Sleep and cognition in South African patients with non-functioning pituitary adenomas.

Strong lines of evidence in the neuroscience literature indicate that (a) healthy sleep facilitates cognitive processing, and (b) sleep disruption is associated with cognitive dysfunction. Despite the fact that patients with pituitary disease often display both disrupted sleep and cognitive dysfunction, few previous studies investigate whether these clinical characteristics in these patients might be related. Hence, we explored whether sleep disruption in patients with pituitary disease mediates their cognitive dysfunction. We recruited 18 patients with non-functioning pituitary adenomas (NFPA) and 19 sociodemographically matched healthy controls. They completed the Global Sleep Assessment Questionnaire (thus providing self-report data regarding sleep disruption) and were administered the Brief Test of Adult Cognition by Telephone, which assesses cognitive functioning in the domains of processing speed, working memory, episodic memory, inhibition, and reasoning. We found no significant differences in cognition between patients and controls. Furthermore, spectra of sleep disturbance did not differ significantly between patients and controls. Our data suggest that NFPA patients' cognition and sleep quality is relatively intact, and that sleep disruption does not mediate cognitive dysfunction. Larger studies should characterize sleep and cognition in patients with NFPA (and other pituitary diseases) to confirm whether disruption of the former mediates impairment in the latter.

Sex Differences in the Cognitive Performance of a South African Cohort of People With HIV and Comorbid Major Depressive Disorder.

Women with HIV (WWH) may be more vulnerable to cognitive impairment than men with HIV (MWH), which may be explained by the direct effects of HIV or by sociodemographic and psychiatric characteristics. We recruited 105 people with HIV (PWH; 76 women) with incomplete antiretroviral therapy adherence, comorbid major depressive disorder, and socioeconomically disadvantaged backgrounds. Participants completed neuropsychological testing and measures gathering sociodemographic, medical, and psychiatric information. We compared WWH and MWH cognitive performance using unadjusted and adjusted regressions, and within each respective group, we explored predictors of cognitive performance. Results showed no significant between-sex differences in cognitive performance, both globally and within domains. Fewer years of education (ß = 0.94), illiteracy (ß = 4.55), and greater food insecurity (ß = -0.28) predicted lower cognitive performance in WWH but not MWH. We conclude that sex differences in PWH are likely due to sample characteristics representing broader inequalities, rather than true biological differences.

Cognitive impairment in people living with HIV: consensus recommendations for a new approach.

Current approaches to classifying cognitive impairment in people living with HIV can overestimate disease burden and lead to ambiguity around disease mechanisms. The 2007 criteria for HIV-associated neurocognitive disorders (HAND), sometimes called the Frascati criteria, can falsely classify over 20% of cognitively healthy individuals as having cognitive impairment. Minimum criteria for HAND are met on the basis of performance on cognitive tests alone, which might not be appropriate for populations with diverse educational and socioeconomic backgrounds. Imprecise phenotyping of cognitive impairment can limit mechanistic research, biomarker discovery and treatment trials. Importantly, overestimation of cognitive impairment carries the risk of creating fear among people living with HIV and worsening stigma and discrimination towards these individuals. To address this issue, we established the International HIV-Cognition Working Group, which is globally representative and involves the community of people living with HIV. We reached consensus on six recommendations towards a new approach for diagnosis and classification of cognitive impairment in people living with HIV, intended to focus discussion and debate going forward. We propose the conceptual separation of HIV-associated brain injury - including active or pretreatment legacy damage - from other causes of brain injury occurring in people living with HIV. We suggest moving away from a quantitative neuropsychological approach towards an emphasis on clinical context. Our recommendations are intended to better represent the changing profile of cognitive impairment in people living with HIV in diverse global settings and to provide a clearer framework of classification for clinical management and research studies.

Cognitive Performance, as well as Depression, Alcohol Use, and Gender, predict Anti-Retroviral Therapy Adherence in a South African Cohort of People with HIV and Comorbid Major Depressive Disorder.

Depression and cognitive impairment, which commonly coexist in people with HIV (PWH), have been identified as potential barriers to optimal antiretroviral therapy (ART) adherence. We investigated associations between cognitive performance, depression (as well as other sociodemographic, psychosocial and psychiatric variables) and ART adherence in a South African cohort of PWH with comorbid major depressive disorder (MDD). Cognitive performance and ART adherence were assessed at two time points 8 months apart (Nbaseline = 105, Nfollow-up = 81). Adherence was indicated by self-report, objective measures (Wisepill usage and plasma tenofovir-diphosphate levels), and HIV viral suppression. Mixed-effects regression models examined associations across both time points. Univariate models detected no significant associations between cognitive performance (globally and within-domain) and ART adherence. Multivariate modelling showed increased depression severity (ß = - 0.54, p < 0.001) and problematic alcohol use (ß = 0.73, p = 0.015) were associated with worse adherence as measured subjectively. Being female (OR 0.27, p = 0.048) and having better global cognitive performance (OR 1.83, p = 0.043) were associated with better adherence as indicated by viral suppression. This study identifies poor global cognitive performance, as well as depression and problematic alcohol use, as potential barriers to optimal ART adherence in PWH and comorbid MDD. Hence, clinicians could consider assessing for cognitive deficits, depression, and problematic alcohol use, and should endeavour to provide the appropriate support so as to improve adherence.

A South African adaptation of the international affective picture system: The influence of socioeconomic status and education level on picture ratings.

The International Affective Picture System (IAPS) is used globally in emotion research. However, normative studies in diverse contexts do not consider the influence of education and socioeconomic status (SES) on picture ratings. We created the South African Affective Picture System (SA-APS) for use in low- and middle-income countries (LMICs) by replacing some original IAPS images with pictures featuring more diverse groups of people and culturally appropriate stimuli. Healthy South African adults from higher and lower education/SES backgrounds (n = 80; n = 70 respectively) provided valence and arousal ratings for 340 images from the original IAPS and 340 images from the new SA-APS. Overall, their ratings of SA-APS images were better aligned with the US normative standards than their ratings of IAPS images, particularly with regard to valence. Those with higher SES/education rated IAPS images differently from those with lower SES/education (e.g., valence ratings of the latter were similar to US normative standards, whereas those of the former were more negative). Regression modelling indicated that sex and SES significantly predicted the current sample's IAPS and SA-APS ratings (e.g., women and higher-SES participants rated high-arousal images as being significantly more arousing than men and lower-SES participants); hence, we created regression-based norms for both picture sets. These norms are especially useful in emotion research, because few studies emerge from LMICs, and few instruments account for substantial sociodemographic diversity. Extending the reach of tools such as the IAPS to LMICs can help ensure a more globally representative body of research in this field.

Preferential consolidation of emotional reactivity during sleep: A systematic review and meta-analysis.

Many studies have investigated whether sleep affects cognitively unmodulated reactivity to emotional stimuli. These studies operationalize emotion regulation by using subjective and/or objective measures to compare pre- and post-sleep reactivity to the same emotional stimuli. Findings have been inconsistent: some show that sleep attenuates emotional reactivity, whereas others report enhanced or maintained reactivity. Across-study methodological differences may account for discrepant findings. To resolve the questions of whether sleep leads to the attenuation, enhancement, or maintenance of emotional reactivity, and under which experimental conditions particular effects are observed, we undertook a synthesized narrative and meta-analytic approach. We searched PubMed, PsycINFO, PsycARTICLES, Web of Science, and Cochrane Library databases for relevant articles, using search terms determined a priori and search limits of language = English, participants = human, and dates = January 2006-June 2021. Our final sample included 24 studies that investigated changes in emotional reactivity in response to negatively and/or positively valenced material compared to neutral material over a period of sleep compared to a matched period of waking. Primary analyses used random effects modeling to investigate whether sleep preferentially modulates reactivity in response to emotional stimuli; secondary analyses examined potential moderators of the effect. Results showed that sleep (or equivalent periods of wakefulness) did not significantly affect psychophysiological measures of reactivity to negative or neutral stimuli. However, self-reported arousal ratings of negative stimuli were significantly increased post-sleep but not post-waking. Sub-group analyses indicated that (a) sleep-deprived participants, compared to those who slept or who experienced daytime waking, reacted more strongly and negatively in response to positive stimuli; (b) nap-exposed participants, compared to those who remained awake or who slept a full night, rated negative pictures less negatively; and (c) participants who did not obtain substantial REM sleep, compared to those who did and those exposed to waking conditions, had attenuated reactivity to neutral stimuli. We conclude that sleep may affect emotional reactivity, but that studies need more consistency in methodology, commitment to collecting both psychophysiological and self-report measures, and should report REM sleep parameters. Using these methodological principles would promote a better understanding of under which conditions particular effects are observed.

Executive function in methamphetamine users with and without psychosis.

Methamphetamine abuse is associated with cognitive deficits across a wide range of domains. It is unclear, however, whether methamphetamine-dependent individuals with co-occurring psychosis are more impaired than those without psychosis on tests assessing executive function. We therefore aimed to compare the executive function performance of three groups: methamphetamine-dependent individuals with methamphetamine-induced psychosis (MA+; n = 20), methamphetamine-dependent individuals without psychosis (MA-; n = 19), and healthy controls (HC; n = 20). All participants were administered a neuropsychological test battery that assessed executive functioning across six sub domains (problem solving, working memory, verbal generativity, inhibition, set switching, and decision making). Analyses of covariance (controlling for between-group differences in IQ) detected significant between-group differences on tests assessing verbal generativity and inhibition, with MA+ participants performing significantly more poorly than HC. The finding that methamphetamine-induced psychosis is associated with performance impairments in particular subdomains of executive function may have implications for treatment adherence and relapse prevention.

Cognitive performance in a South African cohort of people with HIV and comorbid major depressive disorder.

Cognitive performance in people with HIV (PWH) may be affected by brain injury attributable to the infection itself, by other medical and psychiatric comorbidities (including major depressive disorder; MDD), and by psychosocial factors (e.g., education, food insecurity). We investigated effects of these variables on cognitive performance in a South African cohort of PWH with comorbid MDD and incomplete adherence to antiretroviral therapy (ART). We also examined (a) associations of depression severity with cognitive performance, and (b) whether improvement in depression led to improved cognitive performance. Participants (N = 105) completed baseline neuropsychological, psychiatric, and sociodemographic assessments. Subsequently, 33 were assigned to a cognitive-behavioural therapy for ART adherence and depression (CBT-AD) and 72 to standard-of-care treatment. Eight months post-baseline, 81 (nCBT-AD = 29) repeated the assessments. We investigated (a) baseline associations between sociodemographic, medical, and psychiatric variables and cognitive performance, (b) whether, from baseline to follow-up, depression and cognitive performance improved significantly more in CBT-AD participants, and (c) associations between post-intervention improvements in depression and cognitive performance. At baseline, less education (ß = 0.62) and greater food insecurity (ß = -0.20) predicted poorer overall cognitive performance; more severe depression predicted impairment in the attention/working memory domain only (ß = -0.25). From baseline to follow-up, depression decreased significantly more in CBT-AD participants (p = .017). Improvement over time in depression and cognitive performance was not significantly associated except in the attention/working memory domain (p = .026). Overall, factors associated with cognitive performance were unrelated to brain injury. We conclude that clinicians examining PWH presenting with cognitive difficulties must assess depression, and that researchers investigating cognitive impairment in PWH must collect information on psychosocial factors.

Adaptation and norming of the Edinburgh Cognitive and behavioural amyotrophic lateral sclerosis screen (ECAS) for three language groups in South Africa.

Objectives: To adapt and translate the Edinburgh Cognitive and behavioural amyotrophic lateral sclerosis screen (ECAS); to generate preliminary normative data for three language groups in South Africa (SA); to assess the convergent validity of the ECAS in SA samples. Methods: The ECAS was linguistically and culturally adapted for Afrikaans-, isiXhosa-, and English-speaking SA adults (n = 108, 100, and 53, respectively). Each language group was stratified by age and educational level. Cutoff scores for cognitive impairment were set at the group mean minus two standard deviations (SDs). A pilot sample of ALS patients and controls (n = 21 each) were administered the ECAS and an extensive neuropsychological evaluation (NPE) and the Montreal Cognitive Assessment (MoCA) to assess convergent validity. Results: Across the three language groups, the total ECAS cutoff scores ranged from 68 to 97. The ECAS score correlated significantly positively with educational level (p < 0.001) and negatively with age (p < 0.005). The restricted letter fluency task demonstrated a floor effect, particularly in Afrikaans-speakers. The mean total ECAS score (±SD) was similar in ALS patients (103.52 ± 11.90) and controls (100.67 ± 20.49; p = 0.58). Three (14.3%) ALS patients scored below the cutoff for cognitive impairment. Correlations between individual ECAS subtests and analogous NPE tests ranged from weak to moderate. The MoCA score was significantly positively correlated with the ECAS total score (r = 0.59; p = < 0.001). Conclusions: The adapted ECAS and associated normative data will aid cognitive screening of African ALS patients. Larger participant numbers are needed to assess the validity of the adapted instrument.

Risky Decision Making Under Stressful Conditions: Men and Women With Smaller Cortisol Elevations Make Riskier Social and Economic Decisions.

Men often make riskier decisions than women across a wide range of real-life behaviors. Whether this sex difference is accentuated, diminished, or stable under stressful conditions is, however, contested in the scientific literature. A critical blind spot lies amid this contestation: Most studies use standardized, laboratory-based, cognitive measures of decision making rather than complex real-life social simulation tasks to assess risk-related behavior. To address this blind spot, we investigated the effects of acute psychosocial stress on risk decision making in men and women (N = 80) using a standardized cognitive measure (the Iowa Gambling Task; IGT) and a novel task that simulated a real-life social situation (an online chatroom in which participants interacted with other men and women in sexually suggestive scenarios). Participants were exposed to either an acute psychosocial stressor or an equivalent control condition. Stressor-exposed participants were further characterized as high- or low-cortisol responders. Results confirmed that the experimental manipulation was effective. On the IGT, participants characterized as low-cortisol responders (as well as those in the Non-Stress group) made significantly riskier decisions than those characterized as high-cortisol responders. Similarly, in the online chatroom, participants characterized as low-cortisol responders (but not those characterized as high-cortisol responders) were, relative to those in the Non-Stress group, significantly more likely to make risky decisions. Together, these results suggest that at lower levels of cortisol both men and women tend to make riskier decisions in both economic and social spheres.

Impact of HIV on Cognitive Performance in Professional Drivers.

BACKGROUND: The intellectually demanding modern workplace is often dependent on good cognitive health, yet there is little understanding of how neurocognitive dysfunction related to HIV presents in employed individuals working in high-risk vocations such as driving. HIV-associated neurocognitive impairment is also associated with poorer long-term cognitive, health, and employment outcomes. SETTING: This study, set in Cape Town, South Africa, assessed the effects of HIV on neuropsychological test performance in employed male professional drivers. METHOD: We administered a neuropsychological test battery spanning 7 cognitive domains and obtained behavioral data, anthropometry, and medical biomarkers from 3 groups of professional drivers (68 men with HIV, 55 men with cardiovascular risk factors, and 81 controls). We compared the drivers' cognitive profiles and used multiple regression modeling to investigate whether between-group differences persisted after considering potentially confounding sociodemographic and clinical variables (ie, income, home language, depression, and the Framingham risk score). RESULTS: Relative to other study participants, professional drivers with HIV performed significantly more poorly on tests assessing processing speed (P < 0.003) and attention and working memory (P = 0.018). Group membership remained a predictor of cognitive performance after controlling for potential confounders. The cognitive deficits observed in men with HIV were, however, largely characterized as being mild or asymptomatic. Consistent with this characterization, their relatively poor performance on neuropsychological testing did not generalize to self-reported impairment on activities of daily living. CONCLUSION: Drivers with HIV may be at risk of poorer long-term health and employment outcomes. Programs that monitor and support their long-term cognitive health are needed.

A comprehensive view of functional impairment in children and adolescents with obsessive-compulsive disorder adds value.

AIM: This study aimed to contribute to the paucity of literature on disability in youth with OCD, particularly in low- and middle-income countries (LMICs). METHODS: In South Africa (a LMIC), data was collected from 26 children and adolescents with OCD (12 girls, 14 boys; age range 6-18 years), and their parents, on an outpatient basis. Clinical measures aimed at assessing functional impairment due to OCD were administered. RESULTS: Key findings were 1) that children with OCD reported being most significantly affected by their OC symptomatology within the school domain whereas parents placed emphasis on the impairment within the social domain; 2) scores on the Child Obsessive-Compulsive Impact Scale - Revised and the Children's Global Assessment Scale, were consistent, and 3) clinician-rated symptom severity was positively associated with parental reports on children's impairment due to OCD. Findings show similarities with data from similar studies in a high-income country (HIC) context. CONCLUSIONS: Children with OCD and their parents do not necessarily agree on the ways in which OCD impacts their lives. A comprehensive view of functional impairment in children with OCD, that is, from the viewpoints of the patient, parents, and clinicians, is critical when treatment is planned. Such information may assist with selection of relevant treatment targets, and ultimately improve the quality of life of all affected.

Youth perinatal HIV-associated neurocognitive disorders: association with functional impairment.

HIV-associated functional impairment may cause cognitive impairment secondary to the viral infection, hence, associations between cognitive impairment and functional impairment in youth living with HIV are important to assess. We sought to determine whether cognitive impairment is associated with functional impairment and if it carries higher risk for also having functional impairment. We collected parent-rated information regarding youth functional impairment on four different measures and administered a cognitive battery to youth to determine cognitive impairment, 203 HIV-infected youth and 44 HIV-uninfected controls. Degree of cognitive impairment correlated strongly with decreased function: CBCL, r = -.17, p = .01; VABS2, r = -.28, p < .001; repeated-grades, r = .26, p < .001. Presence of cognitive impairment was associated with increased risk of functional impairment: 3.47 (CIS); 1.71 (CBCL); 2.17 (VABS2); 2.97 (repeated-grades). Repeated-grades strongly associated with cognitive impairment and functional impairment. We found strong associations between HIV-infected youth functional impairment on CBCL, VABS2 and repeated-grades with degree of cognitive impairment; and that when cognitive impairment was present youth had higher risk of experiencing functional impairment as well. Asking whether youth have repeated a grade at school could be a helpful screening question for assessing potential functional impairment and provide clinicians with an indication as to whether a further in-depth assessment is required.

Cognitive Differences between Men and Women with HIV: A Systematic Review and Meta-Analysis.

OBJECTIVE: Although many studies report that women with HIV (WWH) are more vulnerable to cognitive impairment than men with HIV (MWH), this trend is not described consistently in the literature. In this systematic review and meta-analysis, we investigated whether the weight of evidence supports the existence of a significant sex difference in cognitive functioning among people with HIV and, if so, whether specific domains are affected. METHOD: A systematic literature search retrieved 4,062 unique articles published between January 2000 and June 2019. Eligibility criteria were that studies directly compared adult WWH and MWH using a neuropsychological test battery. After extensive screening, we included 11 studies in the systematic review (N = 3,333) and 6 in the meta-analysis (N = 2,852). RESULTS: Six studies included in the systematic review found WWH performed significantly more poorly on measures of cognitive performance than MWH; the other five found no sex differences. Meta-analytic results indicated that WWH performed significantly more poorly than MWH in three cognitive domains (psychomotor coordination, visuospatial learning, and memory), but magnitudes of effect sizes were small (d = -.16, -.43, and - .30, respectively). Analyses detected no sex differences in global cognitive functioning and in the other cognitive domains. CONCLUSIONS: Sex differences in cognitive performance are small, and sociodemographic and psychiatric characteristics of WWH and MWH differ between studies. Cognitive differences between WWH and MWH may be explained by sex-based variation in these characteristics, the impact of which seems to outweigh that of HIV-related clinical variables (e.g., CD4 count and viral load).

Rates of cognitive impairment in a South African cohort of people with HIV: variation by definitional criteria and lack of association with neuroimaging biomarkers.

There is wide variation in the reported prevalence of cognitive impairment in people with HIV (PWH). Part of this variation may be attributable to different studies using different methods of combining neuropsychological test scores to classify participants as either cognitively impaired or unimpaired. Our aim was to determine, in a South African cohort of PWH (N = 148), (a) how much variation in reported rates was due to method used to define cognitive impairment and (b) which method correlated best with MRI biomarkers of HIV-related brain pathology. Participants completed detailed neuropsychological assessment and underwent 3 T structural MRI and diffusion tensor imaging (DTI). We used the neuropsychological data to investigate 20 different methods of determining HIV-associated cognitive impairment. We used the neuroimaging data to obtain volumes for cortical and subcortical grey matter and total white matter and DTI metrics for several white matter tracts. Applying each of the 20 methods to the cognitive dataset resulted in a wide variation (20-97%) in estimated rates of impairment. Logistic regression models showed no method was associated with HIV-related neuroimaging abnormalities as measured by structural volumes or DTI metrics. We conclude that for the population from which this sample was drawn, much of the variation in reported rates of cognitive impairment in PWH is due to the method of classification used, and that none of these methods accurately reflects biological effects of HIV in the brain. We suggest that defining HIV-associated cognitive impairment using neuropsychological test performance only is insufficient; pre-morbid functioning, co-morbidities, cognitive symptoms, and functional impairment should always be considered.

An fMRI investigation of neural activation predicting memory formation in children with fetal alcohol spectrum disorders.

Prenatal alcohol exposure (PAE) is associated with physical anomalies, growth restriction, and a range of neurobehavioral deficits. Although declarative memory impairment has been documented extensively in individuals with fetal alcohol spectrum disorders (FASD), this cognitive process has been examined in only one functional magnetic resonance imaging (fMRI) study, and mechanisms underlying this impairment are not well understood. We used an event-related fMRI design to examine neural activations during visual scene encoding that predict subsequent scene memory in 51 right-handed children (age range = 10-14 years, M = 11.3, SD = 1.3) whose mothers had been recruited and interviewed prospectively about their alcohol use during pregnancy. Following examination by expert dysmorphologists, children were assigned to one of three FASD diagnostic groups: FAS/PFAS (nFAS = 7; nPFAS = 4), nonsyndromal heavily exposed (HE; n = 14), and Controls (n = 26). Subsequent memory was assessed in a post-scan recognition test, and subsequent memory activations were examined by contrasting activations during encoding of scenes that were subsequently remembered (hits) to those for incorrectly judged as 'new' (misses). Recognition accuracy did not differ between groups. Pooled across groups, we observed extensive bilateral subsequent memory effects in regions including the hippocampal formation, posterior parietal cortex, and occipital cortex-a pattern consistent with previous similar studies of typically developing children. Critically, in the group of children with FAS or PFAS, we observed activations in several additional regions compared to HE and Control groups. Given the absence of between-group differences in recognition accuracy, these data suggest that in achieving similar memory compared to children in the HE and Control groups, children with FAS and PFAS recruit more extensive neural resources to achieve successful memory formation.

Taking the Test: A Qualitative Analysis of Cultural and Contextual Factors Impacting Neuropsychological Assessment of Xhosa-Speaking South Africans.

OBJECTIVE: There is an urgent need to make neuropsychological (NP) testing more acceptable, accessible, and culturally salient, particularly for culturally, educationally, and linguistically diverse individuals from countries who may have little-to-no experience with NP testing. In settings with limited resources such as South Africa, unique cultural and contextual factors (e.g., structural inequality, poverty) may impact the experience of NP evaluation. Research in this area is limited and requires further exploration. This qualitative study explores the role of cultural and contextual factors that may impact the experience of NP evaluation in a sample of Xhosa-speaking South African adults. Participant interviews explored the context from which individuals arrived at the NP assessment (e.g., quality of education, understanding of cognitive disorders), and their experience of completing NP tests. METHOD: This qualitative study used data from semistructured interviews to conduct a thematic analysis exploring contextual factors and the experience of completing NP tests for the first time among Xhosa-speaking South African adults (N = 22). Results: Although no participants had prior experience with NP testing, most found testing procedures acceptable. Most participants, however, reported a limited understanding of the purpose of NP testing and cognitive problems. Additionally, some participants reported perceptions and attitudes that could affect test performance, such as misinterpreting standard testing procedures (e.g., no feedback from the examiner, being stopped mid-task) as indicative of poor performance. CONCLUSIONS: This study provided much needed exploration into unique cultural factors that may impact the experience of NP assessment in South Africa, which could bias test performance and interpretation, and may aid the field of cross-cultural NP in better serving culturally and linguistically diverse populations. In these countries, neuropsychologists may need to actively evaluate participants' understanding of NP testing to help foster optimal assessment conditions. They may also need to educate participants on possible causes of cognitive disorders.

Bedtime Stress Increases Sleep Latency and Impairs Next-Day Prospective Memory Performance.

The cognitive construct of prospective memory (PM) refers to the capacity to encode, retain and execute delayed intentions (e.g. to remember to buy milk on the way home). Although previous research suggests that PM performance is enhanced by healthy sleep, conclusions tend to be drawn based on designs featuring ecologically unnatural manipulations (e.g. total sleep deprivation). This study investigates whether a more common everyday experience (bedtime stress) affects next-day PM performance and, in so doing, also contributes to the heretofore inconsistent literature on stress and PM. Forty young adults received PM task instructions and were then assigned to either a stress condition (exposure to a laboratory-based stress-induction manipulation; n = 20, 9 women) or a non-stress condition (exposure to a non-stressful control manipulation; n = 20, 12 women). After completing the experimental manipulation, all participants had their objective sleep quality measured over a full night of polysomnographic monitoring. Upon awakening, they completed the PM task. Analyses detected significant between-group differences in terms of stress outcomes, sleep quality and PM performance: Participants exposed to the manipulation experienced heightened signs of stress (captured using a composite variable that included self-report, psychophysiological and endocrinological measures), had longer sleep latencies and poorer sleep depth and displayed significantly longer reaction times to PM cues. An interaction between experimental condition (being exposed to the stressor) and disrupted sleep (longer sleep latency) significantly predicted poorer next-day PM reaction time. We interpret these findings as indicating that bedtime stress, which leads to heightened presleep arousal, affects sleep processes and, consequently, the deployment of attentional resources during next-day execution of a delayed intention.

Reduced Hippocampal Volumes Partially Mediate Effects of Prenatal Alcohol Exposure on Spatial Navigation on a Virtual Water Maze Task in Children.

BACKGROUND: Prenatal alcohol exposure (PAE) has been linked to poorer performance on the Morris water maze (MWM), a test of spatial navigation in rodents that is dependent on hippocampal functioning. We recently confirmed these findings in children with PAE on a human analog of the MWM, the virtual water maze (VWM). Previous studies have shown that the hippocampus is particularly sensitive to PAE. Our aim was to determine whether hippocampal volume mediates the relation between PAE and virtual navigation. METHODS: VWM and MRI hippocampal data were collected from 50 right-handed 10-year-old children in a heavily exposed Cape Town, South African sample. PAE data had been collected from their mothers during pregnancy, and the children were examined by expert fetal alcohol spectrum disorder (FASD) dysmorphologists. In the VWM, the participant attempts to learn the location of a hidden platform in a virtual pool of water across a series of learning trials using only distal room cues. Hippocampal volumes were derived using FreeSurfer from MRI scans administered within 1 week of completing the VWM task. RESULTS: Both the fetal alcohol syndrome (FAS)/partial FAS and nonsyndromal heavy-exposed (HE) groups had smaller hippocampal volumes than controls. PAE was associated with reduced right hippocampal volumes even after control for total intracranial volume (ICV). Hippocampal volume was also positively associated with VWM performance. The relation between PAE and VWM performance was partially mediated by right hippocampal volume but not by total ICV. CONCLUSIONS: These data confirm previous reports linking PAE to poorer spatial navigation on the VWM and are the first to provide direct evidence that volume reductions in this region partially mediate the relation of FASD diagnosis to place learning, suggesting that PAE specifically impairs the ability to encode the spatial information necessary for successful location of the hidden platform on a navigation task.