Telehealth-Based Contingency Management Targeting Stimulant Abstinence: A Case Series From the COVID-19 Pandemic

OBJECTIVE

Contingency management (CM) is the gold standard treatment for stimulant use disorder but typically requires twice- to thrice-weekly in-person treatment visits to objectively verify abstinence and deliver therapeutic incentives. There has been growing interest in telehealth-based delivery of CM to support broad access to this essential intervention--a need that has been emphatically underscored by the COVID-19 pandemic. Herein, we present observations from initial efforts to develop and test a protocol for telehealth-based delivery of prize-based CM treatment incentivizing stimulant abstinence.

METHOD

Four participants engaged in hybrid courses of CM, including one or more telehealth-based treatment sessions, involving self-administered oral fluid testing to confirm abstinence. Observations from initial participants informed iterative improvements to telehealth procedures, and a 12-week course of telehealth-based CM was subsequently offered to two additional participants to further evaluate preliminary feasibility and acceptability.

RESULTS

In most cases, participants were able to successfully join telehealth treatment sessions, self-administer oral fluid testing, and share oral fluid test results to verify stimulant abstinence. However, further improvements in telehealth-based toxicology testing may be necessary to interpret test results accurately and reliably, especially when colorimetric immunoassay results reflect substance concentrations near the cutoff for point-of-care testing devices.

CONCLUSIONS

Preliminary findings suggest that telehealth-based CM is sufficiently feasible and acceptable to support future development, in particular through improved methods for remote interpretation and verification of test results. This is especially important in CM, wherein accurate and reliable detection of both early and sustained abstinence is crucial for appropriate delivery of therapeutic incentives.

Patients with cocaine use disorder exhibit reductions in delay discounting with episodic future thinking cues regardless of incarceration history

Research examining episodic future thinking (EFT; i.e., imagining oneself in future contexts) in community samples has demonstrated reduced discounting of delayed rewards when personalized event cues are included to prompt EFT related to reward latencies. While this EFT effect was recently demonstrated in individuals with substance use disorders, it is not yet known if it manifests similarly in individuals with and without a significant incarceration history-the latter being at elevated risk for negative outcomes including criminal recidivism. Individuals with cocaine use disorder (n = 35) identified personally-relevant future events and participated in a computerized delay discounting task, involving decisions between smaller immediate rewards or larger delayed rewards with and without EFT cues. Individuals with (n = 19) and without (n = 16) a significant history of incarceration were identified using the Addiction Severity Index-Lite. A significant reduction in discounting rates was observed when event cues were included to promote EFT (p = 0.02); however, there was no main effect of incarceration history on discounting behavior, or interaction between episodic future thinking condition and incarceration history. Results suggest personalized cues included to evoke EFT reduce discounting behavior in individuals with cocaine use disorder, regardless of incarceration history. EFT-based interventions may therefore have promise to reduce impulsive decision-making in individuals with cocaine use disorder with and without a significant history of incarceration, potentially supporting improved outcomes with respect to both substance use and future criminality.

Barriers to Long-acting Injectable Antipsychotic Adherence During the COVID-19 Pandemic: Observations From One Site

OBJECTIVE

Long-acting injectable antipsychotics (LAI-As) are a crucial treatment option for individuals with serious mental illness. However, due to the necessity of in-person administration of LAI-As, pandemics pose unique challenges for continuity of care in the population prescribed these medications. This project investigated the impact of the coronavirus disease 2019 (COVID-19) pandemic on LAI-A adherence at a Veterans Health Administration medical facility in the United States, as well as changes in LAI-A prescribing and administration practices during this period.

METHODS

Electronic health records were evaluated for 101 patients prescribed LAI-As. A subset of 13 patients also participated in an interview and rated subjective concerns about pandemic-related barriers to medication adherence.

RESULTS

Pandemic-related barriers to LAI-A adherence and/or changes to LAI-A medications were documented in 33% of the patients. Within-subjects comparison of an adherence metric computed from electronic health record data further suggested a somewhat higher incidence of missed or delayed LAI-A doses during the pandemic compared with before the pandemic. In contrast, only 2 of the 13 patients interviewed anticipated that pandemic-related concerns would interfere with medication adherence.

CONCLUSIONS

The results of this study suggest that LAI-A access and adherence can be disrupted by pandemics and other public health emergencies but this finding may not generalize to other sites. As patients may not foresee the potential for disruption, psychiatric service providers may need to assist in proactively problem-solving barriers to access. Improved preparedness and additional safeguards against pandemic-related disruptions to LAI-A access and adherence may help mitigate adverse outcomes in the future. Identifying patients at elevated risk for such disruptions may help support these efforts.

Epigenetic Effects in HPA Axis Genes Associated with Cortical Thickness, ERP Components and SUD Outcome

Association between familial loading for alcohol use disorders (AUD) and event-related potentials (ERPs) suggests a genetic basis for these oscillations though much less is known about epigenetic pathways influenced by environmental variation. Early life adversity (ELA) influences negative outcomes much later in life. The stress-activated neuropeptide corticotropin-releasing hormone (CRH) contributes to the deleterious effects of ELA on brain structure and function in animals. Accordingly, we hypothesized that ELA would be related to cortical thickness and electrophysiological characteristics through an epigenetic effect on CRH receptor type-1 (CRHR1) methylation. A total of 217 adolescent and young adult participants from either multiplex alcohol dependence or control families were scanned using magnetic resonance imaging (MRI) at 3T and cortical thickness was determined. Longitudinal follow-up across childhood, adolescence, and young adulthood provided developmental ERP data and measures of adversity. Blood samples for genetic and epigenetic analyses were obtained in childhood. Cortical thickness and visual ERP components were analyzed for their association and tested for familial risk group differences. Visual P300 amplitude at Pz and cortical thickness of the left lateral orbitofrontal region (LOFC), were significantly related to risk group status. LOFC cortical thickness showed a negative correlation with CRHR1 methylation status and with childhood total stress scores from the Life Stressors and Social Resources Inventory (LISRES). Stress scores were also significantly related to P300 amplitude recorded in childhood. The present results suggest that early life adversity reflected in greater total LISRES stress scores in childhood can impact the methylation of the CRHR1 gene with implications for brain development as seen in cortical thickness and electrophysiological signals emanating from particular brain regions.

Publication guidelines and recommendations for pupillary measurement in psychophysiological studies

A variety of psychological and physical phenomena elicit variations in the diameter of pupil of the eye. Changes in pupil size are mediated by the relative activation of the sphincter pupillae muscle (decrease pupil diameter) and the dilator pupillae muscle (increase pupil diameter), innervated by the parasympathetic and sympathetic branches, respectively, of the autonomic nervous system. The current guidelines are intended to inform and guide psychophysiological research involving pupil measurement by (1) summarizing important aspects concerning the physiology of the pupil, (2) providing methodological and data-analytic guidelines and recommendations, and (3) briefly reviewing psychological phenomena that modulate pupillary reactivity. Because of the increased ease and tractability of pupil measurement, the goal of these guidelines is to promote accurate recording, analysis, and reporting of pupillary data in psychophysiological research.

Electrophysiological predictors and indicators of contingency management treatment response: Rationale and design for the ways of rewarding abstinence project (WRAP)

Background

Electrophysiological measures can predict and reflect substance use treatment response. Veterans are disproportionately affected by disorders of addiction; cocaine use disorder (CUD) being particularly problematic due to high relapse rates and the absence of approved pharmacotherapies. Prize-based Contingency Management (PBCM) is an evidence-based behavioral intervention for CUD, involving incentives for cocaine abstinence but treatment response is variable. Measurement-based adaptation of PBCM has promise to improve effectiveness but remains to be usefully developed.

Methods

This trial aims to determine if individuals with distinct neurocognitive profiles differentially benefit from one of two existing versions of PBCM. CUD patients will be randomized into treatment-as-usual or 12-weeks of PBCM using either monetary or tangible prize incentives. Prior to randomization, EEG will be used to assess response to monetary versus tangible reward; EEG and cognitive-behavioral measures of working memory, cognitive control, and episodic future thinking will also be acquired. Substance use and treatment engagement will be monitored throughout the treatment interval and assessments will be repeated at post-treatment.

Discussion

Results of this trial may elucidate individual differences contributing to PBCM treatment response and reveal predictors of differential benefits from existing treatment variants. The design also affords the opportunity to evaluate treatment-related changes in neurocognitive functioning over the course of PBCM. Our model posits that PBCM scaffolds future-oriented goal representation and self-control to support abstinence. Individuals with poorer functioning may be less responsive to abstract monetary reward and will therefore achieve better outcomes with respect to abstinence and treatment engagement when tangible incentives are utilized.

Evaluating effects of episodic future thinking on valuation of delayed reward in cocaine use disorder: a pilot study

Background: Episodic future thinking (EFT; i.e., envisioning oneself in future contexts) has been demonstrated to reduce discounting of future reward in healthy adults. While this approach has the potential to support future-oriented decision-making in substance use recovery, the impact of EFT on discounting behavior in illicit stimulant users has not yet been evaluated.Objectives: This pilot study aimed to (1) assess the feasibility of utilizing EFT methods in individuals with cocaine use disorder (CUD) and (2) conduct preliminary measurement of the EFT effect on discounting behavior in this population.Methods: Eighteen treatment-seeking individuals with CUD (17 males) were interviewed about positive and neutral events expected to occur at a range of future latencies. Future event information identified by participants was subsequently included on a subset of trials in an intertemporal choice task to promote EFT; within-subject differences in discounting between standard and EFT conditions were evaluated.Results: Participants identified relevant events and demonstrated decreased discounting of future reward when event descriptors were included (relative to discounting without event descriptors; p = .039). It was further noted that most events identified by participants were goals, rather than plans or significant dates.Conclusion: While methods previously used to study the effect of EFT on discounting behavior in healthy individuals are also effective in individuals with CUD, methodological factors - including types of events identified - should be carefully considered in future work. These preliminary findings suggest that EFT can reduce impulsive decision-making in cocaine use disorder and may therefore have therapeutic value.

Standards in Pupillography

The number of research groups studying the pupil is increasing, as is the number of publications. Consequently, new standards in pupillography are needed to formalize the methodology including recording conditions, stimulus characteristics, as well as suitable parameters of evaluation. Since the description of intrinsically photosensitive retinal ganglion cells (ipRGCs) there has been an increased interest and broader application of pupillography in ophthalmology as well as other fields including psychology and chronobiology. Color pupillography plays an important role not only in research but also in clinical observational and therapy studies like gene therapy of hereditary retinal degenerations and psychopathology. Stimuli can vary in size, brightness, duration, and wavelength. Stimulus paradigms determine whether rhodopsin-driven rod responses, opsin-driven cone responses, or melanopsin-driven ipRGC responses are primarily elicited. Background illumination, adaptation state, and instruction for the participants will furthermore influence the results. This standard recommends a minimum set of variables to be used for pupillography and specified in the publication methodologies. Initiated at the 32nd International Pupil Colloquium 2017 in Morges, Switzerland, the aim of this manuscript is to outline standards in pupillography based on current knowledge and experience of pupil experts in order to achieve greater comparability of pupillographic studies. Such standards will particularly facilitate the proper application of pupillography by researchers new to the field. First we describe general standards, followed by specific suggestions concerning the demands of different targets of pupil research: the afferent and efferent reflex arc, pharmacology, psychology, sleepiness-related research and animal studies.

Event-related potentials reflect impaired temporal interval learning following haloperidol administration

BACKGROUND

Signals carried by the mesencephalic dopamine system and conveyed to anterior cingulate cortex are critically implicated in probabilistic reward learning and performance monitoring. A common evaluative mechanism purportedly subserves both functions, giving rise to homologous medial frontal negativities in feedback- and response-locked event-related brain potentials (the feedback-related negativity (FRN) and the error-related negativity (ERN), respectively), reflecting dopamine-dependent prediction error signals to unexpectedly negative events. Consistent with this model, the dopamine receptor antagonist, haloperidol, attenuates the ERN, but effects on FRN have not yet been evaluated.

METHODS

ERN and FRN were recorded during a temporal interval learning task (TILT) following randomized, double-blind administration of haloperidol (3 mg; n = 18), diphenhydramine (an active control for haloperidol; 25 mg; n = 20), or placebo (n = 21) to healthy controls. Centroparietal positivities, the Pe and feedback-locked P300, were also measured and correlations between ERP measures and behavioral indices of learning, overall accuracy, and post-error compensatory behavior were evaluated. We hypothesized that haloperidol would reduce ERN and FRN, but that ERN would uniquely track automatic, error-related performance adjustments, while FRN would be associated with learning and overall accuracy.

RESULTS

As predicted, ERN was reduced by haloperidol and in those exhibiting less adaptive post-error performance; however, these effects were limited to ERNs following fast timing errors. In contrast, the FRN was not affected by drug condition, although increased FRN amplitude was associated with improved accuracy. Significant drug effects on centroparietal positivities were also absent.

CONCLUSIONS

Our results support a functional and neurobiological dissociation between the ERN and FRN.

Longitudinal predictors of cannabis use and dependence in offspring from families at ultra high risk for alcohol dependence and in control families

Cannabis use is common among adolescents. Identification of the factors associated with continued heavy use into young adulthood and development of cannabis abuse and dependence is of considerable importance. The role of familial risk for addiction and an associated endophenotype, P300 amplitude, has not previously been related to cannabis use and dependence. A prospective longitudinal study spanning childhood and young adulthood provided the opportunity for exploring these factors, along with genetic variation, in the cannabis use behaviors of 338 young adult offspring from high and low familial risk for alcohol dependence families (ages 19-30). P300 data were collected multiple times in childhood. The association between young adult patterns of cannabis use or cannabis abuse/dependence was tested with genetic variation in the cannabinoid gene, CNR1, the ANKK1-DRD2 gene, and childhood developmental trajectories of P300. Young adult patterns of cannabis use was characterized by three patterns: (i) no use throughout; (ii) declining use from adolescence through young adulthood; and (iii) frequent use throughout. Following the low P300 trajectory in childhood predicted cannabis abuse and dependence by young adulthood. A four SNP ANKK1-DRD2 haplotype (G-G-G-C) was found to be significantly associated with the frequency of use patterns (P = 0.0008). Although CNR1 variation overall was not significantly associated with these patterns, among individuals with cannabis abuse/dependence the presence of one or both copies of the rs806368 A > G minor allele conferred a 5.4-fold increase (P = 0.003) in the likelihood that they would be in the frequent and persistent use group rather than the declining use group.

Cholinergic receptor gene (CHRM2) variation and familial loading for alcohol dependence predict childhood developmental trajectories of P300

P300 amplitude in childhood predicts substance use disorders by young adulthood. Trajectories of visual P300 amplitude show an association between low amplitude P300 and familial risk for alcohol dependence (AD). Variation in the cholinergic muscarinic receptor gene (CHRM2) has previously been associated with P300 amplitude and AD. The present study used group based trajectory modeling of auditory P300 data collected longitudinally from offspring in families with and without familial loading for AD to determine if specific trajectories would be associated with familial risk and CHRM2 variation. Trajectory modeling confirms previous reports of an association between the low visual P300 trajectory with high familial risk in male offspring. This association was detected in offspring in the 8-12 age range, but not in 13-18 or 19-29 year olds or in high-risk female offspring. CHRM2 association analysis with P300 finds 8-12 year olds who are homozygous for the T allele of rs1824024 are 2.6 times more likely to follow a P300 trajectory characterized by lower and slower change regardless of familial loading. Combining the odds for being male and having a TT genotype results in odds of 6.5 that individuals will follow the low P300 trajectory.

Pupillary unrest correlates with arousal symptoms and motor signs in Parkinson disease

BACKGROUND

Arousal symptoms (e.g., sleepiness) are common in Parkinson's disease, and pupillary unrest (spontaneous changes in pupil diameter) is positively associated with sleepiness. We explored pupillary unrest in Parkinson's disease.

METHODS

Arousal symptoms (Epworth sleepiness scale and sleep/fatigue domain of the nonmotor symptoms scale for Parkinson's disease) and pupillary unrest were assessed in 31 participants (14 patients with Parkinson's disease, 17 controls). Effect sizes and t tests compared patients with Parkinson's disease with control participants. Correlation coefficients were calculated among arousal symptoms, pupillary unrest, and Unified Parkinson Disease Rating Scale Part III. Linear regression was performed with arousal symptoms or pupillary unrest as outcome.

RESULTS

Participants with Parkinson's disease reported more arousal symptoms than controls. Pupillary unrest, arousal symptoms, and Unified Parkinson Disease Rating Scale Part III were positively correlated. The association between nonmotor symptoms scale-sleep score and pupillary unrest was higher in participants with Parkinson's disease than controls and higher in those with more Parkinsonian motor signs. Unified Parkinson Disease Rating Scale Part III was positively associated with pupillary unrest.

CONCLUSIONS

Pupillary unrest correlates with motor and nonmotor features associated with Lewy-related pathology, suggesting it may be a nonmotor marker of progression in Parkinson's disease. © 2011 Movement Disorder Society.

Remission prognosis for cognitive therapy for recurrent depression using the pupil: utility and neural correlates

BACKGROUND

Although up to 60% of people with major depressive disorder respond to cognitive therapy (CT) in controlled trials, clinicians do not routinely use standardized assessments to inform which patients should receive this treatment. Inexpensive, noninvasive prognostic indicators could aid in matching patients with appropriate treatments. Pupillary response to emotional information is an excellent candidate, reflecting limbic reactivity and executive control. This study examined 1) whether pretreatment assessment of pupillary responses to negative information were associated with remission in CT and 2) their associated brain mechanisms.

METHODS

We examined whether pretreatment pupillary responses to emotional stimuli were prognostic for remission in an inception cohort of 32 unipolar depressed adults to 16 to 20 sessions of CT. Twenty patients were then assessed on the same task using functional magnetic resonance imaging. Pupillary responses were assessed in 51 never-depressed controls for reference.

RESULTS

Remission was associated with either low initial severity or the combination of higher initial severity and low sustained pupillary responses to negative words (87% correct classification of remitters and nonremitters, 93% sensitivity, 80% specificity; 88% correct classification of high-severity participants, p < .01, 90% sensitivity, 92% specificity). Increased pupillary responses were associated with increased activity in dorsolateral prefrontal regions associated with executive control and emotion regulation.

CONCLUSIONS

For patients with higher severity, disruptions of executive control mechanisms responsible for initiating emotion regulation, which are indexed by low sustained pupil responses and targeted in therapy, may be key to remitting in this intervention. These mechanisms can be measured using inexpensive noninvasive psychophysiological assessments.

Autonomic insufficiency in pupillary and cardiovascular systems in Parkinson's disease

BACKGROUND

In Parkinson's disease (PD), neurodegenerative changes have been observed in autonomic pathways involving multiple organ systems. We explore pupillary and cardiac autonomic measures as physiological manifestations of PD neurodegeneration.

METHODS

Pupil measures (pupillary unrest (spontaneous changes of pupil diameter in darkness), constriction velocity and redilation velocity) were assessed in 35 participants (17 PD, 18 controls). Simultaneous cardiac measures (respiratory sinus arrythmia during deep breathing, Valsalva ratio, resting heart rate variability (HRV), orthostatic change in blood pressure and orthostatic change in heart rate) were obtained. Nonparametric statistics were used to compare PD with control participants and to calculate correlation coefficients between pupillary and cardiac measures.

RESULTS

Pupillary unrest and orthostatic decreases in systolic blood pressure were greater in PD than controls. Respiratory sinus arrythmia during deep breathing and resting HRV were lower in PD. Among all participants, there was a negative correlation between HRV and redilation velocity and a positive correlation between orthostatic change in heart rate and pupillary unrest. A modifying effect of PD was found on the association between high frequency HRV and pupillary unrest.

CONCLUSIONS

Results demonstrate simultaneous autonomic dysfunction in both pupillary and cardiac systems in PD. The correlations between pupillary and cardiac measures suggest shared central centers of autonomic integration, while the modifying effect of PD may reflect autonomic effects of PD-related pathology not present in controls.

Sustained gamma-band EEG following negative words in depression and schizophrenia

INTRODUCTION

Sustained and elaborative emotional information processing in depression and decreased affective elaboration in schizophrenia are considered hallmarks of these disorders but have not been directly measured. Gamma-band (35-45 Hz) EEG has been associated with semantic functions such as feature binding and may index these elaborative processing. This study examined whether there were group differences in baseline and sustained gamma-band EEG following emotional stimuli in healthy adults as well as adults with depression and schizophrenia.

METHODS

24 never-depressed healthy controls, 14 patients with DSM-IV unipolar major depressive disorder, and 15 patients with DSM-IV schizophrenia completed a lexical emotion identification task during EEG assessment. Gamma-band (35-45 Hz) EEG in response to negative words was the primary dependent measure.

RESULTS

As predicted, depressed individuals displayed sustained and increased gamma-band EEG throughout the task, and particularly in the seconds following negative words. Individuals with schizophrenia displayed decreased gamma-band activity throughout the task.

CONCLUSIONS

These data suggest that gamma-band EEG, measured over several seconds, may serve as a useful index of sustained semantic information processing. Depressed individuals appear to engage in sustained elaboration following emotional stimuli, whereas individuals with schizophrenia are not as prone to this type of elaborative processing.

Effects of word frequency on semantic memory in schizophrenia: electrophysiological evidence for a deficit in linguistic access

BACKGROUND

Abnormal storage and/or access are among the hypothesized causes of semantic memory deficit in schizophrenia. Neuropsychological and connectionist models have emphasized functional systems that serve the processing of word meaning and frequency: semantic storage disturbance is presumed to result from weak representations of word meaning; defective access is assumed to result from compromises to pathways that activate word frequency knowledge. Candidate biological systems include neuromodulatory pathways that normally function to enhance neural signals (e.g., cholinergic system). Electrophysiological responding may be informative regarding the storage-access distinction for schizophrenia.

METHODS

Visual event-related potentials were recorded for 14 schizophrenia outpatients receiving atypical antipsychotics, and 14 healthy controls group-matched to patients on age, gender, and demographics. N400 was elicited using an incidental semantic priming paradigm, in which semantic relatedness and word frequency were varied, and a letter probe task.

RESULTS

Compared to controls, patients showed reduced N400 (microV) discrimination of semantic relatedness. Groups also showed different patterns of N400 to word frequency. Controls' N400 increased in negativity as words decreased in frequency of occurrence, while patients did not show a linear relationship between N400 and word frequency. Groups also differed for N400 to frequently occurring words. Patients exhibited increased negativity to high and very high frequency words, compared to controls. A subgroup of patients receiving antipsychotics with known affinity binding for muscarinic receptors (clozapine and olanzapine) showed significant albeit limited N400 priming, but their N400 to word frequency remained nonsignificant.

CONCLUSIONS

Results suggest a deficit in semantic access for schizophrenia, as well as an influence of neuromodulators on the activation of connections among semantic representations. Cumulative findings indicating only limited N400 priming for patients receiving either typical or atypical antipsychotics support the hypothesis that semantic memory deficit represents a trait marker for schizophrenia.

Childhood risk factors for young adult substance dependence outcome in offspring from multiplex alcohol dependence families: a prospective study

BACKGROUND

Age of onset to begin drinking is a known risk factor for alcohol dependence. Factors have been identified that contribute to age of onset to begin regular drinking. These include reduced P300, increased postural sway, and personality variation. A longitudinal study spanning childhood to young adulthood provided the opportunity to determine if these same factors would predict the presence and onset of substance use disorders (SUD).

METHODS

Multiplex families were identified through two or more alcohol-dependent brothers. Offspring from these multiplex or control families (n = 133) were followed annually during childhood. Using childhood predictors previously identified as risk factors for age of onset to begin drinking, SUD outcome by young adulthood was modeled.

RESULTS

Familial risk status was a significant predictor of young adult SUD outcome as a main effect and as an interaction with P300 amplitude recorded before the age of 13. In adolescence (age 15), increased postural sway and familial risk predicted the SUD outcome by age 22. Analysis comparing the presence of one or both risk factors showed that those above the median for sway and below the median for P300 amplitude had substantially increased odds of developing SUD (odds ratio = 8.08 [confidence interval = 1.52-42.83]).

CONCLUSIONS

Our findings indicate that among the factors predicting age of onset to begin regular drinking, P300 predicts SUD outcome across an 11-year span. The present findings provide the longest follow-up to date demonstrating that neurobiological factors in childhood are among the most salient predictors of young adult SUD outcome.

Increased amygdala and decreased dorsolateral prefrontal BOLD responses in unipolar depression: related and independent features

BACKGROUND

Major depressive disorder is characterized by increased and sustained emotional reactivity, which has been linked to sustained amygdala activity. It is also characterized by disruptions in executive control, linked to abnormal dorsolateral prefrontal cortex (DLPFC) function. These mechanisms have been hypothesized to interact in depression. This study explored relationships between amygdala and DLPFC activity during emotional and cognitive information processing in unipolar depression.

METHOD

Twenty-seven unmedicated patients with DSM-IV unipolar major depressive disorder and 25 never-depressed healthy control subjects completed tasks requiring executive control (digit sorting) and emotional information processing (personal relevance rating of words) during event-related functional magnetic resonance imaging (fMRI) assessment.

RESULTS

Relative to control subjects, depressed subjects displayed sustained amygdala reactivity on the emotional tasks and decreased DLPFC activity on the digit-sorting task. Decreased relationships between the time-series of amygdala and DLPFC activity were observed within tasks in depression, but different depressed individuals showed each type of bias.

CONCLUSIONS

Depression is associated with increased limbic activity in response to emotional information processing and decreased DLPFC activity in response to cognitive tasks though these may reflect separate mechanisms. Depressed individuals also display decreased relationships between amygdala and DLPFC activity, potentially signifying decreased functional relationships among these structures.

Cerebellar volume in offspring from multiplex alcohol dependence families

BACKGROUND

Increased susceptibility for developing alcohol dependence (AD) might be related to structural differences in brain circuits that influence the salience of rewards and/or modify the efficiency of information processing. The role of the cerebellum in regulating cognitive functions is being increasingly recognized along with its well-known influence on motor performance. Additionally, developmental changes in cerebellar volume during adolescence have been reported.

METHODS

Magnetic resonance imaging was used to measure the cerebellum in 17 high-risk adolescent and young adult offspring from multiplex alcohol dependence families and 16 control subjects matched for gender, age, and IQ.

RESULTS

High-risk (HR) adolescents/young adults showed increased total cerebellum volume and total grey in comparison with control subjects. Age-related decreases in total grey volume were seen with age, a pattern that was not seen in HR offspring.

CONCLUSIONS

Offspring from multiplex families for AD manifest genetic susceptibility by having larger cerebellar volume, which seems to be related to lesser grey matter pruning for age. Larger cerebellar volumes in adult obsessive compulsive disorder (OCD) patients have been reported. This suggests a possible similarity in structural underpinnings for alcohol dependence and OCD.

Indicators of genetic liability to schizophrenia: a sibling study of neuropsychological performance

Despite clear evidence of important genetic influences on schizophrenia, identifying the genes involved has been difficult because of the genetic complexity of the phenotype. The use of additional phenotypic measures that are more sensitive to the genetic liability than is the clinical diagnosis should enhance the power to detect small individual genetic effects. The present study assessed the neuropsychological performance of 30 male schizophrenia probands, 30 of their unaffected male siblings, and 20 well controls matched on age, sex, and education in order to identify measures that may be particularly sensitive to the genetic liability to schizophrenia and thus may be useful in gene mapping studies. Siblings showed impaired neuropsychological performance compared to controls on four out of the five measures used. Additional results suggested that Trails B was especially effective at discriminating index siblings from controls, thus supporting its potential utility as a candidate quantitative phenotype to aid in gene mapping studies of the disorder.

Reduced Electrodermal Activity in Psychopathy-Prone Adolescents

This study tests the hypothesis that psychopathy-prone adolescents show reduced anticipatory skin conductance responding. Electrodermal activity was recorded while participants anticipated and responded to a 105 dB signaled or unsignaled white-noise burst. Using an extreme groups design, the authors used Child Psychopathy Scale (D. R. Lynam, 1997) scores from a community sample of 335 male adolescents (age 16) to form control (n = 65) and psychopathy-prone (n = 65) groups. Significantly more psychopathy-prone participants were nonresponders in the signaled anticipatory (p = .014), signaled responsivity (p = .037), and unsignaled responsivity (p = .003) conditions compared with controls. Anticipatory hyporesponsivity of psychopathy-prone adolescents similar to the electrodermal hyporesponsivity found in psychopathic adults suggests that this autonomic impairment is present by adolescence and may predispose individuals to adult psychopathy.

Respiratory sinus arrhythmia as an index of emotional response in young adults

The relationship between respiratory sinus arrhythmia (RSA) and valence and arousal remains unclear. In the present study, the associations between emotion responses and tonic or task-related changes in RSA were assessed. Specifically, the sensitivities of changes in interbeat interval, RSA, and skin conductance to the valence and arousal values of emotional stimuli were examined. This study also explored the association between tonic RSA and subjective, expressive, and physiological emotional responses. Response measures were collected from 56 adults during baseline and film-viewing periods. Tonic RSA was not significantly related to any of the response measures. Increased skin conductance and decreased RSA were associated with arousal independent of valence. Interbeat interval was related to affective valence and not arousal. These findings suggest that RSA may be a useful adjunct to skin conductance measures in assessing emotional arousal.

Pupillary assessment and computational modeling of the Stroop task in depression

Depressed individuals frequently display disruptions in selective attention, but the time course and specificity of these difficulties are not well-understood. To better understand the nature of attentional disruptions in depression, 28 healthy adults and 23 unmedicated depressed adults completed a Stroop color-naming task using a long inter-stimulus interval and pupil dilation was recorded as a measure of cognitive load. Both groups took longer to name the color for incongruent than congruent trials. Pupil dilation was also larger for incongruent trials than for congruent trials across groups, which suggested that pupil dilation reflected cognitive load on the task. Though the groups did not differ in the magnitude of Stroop effect in pupil dilation, depressed individuals displayed decreased pupil dilation in the seconds following stimuli relative to controls. Computational neural network modeling further suggested that observed effects were consistent with decreased prefrontal cortex activity, associated with decreased cognitive control.

Sympathetic and parasympathetic innervation of pupillary dilation during sustained processing

The contributions of separate sympathetic and parasympathetic pathways to pupillary dilation during a sustained processing task were studied through environmental and pharmacological manipulations. In Experiment 1, 22 healthy volunteers (11 female) performed a serial Subtract 7 task while pupil diameter was recorded both during moderate room light and in darkness. In a control for verbalization, subjects performed an easier Add 1 task. In all conditions, pupil diameter increased significantly during the response period as compared to a pre-verbalization baseline period. Pupillary dilation was increased for the difficult task, and further increase in dilation was associated with recording in light. This suggests a major differential contribution to task difficulty mediated through inhibition of the parasympathetic pathway. In Experiment 2, a subgroup of 12 volunteers (seven female) repeated all conditions at three additional sessions in which one eye was instilled with tropicamide (to block the parasympathetic sphincter muscle), dapiprazole (to block the sympathetic dilator muscle) or placebo. All pharmacological conditions resulted in overall dilation during task performance. Differential performance similar to the placebo condition was seen only in the dapiprazole condition, when parasympathetic activation was intact. The findings suggest that sustained performance during a difficult task is modulated by cortical inhibition of the parasympathetic pathway at the oculomotor nucleus. Moreover, modulation of both ambient light intensity and pharmacological blockade of the final pupillary musculature were observed to provide converging approaches for quantifying the activity of identifiable central autonomic pathways.

Sympathetic and parasympathetic innervation of pupillary dilation during sustained processing

The contributions of separate sympathetic and parasympathetic pathways to pupillary dilation during a sustained processing task were studied through environmental and pharmacological manipulations. In Experiment 1, 22 healthy volunteers (11 female) performed a serial Subtract 7 task while pupil diameter was recorded both during moderate room light and in darkness. In a control for verbalization, subjects performed an easier Add 1 task. In all conditions, pupil diameter increased significantly during the response period as compared to a pre-verbalization baseline period. Pupillary dilation was increased for the difficult task, and further increase in dilation was associated with recording in light. This suggests a major differential contribution to task difficulty mediated through inhibition of the parasympathetic pathway. In Experiment 2, a subgroup of 12 volunteers (seven female) repeated all conditions at three additional sessions in which one eye was instilled with tropicamide (to block the parasympathetic sphincter muscle), dapiprazole (to block the sympathetic dilator muscle) or placebo. All pharmacological conditions resulted in overall dilation during task performance. Differential performance similar to the placebo condition was seen only in the dapiprazole condition, when parasympathetic activation was intact. The findings suggest that sustained performance during a difficult task is modulated by cortical inhibition of the parasympathetic pathway at the oculomotor nucleus. Moreover, modulation of both ambient light intensity and pharmacological blockade of the final pupillary musculature were observed to provide converging approaches for quantifying the activity of identifiable central autonomic pathways.

Automatic activation of the semantic network in schizophrenia: evidence from event-related brain potentials

BACKGROUND

Language disorder associated with schizophrenia might be due to disturbances in both automatic activation and mechanisms of controlled attention. The contribution of each process to semantic memory dysfunction has not been determined for schizophrenia, and the semantic priming paradigm is well-suited for addressing this question. In the present report, event-related potentials (ERPs) elicited under conditions assumed to reveal automatic activation (short prime-target interval and low proportion of related words) are compared directly with ERPs elicited under conditions associated with controlled processing (long prime-target interval and high proportion of related words).

METHODS

Visual ERPs were recorded during a lexical decision task, in which semantic relationship (associated and unassociated words), expectancy (relatedness proportions), and prime-target interval (250- and 850-msec inter-stimulus intervals [ISIs]) were varied. Diagnosis and expectancy were between-subjects factors; semantic relationship and ISI were repeated measures. The N400 priming effect (enhanced negativity to unassociated words) was compared between 34 male normal control subjects tested once and 37 male schizophrenia inpatients evaluated during their participation in a double-blind haloperidol maintenance therapy and placebo replacement protocol.

RESULTS

The N400 priming effect for patients was significantly reduced during both pharmacologic phases, compared with controls. During haloperidol treatment, however, patients showed a significant N400 priming effect over the anterior scalp region and additionally under the automatic activation condition. The N400 priming effect was enhanced under the controlled processing condition for control subjects; this effect was not observed for patients. N400 amplitude elicited under the rapid presentation rate (250-msec ISI) differed between medicated patients and controls; groups did not differ for the 850-msec ISI.

CONCLUSIONS

Findings suggest that automatic activation and mechanisms of controlled attention are both disrupted during semantic memory access for schizophrenia patients. Pharmacologic agents, such as haloperidol, might enhance automatic activation of the semantic network in this patient population, as indexed by the N400 component of the ERP.

Use of concurrent pupil dilation assessment to inform interpretation and analysis of fMRI data

Potential contributions of concurrently acquired pupil dilation data to functional magnetic resonance imaging (fMRI) experiments were examined. Sixteen healthy participants completed a working memory task (digit sorting) during measurement of pupil dilation outside the fMRI environment and during concurrent 3T fMRI assessment. Pupil dilation increased parametrically with task difficulty inside and outside the scanner, on a similar time course, suggesting that task demand was similar in both environments. The time course of pupil dilation during digit sorting was similar to the time course of the fMRI signal in the middle frontal gyrus, suggesting that middle-frontal gyrus activity indexed the engagement working memory processes. Incorporating individual differences in pupil dilation improved the sensitivity and specificity of general linear modeling analyses of activity in the middle frontal gyrus, above and beyond standard analytic techniques. Results suggest concurrent pupil dilation during fMRI assessment can help to (1) specify whether task demand is the same inside and outside the fMRI environment, (2) resolve the extent to which fMRI signals reflect different aspects of event-related designs, and (3) explain variation in fMRI data due to individual differences in information processing.

The language system in schizophrenia: effects of capacity and linguistic structure

Dysfunction in receptive language processes has been reliably observed in individuals diagnosed with schizophrenia and their first degree family members. The present study addressed the unresolved issue of whether receptive syntax is intact in schizophrenia. The principal question concerned whether comprehension dysfunction in schizophrenia involves a disturbance in the processing of syntactic structure, a susceptibility to demands placed on temporal auditory processing, or some combination of these two general factors. Comprehension accuracy was compared between 32 males diagnosed with schizophrenia and 22 males with no lifetime diagnosis of psychiatric disorder. Accuracy was examined for responses to Who questions ("Who did X?" and "Who was done X?") about information in the sentential clauses (main vs. relative) of two types of relative sentences (subject-relatives vs. object-relatives) that were presented aurally at conversational and accelerated rates. The relationship between cognitive functions and comprehension accuracy was also tested. Results showed highly significant effects of diagnosis, syntactic structure, and temporal demand. Patients were characterized by reduced overall comprehension accuracy compared to controls. More important, patients and controls differed in their patterns of accuracy across the different types of syntactic structure. Finally, cognitive functions predicted but did not completely account for comprehension accuracy. Findings suggest the hypothesis that receptive syntax is disrupted in schizophrenia, and this dysfunction may not be entirely explained by compromised general cognitive ability.

Serious delinquent behavior, sensation seeking, and electrodermal arousal

Low tonic skin conductance level (SCL) has been related, inconsistently, to both delinquency and sensation-seeking. This study tests the hypothesis that there is an interaction such that high sensation seeking delinquents, in particular, have low SCLs. Participants consisted of 335 boys from the Pittsburgh Youth Study classified as serious delinquents or controls based upon 10 years of prospectively collected self-report delinquency data. Participants' skin conductance was evaluated at age 16 along with several personality and neuropsychological measures. Both delinquency and sensation seeking were characterized by low SCL. However, there was no evidence to suggest that the presence of both of these factors together lead to especially low skin conductance levels. This finding is not explained by differences between the groups on measures of negative emotionality, IQ, socioeconomic status, or impulsivity.

Can't shake that feeling: event-related fMRI assessment of sustained amygdala activity in response to emotional information in depressed individuals

BACKGROUND

Previous research suggests that depressed individuals engage in prolonged elaborative processing of emotional information. A computational neural network model of emotional information processing suggests this process involves sustained amygdala activity in response to processing negative features of information. This study examined whether brain activity in response to emotional stimuli was sustained in depressed individuals, even following subsequent distracting stimuli.

METHODS

Seven depressed and 10 never-depressed individuals were studied using event-related functional magnetic resonance imaging during alternating 15-sec emotional processing (valence identification) and non-emotional processing (Sternberg memory) trials. Amygdala regions were traced on high-resolution structural scans and co-registered to the functional data. The time course of activity in these areas during emotional and non-emotional processing trials was examined.

RESULTS

During emotional processing trials, never-depressed individuals displayed amygdalar responses to all stimuli, which decayed within 10 sec. In contrast, depressed individuals displayed sustained amygdala responses to negative words that lasted throughout the following non-emotional processing trials (25 sec later). The difference in sustained amygdala activity to negative and positive words was moderately related to self-reported rumination.

CONCLUSIONS

Results suggest that depression is associated with sustained activity in brain areas responsible for coding emotional features.

Respiratory sinus arrhythmia in persons with organic solvent exposure: comparisons with anxiety patients and controls

Persons exposed to organic solvents have psychiatric symptomatology and cognitive impairments. The results of several studies have suggested that some psychiatric symptoms in these patients reflect similar reactions observed in patients with anxiety disorders. Respiratory sinus arrhythmia provides an indication of impaired autonomic functioning. Whereas decreased respiratory sinus arrhythmia has been reported in anxiety patients, investigators have also noted that higher respiratory rates in these patients obscure differentiation of respiratory sinus arrhythmia from normal values. In this study, the authors recorded multiple parameters of respiratory sinus arrhythmia under a paced-breathing condition in 28 patients with solvent exposure, in 18 patients with anxiety disorder, and in 31 controls. The authors observed a high 1-y retest reliability for a subset of the subjects. Significantly reduced respiratory sinus arrhythmia was observed in both anxiety and solvent-exposed patients, compared with controls. Maximum mean heart rates/cycle did not differ among groups, but minimum heart rates were significantly lower for controls than for the two patient groups. The findings suggested that reduced respiratory sinus arrhythmia among patients is not related to higher maximum rates but, rather, to a decrease in vagally mediated alteration associated with respiratory changes observed in both patient groups.

Mood and behavioral symptoms in individuals with chronic solvent exposure

Psychiatric symptoms have been reported for individuals who experience chronic exposure to low levels of organic solvents. However, it is not known what proportion of such individuals experience psychiatric disorder; which specific disorders may be characteristic of this population; or whether bioaccumulation of lead contributes to the relationship between solvent exposure and psychiatric symptoms. Twenty-nine male journeymen painters and 32 male non-painter control subjects were administered semi-structured diagnostic interviews for DSM-III-R Axis I and Axis II disorders. Career solvent exposure and blood lead levels were also measured. Painters and control subjects did not differ significantly with respect to age, intelligence, or demographic characteristics. Results showed that the probability of being diagnosed with a mood disorder differed significantly in painters (41%) and control subjects (16%). Painters (66%) and control subjects (50%) did not differ for substance use diagnoses. Groups also did not differ for personality disorders involving an onset before 25 years of age. In contrast, painters exhibited a sub-clinical pattern of personality dysfunction involving symptomatology that was measured allowing for late onset (after age 25). Finally, a significant dose-response relationship was observed between career solvent exposure, blood lead level, and personality symptoms. In summary, these data showed an increased rate of psychological disturbance in a significant and substantial number of painters. However, not all painters were so characterized. This overall pattern raises a question regarding a potential role for differential vulnerability, which requires empirical validation.

Cognitive modulation of midbrain function: task-induced reduction of the pupillary light reflex

The activation of processing resources has widespread effects in the nervous system. A model of pupillary control systems (Steinhauer S.R. , Hakerem G., 1992. The pupillary response in cognitive psychophysiology and schizophrenia. Ann. N.Y. Acad. Sci. 658, 182-204) had predicted that ongoing cognitive activation should result in inhibition of the light reaction at the level of the oculomotor nucleus, n. III, in the midbrain. In this study, modification of parameters of the pupillary reaction to light were examined during varying task demands. The averaged light reaction was recorded from 33 male and female healthy volunteers during the performance of a serial 7 subtraction task and compared to a 'no task' condition. For 13 subjects, an additional verbalization task with little processing demand (add 1) also was presented. Two types of effects were observed. Firstly, the tonic pupil diameter increased from the no task to the easy (add 1) task, and increased further in the more demanding condition (subtract 7). Secondly, the extent of the phasic light reaction was significantly reduced and the latency at the end of the contraction was significantly decreased in the 'subtract 7' condition compared to both the no task and easy conditions (which did not differ from each other). The locus of interference with the light reaction was the Edinger-Westphal complex of the oculomotor nucleus, which is the motor center for the pupillary sphincter muscles. Descending cortical influences inhibited the activity of the Edinger-Westphal complex. Thus, increasing activation had a tonic inhibitory effect on this center, while higher levels of processing complexity produced a separate component of inhibition that interacted with dynamic activation at this midbrain site. It was suggested that the variation in the light reaction is quantitatively responsive to varying processing loads, and may be utilized as a sensitive metric for a wide variety of cognitive operations.

Absence of visual and auditory P300 reduction in nondepressed male and female alcoholics

BACKGROUND

The P300 component of the event-related potential has been extensively studied as a possible neurobiological risk marker for the development of alcoholism. Although P300 amplitude reduction has frequently been documented in high-risk children, studies of adult alcoholics are inconsistent.

METHODS

P300 amplitude from 121 adult alcoholics was compared to 68 controls utilizing event-related potential paradigms from the auditory and visual modalities. All participants were evaluated clinically with psychiatric interviews and administered the MMPI.

RESULTS

Male alcoholics did not show a reduction in amplitude in either the auditory or visual modality. Female alcoholics showed reduced P300 amplitude, but only when a comorbid lifetime diagnosis of depression was present. Similar results were found using current depressed mood (Scale 2 from the MMPI).

CONCLUSIONS

No differences in P300 amplitude were found between alcoholics and controls unless comorbid depression was present. Therefore, P300 amplitude reduction seen in children at high-risk for developing alcoholism seems to represent a neurodevelopmental delay that normalizes by adulthood.

Developmental delay in P300 production in children at high risk for developing alcohol-related disorders

BACKGROUND

Reduction of P300 amplitude in children and adolescents at high risk for developing alcoholism has frequently been reported. It has been hypothesized that this reduction represents a developmental delay in reaching age-appropriate levels in P300 amplitude. Using latent growth analysis of longitudinal data obtained at yearly intervals, this study seeks to define normal growth, and determine if the pattern seen in high-risk children differs from that obtained in normal low-risk controls.

METHODS

A total of 156 children from either high or low-risk families have been assessed multiple times (two-thirds more than 4 times) using both a clinical assessment (K-SADS) and ERP evaluation performed on the same day. A total of 635 separate assessments were available for modeling.

RESULTS

Quadratic growth curves revealed a slower rate of change in P300 amplitude in high-risk than low-risk males. High-risk girls showed reduced visual P300 amplitude only when the presence of a K-SADS diagnosis was considered. No differences were seen for P300 latency.

CONCLUSIONS

This study confirms the hypothesis that when reduction of P300 amplitude is seen in males at high risk for developing alcoholism, it is due to a developmental delay.

Modulation of language processing in schizophrenia: effects of context and haloperidol on the event-related potential

BACKGROUND

Disturbances in language associations were among the first clinical symptoms reported for individuals described as schizophrenic (Bleuler 1911/1950). Currently, associative language disturbance is a diagnostic feature of schizophrenia (American Psychiatric Association 1994); however, the mechanisms that produce this symptom remain unknown. In the present study, two candidate psychological functions were examined: sensitivity to semantic context and expectancy (attention).

METHODS

Visual event-related potentials were recorded during a lexical decision task in which semantic relationship and expectancy (relatedness proportions) were varied. Semantic priming processes were compared between 34 male normal control subjects tested once and 37 male schizophrenic inpatients evaluated during their participation in a double-blind haloperidol maintenance therapy and placebo replacement protocol.

RESULTS

Schizophrenic patients failed to discriminate between associated and unassociated words, as measured by the amplitude of the N400 component (i.e., absence of the N400 priming effect); however, the overall mean amplitude of N400 did not differ between patients and control subjects. In addition, patients and control subjects did not differ significantly in the amplitude of N400 elicited to associated words or to unassociated words. Finally, the effect of expectancy-based processing on the magnitude of the N400 priming effect did not differ between patients and control subjects.

CONCLUSIONS

On the basis of these findings, a tentative hypothesis is suggested that schizophrenic patients are characterized by a pattern of indiscriminate or random spread of activation in their semantic network during the processing of single-word semantic contexts.

Predictors of involvement in P300 latency in solvent-exposed adults

Persons with a history of exposure to organic solvents have been shown to have cognitive and personality changes, as well as abnormalities on measures of neurophysiology (e.g., delays in P300 latency). Studies assessing long-term sequelae in exposed persons have been limited, especially those using neurophysiologic measures. This study assessed cognitive event-related potentials (ERPs) in 16 persons with a history of organic solvent exposure at two testings, separated, on average, by 1.5 years. The sample was divided into persons who showed improvement on P300 latency (e.g., reduction in latency of 1.5 SD of control group) and those who did not. Sixty-three percent showed no improvement, whereas 37% showed significant improvement. Recency of exposure and the interaction of exposure duration and history of peak exposure significantly predicted group membership. That is, persons with shorter duration of exposure coupled with no peak exposures and longer time from exposure to test were more likely to fall in the improved group. Substituting age for duration of exposure in the interaction term improved classification of the two groups. The results support previous findings that most exposed persons do not show significant improvements over time. The results further suggest that there is a need to assess factors, such as aging, which may make one more vulnerable to the neurotoxic effects of solvents.

Preparing the heart, eye, and brain: foreperiod length effects in a nonaging paradigm

Psychophysiological "preparatory" responses may or may not depend on a focused expectation of when a stimulus will occur. Changes in heart rate, pupillary diameter, and brain potentials were examined during trials in which foreperiod of a simple reaction time (RT) task was fixed or unpredictable. Trials were also included in which stimuli for the speeded motor reaction were triggered by psychophysiological changes occurring spontaneously in the foreperiod. Thirty-two college-aged volunteers equally divided by gender participated in the experiment. Reducing expectancy, by using nonaging foreperiods, eliminated transient prestimulus psychophysiological responses but failed to eliminate slow changes over the foreperiod--slowing of heart rate, dilation of the pupil, and cortical surface negativity. Triggering the reaction stimulus by physiological changes did not influence RT. Correlations between psychophysiological changes in the foreperiod and between these changes and RT were generally low. The results were consistent with a multiprocess view of preparation.

Genetic association between reduced P300 amplitude and the DRD2 dopamine receptor A1 allele in children at high risk for alcoholism

BACKGROUND

There is evidence that both reduction in P300 amplitude and the presence of the A1 allele are risk markers for alcoholism. We hypothesized that demonstration of a relationship between the marker and the trait in young children who had not begun to drink regularly would provide evidence for dopaminergic mediation of the reduction in P300 often seen among high-risk children. A previous association between the A1 and the P300 amplitude in screened controls supports the hypothesis that this association occurs in the general population.

METHODS

Children were assessed using both visual and auditory paradigms to elicit event-related potentials (ERPs). The P300 component of the ERP was investigated with respect to the genetic variation of the Taq1A D2 receptor in these children.

RESULTS

Genetic association between a marker locus (Taq1 A RFLP near the D2 receptor locus) and the amplitude of P300 was found to be present in 58 high-risk children and their relatives (a total of 100 high-risk individuals).

CONCLUSIONS

A higher proportion of children from alcoholic families may exhibit lower P300 because more of these children carry the A1 allele than is seen in the normal population.

Vigilance and iconic memory in children at high risk for alcoholism

OBJECTIVE

Previous studies report reduced visual event-related potential (ERP) amplitudes in young males at high risk for alcoholism. These findings could involve difficulties at several stages of visual processing. This study was aimed at examining vigilance performance and iconic memory functions in children at high risk or low risk for alcoholism.

METHOD

Sustained vigilance and retrieval from iconic memory were evaluated in 54 (29 male) white children at high risk and 47 (25 male) white children at low risk for developing alcoholism. Children were also grouped according to gender and age (younger: 8-12 years; older: 13-18 years).

RESULTS

No differences is visual sensitivity, response criterion or reaction time were associated with risk status on the degraded visual stimulus version of the Continuous Performance Test. For the Span of Apprehension, no differences were found due to risk status when only 1 or 5 distractors were presented, although with 9 distractors a significant effect of risk status was found when it was tested as an interaction with gender and age (decreased accuracy for older high-risk boys compared to older low-risk boys).

CONCLUSIONS

These findings suggest that ERP deviations are not attributable to stages of visual processing deficits, but represent difficulty involving more complex utilization of information. Implications of these results are that the differences between high- and low-risk children that have been reported previously for visual ERP components (e.g., P300) are not attributable to deficits of attentional or iconic memory mechanisms.

Neuropsychological performance of journeymen painters under acute solvent exposure and exposure-free conditions

Journeymen painters were evaluated with a comprehensive battery of neuropsychological tests and compared to demographically similar nonexposed controls. For painters, a cumulative exposure to solvents was estimated from a structured interview that derived an index based on lifetime exposure and exposure in the past year. Painters were tested either shortly after having painted or after an exposure-free interval. Significant between-group differences were found on a cluster of tests measuring learning and memory. Within the painter group, scores on the learning and memory tests were significantly related to the interaction of condition and exposure. That is, those painters who were tested soon after painting and who also had a higher overall lifetime exposure, performed worst on tests of learning and memory. These results are consistent with the view that neuropsychological function--particularly learning and memory--may be compromised in active workers with a history of chronic solvent exposure. Furthermore, both the chronicity of solvent exposure, as well as the acuteness of the exposure, are significant factors in cognitive performance.

Differential associations of P300 amplitude and latency with cognitive and psychiatric function in solvent-exposed adults

Cognitive and mood changes are central components of solvent encephalopathy. This study examined event-related potentials in relation to neuropsychological and psychiatric function in solvent-exposed adults. Results revealed that longer P300 latency was associated with poorer cognitive test scores, whereas reduced P300 amplitude was related to increased psychiatric symptomatology. The findings suggest that the cognitive deficits and the psychiatric disturbance following solvent exposure may have different neurophysiological bases.

A preliminary neuropsychological study of Persian Gulf veterans

A neuropsychological investigation of 21 Persian Gulf veterans and 38 demographically matched controls was conducted in order to make a preliminary determination concerning presence of neuropsychological deficits associated with the Persian Gulf War experience. The neuropsychological test battery consisted of measures of complex attention, memory, and motor skills previously shown to be sensitive to exposure to environmental toxins. It was found that the Persian Gulf veteran group did not demonstrate substantial impairment, but an impairment index derived from 14 test variables was statistically significantly different from controls in the direction of poorer performance.