The Effects of Selective Serotonin Reuptake Inhibitors on Impulsivity in Young Adults with Major Depression in the Early Phase of Treatment. / Majör Depresyonu Olan Genç Eriskinlerde Selektif Serotonin Geri Alim Inhibitörlerinin Tedavinin Erken Döneminde Dürtüsellik Üzerine Etkisi.

OBJECTIVE: Whether selective serotonin reuptake inhibitors (SSRI) increase suicide risk, especially in young adults, is still a controversial issue. This study aimed to examine the change in impulsivity characteristics and to evaluate the relationship between impulsivity and suicidality in young adults with major depression who were started on SSRIs. METHOD: The study included 50 patients between the ages of 18-24 years with a diagnosis of major depression who were planned to start SSRIs. Participants were evaluated with the Beck Depression Scale, Beck Anxiety Scale, Young Mania Rating Scale, Columbia Suicide Severity Rating Scale, Barratt Impulsivity Scale, Daily Impulsivity Scale (DIS), and Go/ No-Go Task (GNG) before and at the end of the first week of treatment. RESULTS: Seventy percent of the patients (n: 35) completed the assessments at baseline and at the end of the first week. At the end of one-week there was a statistically significant decrease in the DIS (t=2.283, p=0.029) and commission errors in GNG (t=3.19, p=0.003). In addition, 7 out of 11 patients who had suicidal ideation at the first evaluation did not continue to have suicidal ideation at the end of the first week and there was a significant decrease in the severity of suicidal ideation at the end of the follow-up (W:132.0, p<0.001). CONCLUSION: One-week SSRI use in young adults resulted in a decrease in impulsivity in self-report scales assessing state impulsivity and in the GNG. It was observed that the severity of suicidal ideation decreased at the end of the one-week treatment period.

On the effects of impulsivity and compulsivity on neural correlates of model-based performance.

Impaired goal-directed behavior is associated with a range of mental disorders, implicating underlying transdiagnostic factors. While compulsivity has been linked to reduced model-based (MB) control, impulsivity has rarely been studied in the context of reinforcement learning despite its links to reward processing and cognitive control. This study investigated the neural mechanisms underlying MB control and the influence of impulsivity and compulsivity, using EEG data from 238 individuals during a two-step decision making task. Single-trial analyses revealed a modulation of the feedback-related negativity (FRN), where amplitudes were higher after common transitions and positive reward prediction error (RPE), indicating a valence effect. Meanwhile, enhanced P3 amplitudes after rare transitions and both positive and negative RPE possibly reflect surprise. In a second step, we regressed the mean b values of the effect of RPE on the EEG signals onto self-reported impulsivity and compulsivity and behavioral MB control (w). The effect of RPE on FRN-related activity was mainly associated with higher w scores, linking the FRN to MB control. Crucially, the modulation of the P3 by RPE was negatively associated with compulsivity, pointing to a deficient mental model in highly compulsive individuals.

ADHD: prevalence and effect on opioid use disorder treatment outcome in a French sample of patients receiving medication for opioid use disorder-the influence of impulsivity as a mediating factor.

BACKGROUND: Opioid use disorder (OUD) poses a global health challenge, and despite medications for opioid use disorder (MOUD) and psychosocial interventions, relapse remains a significant concern. Comorbid psychiatric disorders, including attention deficit hyperactivity disorder (ADHD), are one of the major factors associated with poor OUD treatment outcome. We aimed to estimate the frequency of probable ADHD (in childhood and in adulthood) in patients with OUD; to assess the factors associated with this comorbidity; and to explore the factors that mediate the relationship between ADHD and OUD treatment outcome. METHODS: We conducted an observational study using a sample of 229 patients aged 18 years and older who were diagnosed with OUD and had received MOUD for at least six months. Participants were assessed through a structured interview and self-report questionnaires. Multivariate logistic regressions and a mediation analysis were performed. RESULTS: Almost half of the participants reported probable ADHD in childhood, and ADHD persisted into adulthood among two-thirds of the patients. The factors associated with poor OUD treatment outcome included earlier onset of OUD, lower education, and greater impulsivity. There was no direct effect of probable ADHD in childhood on OUD treatment outcome, but there was an indirect effect through negative urgency, the tendency to respond impulsively to negatively connoted emotional experiences. CONCLUSIONS: The findings suggest that ADHD symptoms, particularly impulsivity, may contribute to vulnerability in opioid use and play a crucial role in treatment outcomes for this population. TRIAL REGISTRATION: ClinicalTrials identifier NCT01847729.

Sleepiness in retired male boxers: daytime sleepiness and its relationship with impulsiveness and depression symptomatology in retired professional male boxers.

BACKGROUND: Boxing exposes fighters to head impacts and potential traumatic brain injury (TBI). Though research has explored the neuropsychiatric consequences of contact sports, there is limited research into Excessive Daytime Sleepiness (EDS) and its relationship to other outcomes, such as impulsiveness and depression. Therefore, this study aimed to describe EDS in retired boxers using the Epworth Sleepiness Scale (ESS) and to examine how boxing and sleepiness relate to impulsiveness and depression symptomatology. METHODS: 86 male retired professional boxers from the Professional Fighters Brain Health Study (PFBHS) met the inclusion criteria. Adjusted multivariable models analyzed relationships between professional boxing bouts, EDS (ESS), impulsiveness (Barratt Impulsiveness Scale Version 11 (BIS-11)), and/or depression (Patient Health Questionnaire-9 (PHQ-9)). A causal mediation analysis was performed to assess whether boxing bouts and ESS scores predicted BIS-11 and PHQ-9 scores. RESULTS: Mean age was ∼51 years, fighters averaged ∼36 professional bouts, and ESS mean(SD) was 7.5(5.3). ESS scores were significantly associated with raw BIS-11 (Beta = 1.26, 95%CI = 0.77-1.75, p < 0.001) and ordinal PHQ-9 (OR = 1.20, 95%CI = 1.11-1.31, p < 0.001) scores in adjusted models, and the significant relationship between boxing bouts and BIS-11/PHQ-9 was mediated by ESS. CONCLUSIONS: EDS in retired male professional boxers may be strongly associated with other neuropsychiatric sequelae of TBI (impulsiveness and depression).Sleepiness; sleep; boxing; contact sports; impulsiveness; impulsivity; depression; Epworth sleepiness scale box.

Relating distractor suppression to problematic drinking behavior.

BACKGROUND: Impaired cognitive control has been linked to weakened self-regulatory processes underlying compulsive substance intake. Previous research has provided evidence for impaired task performance in substance-abusing groups during Stroop and Go/No-Go tasks. Mechanisms of distractor suppression in visual search might also involve overlapping regulatory components that support goal-directed behavior by resolving the attentional competition between distractors and the target of search. However, the efficiency of learning-dependent distractor suppression has not been examined in the context of drug abuse and a direct comparison between cognitive control and distractor suppression is lacking. METHOD: A total of 84 participants were assigned either to the heavy drinking group (ALC, n = 42) or the control group (CTL, n = 42) based on self-reported substance use. Participants completed the Alcohol Use Disorders Identification Test (AUDIT) and Barratt Impulsiveness Scale (BIS). After that, participants completed a computerized version of the Stroop task, Go/No-go task, and a visual search task measuring learning-dependent distractor suppression. RESULTS: The Stroop effect and the frequency of no-go errors did not differ between groups. However, learned distractor suppression was significantly blunted in the ALC group compared to the control group. Across participants, performance on the Stroop and Go/No-go task were correlated, while the magnitude of distractor suppression was related to neither. CONCLUSIONS: Our findings support a divergence of mechanistic processes underlying cognitive control and attentional control, and demonstrate impaired learning-dependent distractor suppression in heavy drinkers relative to a control group. Impaired distractor suppression offers new insight into why drug cues can be difficult to ignore.

Statistical predictors of the co-occurrence between gambling disorder and problematic pornography use.

Co-occurrence between gambling disorder (GD) and other mental disorders is common, but its association with problematic pornography use (PPU) remains unexplored. This study aimed to investigate relationships between sociodemographic variables, personality measures, psychopathology, emotional regulation, and impulsivity and the co-occurrence of GD and PPU using structural equation modeling (SEM). The sample consisted of 359 adults seeking treatment for GD. The short version of the Problematic Pornography Consumption Scale (PPCS-6) identified patients with GD + PPU. Psychopathology, impulsivity, emotional regulation, and personality were also assessed. Higher impulsivity levels statistically predicted co-occurrence between GD and PPU. Impulsivity mediated the relationship between younger age, maladaptive personality features, and emotional dysregulation and co-occurrence. Psychopathological distress did not directly associate with GD + PPU co-occurrence. Impulsivity relates importantly to the co-occurrence of GD and PPU. Younger age, maladaptive personality, and emotional dysregulation contribute to increased impulsivity levels and co-occurrence. The findings highlight the importance of addressing impulsivity in understanding and treating co-occurring GD and PPU.

Impulsivity as a predictor of clinical and psychological outcomes in a naturalistic prospective cohort of subjects at ultra-high risk (UHR) for psychosis from Tunisia.

BACKGROUND: Impulsivity is associated with serious detrimental consequences on physical, mental, behavioral and social aspects of health among patients with psychosis. The present prospective 12-month follow-up study aimed to determine the prevalence of highly impulsive individuals among Ultra High Risk (UHR) patients, how impulsivity evolves over the follow-up period, and whether impulsivity impacts clinical, psychological and functional outcomes in this population. METHOD: UHR patients were invited to complete a battery of measurements at three-time points: at baseline, and at 6 and 12 months of follow-up. Impulsivity was assessed using both behavioral (the Wisconsin Card Sorting Test, WCST) and self-report (the Barratt Impulsiveness Scale, BIS-11) measures. RESULTS: Findings showed that at 6 months of follow-up, higher 6-month BIS-11 attentional and motor impulsivity were significantly associated with lower quality of life and greater general psychological distress. In addition, higher baseline BIS-11 motor impulsivity significantly predicted more severe positive psychotic symptoms at 12 months of follow-up. However, WCST scores did not show any significant associations with study variables at the different times of follow-up. CONCLUSION: Interventions targeting impulsivity in UHR individuals could help decrease psychological distress and positive psychotic symptoms' severity, as well as improve quality of life in UHR individuals.

The association between aggressive behaviour and non-suicidal self-injury and shared risk factors in adults with mild intellectual disability.

BACKGROUND: Aggressive behaviour (AB) and non-suicidal self-injury (NSSI) are common in people with mild intellectual disability or borderline intellectual functioning, leading to adverse consequences for themselves and those around them. METHOD: We investigated the relationship between AB (both total and physical in particular) and NSSI and risk factors in 125 residents in a treatment clinic using incident reports and standard clinical measurements. RESULTS: There was a weak correlation between AB and NSSI, as well as between impulsivity and total AB, and between coping and AB and NSSI. However, NSSI, impulsivity and coping skills did not predict AB. CONCLUSION: Results do not corroborate those of other studies in this area. In future studies impulsivity, coping, aggression and NSSI may be measured using other instruments, and differences between people with and without intellectual disability regarding these variables may be explored.

Triple network resting-state functional connectivity patterns of alcohol heavy drinking.

AIMS: Previous neuroimaging research in alcohol use disorder (AUD) has found altered functional connectivity in the brain's salience, default mode, and central executive (CEN) networks (i.e. the triple network model), though their specific associations with AUD severity and heavy drinking remains unclear. This study utilized resting-state fMRI to examine functional connectivity in these networks and measures of alcohol misuse. METHODS: Seventy-six adult heavy drinkers completed a 7-min resting-state functional MRI scan during visual fixation. Linear regression models tested if connectivity in the three target networks was associated with past 12-month AUD symptoms and number of heavy drinking days in the past 30 days. Exploratory analyses examined correlations between connectivity clusters and impulsivity and psychopathology measures. RESULTS: Functional connectivity within the CEN network (right and left lateral prefrontal cortex [LPFC] seeds co-activating with 13 and 15 clusters, respectively) was significantly associated with AUD symptoms (right LPFC: ß = .337, p-FDR = .016; left LPFC: ß = .291, p-FDR = .028) but not heavy drinking (p-FDR > .749). Post-hoc tests revealed six clusters co-activating with the CEN network were associated with AUD symptoms-right middle frontal gyrus, right inferior parietal gyrus, left middle temporal gyrus, and left and right cerebellum. Neither the default mode nor the salience network was significantly associated with alcohol variables. Connectivity in the left LPFC was correlated with monetary delay discounting (r = .25, p = .03). CONCLUSIONS: These findings support previous associations between connectivity within the CEN network and AUD severity, providing additional specificity to the relevance of the triple network model to AUD.

Relationship between bullying victimization and murderous behaviors and impulsivity's mediating role: Evidence from Chinese early adolescents.

BACKGROUND: Evidence suggests a robust relationship between experiencing bullying victimization (BV) and engaging in murderous behaviors among adolescents. However, the potential mediating effect of impulsivity on the relationship between BV and murderous behaviors in early adolescents remains underexplored. METHODS: A total of 5724 adolescents, with a mean age of 13.5 years, were enrolled from three middle schools in Anhui Province, China. Participants completed self-report questionnaires detailing their experiences with bullying, impulsiveness, and murderous behaviors. To assess the relationship between BV and murderous behaviors, multivariate logistic regression and Poisson regression analyses were conducted. Mediation analysis was performed using structural equation modeling. RESULTS: After controlling for confounding factors, a positive association was found between experiencing BV and engaging in murderous behaviors (p < 0.05). Mediation analysis revealed a significant indirect effect of BV on the occurrence of murderous behaviors through impulsivity (indirect effect = 0.027, 95 % CI: 0.021, 0.033). BV appears to heighten levels of impulsivity, which in turn increases the likelihood of murderous behaviors. Additionally, sex-specific analysis indicated that impulsivity played a greater mediating role in the link between verbal and relational BV and murderous behaviors in females, while physical and cyber BV were more significant in males. CONCLUSIONS: Our findings underscore the necessity of early targeted interventions for adolescents experiencing BV and exhibiting high levels of impulsivity to mitigate their risk of engaging in murderous behaviors.

Personalizing driver safety interfaces via driver cognitive factors inference.

Recent advances in AI and intelligent vehicle technology hold the promise of revolutionizing mobility and transportation through advanced driver assistance systems (ADAS). Certain cognitive factors, such as impulsivity and inhibitory control have been shown to relate to risky driving behavior and on-road risk-taking. However, existing systems fail to leverage such factors in assistive driving technologies adequately. Varying the levels of these cognitive factors could influence the effectiveness and acceptance of ADAS interfaces. We demonstrate an approach for personalizing driver interaction via driver safety interfaces that are are triggered based on the inference of the driver's latent cognitive states from their driving behavior. To accomplish this, we adopt a data-driven approach and train a recurrent neural network to infer impulsivity and inhibitory control from recent driving behavior. The network is trained on a population of human drivers to infer impulsivity and inhibitory control from recent driving behavior. Using data collected from a high-fidelity vehicle motion simulator experiment, we demonstrate the ability to deduce these factors from driver behavior. We then use these inferred factors to determine instantly whether or not to engage a driver safety interface. This approach was evaluated using leave-one-out cross validation using actual human data. Our evaluations reveal that our personalized driver safety interface that captures the cognitive profile of the driver is more effective in influencing driver behavior in yellow light zones by reducing their inclination to run through them.

The computational and neural substrates of individual differences in impulsivity under loss framework.

Numerous neuroimaging studies have identified significant individual variability in intertemporal choice, often attributed to three neural mechanisms: (1) increased reward circuit activity, (2) decreased cognitive control, and (3) prospection ability. These mechanisms that explain impulsivity, however, have been primarily studied in the gain domain. This study extends this investigation to the loss domain. We employed a hierarchical Bayesian drift-diffusion model (DDM) and the inter-subject representational similarity approach (IS-RSA) to investigate the potential computational neural substrates underlying impulsivity in loss domain across two experiments (n = 155). These experiments utilized a revised intertemporal task that independently manipulated the amounts of immediate and delayed-loss options. Behavioral results demonstrated positive correlations between the drift rate, measured by the DDM, and the impulsivity index K in Exp. 1 (n = 97) and were replicated in Exp. 2 (n = 58). Imaging analyses further revealed that the drift rate significantly mediated the relations between brain properties (e.g., prefrontal cortex activations and gray matter volume in the orbitofrontal cortex and precuneus) and K in Exp. 1. IS-RSA analyses indicated that variability in the drift rate also mediated the associations between inter-subject variations in activation patterns and individual differences in K. These findings suggest that individuals with similar impulsivity levels are likely to exhibit similar value processing patterns, providing a potential explanation for individual differences in impulsivity within a loss framework.

Involvement of posterior hypothalamic CaMKII-positive neurons in ADHD-like behaviors in mice.

This study explores the behavioral effects of modulating CaMKII-positive (CaMKII+) neurons in the posterior hypothalamus (PH). Utilizing a chemogenetic approach in mice, we discovered that the activation of CaMKII + neurons within the PH is associated with heightened locomotor activity, reduced social interaction, and impulsive behavior unrelated to anxiety or avoidance. These observed behaviors share a significant resemblance with characteristics commonly found in attention deficit and hyperactivity disorder (ADHD). Notably, treatment with clonidine, which is frequently prescribed for ADHD, effectively reduced impulsive behaviors in our mouse model. Our findings uncover the role of the PH that has not been previously explored and suggest a possible involvement of the PH in the manifestation of ADHD-like behaviors.

Aberrant glutamatergic systems underlying impulsive behaviors: Insights from clinical and preclinical research.

Impulsivity is a broad construct that often refers to one of several distinct behaviors and can be measured with self-report questionnaires and behavioral paradigms. Several psychiatric conditions are characterized by one or more forms of impulsive behavior, most notably the impulsive/hyperactive subtype of attention-deficit/hyperactivity disorder (ADHD), mood disorders, and substance use disorders. Monoaminergic neurotransmitters are known to mediate impulsive behaviors and are implicated in various psychiatric conditions. However, growing evidence suggests that glutamate, the major excitatory neurotransmitter of the mammalian brain, regulates important functions that become dysregulated in conditions like ADHD. The purpose of the current review is to discuss clinical and preclinical evidence linking glutamate to separate aspects of impulsivity, specifically motor impulsivity, impulsive choice, and affective impulsivity. Hyperactive glutamatergic activity in the corticostriatal and the cerebro-cerebellar pathways are major determinants of motor impulsivity. Conversely, hypoactive glutamatergic activity in frontal cortical areas and hippocampus and hyperactive glutamatergic activity in anterior cingulate cortex and nucleus accumbens mediate impulsive choice. Affective impulsivity is controlled by similar glutamatergic dysfunction observed for motor impulsivity, except a hyperactive limbic system is also involved. Loss of glutamate homeostasis in prefrontal and nucleus accumbens may contribute to motor impulsivity/affective impulsivity and impulsive choice, respectively. These results are important as they can lead to novel treatments for those with a condition characterized by increased impulsivity that are resistant to conventional treatments.

Longitudinal examination of marijuana use and physical teen dating violence: Antisocial peers and impulsivity as mediators.

BACKGROUND: Prior studies have shown that marijuana use is often associated with physical teen dating violence. However, few studies have examined the longitudinal mediating effects of associating with antisocial peers and impulsivity on this relationship. Also, few studies have estimated the cascading developmental impact of marijuana use and antisocial peer association, predicting the continued marijuana use and antisocial peer associations while considering the risk of impulsivity in physical teen dating violence. Thus, the current study utilized the problem behavior theory and an alternative path to physical dating violence to address these limitations. OBJECTIVE: The current study tested the longitudinal effects of marijuana use on physical teen dating violence and the indirect effects of antisocial peer association and impulsivity on this relationship (M = 12.29); 52.1 % of males and 47.9 % of females participated. METHODS: Adolescents completed questionnaires at baseline and were assessed six months later (n = 836). Generalized structural equation modeling (GSEM) and cross-lagged mediation models were used first to analyze the direct effect of lifetime marijuana use on physical dating violence and antisocial peer association and impulsivity as potential mediators of this relationship. Then, the cross-lagged mediation models were used to estimate the alternative path to physical teen dating violence using lifetime marijuana use and antisocial peer association as predictors at baseline and continued antisocial peer association, marijuana use, and impulsivity at the subsequent wave as mediators. RESULTS: Results suggested that marijuana use at baseline was not positively associated with physical teen dating violence over time. The association with antisocial peers but not impulsivity mediated the relationship between marijuana use and physical dating violence. Cross-lagged mediation results suggested that marijuana use at baseline positively predicted antisocial peer association in the subsequent wave, which led to an increase in physical teen dating violence. Further, antisocial peer association at baseline is positively associated with continued antisocial peer association at the subsequent wave; thus, antisocial peer association is positively related to physical teen dating violence when controlling for depressive symptoms, family support, number of dates, and parental monitoring. CONCLUSION: These results suggest though marijuana use alone is not statistically associated with physical teen dating violence, it does increase the risk of antisocial social peer associations that could increase adolescents' likelihood to engage in physical teen dating violence. Further, the onset of antisocial peer association could persist over time, thus serving as a risk factor for physical teen dating violence over time.

Psychiatric comorbid disorders and impulsivity in patients with drug-resistant temporal and extra-temporal focal epilepsies.

PURPOSE: To analyze patients with drug-resistant focal epilepsy from temporal (TLE) and extra-temporal origin (ETE) and to compare the prevalence of psychiatric comorbid disorders and impulsivity between them and a control group. METHODS: Consecutively studied patients with TLE and ETE confirmed with Video-EEG were included. Standardized psychiatric assessment was conducted using the Structured Clinical Interview for Axis I and II diagnosis of DSM-IV (SCID I-II), the Barrat-11 scale for impulsivity, and Beck inventory for depression. Parametric and nonparametric tests were performed. RESULTS: Seventy-three patients with temporal lobe epilepsy (TLE), 21 extra-temporal epilepsy (ETE) and 58 healthy control subjects were included. Both groups of patients showed a high frequency of Axis I comorbid psychiatric disorders: Depression was the most frequent disorder followed by Anxiety Disorders. Furthermore, Axis II (Personality disorders) were also diagnosed, similarly in both groups of patients (p > 0.05). In addition, both TLE and ETE groups presented higher impulsivity scores compared with the control group (p < 0.01). ETE showed a tendency to a higher impulsivity in the motor factor (p = 0.05). Among patients with TLE, a left laterality of the epileptogenic zone, and the presence of comorbid psychiatric disorders (depression), were found as independent factors associated with higher impulsivity (p < 0.05). CONCLUSION: Comorbid depression associated with higher impulsivity are important issues to consider in behavioral and clinical evaluation of patients with drug-resistant focal epilepsies, with the aim to set up a prompt treatment.

Trait self-control: A Process Model perspective.

What do self-controlled individuals do that distinguishes them from those who are more impulsive? That is, why are some people better able to align their behavior with personal long-term goals despite alternatives that would be more immediately gratifying? To address this question, we use the Process Model of Self-Control [1], which posits that all impulses are generated via a four-stage, recursive process and can be regulated by intentionally intervening at any of these stages. We suggest that this framework illuminates not only individual states of self-control, but also the diverse ways that stable individual differences in self-control can come about.

Vitamin D Status and Behavioral Impulsivity in Anorexia Nervosa: Insights from a Longitudinal Study.

Anorexia nervosa (AN) is a severe psychiatric disorder marked by extreme weight control behaviors and significant impacts on physical and psychosocial health. This study explores the relationship between vitamin D (Vit-D) levels and impulsivity in women with AN. Forty-six cisgender White women participants were assessed upon admission and before discharge from a specialized eating disorder treatment center, with an average duration of 2.5 ± 0.10 months. Methods included self-reported questionnaires and behavioral tasks to measure impulsivity, alongside serum Vit-D levels. Our results showed significant improvements in Vit-D levels and certain impulsivity measures, such as faster reaction times and fewer errors on the go/no-go task, correlating with higher Vit-D levels. However, no significant correlations were found between Vit-D levels and self-reported impulsivity. These findings suggest that adequate Vit-D levels may enhance cognitive functions related to impulse control in AN. Given this study's limitations, including its exclusive focus on women and small sample size, future research should involve larger, more diverse populations and randomized clinical trials to better understand the causal relationships and therapeutic potential of Vit-D in managing AN-related impulsivity.

Effects of a 5-HT4 receptor antagonist in the caudate nucleus on the performance of macaques in a delayed reward task.

Temporal discounting, in which the recipient of a reward perceives the value of that reward to decrease with delay in its receipt, is associated with impulsivity and psychiatric disorders such as depression. Here, we investigate the role of the serotonin 5-HT4 receptor (5-HT4R) in modulating temporal discounting in the macaque dorsal caudate nucleus (dCDh), the neurons of which have been shown to represent temporally discounted value. We first mapped the 5-HT4R distribution in macaque brains using positron emission tomography (PET) imaging and confirmed dense expression of 5-HT4R in the dCDh. We then examined the effects of a specific 5-HT4R antagonist infused into the dCDh. Blockade of 5-HT4R significantly increased error rates in a goal-directed delayed reward task, indicating an increase in the rate of temporal discounting. This increase was specific to the 5-HT4R blockade because saline controls showed no such effect. The results demonstrate that 5-HT4Rs in the dCDh are involved in reward-evaluation processes, particularly in the context of delay discounting, and suggest that serotonergic transmission via 5-HT4R may be a key component in the neural mechanisms underlying impulsive decisions, potentially contributing to depressive symptoms.