Elucidating the role of negative parenting in the genetic v. environmental influences on adult psychopathic traits.

BACKGROUND: Psychopathic traits involve interpersonal manipulation, callous affect, erratic lifestyle, and antisocial behavior. Though adult psychopathic traits emerge from both genetic and environmental risk, no studies have examined etiologic associations between adult psychopathic traits and experiences of parenting in childhood, or the extent to which parenting practices may impact the heritability of adult psychopathic traits using a genetically-informed design. METHODS: In total, 1842 adult twins from the community reported their current psychopathic traits and experiences of negative parenting during childhood. We fit bivariate genetic models to the data, decomposing the variance within, and the covariance between, psychopathic traits and perceived negative parenting into their genetic and environmental components. We then fit a genotype × environment interaction model to evaluate whether negative parenting moderated the etiology of psychopathic traits. RESULTS: Psychopathic traits were moderately heritable with substantial non-shared environmental influences. There were significant associations between perceived negative parenting and three of four psychopathy facets (interpersonal manipulation, erratic lifestyle, antisocial tendencies, but not callous affect). These associations were attributable to a common non-shared environmental pathway and not to overlapping genetic effects. Additionally, we found that primarily shared environmental influences were stronger on psychopathic traits for individuals with a history of greater negative parenting. CONCLUSIONS: Utilizing a genetically-informed design, we found that both genetic and non-shared environmental factors contribute to the emergence of psychopathic traits. Moreover, perceptions of negative parenting emerged as a clear environmental influence on the development of interpersonal, lifestyle, and antisocial features of psychopathy.

Antisocial behavior is associated with reduced frontoparietal network efficiency in youth.

Youth antisocial behavior (AB) is associated with deficits in socioemotional processing, reward and threat processing and executive functioning. These deficits are thought to emerge from differences in neural structure, functioning and connectivity, particularly within the default, salience and frontoparietal networks. However, the relationship between AB and the organization of these networks remains unclear. To address this gap, the current study applied unweighted, undirected graph analyses to resting-state functional magnetic resonance imaging data in a cohort of 161 adolescents (95 female) enriched for exposure to poverty, a risk factor for AB. As prior work indicates that callous-unemotional (CU) traits may moderate the neurocognitive profile of youth AB, we examined CU traits as a moderator. Using multi-informant latent factors, AB was found to be associated with less efficient frontoparietal network topology, a network associated with executive functioning. However, this effect was limited to youth at low or mean levels of CU traits, indicating that these neural differences were specific to those high on AB but not CU traits. Neither AB, CU traits nor their interaction was significantly related to default or salience network topologies. Results suggest that AB, specifically, may be linked with shifts in the architecture of the frontoparietal network.

Differential associations of parental harshness and parental disengagement with overall cortisol output at 15 years: Implications for adolescent mental health.

Psychosocial stress in childhood and adolescence is linked to stress system dysregulation, although few studies have examined the relative impacts of parental harshness and parental disengagement. This study prospectively tested whether parental harshness and disengagement show differential associations with overall cortisol output in adolescence. Associations between overall cortisol output and adolescent mental health problems were tested concurrently. Adolescents from the Fragile Families and Child Wellbeing Study (FFCWS) provided hair samples for cortisol assay at 15 years (N = 171). Caregivers reported on parental harshness and disengagement experiences at 1, 3, 5, 9, and 15 years, and adolescents reported at 15 years. Both parent and adolescent reported depressive and anxiety symptoms and antisocial behaviors at 15. Greater parental harshness from 1-15 years, and harshness reported at 15 years in particular, was associated with higher overall cortisol output at 15. Greater parental disengagement from 1-15 years, and disengagement at 1 year specifically, was associated with lower cortisol output. There were no significant associations between cortisol output and depressive symptoms, anxiety symptoms, or antisocial behaviors. These results suggest that the unique variances of parental harshness and disengagement may have opposing associations with cortisol output at 15 years, with unclear implications for adolescent mental health.

Parenting moderates the etiology of callous-unemotional traits in middle childhood.

BACKGROUND: Callous-unemotional (CU) traits are associated with chronic and escalating trajectories of antisocial behavior. Extant etiologic studies suggest that heritability estimates for CU traits vary substantially, while also pointing to an environmental association between parenting and CU traits. METHODS: We used twin modeling to estimate additive genetic (A), shared environmental (C), and nonshared environmental (E) influences on CU traits, measured with the Inventory of Callous-Unemotional Traits (ICU) and its subscales. Our sample included 600 twin pairs (age 6-11, 230 monozygotic) from neighborhoods with above-average levels of family poverty, a risk factor for antisocial behavior. We examined the extent to which correlations between parenting, measured via parent and child report on the Parental Environment Questionnaire, and CU traits reflected genetic versus environmental factors. Then, we tested whether parenting moderated the heritability of CU traits. RESULTS: In the context of lower-income neighborhoods, CU traits were moderately to highly heritable (A = 54%) with similar moderate-to-high nonshared environmental influences (E = 46%). Bivariate models revealed that associations between CU traits and warm parenting were genetic (rA = .22) and environmental (rE = .19) in origin, whereas associations between CU traits and harsh parenting were largely genetic in origin (rA = .70). The heritability of CU traits decreased with increasing parental warmth and decreasing harshness. CONCLUSIONS: Callous-unemotional traits are both genetic and environmental in origin during middle childhood, but genetic influences are moderated by parenting quality. Parenting may be an important target for interventions, particularly among youth with greater genetic risk.

Associations Between Parental Psychopathic Traits, Parenting, and Adolescent Callous-Unemotional Traits.

Callous-unemotional (CU) traits (i.e., callousness, low empathy, shallow affect) have been conceptualized as a downward extension of the interpersonal and affective components of adult psychopathy and are associated with stable and severe antisocial behavior. Research suggests that CU traits are moderately heritable, but also influenced by environmental factors, particularly parenting. We examined associations among mother and father psychopathic traits, parenting practices, and offspring CU traits in a community sample of 550 adolescent twins (Mean age = 13.99 years; SD 2.37; 56.4% male), incorporating multiple informants (mothers, fathers, child). Parental interpersonal-affective psychopathic traits were associated with adolescent CU traits and negative parenting (increased harshness, reduced warmth). Moreover, increased parental harshness and reduced warmth partially explained associations between parental interpersonal-affective traits and adolescent CU traits. There was also a significant direct effect specifically between mother interpersonal-affective traits and adolescent CU traits. Finally, using a twin difference design, we confirmed that adolescent CU traits were significantly impacted by non-shared environmental parenting influences (increased harshness, reduced warmth). These results suggest that mother and father interpersonal-affective traits appear to impact parenting practices and serve as risk factors for adolescent CU traits. However, many of the findings did not replicate when using cross-informant reports and were only present within single informant models, highlighting a role for shared informant variance as well. The results suggest the importance of accounting for parent personality in the development of effective parenting interventions for CU traits.

Neurocognitive abilities associated with antisocial behavior with and without callous-unemotional traits in a community sample.

OBJECTIVE: Antisocial behavior (aggression, rule breaking) is associated with lower intelligence and executive function deficits. Research has not clarified whether these associations differ with the presence of callous-unemotional (CU) traits, particularly within levels of antisocial behavior observed in the community. METHOD: We examined whether antisocial behavior and CU traits were differentially associated with intelligence and executive function metrics in 474 adolescent twins (Mean age = 14.18; SD = 2.20) sampled from birth records to represent youth in the community living in neighborhoods with above average levels of poverty. Intelligence was assessed using standardized scores from the Shipley-2. Executive function was assessed using Go/No-Go and Stop Signal tasks. RESULTS: Neither antisocial behavior, nor CU traits alone, were associated with cognitive functioning when accounting for demographic factors. However, antisocial behavior and CU traits interacted to predict reaction time variability. At low levels of CU traits, antisocial behavior was associated with higher reaction time variability (traditionally thought to reflect worse sustained attention). At high levels of CU traits, antisocial behavior was associated with lower reaction time variability (thought to reflect better sustained attention). CONCLUSION: Elevated antisocial behavior and CU traits may be characterized by a distinct neurocognitive profile compared to elevated antisocial behavior in isolation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Physical Activity in Early- and Mid-Adulthood Are Independently Associated With Longitudinal Memory Trajectories in Later Life.

BACKGROUND: Physical activity (PA) in later life may reduce dementia risk, but little is known regarding long-term cognitive effects of PA that occurred earlier in adulthood or mechanisms underlying associations. PA patterns at different ages may independently contribute to dementia risk, which would implicate multiple critical periods for intervention. The current study tested whether retrospective reports of PA in early and mid-adulthood were independently associated with later-life longitudinal memory outcomes and whether associations were mediated by late-life cardiometabolic diseases. METHOD: Participants comprised 5200 Health and Retirement Study Life History Mail Survey respondents. Latent growth curves estimated independent associations between retrospectively reported PA in early adulthood (age 18-29) and mid-adulthood (age 40-49) and 16-year episodic memory trajectories. Indirect pathways involving the maintenance of PA from early- to mid-adulthood and the influence of PA on later-life cardiometabolic diseases (hypertension, diabetes, and heart disease) were also estimated. RESULTS: PA in early- and mid-adulthood independently predicted higher initial memory level and slower memory decline in later life, respectively. Early-adulthood PA was indirectly associated with later-life memory level through higher mid-adulthood PA and lower rates of later-life hypertension, as well as with subsequent memory decline through higher mid-adulthood PA. CONCLUSIONS: The current findings highlight the importance of PA throughout adulthood, such that initiating and/or maintaining exercise in early- or mid-adulthood may be protective for later-life cognitive health, and hypertension appears to represent a key mediator of these effects.

Connections that characterize callousness: Affective features of psychopathy are associated with personalized patterns of resting-state network connectivity.

BACKGROUND: Psychopathic traits are hypothesized to be associated with dysfunction across three resting-state networks: the default mode (DMN), salience (SN), and central executive (CEN). Past work has not considered heterogeneity in the neural networks of individuals who display psychopathic traits, which is likely critical in understanding the etiology of psychopathy and could underlie different symptom presentations. Thus, this study maps person-specific resting state networks and links connectivity patterns to features of psychopathy. METHODS: We examined resting-state functional connectivity among eight regions of interest in the DMN, SN, and CEN using a person-specific, sparse network mapping approach (Group Iterative Multiple Model Estimation) in a community sample of 22-year-old men from low-income, urban families (N = 123). Associations were examined between a dimensional measure of psychopathic traits and network density (i.e., number of connections within and between networks). RESULTS: There was significant heterogeneity in neural networks of participants, which were characterized by person-specific connections and no common connections across the sample. Psychopathic traits, particularly affective traits, were associated with connection density between the DMN and CEN, such that greater density was associated with elevated psychopathic traits. DISCUSSION: Findings emphasize that neural networks underlying psychopathy are highly individualized. However, individuals with high levels of psychopathic traits had increased density in connections between the DMN and CEN, networks that have been linked with self-referential thinking and executive functioning. Taken together, the results highlight the utility of person-specific approaches in modeling neural networks underlying psychopathic traits, which could ultimately inform personalized prevention and intervention strategies.

Association of Childhood Violence Exposure With Adolescent Neural Network Density.

Importance: Adverse childhood experiences are a public health issue with negative sequelae that persist throughout life. Current theories suggest that adverse childhood experiences reflect underlying dimensions (eg, violence exposure and social deprivation) with distinct neural mechanisms; however, research findings have been inconsistent, likely owing to variability in how the environment interacts with the brain. Objective: To examine whether dimensional exposure to childhood adversity is associated with person-specific patterns in adolescent resting-state functional connectivity (rsFC), defined as synchronized activity across brain regions when not engaged in a task. Design, Setting, and Participants: A sparse network approach in a large sample with substantial representation of understudied, underserved African American youth was used to conduct an observational, population-based longitudinal cohort study. A total of 183 adolescents aged 15 to 17 years from Detroit, Michigan; Toledo, Ohio; and Chicago, Illinois, who participated in the Fragile Families and Child Wellbeing Study were eligible for inclusion. Environmental data from birth to adolescence were collected via telephone and in-person interviews, and neuroimaging data collected at a university lab. The study was conducted from February 1, 1998, to April 26, 2017, and data analysis was performed from January 3, 2019, to May 22, 2020. Exposures: Composite variables representing violence exposure and social deprivation created from primary caregiver reports on children at ages 3, 5, and 9 years. Main Outcomes and Measures: Resting-state functional connectivity person-specific network metrics (data-driven subgroup membership, density, and node degree) focused on connectivity among a priori regions of interest in 2 resting-state networks (salience network and default mode) assessed with functional magnetic resonance imaging. Results: Of the 183 eligible adolescents, 175 individuals (98 girls [56%]) were included in the analysis; mean (SD) age was 15.88 (0.53) years and 127 participants (73%) were African American. Adolescents with high violence exposure were 3.06 times more likely (95% CI, 1.17-8.92) to be in a subgroup characterized by high heterogeneity (few shared connections) and low network density (sparsity). Childhood violence exposure, but not social deprivation, was associated with reduced rsFC density (ß = -0.25; 95% CI, -0.41 to -0.05; P = .005), with fewer salience network connections (ß = -0.26; 95% CI, -0.43 to -0.08; P = .005) and salience network-default mode connections (ß = -0.20; 95% CI, -0.38 to -0.03; P = .02). Violence exposure was associated with node degree of right anterior insula (ß = -0.29; 95% CI, -0.47 to -0.12; P = .001) and left inferior parietal lobule (ß = -0.26; 95% CI, -0.44 to -0.09; P = .003). Conclusions and Relevance: The findings of this study suggest that childhood violence exposure is associated with adolescent neural network sparsity. A community-detection algorithm, blinded to child adversity, grouped youth exposed to heightened violence based only on patterns of rsFC. The findings may have implications for understanding how dimensions of adverse childhood experiences impact individualized neural development.

Clarifying the Link Between Amygdala Functioning During Emotion Processing and Antisocial Behaviors Versus Callous-Unemotional Traits Within a Population-Based Community Sample.

Prominent theories suggest that disruptions in amygdala reactivity and connectivity when processing emotional cues are key to the etiology of youth antisocial behavior (AB) and that these associations may be dependent on co-occurring levels of callous-unemotional (CU) traits. We examined the associations among AB, CU traits, and amygdala reactivity and functional connectivity while viewing emotional faces (fearful, angry, sad, happy) in 165 adolescents (46% male; 73.3% African American) from a representative, predominantly low-income community sample. AB was associated with increased amygdala activation in response to all emotions and was associated with greater amygdala reactivity to emotion only at low levels of CU traits. AB and CU traits were also associated with distinct patterns of amygdala connectivity. These findings demonstrate that AB-related deficits in amygdala functioning may extend across all emotions and highlight the need for further research on amygdala connectivity during emotion processing in relation to AB and CU traits within community populations.

Personalized models of personality disorders: using a temporal network method to understand symptomatology and daily functioning in a clinical sample.

BACKGROUND: An ongoing challenge in understanding and treating personality disorders (PDs) is a significant heterogeneity in disorder expression, stemming from variability in underlying dynamic processes. These processes are commonly discussed in clinical settings, but are rarely empirically studied due to their personalized, temporal nature. The goal of the current study was to combine intensive longitudinal data collection with person-specific temporal network models to produce individualized symptom-level structures of personality pathology. These structures were then linked to traditional PD diagnoses and stress (to index daily functioning). METHODS: Using about 100 daily assessments of internalizing and externalizing domains underlying PDs (i.e. negative affect, detachment, impulsivity, hostility), a temporal network mapping approach (i.e. group iterative multiple model estimation) was used to create person-specific networks of the temporal relations among domains for 91 individuals (62.6% female) with a PD. Network characteristics were then associated with traditional PD symptomatology (controlling for mean domain levels) and with daily variation in clinically-relevant phenomena (i.e. stress). RESULTS: Features of the person-specific networks predicted paranoid, borderline, narcissistic, and obsessive-PD symptom counts above average levels of the domains, in ways that align with clinical conceptualizations. They also predicted between-person variation in stress across days. CONCLUSIONS: Relations among behavioral domains thought to underlie heterogeneity in PDs were indeed associated with traditional diagnostic constructs and with daily functioning (i.e. stress) in person-specific networks. Findings highlight the importance of leveraging data and models that capture person-specific, dynamic processes, and suggest that person-specific networks may have implications for precision medicine.

Antisocial behavior with callous-unemotional traits is associated with widespread disruptions to white matter structural connectivity among low-income, urban males.

Antisocial behavior (AB), including violence, criminality, and substance abuse, is often linked to deficits in emotion processing, reward-related learning, and inhibitory control, as well as their associated neural networks. To better understand these deficits, the structural connections between brain regions implicated in AB can be examined using diffusion tensor imaging (DTI), which assesses white matter microstructure. Prior studies have identified differences in white matter microstructure of the uncinate fasciculus (UF), primarily within offender samples. However, few studies have looked beyond the UF or determined whether these relationships are present dimensionally across the range of AB and callous-unemotional (CU) traits. In the current study, we examined associations between AB and white matter microstructure from major fiber tracts, including the UF. Further, we explored whether these associations were specific to individuals high on CU traits. Within a relatively large community sample of young adult men from low-income, urban families (N = 178), we found no direct relations between dimensional, self-report measures of either AB or CU traits and white matter microstructure. However, we found significant associations between AB and white matter microstructure of several tracts only for those with high co-occurring levels of CU traits. In general, these associations did not differ according to race, socioeconomic status, or comorbid psychiatric symptoms. The current results suggest a unique neural profile of severe AB in combination with CU traits, characterized by widespread differences in white matter microstructure, which differs from either AB or CU traits in isolation and is not specific to hypothesized tracts (i.e., the UF).

Amygdala-prefrontal cortex white matter tracts are widespread, variable and implicated in amygdala modulation in adolescents.

The amygdala is critically involved in processing emotion. Through bidirectional connections, the prefrontal cortex (PFC) is hypothesized to influence amygdala reactivity. However, research that elucidates the nature of amygdala-PFC interactions - through mapping amygdala-prefrontal tracts, quantifying variability among tracts, and linking this variability to amygdala activation - is lacking. Using probabilistic tractography to map amygdala-prefrontal white matter connectivity in 142 adolescents, the present study found that white matter connectivity was greater between the amygdala and the subgenual cingulate, orbitofrontal (OFC), and dorsomedial (dmPFC) prefrontal regions than with the dorsal cingulate and dorsolateral regions. Then, using a machine-learning regression, we found that greater amygdala-PFC white matter connectivity was related to attenuated amygdala reactivity. This effect was driven by amygdala white matter connectivity with the dmPFC and OFC, supporting implicit emotion processing theories which highlight the critical role of these regions in amygdala regulation. This study is among the first to map and compare specific amygdala-prefrontal white matter tracts and to relate variability in connectivity to amygdala activation, particularly among a large sample of adolescents from a well-sampled study. By examining the association between specific amygdala-PFC tracts and amygdala activation, the present study provides novel insight into the nature of this emotion-based circuit.

Genetic influences on antisocial behavior: recent advances and future directions.

Understanding the etiology of antisocial behavior (i.e. violence, criminality, rule-breaking), is essential to the development of more effective prevention and intervention strategies. We provide a summary of the genetic correlates of antisocial behavior, drawing upon findings from behavioral, molecular, and statistical genetics. Across methodologies, our review highlights the centrality of environmental moderators of genetic effects, and how behavioral heterogeneity in antisocial behavior is an important consideration for genetic studies. We also review novel analytic techniques and neurogenetic approaches that can be used to examine how genetic variation predicts antisocial behavior. Finally, to illustrate how findings may converge across approaches, we describe pathways from genetic variability in oxytocin signaling to subtypes of antisocial behavior.

Amygdala habituation and uncinate fasciculus connectivity in adolescence: A multi-modal approach.

Despite prior extensive investigations of the interactions between the amygdala and prefrontal cortex, few studies have simultaneously considered activation and structural connectivity in this circuit, particularly as it pertains to adolescent socioemotional development. The current multi-modal study delineated the correspondence between uncinate fasciculus (UF) connectivity and amygdala habituation in a large adolescent sample that was drawn from a population-based sample. We then examined the influence of demographic variables (age, gender, and pubertal status) on the relation between UF connectivity and amygdala habituation. 106 participants (15-17 years) completed DTI and an fMRI emotional face processing task. Left UF fractional anisotropy was associated with left amygdala habituation to fearful faces, suggesting that increased structural connectivity of the UF may facilitate amygdala regulation. Pubertal status moderated this structure-function relation, such that the association was stronger in those who were less mature. Therefore, UF connectivity may be particularly important for emotion regulation during early puberty. This study is the first to link structural and functional limbic circuitry in a large adolescent sample with substantial representation of ethnic minority participants, providing a more comprehensive understanding of socioemotional development in an understudied population.

Unique and Interactive Associations Between Maltreatment and Complex Emotion Recognition Deficits and Psychopathic Traits in an Undergraduate Sample.

Psychopathy is defined by affective and interpersonal deficits, deviant lifestyle, and antisocial behaviors. Poor recognition of emotions and childhood maltreatment are two risk factors implicated in psychopathy. The current study examined whether childhood maltreatment and complex emotion recognition deficits showed unique and interactive associations with psychopathic traits among 261 undergraduate students. Results indicate that maltreatment was related to higher general psychopathy scores within a bifactor model comprising a general psychopathy factor and four specific factors tapping underlying dimensions of psychopathy (i.e., affective, interpersonal, lifestyle, and antisocial). A significant interaction emerged whereby maltreatment was related to higher antisocial factor scores among individuals showing poor recognition of positive emotions. In an intriguing interaction, more maltreatment was related to lower interpersonal factor scores among individuals with low/mean levels of neutral emotion recognition. The interaction of positive emotion recognition deficits and maltreatment highlights a potential intervention target among antisocial individuals who have experienced maltreatment.

Concurrent and developmental correlates of psychopathic traits using a triarchic psychopathy model approach.

Psychopathy refers to a heterogeneous set of harmful dark traits and behaviors, including superficial charm, callousness, irresponsibility, and antisocial behavior. The triarchic psychopathy model (TriPM) posits that psychopathy is the combination of 3 traits: boldness, disinhibition, and meanness. However, little research has examined the concurrent and developmental correlates of these traits. We developed TriPM scales from the NEO Personality Inventory-Revised using an empirical-derived approach in a high-risk sample of 561 young adults (ages 17-25; 70.2% male). Concurrent correlates and developmental precursors of each scale were examined longitudinally using cross-informant reports from 3 critical developmental periods (ages 3-5; 9-11; 15-17). Using this approach, we identified consistent developmental precursors and concurrent correlates of boldness, including lower reactive control, fewer internalizing traits, and greater resiliency. Additionally, starting in adolescence we found that disinhibition was related to lower reactive control, more externalizing problems, substance use, and internalizing traits. Finally, although meanness demonstrated some expected concurrent relationships with criterion variables in early adulthood (e.g., lower adaptive functioning), we identified few consistent developmental precursors of meanness. Thus, a NEO-based approach to measuring the TriPM was successful in delineating boldness, disinhibition, and, to a lesser extent, meanness cross-sectionally during early adulthood. However, only boldness showed relative stability from developmental precursors in early childhood to our TriPM scale in early adulthood. (PsycINFO Database Record

Amygdala reactivity predicts adolescent antisocial behavior but not callous-unemotional traits.

Recent neuroimaging studies have suggested divergent relationships between antisocial behavior (AB) and callous-unemotional (CU) traits and amygdala reactivity to fearful and angry facial expressions in adolescents. However, little work has examined if these findings extend to dimensional measures of behavior in ethnically diverse, non-clinical samples, or if participant sex, ethnicity, pubertal stage, and age moderate associations. We examined links between amygdala reactivity and dimensions of AB and CU traits in 220 Hispanic and non-Hispanic Caucasian adolescents (age 11-15; 49.5% female; 38.2% Hispanic), half of whom had a family history for depression and thus were at relatively elevated risk for late starting, emotionally dysregulated AB. We found that AB was significantly related to increased right amygdala reactivity to angry facial expressions independent of sex, ethnicity, pubertal stage, age, and familial risk status for depression. CU traits were not related to fear- or anger-related amygdala reactivity. The present study further demonstrates that AB is related to increased amygdala reactivity to interpersonal threat cues in adolescents, and that this relationship generalizes across sex, ethnicity, pubertal stage, age, and familial risk status for depression.

White-matter tract abnormalities and antisocial behavior: A systematic review of diffusion tensor imaging studies across development.

Antisocial behavior (AB), including aggression, violence, and theft, is thought be underpinned by abnormal functioning in networks of the brain critical to emotion processing, behavioral control, and reward-related learning. To better understand the abnormal functioning of these networks, research has begun to investigate the structural connections between brain regions implicated in AB using diffusion tensor imaging (DTI), which assesses white-matter tract microstructure. This systematic review integrates findings from 22 studies that examined the relationship between white-matter microstructure and AB across development. In contrast to a prior hypothesis that AB is associated with greater diffusivity specifically in the uncinate fasciculus, findings suggest that adult AB is associated with greater diffusivity across a range of white-matter tracts, including the uncinate fasciculus, inferior fronto-occipital fasciculus, cingulum, corticospinal tract, thalamic radiations, and corpus callosum. The pattern of findings among youth studies was inconclusive with both higher and lower diffusivity found across association, commissural, and projection and thalamic tracts.