Executive functions and borderline personality features in adolescents with major depressive disorder.

Background: Executive functions (EF) consolidate during adolescence and are impaired in various emerging psychiatric disorders, such as pediatric Major Depressive Disorder (pMDD) and Borderline Personality Disorder. Previous studies point to a marked heterogeneity of deficits in EF in pMDD. We examined the hypothesis that deficits in EF in adolescents with pMDD might be related to comorbid Borderline Personality features (BPF). Methods: We examined a sample of 144 adolescents (15.86 ± 1.32) diagnosed with pMDD. Parents rated their child's EF in everyday life with the Behavior Rating Inventory of Executive Function (BRIEF) and BPF with the Impulsivity and Emotion Dysregulation Scale (IED-27). The adolescents completed equivalent self-rating measures. Self- and parent-ratings of the BRIEF scores were compared with paired t-Tests. Correlation and parallel mediation analyses, ICC, and multiple regression analyses were used to assess symptom overlap, parent-child agreement, and the influence of depression severity. Results: Over the whole sample, none of the self- or parent-rated BRIEF scales reached a mean score above T > 65, which would indicate clinically impaired functioning. Adolescents tended to report higher impairment in EF than their parents. Depression severity was the strongest predictor for BPF scores, with Emotional Control predicting parent-rated BPF and Inhibit predicting self-rated BPF. Furthermore, the Behavioral Regulation Index, which includes EF closely related to behavioral control, significantly mediated the relationship between depression severity and IED-27 factors emotional dysregulation and relationship difficulties but not non-suicidal self-injuries. Conclusion: On average, adolescents with depression show only subtle deficits in executive functioning. However, increased EF deficits are associated with the occurrence of comorbid borderline personality features, contributing to a more severe overall psychopathology. Therefore, training of executive functioning might have a positive effect on psychosocial functioning in severely depressed adolescents, as it might also improve comorbid BPF. Clinical trial registration: www.ClinicalTrials.gov, identifier NCT03167307.

Sleep disturbance, but not depression severity, is associated with inflammation in children and adolescents.

STUDY OBJECTIVES: We aimed to examine the association between self-rated and clinician-rated sleep disturbances and C-reactive protein (CRP), an objective marker of inflammation, in pediatric depression. METHODS: Two hundred fifty-six children and adolescents (15.2 ± 1.6 y, 72.3% female) with moderate to severe symptoms of depression participated in the study. Sleep disturbances were assessed by self-reports (Insomnia Severity Index) and clinician ratings (Kiddie-Schedule for Affective Disorder and Schizophrenia), inflammation by plasma CRP levels. RESULTS: Higher levels of CRP correlated positively with clinician-rated middle insomnia and hypersomnia. After adjusting for control variables (body mass index, tobacco, alcohol, stress, age, sex, antidepressants, sleep medication, depression severity), regression models confirmed the significant association of clinician-rated hypersomnia and middle insomnia symptoms with elevated CRP levels. In the adjusted regression models, other clinician-rated manifestations of sleep disturbance (eg, initial insomnia) and insomnia self-ratings were not significantly associated with CRP. Body mass index correlated positively with CRP, but body mass index had no mediating effect on the associations between sleep disturbances and CRP. We did not find an association between depression severity, assessed by the Children's Depression Rating Scale-Revised, and CRP. CONCLUSIONS: Results of the present study indicate a significant association of hypersomnia and middle insomnia symptoms with CRP in pediatric depression, not linked to alterations in the body mass index. CITATION: Strumberger MA, Häberling I, Emery S, et al. Sleep disturbance, but not depression severity, is associated with inflammation in children and adolescents. J Clin Sleep Med. 2023;19(10):1775-1784.

Verbal Memory Performance in Depressed Children and Adolescents: Associations with EPA but Not DHA and Depression Severity.

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been described as positively associated with cognitive functioning. Current meta-analyses have identified eicosapentaenoic acid (EPA) as potentially more effective than docosahexaenoic acid (DHA). An especially vulnerable subgroup that might benefit from these beneficial effects are depressed youths. In this study, we examined associations between red blood cell (RBC) DHA and EPA levels and depression severity and verbal memory performance in a sample of 107 moderately (n = 63) and severely (n = 44) depressed youths. The findings showed that youths with high RBC EPA levels had steeper learning curves compared to those with moderate or low RBC EPA levels (Pillai's Trace = 0.195, p = 0.027, ηp2 = 0.097). No associations between RBC DHA levels or depression severity and verbal memory performance were observed. Our results further confirm previous findings indicating a more important role of EPA compared to DHA in relation to cognitive functioning. Future research should further investigate the differential role of EPA and DHA concerning cognitive functioning in depressed youths. Evidence supporting beneficial supplementation effects could potentially establish a recommendation for a natural and easily accessible intervention for cognitive improvement or remission.

When parents and children disagree: Informant discrepancies in reports of depressive symptoms in clinical interviews.

BACKGROUND: Parents and their children often disagree on the existence and severity of psychopathological symptoms, especially in major depressive disorder (MDD). Discrepant estimations pose a problem for the validity of diagnoses and illness severity with major implications for treatment evaluation. METHODS: 118 adolescents aged 13-18 years and their parents were interviewed and their reports were compared regarding the presence of a MDD diagnosis. In addition, severity ratings of depression symptoms reported in the Children's Depression Rating Scale-Revised (CDRS-R) were compared between parents and their offspring using multivariate analyses and polynomial regressions. The association between borderline features, functional impairment, and treatment history variables with parent-child agreement was assessed. RESULTS: In 38% of the cases, parents and adolescents agreed on DSM-IV diagnostic MDD criteria, while in 53%, only the adolescent endorsed criteria for a MDD. A MDD that was endorsed by parents and adolescents was characterized by higher depression severity, higher number of previous treatments, and higher functional impairment. Using a polynomial approach, neither age nor borderline tendencies were associated with agreement. LIMITATIONS: We did not differentiate between mother's versus father's reports and borderline features were assessed by self-report only. CONCLUSIONS: Adolescents and their parents gave differing reports of the existence and severity of depressive symptoms. The high discrepancy levels combined with the uncertainty of previously published findings due to methodological challenges are concerning. Clinicians and researchers need to consider discrepancies in agreement in relation to diagnosis and illness severity in the context of their clinical and research decisions.

Positive urgency partially mediates the relationship between childhood adversity and problems associated with substance use in an undergraduate population.

BACKGROUND: Childhood adversity predicts the development of substance use problems in young adulthood. Building on past work examining the mediating role of impulsivity in the relationship between childhood maltreatment and substance use in alcohol and nicotine users, this study examined the relationship with other substances in a representative undergraduate sample. In addition, the study aimed to determine whether there was convergence in findings between different measures of childhood adversity and impulsivity. METHOD: 309 undergraduate students completed self-report questionnaires assessing childhood adversity (Childhood Trauma Questionnaire - CTQ; Adverse Childhood Experience Scale - ACE), impulsivity (Short UPPS-P; Barratt Impulsivity Scale - BIS-11) and problems associated with substance use (Drug Abuse Screening Test - DAST-10). RESULTS: The SUPPS-P positive urgency facet partially mediated the relationship between CTQ and DAST-10 (b = 0.0039, 95% CI [0.0008, 0.0086]), as well as between ACE and DAST-10 (b = 0.015, 95% CI [0.0014, 0.0446]). The BIS-11 motor facet partially mediated the effect of CTQ on DAST-10 (b = 0.0017, 95% CI [0.0002, 0.0054]). CONCLUSION: Positive urgency partially mediated the relationship between childhood maltreatment and substance use problems for both the CTQ and ACE. While these results are consistent with past studies showing a selective mediation effect of positive urgency in a sample of young adults, they are inconsistent with those showing a selective mediation effect of negative urgency in a sample of heavy drinkers. Together, these findings suggest that the relationship between childhood adversity, impulsivity, and substance use-related problems may be influenced by experience.

Anxious depression as a clinically relevant subtype of pediatric major depressive disorder.

In adults, anxious depression has been identified as a more severe form of major depressive disorder (MDD), associated with higher depression severity, more suicidal ideation and worse treatment outcome. Research in pediatric depression, however, has been sparse. 126 children and adolescents aged 8-18 years with a primary diagnosis of MDD were categorized into a MDD-only group and an anxious depression group based on clinically elevated scores on the Beck Anxiety Inventory. One-third of the sample was classified as having anxious depression with females being overrepresented in the anxious depressed compared to the MDD-only group. 42.2% of the anxious depressed youth met diagnostic criteria for a comorbid anxiety disorder. Anxious depressed youth were more likely to suffer recurrent depressive episodes, showed higher depression severity and a unique pattern of depressive symptoms characterized by more severe sleep problems, more somatic complaints, more severely depressed mood and more frequent suicidal ideations. Scores on a suicidal ideation scale were increased even when controlling for overall depression severity. However, when comparing depressed patients with and without comorbid anxiety disorders, no differences in depression severity, symptom patterns or suicidal ideations were observed. The results indicate that high anxiety levels in depressed youth are clinically relevant, and given the increase in suicidal ideation, anxiety symptoms during depressive episodes should routinely be screened in clinical practice even in the absence of a fully formed comorbid anxiety disorder.

Dissociative effects of dorsomedial striatum D1 and D2 receptor antagonism in the regulation of anxiety and learned approach-avoidance conflict decision-making.

The dorsal striatum is traditionally known for its role in sensorimotor integration. However, the dorsomedial striatum (DMS) has also been implicated in cost-benefit conflict processing, a role more readily attributed to the ventral striatum (VS), as a site of limbic-motor integration. We recently showed that dopaminergic D1 (D1R) and D2 receptors (D2R) in the VS exert dissociable control over cue-elicited approach-avoidance decision-making, in the presence of conflicting motivational stimuli. We therefore sought to investigate the contribution of DMS dopaminergic receptors in the regulation of cue-elicited and innate approach-avoidance decision-making. Using a conditioned mixed-valence conflict paradigm, we trained rats in a three-arm radial maze to associate visuotactile cues with appetitive, aversive, and neutral outcomes. Rats then received an intra-DMS or intra-dorsolateral striatum (DLS) microinfusion of D1-like antagonist (SCH23390) or D2-like antagonist (sulpiride), and were then tested for the expression of approach-avoidance behavior in a conflict scenario, wherein the appetitive and aversive cues were superimposed within a single maze arm. The results revealed that DMS (but not DLS) D1R antagonism, suppressed approach towards the conflict arm while DMS (but not DLS) D2R antagonism enhanced approach. All rats were subsequently administered an elevated plus maze test as a measure of innate approach-avoidance conflict (anxiety). DMS D1R antagonism decreased anxiety, while DMS D2R and both DLS D1R and D2R antagonism increased anxiety. Our findings suggest that under motivational conflict, activation of DMS D1-like receptors facilitates approach, while activation of D2-like receptors suppress approach behavior. Furthermore, anxiety is regulated by dorsal striatal-mediated dopaminergic mechanisms.

Repeated Cocaine Exposure Attenuates the Desire to Actively Avoid: A Novel Active Avoidance Runway Task.

Drug addiction is a disorder in which drug seeking persists despite aversive consequences. While it is well documented in animal models of drug sensitization that repeated drug exposure enhances positive incentive motivation for drug and natural reinforcers, its effect on negative incentive motivation, defined here as the motivation to avoid a cued aversive outcome, remains an open question. In the present study, we designed a novel active avoidance (AA) runway paradigm to assess the effects of repeated cocaine exposure on the motivation to avoid an aversive outcome. Cocaine and saline pre-exposed rats were first trained to perform a conditioned AA lever press response to prevent the occurrence of foot shock administrations. The rats were subsequently tested in a runway apparatus, wherein they were required to traverse the length of a straight alley maze to reach the lever and emit a conditioned AA response. Run times were measured as an indication of negative incentive motivation. Cocaine pre-exposed rats demonstrated longer latencies to emit the conditioned AA response but showed no differences in latency to initiate runway behavior, nor in their acquisition of the AA response compared to the saline pre-exposed controls. Subsequent testing in an elevated plus maze revealed no differences in the expression of anxiety in cocaine pre-exposed rats compared to saline pre-exposed controls. Our results indicate that prior repeated cocaine exposure attenuated cued negative incentive motivation, which suggests that drug addiction may be attributable to a decrease in motivation to avoid aversive consequences associated with drug use.

Dissociable roles of the nucleus accumbens D1 and D2 receptors in regulating cue-elicited approach-avoidance conflict decision-making.

RATIONALE: Approach and avoidance decisions are made when an animal experiences a state of motivational conflict inflicted by stimuli imbued with both positive and negative valences. The nucleus accumbens (NAc), a site where valenced information and action selection converge, has recently been found to be critically involved in the resolution of approach-avoidance conflict. However, the individual roles of the region's dopamine receptor D1 (D1R)- and D2 (D2R)-expressing medium spiny neurons (MSNs) in regulating conflict resolution have not been well established. OBJECTIVES: Here, we examined the roles of NAc D1R and D2R in cue-elicited approach-avoidance decision-making. METHODS: Using a conditioned mixed-valence conflict paradigm, rats were initially trained in a radial maze to associate separate visuotactile cues with sucrose reward, foot shock punishment, and no outcome. Following acquisition of the cue-outcome associations, rats were subjected to a conditioned approach-avoidance conflict scenario, in which they were presented with a maze arm containing a superimposition of the reward and punishment cues, and another arm containing neutral cues. RESULTS: Post-training intra-NAc D1R antagonism (SCH23390) led to an avoidance of the arm containing the mixed-valence cue over the neutral arm, whereas intra-NAc D2R antagonism (sulpiride) resulted in rats exhibiting a preference for the mixed-valence arm. CONCLUSION: Our results suggest that NAc D1R and D2R exert differential control over decision-making involving cue-elicited approach-avoidance conflict resolution.

A study of the effects of maternal high fat diet on behavioural responses to acute and repeated administrations of cocaine in rat offspring.

Building on previous work in the field, we examined the effect of maternal high fat diet (HFD) during gestation and lactation on the sensitivity of male and female adult offspring to acute and repeated cocaine exposures, and to the expression of cocaine-induced anxiety in the elevated plus maze (EPM). In both male and female offspring, acute injections of cocaine induced a strong locomotor-activating effect; repeated injections produced a robust conditioned locomotor response to the context in which they were given cocaine, and heightened activity in response to a subsequent acute challenge of cocaine. Although female offspring of HFD relative to control house chow diet (CHD) dams exhibited a generally elevated level of locomotor activity, this effect was not further enhanced by cocaine administration/s and there were no significant interactions between maternal diet and cocaine in either male or female offspring. Finally, female offspring of HFD relative to CHD dams exhibited enhanced behavioral anxiety in the EPM, an effect that was reversed when the offspring were exposed to cocaine 48 h prior. Although, in contradiction to our hypotheses, the present study failed to demonstrate an effect of maternal diet on the locomotor-activating effects of cocaine, it did replicate all of the established findings upon which its rationale and predictions were based. Thus, we believe that our results provide important context for future studies.

Aberrant approach-avoidance conflict resolution following repeated cocaine pre-exposure.

RATIONALE: Addiction is characterized by persistence to seek drug reinforcement despite negative consequences. Drug-induced aberrations in approach and avoidance processing likely facilitate the sustenance of addiction pathology. Currently, the effects of repeated drug exposure on the resolution of conflicting approach and avoidance motivational signals have yet to be thoroughly investigated. OBJECTIVE: The present study sought to investigate the effects of cocaine pre-exposure on conflict resolution using novel approach-avoidance paradigms. METHODS: We used a novel mixed-valence conditioning paradigm to condition cocaine-pre-exposed rats to associate visuo-tactile cues with either the delivery of sucrose reward or shock punishment in the arms in which the cues were presented. Following training, exploration of an arm containing a superimposition of the cues was assessed as a measure of conflict resolution behavior. We also used a mixed-valence runway paradigm wherein cocaine-pre-exposed rats traversed an alleyway toward a goal compartment to receive a pairing of sucrose reward and shock punishment. Latency to enter the goal compartment across trials was taken as a measure of motivational conflict. RESULTS: Our results reveal that cocaine pre-exposure attenuated learning for the aversive cue association in our conditioning paradigm and enhanced preference for mixed-valence stimuli in both paradigms. CONCLUSIONS: Repeated cocaine pre-exposure allows appetitive approach motivations to gain greater influence over behavioral output in the context of motivational conflict, due to aberrant positive and negative incentive motivational processing.

Potentiation of the expression of cocaine-induced sensitization by a conditioned stressor.

Repeated exposures to physical stressors cross-sensitize to the locomotor activating effects of psychostimulants in rodents. In the present study, we examined the effect of a conditioned stressor on expression of cocaine-induced sensitization in rats. We determined whether a mint odor cue previously paired with footshock stress (FS) would elicit a sensitized locomotor response in cocaine pre-exposed rats. Rats were given once daily injections of cocaine (30 mg/kg, i.p.) or saline for 6 days in activity monitoring chambers. Subsequently, and in a different and distinct context, equal numbers of rats in each drug condition were exposed to 10 min of brief, intermittent FS or no FS, either in the presence or absence of the mint odor cue. Upon re-exposure to the activity chambers (in which cocaine exposures had been given), all rats previously exposed to cocaine showed robust conditioned locomotion. In response to a cocaine challenge (10 mg/kg, i.p.), cocaine relative to saline pre-exposed rats showed a sensitized locomotor response. Finally, in those cocaine pre-exposed rats that had been given prior odor-FS pairings, concurrent delivery of the cocaine challenge and presentation of the odor cue markedly potentiated the expression of sensitization. To our knowledge, this is the first report of a facilitation of cocaine-induced locomotor sensitization by a conditioned stressor.

Repeated intravenous administrations of teneurin-C terminal associated peptide (TCAP)-1 attenuates reinstatement of cocaine seeking by corticotropin-releasing factor (CRF) in rats.

The teneurin c-terminal associated peptides (TCAP) have been implicated in the regulation of the stress response, possibly via a corticotropin-releasing factor (CRF)-related mechanism. We have previously shown that repeated intracerebroventricular (ICV) injections of TCAP-1 attenuate the reinstatement of cocaine seeking by CRF in rats. Here, we determined whether intravenous (IV) administrations of TCAP-1 would likewise attenuate CRF-induced reinstatement, and whether this effect would vary depending on the rat's history of cocaine self administration. Rats were trained to self-administer cocaine for 10 days, during once daily sessions that were either 3h ("short access"; ShA) or 6h ("long access"; LgA). Rats were then given five daily injections of TCAP-1 (0, 300, or 3,000 pmol, IV) in their home cage. Subsequently, they were returned to the self-administration chambers where extinction of cocaine seeking and testing for CRF-induced reinstatement of cocaine seeking was carried out. Repeated IV administrations of TCAP-1 were efficacious in attenuating CRF-induced reinstatement of cocaine seeking, but at different doses in ShA and LgA rats. Taken together, the findings extend previous work showing a consistent effect of repeated ICV TCAP-1 on CRF-induced reinstatement of cocaine seeking, and point to a potential therapeutic benefit of TCAP-1 in attenuating cocaine seeking behaviors.

Cocaine exposure prior to pregnancy alters the psychomotor response to cocaine and transcriptional regulation of the dopamine D1 receptor in adult male offspring.

There is evidence that maternal experience prior to pregnancy can play an important role in behavioral, physiological, and genetic programming of offspring. Likewise, exposure to cocaine in utero can result in marked changes in central nervous system function of offspring. In this study, we examined whether exposure of rat dams to cocaine prior to pregnancy subsequently alters indices of behavior, physiology, and gene expression in offspring. Multiple outcome measures were examined in adult male offspring: (1) behavioral expression of cocaine-induced psychomotor activation; (2) levels of corticosterone in response to immobilization stress; and (3) expression of multiple genes, including dopamine receptor D1 (DRD1) and D2 (DRD2), glucocorticoid receptor (GR), and corticotropin-releasing factor (CRF), in functionally relevant brain regions. Adult Sprague-Dawley females were exposed to cocaine (15-30 mg/kg, i.p.) or saline for 10 days, and were then mated to drug naïve males of the same strain. Separate groups of adult male offspring were tested for their acute psychomotor response to cocaine (0, 15, 30 mg/kg, i.p.), corticosterone responsivity to 20 min of immobilization stress, and expression of multiple genes using quantitative PCR. Offspring of dams exposed to cocaine prior to conception exhibited increased psychomotor sensitivity to cocaine, and upregulated gene expression of DRD1 in the medial prefrontal cortex (mPFC). Neither stress-induced corticosterone levels nor gene expression of GR or CRF genes were altered. These data suggest that cocaine exposure before pregnancy can serve to enhance psychomotor sensitivity to cocaine in offspring, possibly via alterations in dopamine function that include upregulation of the DRD1.

Reinstatement of cocaine seeking in rats by the pharmacological stressors, corticotropin-releasing factor and yohimbine: role for D1/5 dopamine receptors.

RATIONALE: Two pharmacological stressors commonly used in the study of stress-induced reinstatement of drug seeking are central injections of the stress peptide, corticotropin-releasing factor (CRF), and systemic administration of the α(2)-adrenoceptor antagonist, yohimbine. Despite the widespread use of these stressors, the neurochemical systems mediating their ability to reinstate cocaine-seeking behaviour have not been fully characterized. OBJECTIVE: The present study was designed to characterize the role, specifically, of dopamine transmission in the reinstating effects of CRF and yohimbine on cocaine seeking. METHODS: Male Long-Evans rats were trained to self-administer cocaine (0.23 mg/kg/infusion) for 8-10 days. Subsequently, responding for drug was extinguished, and tests for CRF- (0.5 µg; i.c.v.) and yohimbine-induced (1.25 mg/kg; i.p.) reinstatement were conducted following pretreatment with the dopamine D1/5 receptor antagonists, SCH23390 (0.05, 0.1 mg/kg; i.p.) and/or SCH31966 (0.2 mg/kg; i.p.), and the D2/3 receptor antagonist, raclopride (0.25, 0.5 mg/kg; i.p.). RESULTS: Pretreatment with SCH23390, but not raclopride, blocked CRF-induced reinstatement of cocaine seeking. Pretreatment with SCH23390 and SCH31966, but not raclopride, blocked yohimbine-induced reinstatement of cocaine seeking. CONCLUSIONS: These findings demonstrate that transmission at D1/5, but not D2/3, receptors mediates the reinstatement of cocaine seeking induced by CRF and yohimbine.

Expression and resilience of a cocaine-conditioned locomotor response after brief and extended drug-free periods.

Conditioned associations between drug experience and its context are maintained long after drug use ceases, and may contribute to relapse after extended abstinence. These include operantly conditioned associations directed toward seeking drug, but also Pavlovian conditioned associations between drug reward and contextual cues present at the time of drug administration. The present study sought to determine whether expression of a Pavlovian conditioned locomotor (CL) response to a cocaine-associated context increases over time in the same manner observed for instrumental responses, and whether the CL memory is differentially susceptible to extinction and recovery after brief versus extended abstinence. Male rats received injections of cocaine (30mg/kg, i.p.) or vehicle once per day for 6 days. In Exp. 1, CL activity was measured 1, 7, 21, or 42 days later. Rats that had received cocaine injections displayed robust CL, regardless of when testing occurred. In Exp. 2, extinction and recovery of CL were assessed after 1 or 42 days. The CL response was more readily extinguished in rats tested 1 day after drug exposure, as compared to rats tested 42 days later. Exp. 3 confirmed that conditioning in the testing context was necessary for expression of CL. Overall, our results indicate that Pavlovian associations underlying the CL response are maintained long after drug experience. Although the expression of CL does not change with the passage of time, as has been observed for instrumental drug-related responses, the memory trace does appear to become more resilient over time.

Development of a novel, ecologically oriented virtual reality measure of executive function: the Multitasking in the City Test.

A novel virtual reality executive function task (Multitasking in the City Test [MCT]) was developed with the aim of investigating planning and multitasking with ecological validity in mind in a normal population. Thirty healthy participants (21 females) completed a neuropsychological test battery that included the MCT along with standardized tests of executive and other cognitive functions. The sample performed within normal limits on the standardized tests. The MCT was performed successfully, although specific types of errors occurred frequently. Spearman correlation coefficients were computed between the various test measures. Only the plan score from the MCT was significantly associated with one of the executive function tests administered (Modified Six Elements Test), suggesting that both variables may be measuring a similar construct. Statistically significant correlations were also found between the MCT and the Trail-Making Test Part A and Judgment of Line Orientation, suggesting that "basic" cognitive functions such as information-processing speed and visuospatial skills are being tapped on the MCT. Preliminary evidence from this study suggested that the MCT may be an ecologically valid method of evaluating executive functioning. The clinical implications of these findings are discussed.

Ecologically valid assessment of executive dysfunction using a novel virtual reality task in patients with acquired brain injury.

The current investigation sought to further establish the psychometric properties and ecological validity of the Multitasking in the City Test (MCT) in a clinical population. Ecological validity was addressed via correlational analyses between performance on this test and a subjective measure of everyday executive functioning (Frontal Systems Behavior Scale; FrSBe). The sample was composed of 13 individuals (11 males) who suffered a stroke or traumatic brain injury. A neuropsychological test battery consisting of the MCT and common executive and nonexecutive measures was administered. The only executive function tests that were significantly related to the FrSBe were the MCT and a semantic fluency test. Compared with a sample of normal participants, the patient group produced better plans but completed fewer tasks on the MCT. Patients made similar types of errors as normals, although some of these errors occurred more frequently in the patient sample. This study demonstrated the ecological validity of the MCT and suggested that patients can be differentiated from healthy individuals by quantitative (i.e., number of errors) rather than qualitative (i.e., type of errors) aspects of performance. Further interpretation of MCT performance and comparison with existing executive function tests is discussed.

A procedure for studying the footshock-induced reinstatement of cocaine seeking in laboratory rats.

The most insidious aspect of drug addiction is the high propensity for relapse. Animal models of relapse, known as reinstatement procedures, have been used extensively to study the neurobiology and phenomenology of relapse to drug use. Although procedural variations have emerged over the past several decades, the most conventional reinstatement procedures are based on the drug self-administration (SA) model. In this model, an animal is trained to perform an operant response to obtain drug. Subsequently, the behavior is extinguished by withholding response-contingent reinforcement. Reinstatement of drug seeking is then triggered by a discrete event, such as an injection of the training drug, re-exposure to drug-associated cues, or exposure to a stressor. Reinstatement procedures were originally developed to study the ability of acute non-contingent exposure to the training drug to reinstate drug seeking in rats and monkeys. Reinstatement procedures have since been modified to study the role of environmental stimuli, including drug-associated cues and exposure to various forms of stress, in relapse to drug seeking. Over the past 15 years, a major focus of the reinstatement literature has been on the role of stress in drug relapse. One of the most commonly used forms of stress for studying this relationship is acute exposures to mild, intermittent, electric footshocks. The ability of footshock stress to induce reinstatement of drug seeking was originally demonstrated by Shaham and colleagues (1995) in rats with a history of intravenous heroin SA(5). Subsequently, the effect was generalized to rats with histories of intravenous cocaine, methamphetamine, and nicotine SA, as well as oral ethanol SA. Although footshock-induced reinstatement of drug seeking can be achieved reliably and robustly, it is an effect that tends to be sensitive to certain parametrical variables. These include the arrangement of extinction and reinstatement test sessions, the intensity and duration of footshock stress, and the presence of drug-associated cues during extinction and testing for reinstatement. Here we present a protocol for footshock-induced reinstatement of cocaine seeking that we have used with consistent success to study the relationship between stress and cocaine seeking.