Measure Of Sustained Attention Research Articles

Prenatal exposure to the brominated flame retardant hexabromocyclododecane (HBCD) impairs measures of sustained attention and increases age-related morbidity in the Long–Evans rat

Hexabromocyclododecane (HBCD) is a brominated flame retardant that is widely-used in foam building materials and to a lesser extent, furniture and electronic equipment. After decades of use, HBCD and its metabolites have become globally-distributed environmental contaminants that can be measured in the atmosphere, water bodies, wildlife, food staples and human breastmilk. Emerging evidence suggests that HBCD can affect early brain development and produce behavioral consequences for exposed organisms. The current study examined some of the developmental and lifelong neurobehavioral effects of prenatal HBCD exposure in a rat model. Pregnant rats were gavaged with 0, 3, 10, or 30mg/kg HBCD from gestation day 1 to parturition. A functional observation battery was used to assess sensorimotor behaviors in neonates. Locomotor and operant responding under random ratio and Go/no-go schedules of food reinforcement were examined in cohorts of young adult and aged rats. HBCD exposure was associated with increased reactivity to a tailpinch in neonates, decreased forelimb grip strength in juveniles, and impaired sustained attention indicated by Go/no-go responding in aged rats. In addition, HBCD exposure was associated with a significant increase in morbidity in the aged cohort. One health complication, a progressive loss of hindleg function, was observed only in the aged, 3mg/kg HBCD animals. These effects suggest that HBCD is a developmental neurotoxicant that can produce long-term behavioral impairments that emerge at different points in the lifespan following prenatal exposure.

Influence of the COMT val108/158met polymorphism on continuous performance task indices

The Continuous Performance Task (CPT) is a widely-used measure of sustained attention and impulsivity. Deficits in CPT performance have been found in several psychiatric disorders, such as Attention-Deficit/Hyperactivity Disorder (ADHD) and schizophrenia. Molecular genetic studies of CPT performance are currently limited and have generally revealed inconsistent findings. The current study tested the associations of the COMT val108/158met polymorphism with AX-CPT indices (i.e., omission and commission errors, d׳, and lnβ), as well as the variability of these indices across blocks, in a sample of clinic-referred and non-referred children (N=380). We found significant associations between COMT and variability in the Signal Detection Theory (SDT) indices d׳ and lnβ across blocks, as well as a statistical trend for association between COMT and commission errors. Higher externalizing psychopathology was associated with general impairment on AX-CPT performance, and for some indices (i.e., d׳ variability and lnβ variability) the effect of COMT was stronger at higher levels of psychopathology. Our findings support the role of COMT in components of CPT performance and highlight the potential utility of using SDT indices, particularly in relation to variability in performance. Moreover, our results suggest that for some indices the effect of COMT is stronger at higher levels of externalizing psychopathology. Our study yields some preliminary insights regarding the neurobiology of CPT performance, which may elucidate the mechanisms by which specific genes confer risk for various cognitive deficits, as well as relevant disorders characterized by these deficits.

Longitudinal Study of Sustained Attention in Outpatients with Bipolar Disorder

Individuals with bipolar disorder (BD) may exhibit attentional deficits, however, the extent of impairment and long-term fluctuations in performance in attention are relatively unknown. We investigated the relationship between sustained attention and affective symptoms over time among BD patients. We also examined whether global differences in attentional capacity differed among BD versus normal comparison (NC) subjects. Participants included 106 outpatients with BD and 66 NC subjects who were administered symptom rating scales and a measure of sustained attention (Continuous Performance Test- Identical Pairs). Measures were repeated 6, 12, and 26 weeks post-baseline. Compared to NC subjects, participants with BD showed impairment in sustained attention across time. Within patient increases in manic symptoms were associated with increased false alarms; both manic and depressive symptoms were associated with worse discrimination. Neither manic nor depressive symptoms were related to hit rates. Our results indicate that the ability to inhibit a response to near miss stimuli (i.e., those that are close to but not identical to the target) is globally impaired among BD patients relative to NC subjects, as well as state-dependent, covarying with affective symptoms. Psychosocial interventions requiring high levels of attentional capacity may need to be adapted according to patients' current symptomatology.

Contributions of COMT Val158Met to cognitive stability and flexibility in infancy

Adaptive behavior requires focusing on relevant tasks while remaining sensitive to novel information. In adult studies of cognitive control, cognitive stability involves maintaining robust cognitive representations while cognitive flexibility involves updating of representations in response to novel information. Previous adult research has shown that the Met allele of the COMT Val(158) Met gene is associated with enhanced cognitive stability whereas the Val allele is associated with enhanced cognitive flexibility. Here we propose that the stability/flexibility framework can also be applied to infant research, with stability mapping onto early indices of behavioral regulation and flexibility mapping onto indices of behavioral reactivity. From this perspective, the present study examined whether COMT genotype was related to 7-month-old infants' reactivity to novel stimuli and behavioral regulation. Cognitive stability and flexibility were assessed using (1) a motor approach task, (2) a habituation task, and (3) a parental-report measure of temperament. Val carriers were faster to reach for novel toys during the motor approach task and received higher scores on the temperament measure of approach to novelty. Met carriers showed enhanced dishabituation to the novel stimulus during the habituation task and received higher scores on the temperament measures of sustained attention and behavioral regulation. Overall, these results are consistent with adult research suggesting that the Met and Val alleles are associated with increased cognitive stability and flexibility, respectively, and thus suggest that COMT genotype may similarly affect cognitive function in infancy.

Assessing Long-Term Test-Retest Reliability of the CPT-IP in Schizophrenia

BackgroundThe Continuous Performance Test-Identical Pairs version (CPT-IP) is a well-established measure of sustained attention, and its more challenging versions are particularly suited to detect subtle processing deficits in patients with schizophrenia. However, while there are few longitudinal samples for the CPT-IP, no study has addressed stability for more than two month in patients with schizophrenia. Assessing long-term test-retest reliability of the CPT-IP would facilitate the ability of clinicians to draw conclusions from studies involving interventions as long term cognitive or pharmacological treatments. The present study assessed 12 month test-retest reliability for the two most challenging versions of CPT-IP (4-digit and shapes) in a matched sample of clinically stable schizophrenia outpatients and healthy controls.MethodsFifty clinically stable schizophrenia outpatients and 50 healthy controls were assessed with the CPT-IP for the 4-digit and shape conditions. From these, 40 patients and 47 controls were reassessed with an average interval of 12.3 months between test sessions. Test-retest reliability was analyzed with Pearson correlations and results were compared with previous data involving healthy controls and short-term studies in patients with schizophrenia.ResultsEspecially d’ and hit rate discriminated well between patients with schizophrenia and healthy controls for both CPT-IP conditions and at both test sessions. Healthy controls demonstrated sufficient long term test-retest correlations of d’, hit rate and reaction time for both the 4-digit and shape conditions. However, in schizophrenia patients, long-term reliability correlations were at best moderate for d’ and hit rate only.ConclusionsThe current study provides further evidence that d’ and hit rate yield consistent cross-sectional discrimination sensitivity. At best moderate long-term test-retest reliability of d’ in schizophrenia outpatients may be not sufficient for practical use of this measure in long term clinical trials.

Reward reveals dissociable aspects of sustained attention.

Although reward is known to have a powerful influence on performance, its effects on the ability to continuously sustain performance over time are poorly understood. The current study examines multiple measures of sustained attention (accuracy and variability) and their decrements over time, while introducing reward in the form of a monetary incentive or the promise of early completion. Compared with unrewarded participants, rewarded participants demonstrated greater overall accuracy and lower reaction time variability. However, rewarded and unrewarded participants displayed nearly identical decrements in performance over time, suggesting that these aspects of sustained attention are far less malleable by enhanced effort. This study helps to resolve conflicting models of sustained attention as it reveals that some aspects of performance are due to motivational lapses whereas others are due to the depletion of cognitive resources that cannot be easily overcome.

Sustained attention, selective attention and cognitive control in deaf and hearing children

Deaf children have been characterized as being impulsive, distractible, and unable to sustain attention. However, past research has tested deaf children born to hearing parents who are likely to have experienced language delays. The purpose of this study was to determine whether an absence of auditory input modulates attentional problems in deaf children with no delayed exposure to language. Two versions of a continuous performance test were administered to 37 deaf children born to Deaf parents and 60 hearing children, all aged 6–13 years. A vigilance task was used to measure sustained attention over the course of several minutes, and a distractibility test provided a measure of the ability to ignore task irrelevant information – selective attention. Both tasks provided assessments of cognitive control through analysis of commission errors. The deaf and hearing children did not differ on measures of sustained attention. However, younger deaf children were more distracted by task-irrelevant information in their peripheral visual field, and deaf children produced a higher number of commission errors in the selective attention task. It is argued that this is not likely to be an effect of audition on cognitive processing, but may rather reflect difficulty in endogenous control of reallocated visual attention resources stemming from early profound deafness.

The role of calmness in a high-Go target detection task

Individual differences (e.g., extroversion) have been noted to influence performance on sustained attention tasks (Davies & Parasuraman, 1982). It has been proposed that the sustained attention to response task (SART) is a valid measure of lapses in attention and has been extensively used in attention studies (Manly, Robertson, Galloway, & Hawkins, 1999; Robertson, Manly, Andrade, Baddeley, & Yiend, 1997). In the current investigation we test whether SART is a measure of sustained attention versus a measure of motor control. Additionally, we tested how individual differences using an abridged version of the Big Five personality traits scale related to SART performance. Two-hundred and ninety-six university students completed a SART and the Big Five scale. The behavioral results revealed a negative correlation between errors of commission and response time which is indicative of a speed-accuracy trade-off. The individual difference results revealed that those who report themselves higher on the calmness trait (non-neurotic) make less errors of commission (inappropriate response) and have slower response times. However, mediation regression analysis revealed that the relationship between the calmness individual difference and commission errors may be mediated by response time. Collectively, the SART may be a better measure of response inhibition than sustained attention and SART performance can be influenced by individual differences which influence the speed-accuracy trade-off.

Effects of bupropion on cognitive performance during initial tobacco abstinence

BackgroundBupropion may aid tobacco abstinence by quickly relieving symptoms of nicotine withdrawal, perhaps including impaired cognitive performance. We examined whether bupropion would attenuate abstinence-induced cognitive deficits on the first day of a brief quit attempt, when smokers are most likely to relapse. MethodsSmokers (N=24) with high quit interest were recruited for within-subjects cross-over test of bupropion vs placebo on ability to abstain during separate short-term practice quit smoking attempts. After introduction to working memory (N-back) and sustained attention (continuous performance task; CPT) tasks during the pre-quit smoking baseline, performance on these tasks was assessed after abstaining overnight (CO<10ppm) on the first day of each quit attempt, while on bupropion and on placebo. ResultsCompared to placebo, bupropion after abstinence improved correct response times for working memory (p=.01 for medication by memory load interaction) and for one measure of sustained attention (numbers, but not letters; p<.05). DiscussionBupropion may attenuate some features of impaired cognitive performance due to withdrawal on the first day of a quit attempt. Future studies could examine whether this effect of bupropion contributes to its efficacy for longer-term smoking cessation.

Executive functions in girls with and without childhood ADHD: developmental trajectories and associations with symptom change

We prospectively followed an ethnically and socioeconomically diverse sample of girls with attention-deficit/hyperactivity disorder (ADHD) (n=140) and a matched comparison sample (n=88) from childhood through young adulthood to evaluate developmental trajectories of executive functions (EF) and associations between EF trajectories and dimensional measures of ADHD symptoms. We hypothesized that (a) EF trajectories would be similar in girls both with and without childhood ADHD, with the ADHD group showing greater impairment across time; and (b) changes in EF abilities would predict changes in ADHD symptoms across time, consistent with the theory that ADHD symptom reductions partially result from prefrontally mediated EF development. Latent growth curve models were used to evaluate development of sustained attention, response inhibition, working memory, and global EF abilities, and associations between EF trajectories and ADHD symptom trajectories. Girls with childhood-diagnosed ADHD showed greater improvement across development on measures of sustained attention and global EF, but similar rates of improvement on measures of working memory and response inhibition. Changes in the global EF measure predicted changes in both inattentive and hyperactive-impulsive symptoms across time, whereas changes in response inhibition predicted changes in hyperactive-impulsive symptoms; associations between changes in other EF variables and symptoms were not significant. Findings suggest variability in patterns of EF improvement over time in females with ADHD histories and indicate that EF development may play a role in symptom change.

Victoria Symptom Validity Test Performance in Children and Adolescents with Neurological Disorders

It is becoming increasingly more important to study, use, and promote the utility of measures that are designed to detect non-compliance with testing (i.e., poor effort, symptom non-validity, response bias) as part of neuropsychological assessments with children and adolescents. Several measures have evidence for use in pediatrics, but there is a paucity of published support for the Victoria Symptom Validity Test (VSVT) in this population. The purpose of this study was to examine the performance on the VSVT in a sample of pediatric patients with known neurological disorders. The sample consisted of 100 consecutively referred children and adolescents between the ages of 6 and 19 years (mean = 14.0, SD = 3.1) with various neurological diagnoses. On the VSVT total items, 95% of the sample had performance in the "valid" range, with 5% being deemed "questionable" and 0% deemed "invalid". On easy items, 97% were "valid", 2% were "questionable", and 1% was "invalid." For difficult items, 84% were "valid," 16% were "questionable," and 0% was "invalid." For those patients given two effort measures (i.e., VSVT and Test of Memory Malingering; n = 65), none was identified as having poor test-taking compliance on both measures. VSVT scores were significantly correlated with age, intelligence, processing speed, and functional ratings of daily abilities (attention, executive functioning, and adaptive functioning), but not objective performance on the measure of sustained attention, verbal memory, or visual memory. The VSVT has potential to be used in neuropsychological assessments with pediatric patients.

Standardizing the use of the Continuous Performance Test in schizophrenia research: A validation study

BackgroundThe Continuous Performance Test (CPT) has emerged as the most commonly administered measure of sustained attention, but use of discrepant versions reduces the ability of researchers and clinicians to accurately draw cross-study conclusions. In an effort to standardize use of the CPT, this study compared four versions of the Identical Pairs CPT for their reliability and ability to discriminate between patients with schizophrenia and healthy volunteers. The relationship of performance on the different versions of the CPT with measures of psychopathology, functioning, and other aspects of cognition was also examined. MethodsPerformance on the 2-digit, 3-digit, 4-digit, and Shapes Identical Pairs CPT was assessed at three test sessions over five weeks, during which subjects also completed the Brief Assessment of Cognition in Schizophrenia (BACS) and questionnaires assessing psychopathology and functioning. ResultsAll four CPTs discriminated between patients with schizophrenia and healthy volunteers, but there were no statistical differences in sensitivity among the versions. The 3-digit CPT showed non-statistical advantages in that it had high test–retest reliability, low potential for a ceiling effect, and a very low rate of false alarms. There were also moderate correlations between CPT performance and performance of the BACS subtests, but no significant correlations between CPT performance and measures of psychopathology and functioning. ConclusionsWhile all versions of the CPT tested here had good psychometric characteristics, the 3-digit CPT-IP has some advantages in repeated measures studies such as clinical trials.

Delineating the contributions of sustained attention and working memory to individual differences in mindfulness

Mindfulness can be deconstructed into two constituent components: present-moment awareness and acceptance. Attention and working memory are theorized to contribute to individual differences in trait mindfulness, although the precise relationship among these constructs remains unclear. The purpose of the present study was to evaluate the association of neurocognitive indices of attention and working memory with a bidimensional trait measure of mindfulness. Fifty-five psychiatrically and neurologically healthy adults completed the Conners Continuous Performance Test, Penn Letter N-back Test, and Philadelphia Mindfulness Scale. Results indicated that present-moment awareness was associated with a response speed variability measure of sustained attention, whereas acceptance was more strongly linked to working memory efficiency, even after accounting for general intellectual ability. These findings suggest that sustained attention and working memory capacities may differentially subserve individual differences in present-moment awareness and acceptance, thereby illuminating our understanding of the cognitive mechanisms which may underlie trait mindfulness.

Cognitive Outcomes Following Contemporary Treatment Without Cranial Irradiation for Childhood Acute Lymphoblastic Leukemia

Treatment of acute lymphoblastic leukemia (ALL) has included the use of prophylactic cranial irradiation in up to 20% of children with high-risk disease despite known cognitive risks of this treatment modality. Patients enrolled on the St Jude ALL Total Therapy Study XV, which omitted prophylactic cranial irradiation in all patients, were assessed 120 weeks after completion of consolidation therapy (n = 243) using a comprehensive cognitive battery. χ(2) analysis was used to compare the percentage of below-average performers among the entire ALL patient group to the expected rate based on the normative sample. Univariate logistic regression was used to estimate the effect of intensity of chemotherapy (treatment arm), age at diagnosis, and sex on the probability of below-average performance. All statistical tests were two-sided. Overall, the ALL group had a statistically significantly higher risk for below-average performance on a measure of sustained attention (67.31% more than 1 SD below the normative mean for omission errors, P < .001) but not on measures of intellectual functioning, academic skills, or memory. Patients given higher intensity chemotherapy were at greater risk for below-average performance compared with those given lower intensity therapy on measures of processing speed (27.14% vs 6.25%, P = .009) and academic abilities (Math Reasoning: 18.60% vs 3.90%, P = .008; Word Reading: 20.00% vs 2.60%, P = .007; Spelling: 27.91% vs 3.90%, P = .001) and had higher parent-reported hyperactivity (23.00% vs 9.84%, P = .018) and learning problems (35.00% vs 16.39%, P = .005). Neither age at diagnosis nor sex was associated with risk for below-average cognitive performance. Omitting cranial irradiation may help preserve global cognitive abilities, but treatment with chemotherapy alone is not without risks. Caregiver education and development of interventions should address both early attention deficits and cognitive late effects.

Modafinil, but not escitalopram, improves working memory and sustained attention in long-term, high-dose cocaine users

ObjectiveThe purpose of the present study was to determine the effects of modafinil, escitalopram, and modafinil + escitalopram administration on neurocognition in a sample of long-term, high-dose cocaine users. MethodSixty-one cocaine-dependent individuals were randomly assigned to receive placebo (n = 14), modafinil, 200 mg, once daily (n = 16), escitalopram, 20 mg, once daily (n = 16), or modafinil and escitalopram, once daily (n = 15), for five days on an inpatient basis. Urinanalysis was used to confirm abstinence from cocaine on the day of admission and the next five days. Baseline neurocognitive assessment, which included measures of attention/information processing, episodic memory, and working memory, was conducted immediately after the washout phase and prior to the administration of modafinil. The follow-up assessment was conducted after participants had received modafinil or placebo for five days. ResultsRepeated-measures, mixed model analysis of variance showed that modafinil administration was associated with significantly improved performance on two measures of working memory span (mean n-back span, maximum n-back span) and a trend toward significant improvement on a measure of visual working memory (visual accuracy) and two measures of sustained attention, consistency of response time (Variability) and reduced impulsivity (Perseveration). Modafinil administration did not modulate performance on measures of information processing speed or episodic memory. Escitalopram did not modulate performance on measures of cognition, either alone or in combination with modafinil. ConclusionsThis study provides initial data showing that, in a sample of long-term, high-dose cocaine users, administration of psychotropic medications, such as modafinil, can improve performance on measures of working memory. Moreover, it confirms the utility of studying the interactive effects of psychotropic medications to confirm the manner in which the candidate medications independently and interactively affect neurocognition. These effects are likely relevant in the treatment of cocaine dependence, in which the remediation of impaired working memory may be associated with improved treatment outcomes.This article is part of a Special Issue entitled ‘Cognitive Enhancers’.

P3‐272: Longitudinal profiling of mild congitive impairment subtypes

Mild Cognitive Impairment (MCI) was originally conceptualized as a condition that manifested prior to the onset of clinical dementia, particularly Alzheimer’s disease. However, longitudinal studies show that MCI has an unstable course and may lead to various outcomes including dementia, but also stability of cognitive deficits or recovery to age appropriate levels of functioning. As a result, the status of MCI as a genuine diagnostic entity remains questionable. The aim of the present thesis was to examine the validity of the MCI concept by tracking groups of individuals classified into one of the MCI subtypes and to monitor their neuropsychological profiles over time. To avoid previous criticisms of circularity, participants were classified as MCI on a neuropsychological test battery and then reassessed longitudinally using an alternate battery of neuropsychological tests. At each stage of testing, participants were assessed on a comprehensive neuropsychological test battery tapping the cognitive domains implicated in MCI. Findings from this thesis indicate that multiple domain amnestic MCI may be the most valid subtype of MCI due to consistently poor performance over time on a range of neuropsychological measures. Results also demonstrate that those who are likely to remain on the MCI spectrum can be differentiated from healthy older adults using reliable and valid measures of sustained attention, semantic memory, verbal episodic memory, visual and verbal working memory, selective attention and strategy use. Despite these findings, evidence from this thesis indicates that existing MCI clinical criteria lack sufficient sensitivity and specificity. Although the concept of MCI remains useful, it cannot be considered a clinical diagnostic entity. Future research should prioritize the observation of those presenting with a multiple domain amnestic profile as these individuals may have the poorest prognosis. Further, studies must utilize comprehensive testing protocols to increase the sensitivity and specificity of identifying those with genuine subclinical impairments.

Exploring the relationship between boredom and sustained attention

Boredom is a common experience, prevalent in neurological and psychiatric populations, yet its cognitive characteristics remain poorly understood. We explored the relationship between boredom proneness, sustained attention and adult symptoms of attention deficit hyperactivity disorder (ADHD). The results showed that high boredom-prone individuals (HBP) performed poorly on measures of sustained attention and showed increased symptoms of ADHD and depression. The results also showed that HBP individuals can be characterised as either apathetic-in which the individual is unconcerned with his/her environment, or as agitated-in which the individual is motivated to engage in meaningful activities, although attempts to do so fail to satisfy. Apathetic boredom proneness was associated with attention lapses, whereas agitated boredom proneness was associated with decreased sensitivity to errors of sustained attention, and increased symptoms of adult ADHD. Our results suggest there is a complex relationship between attention and boredom proneness.

What Grasps and Holds 8-Month-Old Infants' Looking Attention? The Effects of Object Size and Depth Cues

The current eye-tracking study explored the relative impact of object size and depth cues on 8-month-old infants' visual attention processes. A series of slides containing 3 objects of either different or same size were displayed on backgrounds with varying depth cues. The distribution of infants' first looks (a measure of initial attention switch) and infants' looking durations (a measure of sustained attention) at the objects were analyzed. Results revealed that the large objects captured infants' attention first, that is, most of the times infants directed their visual attention first to the largest object in the scene regardless of depth cues. For sustained attention, infants preferred maintaining their attention to the largest object also, but this occurred only when depth cues were present. These findings suggest that infants' initial attention response is driven mainly by object size, while infants' sustained attention is more the product of combined figure and background processing, where object sizes are perceived as a function of depth cues.

Accommodative response and cortical activity during sustained attention

Greater accommodative lag and vergence deficits have been linked to attentional deficits similar to those observed in Attention Deficit Hyperactivity Disorder (ADHD). The purpose of the present study was to assess the effect of accommodative–vergence stress on a measure of sustained attention (Conners CPT) used in the diagnosis of ADHD. Twenty-seven normal non-ADHD adults completed the Conners CPT twice: wearing −2.00 D lenses and normally (without the −2.00 D lenses) in a counterbalanced order with at least 24h between the sessions. Simultaneous recording of participants’ dynamic accommodative responses was performed from the right eye using the Grand Seiko WAM-5500 auto-refractor and electroencephalographic activity (EEG) in the left prefrontal region using the Neurosky Mindset headset. The results demonstrated a significantly greater accommodative lag in the −2.00 D stress condition and a significantly poorer performance on the Conners CPT as indexed by slower reaction time, greater standard error of hit reaction time, grater response variability, poorer stimulus detectability and a greater number of perseverations. No differences were observed on measures of EEG in the theta (4–7Hz), alpha (8–12Hz), and beta (12–20Hz) bands. Moreover, when directly juxtaposed with each EEG band in multiple linear regression analyses, greater accommodative lag in the stress condition was significantly associated with a greater probability of clinical classification on the Conners CPT, and was also marginally predictive of the number of omissions recorded in the stress condition. The results demonstrated that sustained attention can be influenced by such factors as accommodative–vergence stress and suggest that bottom-up processes can contribute to and potentially exacerbate attentional problems in individuals with ADHD. The study also showed that cortical dysfunction (while sufficient) may not be a necessary condition for attentional deficits.

Ameliorating Attention Problems in Children With Sickle Cell Disease

This pilot study examined whether methylphenidate (MPH) was effective in enhancing cognitive performance and attention for children with sickle cell disease (SCD) with cerebrovascular complications who evidence attention problems. In this multisite, pilot study, we evaluated 2 separate double-blind controlled clinical trials, including a laboratory trial of the short-term efficacy of MPH, with the second study a 3-week home/school crossover trial evaluating the efficacy of MPH. The laboratory trial included 14 participants between the age of 7 and 16 years. Assessments included measures of sustained attention, reaction time, executive functions, and verbal memory. The home/school trial included 20 participants. The outcome measures were parent and teacher ratings of attention. The first study compared MPH with placebo, while the second trial compared placebo, low-dose (LD) MPH, and moderate-dose MPH. In the laboratory trial, significant effects were revealed for measures of memory and inhibitory control. Parent and teacher reports from the home/school trial indicate that moderate-dose MPH produced superior improvement in attention relative to the placebo and LD MPH. Stimulant medication positively impacted select measures of memory and inhibitory control in some children with SCD. Attention, as rated by parent and teachers, was improved for a greater number of children and adolescents on higher doses of MPH relative to LD MPH and placebo. Stimulant medication may provide an effective intervention for some children with SCD and cerebrovascular complications who demonstrate attention problems.