Neural deficits in anticipatory and consummatory reward processing are uniquely associated with current depressive symptoms during adolescence.

Deficits within the consummatory phase of reward processing are associated with increased depression symptoms and risk; however, few studies have also examined other aspects of reward processing in relation to depression. In the current study, a community sample of 121 adolescents (Mage  = 13.1, Min = 11.14; Max = 15.12; 54% male) completed self-report questionnaires to assess depressive symptoms and the monetary incentive delay (MID) task while EEG was recorded. Results indicated that a reduced cue-P300 as well as a reduced reward positivity (RewP) and feedback negativity (FN) to gain and loss feedback, respectively, were associated with increased depressive symptoms; on the other hand, SPN and feedback P300 were unrelated to depressive symptoms. An exploratory multiple regression analysis revealed that a reduced money cue-P300, a reduced RewP, and a reduced (i.e., less negative) FN, all explained unique variance in depressive symptoms. The current study demonstrates that reduced cue-P300, RewP, and FN amplitudes may reflect distinct deficits in reward processing among adolescents with increased depressive symptoms. Notably, this study is one of the first to leverage the MID task in adolescents in relation to depressive symptoms, allowing for a more in-depth view of the individual differences in reward processing among adolescents with increased depressive symptomatology.

Error-related brain activity: A time-domain and time-frequency investigation in pediatric obsessive-compulsive disorder.

Increased error-related negativity (ERN), a measure of error monitoring, has been suggested as a biomarker of obsessive-compulsive disorder (OCD). Additional insight into error monitoring is possible using time-frequency decomposition of electroencephalographic (EEG) data, as it allows disentangling the brain's parallel processing of information. Greater error-related theta is thought to reflect an error detection signal, while delta activity may reflect more elaborative post-detection processes (i.e., strategic adjustments). Recent investigations show that decreased error-related alpha may index attentional engagement following errors; additionally, increases and decreases in error-related beta could reflect motor inhibition and motor preparation, respectively. However, time-frequency dynamics of error monitoring in OCD are largely unknown. The present study examined time-frequency theta, delta, alpha and beta power in early adolescents with OCD using a data-driven, cluster-based approach. The aim was to explore electrocortical measures of error monitoring in early adolescents with (n = 27, 15 females) and without OCD (n = 27, 14 females) during an arrowhead version of the flanker task while EEG activity was recorded. Results indicated that the OCD group was characterized by increased ERN and error-related theta, as well as reduced error-related beta power decrease (i.e., greater power) compared to participants without OCD. Greater error-related beta explained variance in OCD over and above the ERN and error-related theta. By examining separate time-frequency measures, the present study provides novel insights into the dynamics of error monitoring, suggesting that pediatric OCD may be characterized by enhanced error monitoring (i.e., greater theta power) and post-error inhibition (i.e., reduced beta power decrease).

Reduced P300 amplitude is consistently associated with trait anhedonia across repeated assessments.

Understanding how event-related potentials (ERPs) change following repeated assessments is critical to advance our understanding of neural mechanisms implicated in psychopathology. Specifically, it is unclear if associations between ERPs and individual differences can be reproduced when repeatedly measured within the same participants, or if clinical characteristics impact ERP trajectories over repeated assessments. The present study assessed P300 amplitude and latency from a flanker task at four time points over one month (M = 7.24 days between assessments [SD = 1.02]) in 79 female undergraduates to examine how P300 amplitude/latency changes across repeated assessments, the presence of associations between within- and between-subjects measures of current depressive symptoms and the P300, and if between-subjects depressive symptoms moderated change in P300 over repeated assessment. Results using multilevel modeling indicated a significant reduction in P300 amplitude and latency across assessments. Individuals with increased trait anhedonia (i.e., between-subjects) exhibited reduced P300 amplitudes across assessments; there were no associations of within-subjects fluctuations in anhedonia symptoms and P300 amplitude across assessments. There was also no interaction between number of assessments and between-subjects anhedonia in relation to P300 amplitude. Unlike anhedonia, between-subjects dysphoria was unrelated to P300. These results demonstrate a relatively specific and consistent association between an attenuated P300 amplitude and trait anhedonia across repeated assessments - data that may further suggest that flanker P300 amplitude reflects hedonic and motivational processes.

Greater Cumulative Lifetime Stressor Exposure Predicts Blunted Reward Positivity in Adolescent Girls Followed for 2 Years.

BACKGROUND: Although research has found that life stress is associated with reward-related brain activity, few studies have examined how cumulative stressors occurring over the entire lifetime affect reward processing during adolescence. METHODS: To address this issue, we investigated how lifetime stressor exposure related to reward processing, indexed by the reward positivity, in 240 adolescent girls between ages 8 and 14 years (mean age = 12.4). Participants were followed for 2 years. They completed a reward task at baseline and follow-up and the Stress and Adversity Inventory at follow-up. RESULTS: As hypothesized, greater lifetime stressor exposure was related to a blunted reward positivity at the follow-up session while controlling for baseline age, baseline reward positivity, and time between assessments. Furthermore, this association was evident for acute but not chronic lifetime stressors. CONCLUSIONS: These data suggest that the development of adaptive reward processing may be adversely affected by experiencing major life stressors. The results may thus have implications for understanding how stressors increase risk for psychopathology, such as major depressive disorder.

Associations of depression severity with heart rate and heart rate variability in young adults across normative and clinical populations.

Limitations of current depression treatments may arise from a lack of knowledge about unique psychophysiological processes that contribute to depression across the full range of presentations. This study examined how individual variations in heart rate (HR) and heart rate variability (HRV) are related to depressive symptoms across normative and clinical populations in 152 young adults (aged 18-35 years). Moderating effects of sex and antidepressant medication status were considered. Electrocardiogram data were collected during "vanilla" baseline and in response to positive and negative emotional cues. Linear regressions and repeated-measures mixed models were used to assess the relationships between Beck Depression Inventory-II (BDI-II) scores, sex, antidepressant use, and cardiovascular outcomes. Baseline models yielded significant main effects of BDI-II and sex on HR and significant interactions between antidepressant medication status and BDI-II on HRV outcomes. The main effects of BDI-II and sex on HR were no longer significant after controlling for cardiorespiratory fitness. Participants who denied current antidepressant use (n = 137) exhibited a negative association and participants who endorsed current antidepressant (n = 15) use exhibited a positive association between BDI-II scores and HRV. Emotional reactivity models were largely non-significant with the exception of a significant main effect of antidepressant medication status on high-frequency HRV reactivity. Results indicated antidepressant medication use may moderate the relationship between depression severity and cardiovascular functioning, but this requires replication given the modest proportion of medicated individuals in this study. Overall, findings suggest cardiovascular processes and cardiorespiratory fitness are linked to depression symptomatology and may be important to consider in depression treatment.

Lower resting cardiac autonomic balance in young adults with current major depression.

Research on cardiac autonomic function in major depressive disorder (MDD) has predominantly examined cardiac vagal control and adopted a model of reciprocal autonomic balance. A proposed bivariate autonomic continuum uses cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR) models, derived from normalized values of respiratory sinus arrhythmia and pre-ejection period, to more adequately index patterns of autonomic control. The purpose of this study was to assess resting levels of CAB and CAR among young adults with and without a current diagnosis of major depression. One hundred forty-two young adults (n = 65 MDD, n = 77 healthy controls; 20.8 ± 2.6 years) completed a structured diagnostic interview, cardiovascular assessment, and a maximal aerobic fitness test. The findings revealed that CAB, but not CAR, significantly predicted current MDD status (OR = 0.70, 95% CI [0.53, 0.93]), an effect that remained after controlling for aerobic fitness and body mass index. Although CAB was found to be a significant predictor of current MDD status among a sample of young adults, there remained substantial variation in autonomic control that was not captured by the traditional model of reciprocal autonomic balance.

Using Multilevel Modeling to Examine Blunted Neural Responses to Reward in Major Depression.

BACKGROUND: Major depressive disorder (MDD) is a pernicious disorder characterized by deficits in reward processing. A better understanding of these deficits may help to elucidate the underlying pathophysiology and guide treatment development. METHODS: This study assessed reward positivity and feedback negativity event-related potentials and their difference scores elicited in response to monetary gains and losses among 100 young adults (52 with MDD). Multilevel modeling was used to assess individual- and trial-level change in neural responses over time. RESULTS: Trial-level analyses indicated that a diagnosis of MDD and depressive symptom severity significantly moderated the trajectory of reward positivity, with individuals with higher symptoms of depression demonstrating less sensitivity to rewards over time. CONCLUSIONS: These results provide further support for reward dysfunction in MDD and highlight important individual differences in the trajectory of neural responses to reward. Future studies are warranted to investigate reward sensitivity over time to elucidate important individual- and trial-level differences in reward processing.

A history of sport-related concussion is associated with sustained deficits in conflict and error monitoring.

Previous research has demonstrated long-term deficits in neurocognitive function in individuals with a history of sport-related concussion. The purpose of this study was to examine the relationship between a history of concussion and behavioral and event-related potential (ERP) indices of pre- and post-response conflict and error monitoring. A secondary aim was to determine whether years of high risk sport participation were related to impairments in these cognitive control processes. Forty-seven former athletes (age = 20.8 ±â€¯2.2 years) with (n = 25; 5 females) and without (n = 22; 9 females) a history of concussion completed a modified flanker task while behavioral performance, N2, error-related negativity (ERN), and error positivity (Pe) components were assessed. An increase in post-response error-related (ERN) brain activity and a nonsignificant trend of increased pre-response conflict (N2) was observed in individuals with a prior sport-related concussion relative to non-concussed controls; however, no behavioral performance differences were found between groups. No significant associations were found between ERP and behavioral measures and the number of years of high-risk sport participation; however, time since last head injury was associated with shorter N2 latency. Together, these findings suggest a persistent impairment in cognitive control and error-related processing in individuals with a history of concussion. These findings are interpreted within the framework of the compensatory error-monitoring hypothesis.

Do sport-related concussions result in long-term cognitive impairment? A review of event-related potential research.

Sport-related concussions have become a major public health concern although the long-term effects on cognitive function remain largely unknown. Event-related potentials (ERPs) are ideal for studying the long-term impact of sport-related concussions, as they have excellent temporal precision and provide insight that cannot be obtained from behavioral or neuropsychological measures alone. We reviewed all available published studies that have used stimulus or response-locked ERPs to document cognitive control processes in individuals with a history of concussion. Collectively, cross-sectional evidence suggests consistent reductions in P3 amplitude in previously concussed individuals, as well as a possible impairment in cognitive processing speed (P3 latency) and error monitoring processes (ERN). The persistent neurophysiological changes found may be related to the number of previous concussions sustained and the time since injury. Future studies incorporating prospective research designs are warranted before definitive statements can be offered regarding the long-term impact of sport-related concussions on cognitive control.

A randomized trial of aerobic exercise on cognitive control in major depression.

OBJECTIVE: The aim of this study was to examine the effects of an 8-week moderate-intensity aerobic exercise training intervention on cognitive control in individuals with major depressive disorder (MDD). METHODS: Participants with a current diagnosis of MDD (n=30; 21.1±2.0years) were stratified by depressive symptoms and randomized to an 8-week intervention of aerobic exercise (AE) or placebo exercise (PE). AE consisted of three sessions/week of moderate-intensity exercise training while PE consisted of three sessions/week of light-intensity stretching. Cognitive control was assessed pre- and post-treatment using behavioral performance (i.e., reaction time and accuracy) and event-related potentials (i.e., N2 amplitude). Depressive symptoms and rumination were also assessed before and after the intervention. RESULTS: Compared with PE, the AE treatment arm was associated with an increase in N2 amplitude to incongruent flanker task trials, reflecting an increase in cognitive control processes. Symptoms of depression also decreased after AE although the treatments did not differ in their effects on rumination. Exploratory mediation analysis indicated that changes in N2 amplitude did not mediate pre-to-post treatment reductions in depressive symptoms. CONCLUSIONS: An 8-week moderate-intensity AE program is associated with improved neural indices of conflict monitoring and reduced depressive symptoms among individuals with MDD. SIGNIFICANCE: Future research examining the influence of exercise in combination with behavioral and pharmacological treatments for neurocognitive function in MDD is warranted.

Active Workstations Do Not Impair Executive Function in Young and Middle-Age Adults.

PURPOSE: This study aimed to examine the effects of self-selected low-intensity walking on an active workstation on executive functions (EF) in young and middle-age adults. METHODS: Using a within-subjects design, 32 young (20.6 ± 2.0 yr) and 26 middle-age (45.6 ± 11.8 yr) adults performed low-intensity treadmill walking and seated control conditions in randomized order on separate days, while completing an EF test battery. EF was assessed using modified versions of the Stroop (inhibition), Sternberg (working memory), Wisconsin Card Sorting (cognitive flexibility), and Tower of London (global EF) cognitive tasks. Behavioral performance outcomes were assessed using composite task z-scores and traditional measures of reaction time and accuracy. Average HR and step count were also measured throughout. RESULTS: The expected task difficulty effects were found for reaction time and accuracy. No significant main effects or interactions as a function of treadmill walking were found for tasks assessing global EF and the three individual EF domains. Accuracy on the Tower of London task was slightly impaired during slow treadmill walking for both age-groups. Middle-age adults displayed longer planning times for more difficult conditions of the Tower of London during walking compared with sitting. A 50-min session of low-intensity treadmill walking on an active workstation resulted in accruing approximately 4500 steps. CONCLUSIONS: These findings suggest that executive function performance remains relatively unaffected while walking on an active workstation, further supporting the use of treadmill workstations as an effective approach to increase physical activity and reduce sedentary time in the workplace.

Dose-Response and Time Course Effects of Acute Resistance Exercise on Executive Function.

The purpose of this study was to examine possible dose-response and time course effects of an acute bout of resistance exercise on the core executive functions of inhibition, working memory, and cognitive flexibility. Twenty-eight participants (14 female; Mage = 20.5 ± 2.1 years) completed a control condition and resistance exercise bouts performed at 40%, 70%, and 100% of their individual 10-repetition maximum. An executive function test battery was administered at 15 min and 180 min postexercise to assess immediate and delayed effects of exercise on executive functioning. At 15 min postexercise, high-intensity exercise resulted in less interference and improved reaction time (RT) for the Stroop task, while at 180 min low- and moderate-intensity exercise resulted in improved performance on plus-minus and Simon tasks, respectively. These findings suggest a limited and task-specific influence of acute resistance exercise on executive function in healthy young adults.

Neurophysiological and behavioral correlates of cognitive control during low and moderate intensity exercise.

The aim of this study was to examine neurophysiological and behavioral correlates of cognitive control elicited by a modified flanker task while exercising at low and moderate intensities. A secondary aim was to examine cognitive control processes at several time points during an acute bout of exercise to determine whether cognition is selectively influenced by the duration of exercise. Twenty-seven healthy participants completed a modified version of the Eriksen flanker task while exercising on a cycle ergometer at 40% and 60% VO2 peak and during a no-exercise seated control across three separate days. During task performance, continuous EEG was collected to assess neurocognitive function using the N2 and P3 event-related brain potentials (ERPs). Neurocognitive performance was assessed at 5, 15, and 25min time points during steady-state exercise. Regardless of intensity, behavioral findings revealed impaired accuracy during both exercise conditions for the flanker task trials that require greater cognitive control. However, faster reaction times were found during moderate-intensity exercise. Neuroelectric measures revealed increased N2 and P3 amplitudes during both exercise conditions relative to rest. Together, these findings suggest divergent effects of exercise on behavioral performance measures accompanied by an upregulation of cognitive control during aerobic exercise. These impairments are discussed in terms of dual-task paradigms and the transient hypofrontality theory.

Rumination in major depressive disorder is associated with impaired neural activation during conflict monitoring.

Individuals with major depressive disorder (MDD) often ruminate about past experiences, especially those with negative content. These repetitive thoughts may interfere with cognitive processes related to attention and conflict monitoring. However, the temporal nature of these processes as reflected in event-related potentials (ERPs) has not been well-described. We examined behavioral and ERP indices of conflict monitoring during a modified flanker task and the allocation of attention during an attentional blink (AB) task in 33 individuals with MDD and 36 healthy controls, and whether their behavioral performance and ERPs varied with level of rumination. N2 amplitude elicited by the flanker task was significantly reduced in participants with MDD compared to healthy controls. Level of self-reported rumination was also correlated with N2 amplitude. In contrast, P3 amplitude during the AB task was not significantly different between groups, nor was it correlated with rumination. No significant differences were found in behavioral task performance measures between groups or by rumination levels. These findings suggest that rumination in MDD is associated with select deficits in cognitive control, particularly related to conflict monitoring.