowing was associated with greater positive parent representations and fewer emerging peer problems. Cardiac slowing served as a mediator between positive parent representations and peer problems, supporting a potential psychophysiological mechanism underlying the generalization of attachment-related representations to peer relationships.

Neural synchrony in mother-child conversation: Exploring the role of conversation patterns.

Conversations are an essential form of communication in daily family life. Specific patterns of caregiver-child conversations have been linked to children's socio-cognitive development and child-relationship quality beyond the immediate family environment. Recently, interpersonal neural synchronization has been proposed as a neural mechanism supporting conversation. Here, we present a functional near-infrared spectroscopy (fNIRS) hyperscanning study looking at the temporal dynamics of neural synchrony during mother-child conversation. Preschoolers (20 boys and 20 girls, M age 5;07 years) and their mothers (M age 36.37 years) were tested simultaneously with fNIRS hyperscanning while engaging in a free verbal conversation lasting for 4 min. Neural synchrony (using wavelet transform coherence analysis) was assessed over time. Furthermore, each conversational turn was coded for conversation patterns comprising turn-taking, relevance, contingency and intrusiveness. Results from linear mixed-effects modeling revealed that turn-taking, but not relevance, contingency or intrusiveness predicted neural synchronization during the conversation over time. Results are discussed to point out possible variables affecting parent-child conversation quality and the potential functional role of interpersonal neural synchronization for parent-child conversation.

Neural bases of social feedback processing and self-other distinction in late childhood: The role of attachment and age.

Attachment plays a key role in how children process information about the self and others. Here, we examined the neural bases of interindividual differences in attachment in late childhood and tested whether social cognition-related neural activity varies as function of age. In a small sample of 8-year-old to 12-year-old children (n = 21/19), we used functional magnetic resonance imaging to measure neural responses during social feedback processing and self-other distinction. Attachment was assessed using child self-report. The social feedback processing task presented smiling and angry faces either confirming or disconfirming written information about participant performance on a perceptual game. In addition to observing main effects of facial emotion and performance, an increase in age was related to a shift from negative (i.e., angry faces/bad performance) to positive (i.e., smiling faces/good performance) information processing in the left amygdala/hippocampus, bilateral fusiform face area, bilateral anterior temporal pole (ATP), and left anterior insula. There were no effects of attachment on social feedback processing. The self-other distinction task presented digital morphs between children's own faces and faces of their mother or stranger females. We observed differential activation in face processing and mentalizing regions in response to self and mother faces versus morphed faces. Furthermore, left ATP activity was associated with attachment anxiety such that greater attachment anxiety was related to a shift from heightened processing of self and mother faces to morphed faces. There were no effects of age on self-other distinction. We discuss our preliminary findings in the context of attachment theory and previous work on social evaluation and self-other processing.

A functional neuro-anatomical model of human attachment (NAMA): Insights from first- and second-person social neuroscience.

Attachment theory, developed by Mary Ainsworth and John Bowlby about seventy years ago, has become one of the most influential and comprehensive contemporary psychology theories. It predicts that early social interactions with significant others shape the emergence of distinct self- and other-representations, the latter affecting how we initiate and maintain social relationships across the lifespan. A person's attachment history will therefore associate with inter-individual differences in emotional and cognitive mechanisms sustaining representations, modeling, and understanding of others on the biological and brain level. This review aims at summarizing the currently available social neuroscience data in healthy participants on how inter-individual differences in attachment associate with brain anatomy and activity across the lifespan, and to integrate these data into an extended and refined functional neuro-anatomical model of human attachment (NAMA). We first propose a new prototypical initial attachment pathway and its derivatives as a function of attachment security, avoidance, and anxiety. Based on these pathways, we suggest a neural attachment system composed of two emotional mentalization modules (aversion and approach) and two cognitive mentalization modules (emotion regulation and mental state representation) and provide evidence on their functionality depending on inter-individual differences in attachment. We subsequently expand this first-person social neuroscience account by also considering a second-person social neuroscience perspective comprising the concepts of bio-behavioral synchrony and particularly inter-brain coherence. We hope that such extended and refined NAMA can inform attachment theory and ultimately help devising new prevention and intervention strategies for individuals and families at risk for attachment-related psychopathology.

The effects of interaction quality on neural synchrony during mother-child problem solving.

Understanding others is fundamental to interpersonal coordination and successful cooperation. One mechanism posited to underlie both effective communication and behavioral coordination is interpersonal neural synchrony. Although presumably foundational for children's social development, research on neural synchrony in naturalistic caregiver-child interactions is lacking. Using dual-functional near-infrared spectroscopy (fNIRS), we examined the effects of interaction quality on neural synchrony during a problem-solving task in 42 dyads of mothers and their preschool children. In a cooperation condition, mothers and children were instructed to solve a tangram puzzle together. In an individual condition, mothers and children performed the same task alone with an opaque screen between them. Wavelet transform coherence (WTC) was used to assess the cross-correlation between the two fNIRS time series. Results revealed increased neural synchrony in bilateral prefrontal cortex and temporo-parietal areas during cooperative as compared to individual problem solving. Higher neural synchrony during cooperation correlated with higher behavioral reciprocity and neural synchrony predicted the dyad's problem-solving success beyond reciprocal behavior between mothers and children. State-like factors, such as maternal stress and child agency during the task, played a bigger role for neural synchronization than trait-like factors, such as child temperament. Our results emphasize neural synchrony as a biomarker for mother-child interaction quality. These findings further highlight the role of state-like factors in interpersonal synchronization processes linked to successful coordination with others and in the long-term might improve the understanding of others.

Conceptual Analysis: A Social Neuroscience Approach to Interpersonal Interaction in the Context of Disruption and Disorganization of Attachment (NAMDA).

Humans are strongly dependent upon social resources for allostasis and emotion regulation. This applies especially to early childhood because humans-as an altricial species-have a prolonged period of dependency on support and input from caregivers who typically act as sources of co-regulation. Accordingly, attachment theory proposes that the history and quality of early interactions with primary caregivers shape children's internal working models of attachment. In turn, these attachment models guide behavior, initially with the set goal of maintaining proximity to caregivers but eventually paving the way to more generalized mental representations of self and others. Mounting evidence in non-clinical populations suggests that these mental representations coincide with differential patterns of neural structure, function, and connectivity in a range of brain regions previously associated with emotional and cognitive capacities. What is currently lacking, however, is an evidence-based account of how early adverse attachment-related experiences and/or the emergence of attachment disorganization impact the developing brain. While work on early childhood adversities offers important insights, we propose that how these events become biologically embedded crucially hinges on the context of the child-caregiver attachment relationships in which the events take place. Our selective review distinguishes between direct social neuroscience research on disorganized attachment and indirect maltreatment-related research, converging on aberrant functioning in neurobiological systems subserving aversion, approach, emotion regulation, and mental state processing in the wake of severe attachment disruption. To account for heterogeneity of findings, we propose two distinct neurobiological phenotypes characterized by hyper- and hypo-arousal primarily deriving from the caregiver serving either as a threatening or as an insufficient source of co-regulation, respectively.

Only vulnerable adults show change in chronic low-grade inflammation after contemplative mental training: evidence from a randomized clinical trial.

Growing evidence suggests that chronic low-grade inflammation can be reduced through mindfulness-based mental training interventions. However, these results are inconsistent and based on patient populations with heterogeneous conditions. Similar research in healthy adults is lacking. Moreover, common intervention protocols involve varying combinations of different contemplative practices, such that it remains unclear which types of training most effectively influence biomarkers of inflammation. The present study investigated the effect of three distinct 3-month training modules cultivating a) interoception and present-moment focus (Presence), b) socio-affective skills (Affect), or c) socio-cognitive skills (Perspective) on the inflammatory biomarkers interleukin-6 (IL-6) and high sensitive C-reactive protein (hs-CRP) in 298 healthy adults. We observed no group-level effect of training on either biomarker, but trend-level interactions of training type and participant sex. In additionally exploring the influence of participants' baseline inflammation, a selective training effect emerged: Following the Presence module, participants with relatively higher inflammatory load showed stronger reduction in IL-6 on average, and in hs-CRP if they were male. Mindfulness- and attention-based mental practice thus appears most effective when targeting chronic low-grade inflammation in healthy adults, particularly in men. Overall, our data point to a floor effect in the reduction of inflammatory markers through contemplative mental training, suggesting that mental training may be less effective in improving basal biological health outcomes in healthy, low-stressed adults than in vulnerable populations.

Association of Short-term Change in Leukocyte Telomere Length With Cortical Thickness and Outcomes of Mental Training Among Healthy Adults: A Randomized Clinical Trial.

Importance: Telomere length is associated with the development of age-related diseases and structural differences in multiple brain regions. It remains unclear, however, whether change in telomere length is linked to brain structure change, and to what extent telomere length can be influenced through mental training. Objectives: To assess the dynamic associations between leukocyte telomere length (LTL) and cortical thickness (CT), and to determine whether LTL is affected by a longitudinal contemplative mental training intervention. Design, Setting, and Participants: An open-label efficacy trial of three 3-month mental training modules with healthy, meditation-naive adults was conducted. Data on LTL and CT were collected 4 times over 9 months between April 22, 2013, and March 31, 2015, as part of the ReSource Project. Data analysis was performed between September 23, 2016, and June 21, 2019. Of 1582 eligible individuals, 943 declined to participate; 362 were randomly selected for participation and assigned to training or retest control cohorts, with demographic characteristics matched. The retest control cohorts underwent all testing but no training. Intention-to-treat analysis was performed. Interventions: Training cohort participants completed 3 modules cultivating interoception and attention (Presence), compassion (Affect), or perspective taking (Perspective). Main Outcomes and Measures: Change in LTL and CT. Results: Of the 362 individuals randomized, 30 participants dropped out before study initiation (initial sample, 332). Data were available for analysis of the training intervention in 298 participants (n = 222 training; n = 76 retest control) (175 women [58.7%]; mean [SD] age, 40.5 [9.3] years). The training modules had no effect on LTL. In 699 observations from all 298 participants, mean estimated changes in the relative ratios of telomere repeat copy number to single-copy gene (T/S) were for no training, 0.004 (95% CI, -0.010 to 0.018); Presence, -0.007 (95% CI, -0.025 to 0.011); Affect, -0.005 (95% CI, -0.019 to 0.010); and Perspective, -0.001 (95% CI, -0.017 to 0.016). Cortical thickness change data were analyzed in 167 observations from 67 retest control participants (37 women [55.2%], mean [SD] age, 39.6 [9.0] years). In this retest control cohort subsample, naturally occurring LTL change was related to CT change in the left precuneus extending to the posterior cingulate cortex (mean t161 = 3.22; P < .001; r = 0.246). At the individual participant level, leukocyte telomere shortening as well as lengthening were observed. Leukocyte telomere shortening was related to cortical thinning (t77 = 2.38; P = .01; r = 0.262), and leukocyte telomere lengthening was related to cortical thickening (t77 = 2.42; P = .009; r = 0.266). All analyses controlled for age, sex, and body mass index. Conclusions and Relevance: The findings of this trial indicate an association between short-term change in LTL and concomitant change in plasticity of the left precuneus extending to the posterior cingulate cortex. This result contributes to the evidence that LTL changes more dynamically on the individual level than previously thought. Further studies are needed to determine potential long-term implications of such change in relation to cellular aging and the development of neurodegenerative disorders. No effect of contemplative mental training was noted in what may be, to date, the longest intervention with healthy adults. Trial Registration: ClinicalTrials.gov identifier: NCT01833104.