Annual Research Review: The power of predictability - patterns of signals in early life shape neurodevelopment and mental health trajectories.

The global burden of early life adversity (ELA) is profound. The World Health Organization has estimated that ELA accounts for almost 30% of all psychiatric cases. Yet, our ability to identify which individuals exposed to ELA will develop mental illness remains poor and there is a critical need to identify underlying pathways and mechanisms. This review proposes unpredictability as an understudied aspect of ELA that is tractable and presents a conceptual model that includes biologically plausible mechanistic pathways by which unpredictability impacts the developing brain. The model is supported by a synthesis of published and new data illustrating the significant impacts of patterns of signals on child development. We begin with an overview of the existing unpredictability literature, which has focused primarily on longer patterns of unpredictability (e.g. years, months, and days). We then describe our work testing the impact of patterns of parental signals on a moment-to-moment timescale, providing evidence that patterns of these signals during sensitive windows of development influence neurocircuit formation across species and thus may be an evolutionarily conserved process that shapes the developing brain. Next, attention is drawn to emerging themes which provide a framework for future directions of research including the evaluation of functions, such as effortful control, that may be particularly vulnerable to unpredictability, sensitive periods, sex differences, cross-cultural investigations, addressing causality, and unpredictability as a pathway by which other forms of ELA impact development. Finally, we provide suggestions for prevention and intervention, including the introduction of a screening instrument for the identification of children exposed to unpredictable experiences.

DHEA: a neglected biological signal that may affect fetal and child development.

BACKGROUND: The stress-sensitive maternal hypothalamic-pituitary-adrenal (HPA) axis through the end-product cortisol, represents a primary pathway through which maternal experience shapes fetal development with long-term consequences for child neurodevelopment. However, there is another HPA axis end-product that has been widely ignored in the study of human pregnancy. The synthesis and release of dehydroepiandosterone (DHEA) is similar to cortisol, so it is a plausible, but neglected, biological signal that may influence fetal neurodevelopment. DHEA also may interact with cortisol to determine developmental outcomes. Surprisingly, there is virtually nothing known about human fetal exposure to prenatal maternal DHEA and offspring neurodevelopment. The current study examined, for the first time, the joint impact of fetal exposure to prenatal maternal DHEA and cortisol on infant emotional reactivity. METHODS: Participants were 124 mother-infant dyads. DHEA and cortisol were measured from maternal hair at 15 weeks (early gestation) and 35 weeks (late gestation). Observational assessments of positive and negative emotional reactivity were obtained in the laboratory when the infants were 6 months old. Pearson correlations were used to examine the associations between prenatal maternal cortisol, prenatal maternal DHEA, and infant positive and negative emotional reactivity. Moderation analyses were conducted to investigate whether DHEA might modify the association between cortisol and emotional reactivity. RESULTS: Higher levels of both early and late gestation maternal DHEA were linked to greater infant positive emotional reactivity. Elevated late gestation maternal cortisol was associated with greater negative emotional reactivity. Finally, the association between fetal cortisol exposure and infant emotional reactivity was only observed when DHEA was low. CONCLUSIONS: These new observations indicate that DHEA is a potential maternal biological signal involved in prenatal programming. It appears to act both independently and jointly with cortisol to determine a child's emotional reactivity. Its role as a primary end-product of the HPA axis, coupled with the newly documented associations with prenatal development shown here, strongly calls for the inclusion of DHEA in future investigations of fetal programming.

The future of intergenerational transmission research: A prospective, three-generation approach.

Dr. Dante Cicchetti's pioneering theory and research on developmental psychopathology have been fundamental to the proliferation of research on intergenerational transmission over the last 40 years. In part due to this foundation, much has been learned about continuities and discontinuities in child maltreatment, attachment, parenting, and psychopathology across generations. Looking towards the future, we propose that this field stands to benefit from a prospective, three-generation approach. Specifically, following established prospective, longitudinal cohorts of children over their transition to parenting the next generation will afford the opportunity to investigate the developmental origins of intergenerational transmission. This approach also can address key outstanding questions and methodological limitations in the extant literature related to the confounding of retrospective and prospective measures; examination of mediators and moderators; and investigation of the roles of biology, environment, and their interplay. After considering these advantages, we offer several considerations and recommendations for future research, many of which are broadly applicable to the study of two or more generations. We hope that this discussion will inspire the leveraging of existing prospective cohorts to carry forward Dr. Cicchetti's remarkable contributions, with the ultimate aim to inform the development of preventions and interventions that disrupt deleterious intergenerational cycles.

Temporal relation between pubertal development and peer victimization in a prospective sample of US adolescents.

Peer victimization typically peaks in early adolescence, leading researchers to hypothesize that pubertal timing is a meaningful predictor of peer victimization. However, previous methodological approaches have limited our ability to parse out which puberty cues are associated with peer victimization because gonadal and adrenal puberty, two independent processes, have either been conflated or adrenal puberty timing has been ignored. In addition, previous research has overlooked the possibility of reverse causality-that peer victimization might drive pubertal timing, as it has been shown to do in non-human primates. To fill these gaps, we followed 265 adolescents (47% female) prospectively across three-time points (Mage : T1 = 9.6, T2 = 12.0, T3 = 14.4) and measured self-report peer victimization and self- and maternal-report of gonadal and adrenal pubertal development on the Pubertal Development Scale. Multilevel modeling revealed that females who were further along in adrenal puberty at age 9 were more likely to report peer victimization at age 12 (Cohen's d = 0.25, p = .005). The relation between gonadal puberty status and peer victimization was not significant for either sex. In terms of the reverse direction, the relation between early peer victimization and later pubertal development was not significant in either sex. Overall, our findings suggest that adrenal puberty status, but not gonadal puberty status, predicted peer victimization in females, highlighting the need to separate gonadal and adrenal pubertal processes in future studies.

The role of positive affect in asthma control and symptom severity in adolescents.

INTRODUCTION: We test the effects of positive affect and its arousal subscale components of calm, wellbeing, and vigor on asthma control and symptom severity in adolescents with moderate to severe asthma. Additionally, we test whether positive affect (and its arousal components) moderate how stress impacts asthma control and symptom severity. METHODS: Adolescents with asthma (N = 66, ages 12-17) completed brief surveys 4 times a day for 7 days reporting on their positive affect, stress, and asthma symptom severity and conducted a morning peak expiratory flow assessment each day. Asthma control and psychological asthma triggers were assessed at the end of the 7 days. RESULTS: Positive affect moderated the association between stress and asthma control (b = -0.33, p = 0.009) as well as the association between psychological triggers and asthma control (b = -0.74, p = 0.007). When assessing the positive affect arousal components, calm and wellbeing seemed to be driving these effects. Additionally, calm moderated the association between stress and asthma symptom severity (b = -0.33, p = 0.036) as well as the association between psychological triggers and asthma symptom severity (b = -0.75, p = 0.021). CONCLUSIONS: When considering patient stress (e.g., general stress, psychological asthma triggers), positive affect and its arousal components of calm and wellbeing may be helpful for patients with higher levels of stress and/or for patients experiencing greater numbers of psychological triggers.

Identifying the neural correlates of anticipatory postural control: A novel fMRI paradigm.

Altered postural control in the trunk/hip musculature is a characteristic of multiple neurological and musculoskeletal conditions. Previously it was not possible to determine if altered cortical and subcortical sensorimotor brain activation underlies impairments in postural control. This study used a novel fMRI-compatible paradigm to identify the brain activation associated with postural control in the trunk and hip musculature. BOLD fMRI imaging was conducted as participants performed two versions of a lower limb task involving lifting the left leg to touch the foot to a target. For the supported leg raise (SLR) the leg is raised from the knee while the thigh remains supported. For the unsupported leg raise (ULR) the leg is raised from the hip, requiring postural muscle activation in the abdominal/hip extensor musculature. Significant brain activation during the SLR task occurred predominantly in the right primary and secondary sensorimotor cortical regions. Brain activation during the ULR task occurred bilaterally in the primary and secondary sensorimotor cortical regions, as well as cerebellum and putamen. In comparison with the SLR, the ULR was associated with significantly greater activation in the right premotor/SMA, left primary motor and cingulate cortices, primary somatosensory cortex, supramarginal gyrus/parietal operculum, superior parietal lobule, cerebellar vermis, and cerebellar hemispheres. Cortical and subcortical regions activated during the ULR, but not during the SLR, were consistent with the planning, and execution of a task involving multisegmental, bilateral postural control. Future studies using this paradigm will determine mechanisms underlying impaired postural control in patients with neurological and musculoskeletal dysfunction.

Intergenerational risk and resilience pathways from discrimination and acculturative stress to infant mental health.

Preconception and prenatal stress impact fetal and infant development, and women of color are disproportionately exposed to sociocultural stressors like discrimination and acculturative stress. However, few studies examine links between mothers' exposure to these stressors and offspring mental health, or possible mitigating factors. Using linear regression, we tested associations between prenatally assessed maternal acculturative stress and discrimination on infant negative emotionality among 113 Latinx/Hispanic, Asian American, Black, and Multiethnic mothers and their children. Additionally, we tested interactions between stressors and potential pre- and postnatal resilience-promoting factors: community cohesion, social support, communalism, and parenting self-efficacy. Discrimination and acculturative stress were related to more infant negative emotionality at approximately 12 months old (M = 12.6, SD = .75). In contrast, maternal report of parenting self-efficacy when infants were 6 months old was related to lower levels of infant negative emotionality. Further, higher levels of parenting self-efficacy mitigated the relation between acculturative stress and negative emotionality. Preconception and prenatal exposure to sociocultural stress may be a risk factor for poor offspring mental health. Maternal and child health researchers, policymakers, and practitioners should prioritize further understanding these relations, reducing exposure to sociocultural stressors, and promoting resilience.

One size doesn't fit all: Attitudes towards work modify the relation between parental leave length and postpartum depression.

The present study aimed to investigate the relationship between parental leave length and maternal depressive symptoms at six- and twelve-months postpartum and whether this relation was influenced by women's attitudes towards leave, whether leave was paid or unpaid, and the reason they returned to work. The sample included 115 working women recruited during pregnancy as part of a larger longitudinal study. Analyses revealed that maternal attitudes toward leave influenced the association between leave length and depressive symptoms. Specifically, longer leaves were associated with increased depressive symptoms for women who missed their previous activities at work. Furthermore, women who missed work and had leave for 16 weeks or more, exhibited higher depressive symptoms at six- and twelve-months. Last, results also indicated that women who returned to work solely for monetary reasons exhibited more depressive symptoms at six-months postpartum than those who returned to work for other reasons. This study is among the first to show that women's attitudes towards parental leave and their individual reasons for returning to work are important factors to consider that may have potential implications for parental leave policies.

Discrimination and adverse birth outcomes among Latina women: The protective role of social support.

OBJECTIVE: Interpersonal discrimination has been associated with adverse birth outcomes among Black populations, but few studies have examined the impact of discrimination among Latinx/Hispanic populations in the United States, especially in conjunction with resources that could be protective. The present study examined (a) if exposure to discrimination is associated with adverse birth outcomes for Latina/Hispanic women and (b) if prenatal social support buffers these links. METHOD: In two independent prospective studies of Latina/Hispanic women in Southern California (N = 84 and N = 102), the relation between maternal experience of discrimination and birth outcomes (length of gestation and birth weight) was examined. Additionally, social support was tested as a moderator of these relations. RESULTS: In both Studies 1 and 2, exposures to discrimination predicted adverse birth outcomes. Specifically, lifetime experiences of major discrimination predicted lower birth weight. Additionally, in Study 2, chronic experiences of everyday discrimination were linked to lower birth weight. In Study 1, major discrimination also predicted shorter gestational length. Importantly, in both studies, the presence of prenatal social support buffered associations between discrimination and poorer birth outcomes. CONCLUSIONS: Findings implicate discrimination as an important risk factor for adverse birth outcomes among women of Latina/Hispanic descent. Further policies, practice, and research on reducing discrimination and enhancing factors that promote resilience such as social support are needed to facilitate healthy births among Latina/Hispanic women, mitigate intergenerational harm of discrimination-related stress, and advance health equity at birth and across the lifespan. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Patterns of Maternal Distress from Pregnancy Through Childhood Predict Psychopathology During Early Adolescence.

Capitalizing on a longitudinal cohort followed from gestation through adolescence (201 mother-child dyads), we investigate the contributions of severity and stability of both maternal depressive and perceived stress symptoms to adolescent psychopathology. Maternal depressive and perceived stress trajectories from pregnancy through adolescence were identified with latent class growth analyses, and associations with adolescent internalizing and externalizing symptoms were examined. For both depression and stress, the most common trajectory group comprised mothers displaying stable and low symptom levels over time, and adolescents of these mothers had the fewest internalizing and externalizing symptoms. Maternal membership to one or more aberrant trajectory groups predicted higher levels of internalizing and externalizing symptoms, determined by both maternal and adolescent self-report. This study indicates that profiles of multiple indicators of maternal psychopathology assessed across childhood, beginning prenatally, can provide critical additional insight into child psychopathology risk.

Aberrant Maturation of the Uncinate Fasciculus Follows Exposure to Unpredictable Patterns of Maternal Signals.

Across species, unpredictable patterns of maternal behavior are emerging as novel predictors of aberrant cognitive and emotional outcomes later in life. In animal models, exposure to unpredictable patterns of maternal behavior alters brain circuit maturation and cognitive and emotional outcomes. However, whether exposure to such signals in humans alters the development of brain pathways is unknown. In mother-child dyads, we tested the hypothesis that exposure to more unpredictable maternal signals in infancy is associated with aberrant maturation of corticolimbic pathways. We focused on the uncinate fasciculus, the primary fiber bundle connecting the amygdala to the orbitofrontal cortex and a key component of the medial temporal lobe-prefrontal cortex circuit. Infant exposure to unpredictable maternal sensory signals was assessed at 6 and 12 months. Using high angular resolution diffusion imaging, we quantified the integrity of the uncinate fasciculus using generalized fractional anisotropy (GFA). Higher maternal unpredictability during infancy presaged greater uncinate fasciculus GFA in children 9-11 years of age (n = 69, 29 female). In contrast to the uncinate, GFA of a second corticolimbic projection, the hippocampal cingulum, was not associated with maternal unpredictability. Addressing the overall functional significance of the uncinate and cingulum relationships, we found that the resulting imbalance of medial temporal lobe-prefrontal cortex connectivity partially mediated the association between unpredictable maternal sensory signals and impaired episodic memory function. These results suggest that unbalanced maturation of corticolimbic circuits is a mechanism by which early unpredictable sensory signals may impact cognition later in life.SIGNIFICANCE STATEMENT Our prior work across species demonstrated that unpredictable patterns of maternal care are associated with compromised memory function. However, the neurobiological mechanisms by which this occurs in humans remain unknown. Here, we identify an association of exposure to unpredictable patterns of maternal sensory signals with the integrity of corticolimbic circuits involved in emotion and cognition using state-of-the-art diffusion imaging techniques and analyses. We find that exposure to early unpredictability is associated with higher integrity of the uncinate fasciculus with no effect on a second corticolimbic pathway, the cingulum. The resulting imbalance of corticolimbic circuit development is a novel mediator of the association between unpredictable patterns of maternal care and poorer episodic memory.

Contribution of early-life unpredictability to neuropsychiatric symptom patterns in adulthood.

BACKGROUND: Recent studies in both human and experimental animals have identified fragmented and unpredictable parental and environmental signals as a novel source of early-life adversity. Early-life unpredictability may be a fundamental developmental factor that impacts brain development, including reward and emotional memory circuits, affecting the risk for psychopathology later in life. Here, we tested the hypothesis that self-reported early-life unpredictability is associated with psychiatric symptoms in adult clinical populations. METHODS: Using the newly validated Questionnaire of Unpredictability in Childhood, we assessed early-life unpredictability in 156 trauma-exposed adults, of which 65% sought treatment for mood, anxiety, and/or posttraumatic stress disorder (PTSD) symptoms. All participants completed symptom measures of PTSD, depression and anhedonia, anxiety, alcohol use, and chronic pain. Relative contributions of early-life unpredictability versus childhood trauma and associations with longitudinal outcomes over a 6-month period were determined. RESULTS: Early-life unpredictability, independent of childhood trauma, was significantly associated with higher depression, anxiety symptoms, and anhedonia, and was related to higher overall symptom ratings across time. Early-life unpredictability was also associated with suicidal ideation, but not alcohol use or pain symptoms. CONCLUSIONS: Early-life unpredictability is an independent and consistent predictor of specific adult psychiatric symptoms, providing impetus for studying mechanisms of its effects on the developing brain that promote risk for psychopathology.

Maternal caregiving ameliorates the consequences of prenatal maternal psychological distress on child development.

Children exposed to prenatal maternal psychological distress are at elevated risk for a range of adverse outcomes; however, it remains poorly understood whether postnatal influences can ameliorate impairments related to prenatal distress. The current study evaluated if sensitivematernal care during the first postnatal year could mitigate child cognitive and emotional impairments associated with prenatal psychological distress. Prenatal maternal psychological distress was assessed via self-reports of anxiety, depression, and perceived stress for 136 mothers at five prenatal and four postpartum time points. Quality of maternal care (sensitivity to nondistress, positive regard, and intrusiveness reverse-scored) were assessed during a mother-child play interaction at 6 and 12 months. Child cognitive function and negative emotionality were assessed at 2 years, using The Bayley Scales and the Early Childhood Behavior Questionnaire. Elevated prenatal distress was associated with poorer child cognitive function and elevated negative emotionality. Children exposed to elevated prenatal maternal distress did not, however, display these outcomes if they received high-quality caregiving. Specifically, maternal care moderated the relation between prenatal psychological distress and child cognitive function and negative emotionality. This association remained after consideration of postnatal maternal psychological distress and relevant covariates. Sensitive maternal care was associated with altered offspring developmental trajectories, supporting child resilience following prenatal distress exposure.

Maternal Depressive Symptoms Predict General Liability in Child Psychopathology.

Objective: The current study examines how maternal depressive symptoms relate to child psychopathology when structured via the latent bifactor model of psychopathology, a new organizational structure of psychopathological symptoms consisting of a general common psychopathology factor (p-factor) and internalizing- and externalizing-specific risk.Method: Maternal report of depressive symptoms (Beck Depression Inventory - II) and child psychopathological symptoms (Child Behavior Checklist and Children's Behavior Questionnaire) were provided by 554 mother-child pairs. Children in the sample were 7.7 years old on average (SD = 1.35, range = 5-11 years), and were 49.8% female, 46% Latinx, and 67% White, 6% Black, 5% Asian/Pacific Islander, and 21% multiracial.Results: Maternal depressive symptoms were positively associated with the child p-factor but not with the internalizing- or externalizing-specific factors. We did not find evidence of sex/gender or race/ethnicity moderation when using latent factors of psychopathology. Consistent with past research, maternal depressive symptoms were positively associated with internalizing and externalizing composite scores on the Child Behavior Checklist.Conclusions: Findings suggest that maternal depressive symptoms are associated with transdiagnostic risk for broad child psychopathology (p-factor). Whereas the traditional Achenbach-style approach of psychopathological assessment suggests that maternal depressive symptoms are associated with both child internalizing and externalizing problems, the latent bifactor model suggests that these associations may be accounted for by risk pathways related to the p-factor rather than internalizing or externalizing specific risk. We discuss clinical and research implications of using a latent bifactor structure of psychopathology to understand how maternal depression may impact children's mental health.

Prenatal exposure to maternal psychological distress and telomere length in childhood.

Telomere length (TL) is a biological marker of cellular aging, and shorter TL in adulthood is associated with increased morbidity and mortality risk. It is likely that these differences in TL are established long before adulthood, and there is growing evidence that TL can reflect prenatal experiences. Although maternal prenatal distress predicts newborn TL, it is unknown whether the relation between prenatal exposure to maternal distress and child TL persists through childhood. The purpose of the current longitudinal, prospective study is to examine the relation between prenatal exposure to maternal distress (perceived stress, depressive symptoms, pregnancy-related anxiety) and TL in childhood. Participants included 102 children (54 girls) and their mothers. Mothers' distress was assessed five times during pregnancy, at 12 weeks postpartum, and at the time of child telomere measurement between 6 and 16 years of age. Maternal distress during pregnancy predicted shorter offspring TL in childhood, even after accounting for postnatal exposure to maternal distress and other covariates. These findings indicate that maternal mental health predicts offspring TL biology later in childhood than previously observed. This study bolsters claims that telomere biology is subject to fetal programming and highlights the importance of supporting maternal mental health during pregnancy.

Development of the infant gut microbiome predicts temperament across the first year of life.

Perturbations to the gut microbiome are implicated in altered neurodevelopmental trajectories that may shape life span risk for emotion dysregulation and affective disorders. However, the sensitive periods during which the microbiome may influence neurodevelopment remain understudied. We investigated relationships between gut microbiome composition across infancy and temperament at 12 months of age. In 67 infants, we examined if gut microbiome composition assessed at 1-3 weeks, 2, 6, and 12 months of age was associated with temperament at age 12 months. Stool samples were sequenced using the 16S Illumina MiSeq platform. Temperament was assessed using the Infant Behavior Questionnaire-Revised (IBQ-R). Beta diversity at age 1-3 weeks was associated with surgency/extraversion at age 12 months. Bifidobacterium and Lachnospiraceae abundance at 1-3 weeks of age was positively associated with surgency/extraversion at age 12 months. Klebsiella abundance at 1-3 weeks was negatively associated with surgency/extraversion at 12 months. Concurrent composition was associated with negative affectivity at 12 months, including a positive association with Ruminococcus-1 and a negative association with Lactobacillus. Our findings support a relationship between gut microbiome composition and infant temperament. While exploratory due to the small sample size, these results point to early and late infancy as sensitive periods during which the gut microbiome may exert effects on neurodevelopment.

The influence of unpredictable, fragmented parental signals on the developing brain.

Mental illnesses originate early in life, governed by environmental and genetic factors. Because parents are a dominant source of signals to the developing child, parental signals - beginning with maternal signals in utero - are primary contributors to children's mental health. Existing literature on maternal signals has focused almost exclusively on their quality and valence (e.g. maternal depression, sensitivity). Here we identify a novel dimension of maternal signals: their patterns and especially their predictability/unpredictability, as an important determinant of children's neurodevelopment. We find that unpredictable maternal mood and behavior presage risk for child and adolescent psychopathology. In experimental models, fragmented/unpredictable maternal care patterns directly induce aberrant synaptic connectivity and disturbed maturation of cognitive and emotional brain circuits, with commensurate memory problems and anhedonia-like behaviors. Together, our findings across species demonstrate that patterns of maternal signals influence brain circuit maturation, promoting resilience or vulnerability to mental illness.

Prenatal Maternal Stress, Child Cortical Thickness, and Adolescent Depressive Symptoms.

Prenatal maternal stress predicts subsequent elevations in youth depressive symptoms, but the neural processes associated with these links are unclear. This study evaluated whether prenatal maternal stress is associated with child brain development, and adolescent depressive symptoms using a prospective design with 74 mother child pairs (40 boys). Maternal stress was assessed during pregnancy, child cortical thickness at age 7, and depressive symptoms at age 12. Prenatal maternal stress was associated with less cortical thickness primarily in frontal and temporal regions and with elevated depressive symptoms; child cortical thickness additionally correlated with adolescent depressive symptoms. The observed associations are consistent with the possibility that cortical thickness in superior frontal regions links associations between prenatal maternal stress and adolescent depressive symptoms.

Prenatal maternal psychological distress and fetal developmental trajectories: associations with infant temperament.

Associations between prenatal maternal psychological distress and offspring developmental outcomes are well documented, yet relatively little research has examined links between maternal distress and development in utero, prior to postpartum influences. Fetal heart rate (FHR) parameters are established indices of central and autonomic nervous system maturation and function which demonstrate continuity with postnatal outcomes. This prospective, longitudinal study of 149 maternal-fetal pairs evaluated associations between prenatal maternal distress, FHR parameters, and dimensions of infant temperament. Women reported their symptoms of psychological distress at five prenatal visits, and FHR monitoring was conducted at the last three visits. Maternal report of infant temperament was collected at 3 and 6 months of age. Exposure to elevated prenatal maternal psychological distress was associated with higher late-gestation resting mean FHR (FHRM) among female but not male fetuses. Higher late-gestation FHRM was associated with lower infant orienting/regulation and with higher infant negative affectivity, and these associations did not differ by infant sex. A path analysis identified higher FHRM as one pathway by which elevated prenatal maternal distress was associated with lower orienting/regulation among female infants. Findings suggest that, for females, elevated maternal distress alters fetal development, with implications for postnatal function. Results also support the notion that, for both sexes, individual differences in regulation emerge prenatally and are maintained into infancy. Collectively, these findings underscore the utility of direct assessment of development in utero when examining if prenatal experiences are carried forward into postnatal life.

Exposure to unpredictable maternal sensory signals influences cognitive development across species.

Maternal care is a critical determinant of child development. However, our understanding of processes and mechanisms by which maternal behavior influences the developing human brain remains limited. Animal research has illustrated that patterns of sensory information is important in shaping neural circuits during development. Here we examined the relation between degree of predictability of maternal sensory signals early in life and subsequent cognitive function in both humans (n = 128 mother/infant dyads) and rats (n = 12 dams; 28 adolescents). Behaviors of mothers interacting with their offspring were observed in both species, and an entropy rate was calculated as a quantitative measure of degree of predictability of transitions among maternal sensory signals (visual, auditory, and tactile). Human cognitive function was assessed at age 2 y with the Bayley Scales of Infant Development and at age 6.5 y with a hippocampus-dependent delayed-recall task. Rat hippocampus-dependent spatial memory was evaluated on postnatal days 49-60. Early life exposure to unpredictable sensory signals portended poor cognitive performance in both species. The present study provides evidence that predictability of maternal sensory signals early in life impacts cognitive function in both rats and humans. The parallel between experimental animal and observational human data lends support to the argument that predictability of maternal sensory signals causally influences cognitive development.