The effects of early life stress on impulsivity

Food insecurity and adolescent impulsivity: The mediating role of functional connectivity in the context of family flexibility

Adolescent food insecurity is a salient adversity hypothesized to affect neural systems associated with increased impulsive behavior. Family environments shape how adverse experiences influence development. In this study, hypotheses were tested regarding the conjoint effects of food insecurity and family flexibility on impulsivity via alterations in connectivity between regions within the salience and central executive networks. Such alterations are reflected in resting-state functional connectivity (rsFC) metrics between the anterior insula (AI) and the middle frontal gyrus (MFG). Hypotheses were tested in a longitudinal moderated mediation model with two waves of data from 142 adolescents (Time 1 [T1] Mage = 12.89, SD = 0.85; Time 2 [T2] Mage = 15.01, SD = 1.07). Data on past-year household food insecurity, family flexibility, and rsFC were obtained at T1. Impulsivity was self-reported by the adolescent at T1 and T2. Findings revealed that high T1 left-to-left rsFC between the AI and MFG was associated with increased impulsivity at T2. The interaction of family flexibility and food insecurity was associated with AI and MFG rsFC. In the context of low family flexibility, food insecurity was linked to high levels of AI and MFG rsFC. Conversely, in the context of optimal family flexibility, food insecurity was associated with low levels of AI and MFG rsFC. Conditional indirect analysis suggests that the links among food insecurity, rsFC, and impulsive behavior depend on family flexibility. RESEARCH HIGHLIGHTS: Adolescent food insecurity was associated with anterior insula and middle frontal gyrus connectivity only at certain levels of family flexibility. High family flexibility attenuated the link between food insecurity and neural connectivity, while low levels of family flexibility increased this risk. High left anterior insula and left middle frontal gyrus connectivity was associated with increased impulsivity 1 year later.

Effects of chronic stress on cognitive function - From neurobiology to intervention

Exposure to chronic stress contributes considerably to the development of cognitive impairments in psychiatric disorders such as depression, generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), and addictive behavior. Unfortunately, unlike mood-related symptoms, cognitive impairments are not effectively treated by available therapies, a situation in part resulting from a still incomplete knowledge of the neurobiological substrates that underly cognitive domains and the difficulty in generating interventions that are both efficacious and safe. In this review, we will present an overview of the cognitive domains affected by stress with a specific focus on cognitive flexibility, behavioral inhibition, and working memory. We will then consider the effects of stress on neuronal correlates of cognitive function and the factors which may modulate the interaction of stress and cognition. Finally, we will discuss intervention strategies for treatment of stress-related disorders and gaps in knowledge with emerging new treatments under development. Understanding how cognitive impairment occurs during exposure to chronic stress is crucial to make progress towards the development of new and effective therapeutic approaches.

Maternal separation as early-life stress: Mechanisms of neuropsychiatric disorders and inspiration for neonatal care

The establishment of positive early parent-infant relationships provide essential nourishment and social stimulation for newborns. During the early stages of postnatal brain development, events such as synaptogenesis, neuronal maturation and glial differentiation occur in a highly coordinated manner. Maternal separation, as an early-life stress introducer, can disrupt the formation of parent-child bonds and exert long-term adverse effects throughout life. When offspring are exposed to maternal separation, the body regulates the stress of maternal separation through multiple mechanisms, including neuroinflammatory responses, neuroendocrinology, and neuronal electrical activity. In adulthood, early maternal separation has long-term effects, such as the induction of neuropsychiatric disorders such as anxiety, depression, and cognitive dysfunction. This review summarized the application of maternal separation models and the mechanisms of stress system response in neuropsychiatric disorders, serving as both a reminder and inspiration for approaches to improve neonatal care, "from bench to bedside".

Impact of emotional abuse on eating disorder psychopathology: A multiple mediation analysis

INTRODUCTION

Childhood maltreatment, particularly emotional abuse (EA), has been identified as a significant risk factor for the development of eating disorders (EDs). This study investigated the association between EA and ED symptoms while considering multiple potential mediators.

METHODS

Participants included 151 individuals with Anorexia Nervosa (AN), 115 with Bulimia Nervosa (BN), and 108 healthy controls. The Childhood trauma questionnaire, the Toronto Alexithymia scale, the Behavioral inhibition System, and the Eating Disorder Inventory 2 scale were completed before treatment. A mediator path model was conducted in each group: EA was set as independent variable, eating symptoms as dependent variables and ineffectiveness, sensitivity to punishment, alexithymia, and impulsivity as mediators.

RESULTS

In individuals with AN, impulsivity emerged as a significant mediator between EA and desire for thinness and bulimic behaviors. Conversely, in individuals with BN, sensitivity to punishment was found to mediate the association between EA and dissatisfaction with one's body. Ineffectiveness and difficulty identifying emotions were identified as transdiagnostic mediators in both clinical groups. No mediation effect was found in healthy individuals.

DISCUSSION

The simultaneous assessment of multiple mediators in a unique model outlines the complex interplay between childhood EA and ED psychopathology. Improving ineffectiveness, emotion identification, sensitivity to punishment and impulsivity and exploring their relations with early emotional abuse may represent treatment targets in individuals with EDs and childhood trauma.

Brain Stimulation of Dorsolateral Prefrontal Cortices Influences Impulsivity in Delay Discounting Choices

Intertemporal decision-making is pivotal for human interests and health. Recently, studies instructed participants to make intertemporal choices for both themselves and others, but the specific mechanisms are still debated. To address the issue, in the current study, the cost-unneeded conditions (i.e., "Self Immediately - Self Delay" and "Other Immediately - Other Delay" conditions) and the cost-needed conditions (i.e., "Self Immediately - Other Delay" and "Self Delay - Other Immediately" conditions) were set with the identity of OTHER being a stranger. We manipulated the magnitude of reward (Experiment 1) and disrupted the activation of the dorsolateral prefrontal cortex with repetitive transcranial magnetic stimulation (rTMS; Experiment 2). We found that both the behavioral and rTMS manipulations increased smaller but sooner choice probability via reducing self-control function. The reduced self-control function elicited by rTMS affected both self- and other-related intertemporal choices via increasing the choice preference for smaller but sooner reward options, which may help people deeply understand the relationship between self- and other-related intertemporal choices in processing mechanism, especially when the OTHER condition is set as a stranger.

Breadth of substance use is associated with the selection of a larger food portion size via elevated impulsivity

Substance use is associated with altered or elevated food consumption and disordered eating. In the present study we examined whether breadth (variety) of drug use was associated with elevated portion size in a general population sample as it was in persons in recovery from substance use disorder. Furthermore, measures of emotional eating, impulsivity, food misuse, food craving were taken as possible mediators and reward responsiveness was examined as a potential moderator of this association. 444 adults (48.6 % women, mean age of 47.8 years) completed an online study in which they were asked to make judgements of ideal portion size for 6 different foods using a validated online tool that allowed participants to adjust the portion size of images of foods. Ideal portion size has been identified as a strong predictor of actual consumption. Participants were also asked to report the number of substances used in the past and provide anthropometric information. The results confirmed that breadth of drug use was associated with selection of higher portion size. Reward responsiveness was not a moderator of this relationship. Of the tested mediators, only impulsivity mediated the association between breadth of drug use and portion size. The results show that impulsivity may underlie the association between eating and substance use.

Adverse childhood experiences, low self-esteem, and salient stimulus response in eating disorders

BACKGROUND

Adverse childhood experiences (ACEs) are elevated in individuals with eating disorders (EDs), but how the neurobiology of EDs and ACEs interact is unclear.

METHODS

Women 18-45 years old with anorexia nervosa (AN, n = 38), bulimia nervosa (BN, n = 32), or healthy controls (n = 60) were assessed for ACEs and ED behaviours and performed a taste-conditioning task during brain imaging. Mediation analyses tested relationships between ACE score, self-esteem, and ED behaviours.

RESULTS

ACE scores were elevated in EDs and correlated positively with body mass index (p = 0.001), drive for thinness (p = 0.001), and body dissatisfaction (p = 0.032); low self-esteem mediated the relationship between ACEs and body dissatisfaction, drive for thinness, and bulimia severity. ACE scores correlated negatively (FDR-corrected) with unexpected, salient stimulus receipt in AN (substantia nigra) and BN (anterior cingulate, frontal and insular cortex, ventral striatum, and substantia nigra). When ACE scores were included in the model, unexpected stimulus receipt brain response was elevated in EDs in the anterior cingulate and ventral striatum.

CONCLUSIONS

ACEs attenuate unexpected salient stimulus receipt response, which may be a biological marker for altered valence or hedonic tone perception in EDs. Low self-esteem mediates the relationships between ACEs and ED behaviours. Adverse childhood experiences should be assessed in biological studies, and their effects targeted in treatment.

Food selection in a buffet scenario by persons in recovery from substance use disorder: Testing a parallel mediation model including impulsivity, food craving, and breadth of drug use

Elevated food cravings and higher food consumption and body weight have been reported in studies of people in recovery from substance use disorder (SUD). In a previous study, SUD recovery status predicted the energy from selected food images in a virtual buffet meal, most strongly in those with high reward responsiveness. The present study was conducted to determine which psychological variables might mediate the relationship between SUD recovery status and food selection and to replicate the finding that reward responsiveness moderated this relationship. In an online study, 216 women and men (109 in recovery from SUD) were asked to choose from among 16 food images in an all-you-can-eat buffet scenario. Food craving, impulsivity, "food addiction", irrational food beliefs, anhedonia, and breadth of drug use were examined as potential mediators while reward responsiveness was examined as a potential moderator. The amount of energy in the selected foods was the outcome variable. Results indicated that breadth of drug use was a mediator; being in SUD recovery predicted higher variety of drug use which predicted higher food selection. However, reward responsiveness did not moderate the relationship between SUD recovery status and energy from the selected foods. Exploratory analysis indicated that lack of premeditation, a measure of impulsivity, with food craving partially mediated the relationship between breadth of drug use and energy from selected foods and that lack of premeditation fully mediated it for sweet foods. The results confirm an association between substance use and food selection and suggest a mechanism via impulsivity.

A mixed methods experience sampling study of a posttraumatic growth model for addiction recovery

Problematic substance use and addiction is a growing crisis in the United States. As a result, identifying factors that effectively promote addiction recovery is, currently, of particular societal importance. Informed by evidence that-while addiction can be perpetuated by stress-related impulsivity and decreased self-regulation-perceived social support is protective against addiction, we test a model for addiction recovery as a form of posttraumatic growth (PTG), focused specifically on close relationships and personal strength-two domains of PTG. In an initial study, we found that perceived social support and impulsivity predicted number of relapses in individuals in a substance use disorder recovery program. Using experience sampling, we then observed that experiencing a stressful event predicted impulsive behavior. However, experiencing closeness with others-a domain of PTG-was directly associated with perceived social support, and both predicted positive emotional states, which were, in turn, inversely associated with experiencing a stressful event. Further, when experiencing a stressful event, personal strength-also a domain of PTG-was inversely associated with impulsive behavior and was predicted by both perceived social support and positive emotional states. Finally, in a follow-up experiment, we found that an ecological momentary intervention targeting perceived social support decreased impulsivity and increased self-regulation-an aspect of personal strength-in a dose-dependent fashion. Taken together, our findings: (1) support a PTG model for recovery; (2) provide evidence for processes by which close supportive relationships are protective against addiction and relapse; and (3) indicate that self-regulation is responsive to a short in-the-moment perceived social support intervention. We suggest that these findings support the theory that addiction is a social disease in the sense that close personal interactions and supportive relationships: (a) buffer against stress-related impulsivity, thereby protecting against addiction and relapse; and (b) increase personal strength, thereby decreasing the probability of impulsive-including addictive-behavior and promoting recovery.

The interplay of childhood trauma, oxytocin, and impulsivity in predicting the onset of methamphetamine use

BACKGROUND

Childhood trauma is associated with substance use disorders, including methamphetamine use disorder (MUD). Oxytocin, involved in social bonding, stress regulation, and reward processing, may influence addiction vulnerability and impulsivity in individuals with a history of childhood trauma.

OBJECTIVE

To investigate the relationships among childhood trauma, oxytocin levels, impulsivity, and the age of first methamphetamine use in individuals with MUD.

PARTICIPANTS AND SETTING

The study included 298 male participants (148 individuals with MUD and 150 healthy controls) from both probation offices and psychiatric clinics.

METHODS

Childhood trauma was assessed using the Childhood Trauma Questionnaire-Short Form (CTQ-SF), impulsivity with the Barratt Impulsiveness Scale-11 (BIS-11), and plasma oxytocin levels were obtained.

RESULTS

Individuals with MUD exhibited higher levels of childhood trauma, impulsivity, and lower plasma oxytocin levels compared to healthy controls. Childhood trauma was associated with a younger age of first methamphetamine use, higher impulsivity, and lower oxytocin levels among individuals with MUD. Plasma oxytocin levels partially mediated the relationship between childhood trauma and both the age of first methamphetamine use and impulsivity. Serial mediation analysis demonstrated that oxytocin levels and impulsivity sequentially mediated the relationship between childhood trauma and the age of first methamphetamine use.

CONCLUSIONS

The findings reveal the complex interplay among childhood trauma, oxytocin, impulsivity, and methamphetamine use, emphasizing the importance of considering these factors in prevention and intervention strategies for MUD. Future research should explore oxytocin and impulsivity-focused interventions to mitigate the effects of childhood trauma and reduce MUD development risk.

Anxiety, aggression, reward sensitivity, and forebrain dopamine receptor expression in a laboratory rat model of early-life disadvantage

Despite early-life disadvantage (ELD) in humans being a highly heterogenous construct, it consistently predicts negative neurobehavioral outcomes. The numerous environmental contributors and neural mechanisms underlying ELD remain unclear, though. We used a laboratory rat model to evaluate the effects of limited resources and/or heavy metal exposure on mothers and their adult male and female offspring. Dams and litters were chronically exposed to restricted (1-cm deep) or ample (4-cm deep) home cage bedding postpartum, with or without lead acetate (0.1%) in their drinking water from insemination through 1-week postweaning. Restricted-bedding mothers showed more pup-directed behaviors and behavioral fragmentation, while lead-exposed mothers showed more nestbuilding. Restricted bedding-raised male offspring showed higher anxiety and aggression. Either restricted bedding or lead exposure impaired goal-directed performance in a reinforcer devaluation task in females, whereas restricted bedding alone disrupted it in males. Lead exposure, but not limited bedding, also reduced sucrose reward sensitivity in a progressive ratio task in females. D1 and D2 receptor mRNA in the medial prefrontal cortex and nucleus accumbens (NAc) were each affected by the early-life treatments and differently between the sexes. Most notably, adult males (but not females) exposed to both early-life treatments had greatly increased D1 receptor mRNA in the NAc core. These results illuminate neural mechanisms through which ELD threatens neurobehavioral development and highlight forebrain dopamine as a factor.

Addiction substitution and concurrent recovery in gambling disorder: Who substitutes and why?

Objectives

When individuals recover from gambling disorder, their involvement in other potentially addictive substances and behaviors may also subsequently increase (substitution) or decrease (concurrent recovery). The objectives of this study were to identify and compare recovery processes associated with substitution and concurrent recovery in gambling disorder.

Methods

A mixed-method study was conducted with 185 people who were recovered from gambling disorder. Semi-structured interviews were used to: (i) establish onset and recovery of gambling disorder as well as other substance and behavioral addictions; and (ii) assess processes (e.g., reasons, emotional state, helpfulness) associated with addiction substitution and concurrent recovery. Participants also completed a survey assessing demographic characteristics, gambling behaviors, and psychological characteristics to compare demographic and clinical differences between participants who engaged in addiction substitution, concurrent recovery, or neither (controls).

Results

The most frequently reported reason for engaging in addiction substitution was as a substitute coping mechanism. The most reported reason for engaging in concurrent recovery was due to the addictions being mutually influenced. Negative emotional states were common when engaging in both addiction substitution and concurrent recovery. Although the three groups did not differ on gambling characteristics, addiction substitution was associated with greater underlying vulnerabilities including childhood adversity, impulsivity, emotion dysregulation, and, maladaptive coping skills.

Conclusion

Transdiagnostic treatments that target the underlying mechanisms of addictions may reduce the likelihood of engaging in addiction substitution.

Post-weaning social isolation in male mice leads to abnormal aggression and disrupted network organization in the prefrontal cortex: Contribution of parvalbumin interneurons with or without perineuronal nets

Adverse social experiences during childhood increase the risk of developing aggression-related psychopathologies. The prefrontal cortex (PFC) is a key regulator of social behavior, where experience-dependent network development is tied to the maturation of parvalbumin-positive (PV+) interneurons. Maltreatment in childhood could impact PFC development and lead to disturbances in social behavior during later life. However, our knowledge regarding the impact of early-life social stress on PFC operation and PV+ cell function is still scarce. Here, we used post-weaning social isolation (PWSI) to model early-life social neglect in mice and to study the associated neuronal changes in the PFC, additionally distinguishing between the two main subpopulations of PV+ interneurons, i.e. those without or those enwrapped by perineuronal nets (PNN). For the first time to such detailed extent in mice, we show that PWSI induced disturbances in social behavior, including abnormal aggression, excessive vigilance and fragmented behavioral organization. PWSI mice showed altered resting-state and fighting-induced co-activation patterns between orbitofrontal and medial PFC (mPFC) subregions, with a particularly highly elevated activity in the mPFC. Surprisingly, aggressive interaction was associated with a higher recruitment of mPFC PV+ neurons that were surrounded by PNN in PWSI mice that seemed to mediate the emergence of social deficits. PWSI did not affect the number of PV+ neurons and PNN density, but enhanced PV and PNN intensity as well as cortical and subcortical glutamatergic drive onto mPFC PV+ neurons. Our results suggest that the increased excitatory input of PV+ cells could emerge as a compensatory mechanism for the PV+ neuron-mediated impaired inhibition of mPFC layer 5 pyramidal neurons, since we found lower numbers of GABAergic PV+ puncta on the perisomatic region of these cells. In conclusion, PWSI leads to altered PV-PNN activity and impaired excitatory/inhibitory balance in the mPFC, which possibly contributes to social behavioral disruptions seen in PWSI mice. Our data advances our understanding on how early-life social stress can impact the maturing PFC and lead to the development of social abnormalities in adulthood.

Early-life stress affects Mongolian gerbil interactions with conspecific vocalizations in a sex-specific manner

During development, early-life stress (ELS) impairs cognition, learning, and emotional regulation, in part by disrupting neural circuitry in regions underlying these higher-order functions. In addition, our recent work indicates that ELS also alters simple sensory perception: ELS impaired auditory perception and neural encoding of short gaps in sounds, which are essential for vocal communication. The combination of higher-order and basic sensory disruption suggests that ELS is likely to affect both the perception and interpretation of communication signals. We tested this hypothesis by measuring behavioral responses to conspecific vocalizations (those emitted by other gerbils) in ELS and untreated Mongolian gerbils. Because stress effects often differ by sex, we separately examined females and males. To induce ELS, pups were intermittently maternally separated and restrained from post-natal days (P) 9-24, a time window when the auditory cortex is most sensitive to external disruption. We measured the approach responses of juvenile (P31-32) gerbils to two types of conspecific vocalizations: an alarm call, which is emitted to alert other gerbils of a potential threat, and the prosocial contact call, which is emitted near familiar gerbils, especially after separation. Control males, Control females, and ELS females approached a speaker emitting pre-recorded alarm calls, while ELS males avoided this source, suggesting that ELS affects the response to alarm calls in male gerbils. During playback of the pre-recorded contact call, Control females and ELS males avoided the sound source, while Control males neither approached nor avoided, and ELS females approached the sound. These differences cannot be accounted for by changes in locomotion or baseline arousal. However, ELS gerbils slept more during playback, suggesting that ELS may reduce arousal during vocalization playback. Further, male gerbils made more errors than females on a measure of working memory, but the sex difference of cognition in this context may stem from novelty aversion rather than impaired memory. These data indicate that ELS influences behavioral responses to ethologically relevant communication sounds in a sex-specific manner, and are among the first to demonstrate an altered response to auditory stimuli following ELS. Such changes may arise from differences in auditory perception, cognition, or a combination of factors, and suggest that ELS may affect auditory communication in human adolescents.

Sex differences in addiction-relevant behavioral outcomes in rodents following early life stress

In humans, exposure to early life stress (ELS) is an established risk factor for the development of substance use disorders (SUDs) during later life. Similarly, rodents exposed to ELS involving disrupted mother-infant interactions, such as maternal separation (MS) or adverse caregiving due to scarcity-adversity induced by limited bedding and nesting (LBN) conditions, also exhibit long-term alterations in alcohol and drug consumption. In both humans and rodents, there is a range of addiction-related behaviors that are associated with drug use and even predictive of subsequent SUDs. In rodents, these include increased anxiety-like behavior, impulsivity, and novelty-seeking, altered alcohol and drug intake patterns, as well as disrupted reward-related processes involving consummatory and social behaviors. Importantly, the expression of these behaviors often varies throughout the lifespan. Moreover, preclinical studies suggest that sex differences play a role in how exposure to ELS impacts reward and addiction-related phenotypes as well as underlying brain reward circuitry. Here, addiction-relevant behavioral outcomes and mesolimbic dopamine (DA) dysfunction resulting from ELS in the form of MS and LBN are discussed with a focus on age- and sex-dependent effects. Overall, these findings suggest that ELS may increase susceptibility for later life drug use and SUDs by interfering with the normal maturation of reward-related brain and behavioral function.

Distinct neuronal excitability alterations of medial prefrontal cortex in early-life neglect model of rats

OBJECT

Early-life neglect has irreversible emotional effects on the central nervous system. In this work, we aimed to elucidate distinct functional neural changes in medial prefrontal cortex (mPFC) of model rats.

METHODS

Maternal separation with early weaning was used as a rat model of early-life neglect. The excitation of glutamatergic and GABAergic neurons in rat mPFC was recorded and analyzed by whole-cell patch clamp.

RESULTS

Glutamatergic and GABAergic neurons of mPFC were distinguished by typical electrophysiological properties. The excitation of mPFC glutamatergic neurons was significantly increased in male groups, while the excitation of mPFC GABAergic neurons was significant in both female and male groups, but mainly in terms of rest membrane potential and amplitude, respectively.

CONCLUSIONS

Glutamatergic and GABAergic neurons in medial prefrontal cortex showed different excitability changes in a rat model of early-life neglect, which can contribute to distinct mechanisms for emotional and cognitive manifestations.