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Using cluster analysis Libon et al. (2010) found three verbal serial list-learning profiles involving delay memory test performance in patients with mild cognitive impairment (MCI). Amnesic MCI (aMCI) patients presented with low scores on delay free recall and recognition tests; mixed MCI (mxMCI) patients scored higher on recognition compared to delay free recall tests; and dysexecutive MCI (dMCI) patients generated relatively intact scores on both delay test conditions. The aim of the current research was to further characterize memory impairment in MCI by examining forgetting/savings, interference from a competing word list, intrusion errors/perseverations, intrusion word frequency, and recognition foils in these three statistically determined MCI groups compared to normal control (NC) participants. The aMCI patients exhibited little savings, generated more highly prototypic intrusion errors, and displayed indiscriminate responding to delayed recognition foils. The mxMCI patients exhibited higher saving scores, fewer and less prototypic intrusion errors, and selectively endorsed recognition foils from the interference list. dMCI patients also selectively endorsed recognition foils from the interference list but performed similarly compared to NC participants. These data suggest the existence of distinct memory impairments in MCI and caution against the routine use of a single memory test score to operationally define MCI.

It is poorly understood why people with Down syndrome (DS) are at extremely high-risk of developing Alzheimer's disease (AD) compared to the general population. One explanation may be related to their extra copy of risk factors modulated by chromosome 21. Myo-inositol (mI), whose transporter gene is located on chromosome 21, has been associated with dementia in the non-DS population; however, nobody has contrasted brain mI in DS with (DS+) and without (DS-) dementia to other non-DS groups. Our primary aim was to compare the hippocampal concentration of mI ([mI]) and other brain metabolites such as N-acetylaspartate (NAA; a proxy measure of neuronal density and mitochondrial function) in DS+, DS-, and age-matched healthy controls using proton Magnetic Resonance Spectroscopy (((1))H-MRS). We compared hippocampal [mI] and other metabolites in 35 individuals with genetically-confirmed DS [DS+ (n=17, age=53±6) and DS- (n=18, age=47±8)] to age-matched healthy controls (n=13, age=51±10) adjusting for proportion of the MRS voxel occupied by cerebrospinal spinal fluid, and gray/white matter. DS+ had a significantly higher [mI] than both DS- and healthy controls. In contrast neither DS+ nor DS- differed significantly from controls in [NAA] (although NAA in DS+ was significantly lower than DS-). Our secondary aim of comparing brain metabolites in DS+ and DS- to Alzheimer's disease (AD; n=39; age=77±5) revealed that the DS+ group had significantly elevated [mI] compared to AD or DS-. [mI] may modify risk for dementia in this vulnerable population., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Models of calcium (Ca(2 +)) release sites derived from continuous-time Markov chain (CTMC) models of intracellular Ca(2 +) channels exhibit collective gating reminiscent of the experimentally observed phenomenon of Ca(2 +) puffs and sparks. In order to overcome the state-space explosion that occurs in compositionally defined Ca(2 +) release site models, we have implemented an automated procedure for model reduction that replaces aggregated states of the full release site model with much simpler CTMCs that have similar within-group phase-type sojourn times and inter-group transitions. Error analysis based on comparison of full and reduced models validates the method when applied to release site models composed of 20 three-state channels that are both activated and inactivated by Ca(2 +). Although inspired by existing techniques for fitting moments of phase-type distributions, the automated reduction method for compositional Ca(2 +) release site models is unique in several respects and novel in this biophysical context.

Objective: Subjective cognitive complaints are often used in the diagnosis of memory and other cognitive impairment. This study examined whether cognitive complaints are associated with longitudinal changes in cognition and cross-sectional differences in regional brain function during memory performance in 98 participants with a mean age of 75., Method: The Cognitive Failures Questionnaire (CFQ) assessed cognitive complaints and mixed effects regression models were used to determine whether mean CFQ scores predicted rates of change in cognitive function over a period of 11.5 years., Results: Higher CFQ scores, reflecting increased subjective complaints, were associated with steeper rates of decline in immediate and delayed recall on the California Verbal Learning Test. Voxel-based regression analysis was used to determine the cross-sectional relationship between CFQ scores and regional cerebral blood flow measured by PET during a resting condition and during verbal and figural memory tasks. Higher levels of cognitive complaints were associated with increased activity in insular, lingual and cerebellar areas during memory tasks., Conclusions: These findings offer some support for the validity of subjective cognitive complaints as markers of age related changes in memory and brain activity., ((c) 2010 APA, all rights reserved.)

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection.

Introduction: Acute tryptophan depletion (ATD) temporarily lowers brain serotonin (5-HT) synthesis, and behavioral studies have shown that this alters the processing of facial expressions of emotion., Materials and Methods: The neural basis for these alterations is not known. Therefore, we employed ATD and event-related functional magnetic resonance imaging (fMRI) to examine neural responses during incidental processing of fearful, happy, sad, and disgusted facial expressions. Fourteen healthy male controls (age, 28 +/- 10) were scanned under both placebo (SHAM) and depletion (ATD) conditions., Results and Discussion: We predicted that ATD would be associated with changes in neural activity within facial emotion-processing networks. We found that serotonergic modulation did not affect performance on the fMRI tasks, but was associated with widespread effects on neural response to components of face processing networks for fearful, disgusted, and happy but not sad expressions across differing intensities., Conclusion: Hence, the 5-HT system affects brain function (in 'limbic' and 'face processing' regions) during incidental processing of emotional facial expressions; but this varies with emotion type and intensities.

Objectives: Clinical depression in the elderly is associated with cerebral small vessel disease. It is less certain whether the endorsement of depressive symptoms in the absence of clinical depression, relatively common in euthymic older adults, is also associated with white matter damage. The majority of studies exploring this issue have produced mixed results, perhaps due, in part, to differences in defining the threshold for depression, notating vascular risk factors, and/or the neuroimaging tools used to quantify white matter damage. We aimed to address these issues with non-demented euthymic older adults., Design and Participants: We performed diffusion tensor imaging (DTI) and T2-weighted magnetic resonance imaging (MRI) in a population based cohort of 79 individuals (mean age = 68 years)., Measurements: In addition to neuroimaging, the authors report assessments of overall cognition, executive functioning, and depression., Results: Scores on the Geriatric Depression Scale 15-item (GDS-15) correlated with DTI measures of mean diffusivity (r [77] = 0.23, p = 0.039) and fractional anisotropy (r [77] = -0.22, p = 0.045) but only approached significance for T2-weighted MRI measures of white matter hyperintensities (WMH; r [77] = 0.21, p = 0.053). After adjusting for factors known to influence the development of WMH and depression, including age and vascular risks, DTI-derived indices of white matter integrity remained significantly associated with GDS-15 scores. Furthermore, only DTI-derived measures of white matter integrity contributed to the variance in GDS-15 scores in logistical regression modeling., Conclusions: These findings demonstrate an association between white matter damage and the endorsement of depressive symptoms in euthymic older adults and suggest that DTI may be more sensitive to this damage than T2-WMH in an aging cohort with multiple vascular risk factors.

We explore the effect of correlations between the in and out degrees of random directed networks on the synchronization of identical pulse-coupled oscillators. Numerical experiments demonstrate that the proportion of initial conditions resulting in a globally synchronous state (prior to a large but finite time) is an increasing function of node-degree correlation. For those networks observed to globally synchronize, both the mean and standard deviation of time to synchronization are decreasing functions of node-degree correlation. Pulse-coupled oscillator networks with negatively correlated node degree often exhibit multiple coherent attracting states, with trajectories performing fast transitions between them. These effects of node-degree correlation on dynamics of pulse-coupled oscillators are consistent with aspects of network topology (e.g., the effect of node-degree correlation on the eigenvalues of the Laplacian matrix) that have been shown to affect synchronization in other contexts.

A group of 94 nondemented patients self-referred to an outpatient memory clinic for memory difficulties were studied to determine the incidence of single versus multi-domain mild cognitive impairment (MCI) using Petersen criteria. Fifty-five community dwelling normal controls (NC) participants without memory complaints also were recruited. Tests assessing executive control, naming/lexical retrieval, and declarative memory were administered. Thirty-four patients exhibited single-domain MCI, 43 patients presented with multi-domain MCI. When the entire MCI sample (n = 77) was subjected to a cluster analysis, 14 patients were classified with amnesic MCI, 21 patients with dysexecutive MCI, and 42 patients were classified into a mixed/multi-domain MCI group involving low scores on tests of letter fluency, "animal" fluency, and delayed recognition discriminability. Analyses comparing the three cluster-derived MCI groups versus a NC group confirmed the presence of memory and dysexecutive impairment for the amnesic and dysexecutive MCI groups. The mixed MCI group produced lower scores on tests of letter fluency compared with the amnesic MCI and NC groups and lower scores on tests of naming and memory compared with the NC group. In summary, multi-domain MCI is quite common. These data suggest that MCI is a highly nuanced and complex clinical entity.

The introduction of diagnostic criteria for vascular dementia has helped to re-define the impact of various subcortical neuropathologies on aging; however, state-of-the-art neuroimaging techniques and autopsy studies suggest that not all structural brain alterations associated with vascular dementia are exclusive to this neurodegenerative process alone. Thus, a detailed analysis of the cognitive phenotype associated with ischaemic vascular disease is key to our understanding of subcortical neuropathology and its associated behaviors. Over the past twenty years, we have operationally defined this cognitive phenotype using the Boston Process Approach to neuropsychological assessment. This has led to both an empirical, as well as a theoretical understanding of three core constructs related to the dysexecutive syndrome associated with ischaemic vascular disease affecting periventricular and deep white matter as well as subcortical structures connecting these regions with the prefrontal cortex. Thus, difficulties with mental set, cognitive control and mental manipulation negatively impact executive functioning. This review will outline the subtle markers underlying this prefrontal dysfunction, i.e., the dysexecutive phenotype, associated with ischaemic vascular disease and relate it to fundamental impairments of gating subserved by basal ganglia-thalamic pathways within and across various dementia syndromes.

Recent evidence suggests that patients with Alzheimer's disease (AD) and vascular comorbidities (VC) perform worse across measures of verbal reasoning and abstraction when compared to patients with AD alone. We performed a qualitative error analysis of Wechsler Adult Intelligence Scale-III Similarities zero-point responses in 45 AD patients with varying numbers of VC, including diabetes, hypertension, and hypercholesterolemia. Errors were scored in set if the answer was vaguely related to how the word pair was alike (e.g., dog-lion: "they can be trained") and out of set if the response was unrelated ("a lion can eat a dog"). AD patients with 2-3 VC did not differ on Similarities total score or qualitative errors from AD patients with 0-1 VC. When analyzing the group as a whole, we found that increasing numbers of VC were significantly associated with increasing out of set errors and decreasing in set errors in AD. Of the vascular diseases investigated, it was only the severity of diastolic blood pressure that significantly correlated with out of set responses. Understanding the contribution of VC to patterns of impairment in AD may provide support for directed patient and caregiver education concerning the presentation of a more severe pattern of cognitive impairment in affected individuals.

Age-related declines in prefrontal functions and age-related declines in prefrontal serotonin (5-HT) are documented. The effect of 5-HT on prefrontal cortex (PFC) is also documented; however, no one has examined the effect of experimental 5-HT modulation on PFC in healthy older adults. We investigated the effect of 5-HT on brain functioning in 10 women over 55 (mean=63.0+/-5.3 years) during cognitive interference inhibition (Simon task) using fMRI and acute tryptophan depletion (ATD). ATD did not affect task performance; it did affect brain function. During sham/no depletion, participants activated brain regions associated with the Simon (e.g., left inferior PFC). During ATD, there was no prefrontal but alternative posterior brain activation. ATD relative to sham reduced activity in left inferior PFC, anterior cingulate and basal ganglia but increased activity within neocerebellum and parietal lobe. In older adults, ATD modulates task-relevant brain activation for cognitive interference inhibition and is associated with an anterior-to-posterior activation shift. Maintaining successful Simon performance during ATD is achieved by increasing cerebellar and parietal contributions to compensate for decreased fronto-cingulo-striatal involvement.

MRI leukoaraiosis (LA) is less likely to interfere with simple compared to more complex working memory (WM) skills. We hypothesize that LA within the left hemisphere negatively impacts higher-level WM processes in dementia. Participants with dementia (n=64; MMSE=22.0+/-3.4) performed a Backward Digit Task measuring simple storage/rehearsal (ANY-ORDER) and complex disengagement/temporal re-ordering (SERIAL-ORDER) recall. A visual rating scale categorized MRI-LA in five regions per hemisphere: frontal and parietal centrum semiovale, white matter around the frontal horns, body of the lateral ventricles and posterior horns. Amidst equivalent hemispheric LA scores [t(62)=-1.12, p>0.05], correlations revealed an association between left-sided LA and SERIAL-ORDER recall (r=-0.31, p=0.007) with LA around the posterior horn (rho=-0.30, p=0.008) and frontal centrum semiovale (rho=-0.29, p=0.01) showing the greatest association. Regression modeling confirmed the left posterior horn contribution to SERIAL-ORDER performance variance. Results suggest involvement of anterior (fronto-striatal) and more posterior (inferior parietal) white matter tracts in higher order WM deficits in dementia.

Mathematical models of calcium release sites derived from Markov chain models of intracellular calcium channels exhibit collective gating reminiscent of the experimentally observed phenomenon of stochastic calcium excitability (i.e., calcium puffs and sparks). We present a Kronecker structured representation for calcium release site models and perform benchmark stationary distribution calculations using numerical iterative solution techniques that leverage this structure. In this context we find multi-level methods and certain preconditioned projection methods superior to simple Gauss-Seidel type iterations. Response measures such as the number of channels in a particular state converge more quickly using these numerical iterative methods than occupation measures calculated via Monte Carlo simulation.

Cross-sectional and longitudinal findings from the Baltimore Longitudinal Study of Aging (BLSA) neuroimaging study indicate that the orbitofrontal cortex (OFC) is among those regions vulnerable to age-associated tissue loss in older adults without dementia. Neuropathologic and recent in vivo amyloid imaging studies indicate that the OFC is also among the earliest neocortical regions to show deposition of amyloid plaques in aging and Alzheimer's disease. We performed behavioral and imaging studies to investigate age effects on specific aspects of OFC function. We compared performance in young (age 20-40) and old (age 60 and older) adults on cognitive tasks selected for differential sensitivity to OFC versus dorsolateral prefrontal cortex (DLPFC). Overall, greater age differences were seen in the OFC tasks compared to DLPFC tasks, with Delayed Match and Non-Match to Sample tasks showing the greatest effect size among OFC tasks and Self-Ordered Pointing Task showing the greatest effect size among DLPFC tasks. A functional magnetic resonance imaging study was conducted in parallel to probe the neural underpinnings of age differences in OFC function using the Delayed Match and Non-Match to Sample paradigm. Young but not old adults showed the expected OFC activation. Older compared with young adults showed greater activation in association with successful performance for several posterior regions, perhaps indicating compensation in the face of OFC deficits. Together, these findings indicate a vulnerability of the OFC to age-related decline in brain structure and function. Future studies using new in vivo imaging probes will help determine whether neuropathologic changes underlie the structural and functional changes.

Attention, suggestion, context and expectation can all exert top-down influence on bottom-up processes (e.g., stimulus-driven mechanisms). Identifying the functional neuroanatomy that subserves top-down influences on sensory information processing can unlock the neural substrates of how suggestion can modulate behavior. Using functional magnetic resonance imaging (fMRI), we scanned 10 healthy participants (five men) viewing five bistable figures. Participants received a directional cue to perceive a particular spatial orientation a few seconds before the bistable figure appeared. After presentation, participants pressed a button to indicate their locking into the one desired orientation of the two possible interpretations. Participants additionally performed tests of impulse control and sustained attention. Our findings reveal the role of specific frontostriatal structures in selecting a particular orientation for bistable figures, including dorsolateral prefrontal regions and the putamen. Additional contrasts further bolstered the role of the frontostriatal system in the top-down processing of competing visual perceptions. Separate correlations of behavioral variables with fMRI activations support the idea that the frontostriatal system may mediate attentional control when selecting among competing visual perceptions. These results may generalize to other psychological functions. With special relevance to clinical neuroscience and applications involving attention, expectation and suggestion (e.g., hypnosis), our results address the importance of frontostriatal circuitry in behavioral modulation.

Dementia research suggests executive dysfunction is best understood within the context of disease-specific neuropathology. Leukoaraiosis (LA) results in executive dysfunction yet little is known about its impact on specific aspects of working memory (WM). This study aimed to investigate the relationship between MRI LA severity and WM in dementia. A visual rating scale was used to assign patients with dementia into groups with minimal-mild LA (Low LA; n=34) and moderate-severe LA (High LA; n=32). A modified Digit Span Backward Task consisting of 3-, 4-, and 5-span trials measured specific components of WM. Short-term storage and rehearsal in WM were assessed by the total number of digits reported regardless of recall order (ANY-ORDER; e.g., 47981 recalled '18943', score=4). Mental manipulation in the form of disengagement and temporal re-ordering was assessed by the total number of digits recalled in correct position (SERIAL-ORDER; e.g., 47981 recalled '18943', score=3). There was no difference between LA groups on ANY-ORDER comparisons. The High LA group obtained lower SERIAL-ORDER scores than the Low LA group. Stepwise regression analyses were conducted that first entered MMSE scores then composite z-scores reflecting executive functioning, language and memory. ANY-ORDER performance variance was explained solely by dementia severity. SERIAL-ORDER performance variance was further explained by executive dysfunction. Results suggest that high degrees of LA do not interfere with immediate (digit) recall but do interfere with disengagement and temporal re-ordering. LA may disconnect the frontal lobes from subcortical and cortical structures that form the neuronal networks critical for these WM functions.

Several investigations have suggested that the orbitofrontal cortex (OFC) may be particularly vulnerable to the effects of age-related changes. We recently reported behavioral data indicating greater age differences in orbitofrontal tasks when directly compared to tasks tapping dorsolateral prefrontal functions. The present study was designed to investigate the neural underpinnings of age differences in OFC functioning. Event-related functional magnetic resonance imaging (fMRI) was performed during delayed match and nonmatch to sample tasks, previously shown to differentially activate medial and lateral OFC in young adults. Sixteen healthy younger [age = 26.7(5.6)] and 16 healthy older individuals [age = 69.1 + 5.6] with similar levels of education and general cognitive functioning participated in the experiment. Participants chose the stimulus from a pair of stimuli matching a previously viewed target (match to sample) or chose the nontarget item (nonmatch to sample) depending upon a trial-specific instruction word. Consistent with previous studies, SPM99 analyses of the younger age group revealed activation for medial OFC regions during the match task compared to the nonmatch task and lateral OFC activation during the nonmatch task compared to the match task. In contrast, older adults showed prefrontal activation only during the match relative to the nonmatch task and posterior temporal and limbic involvement during the nonmatch relative to the match task. Between-group analyses confirmed within-group results suggesting differential age-related recruitment of prefrontal regions when performing match and nonmatch tasks. Results suggest that OFC recruitment during these cognitive tasks changes with age and should be evaluated within the context of other prefrontal subregions to further define differential age effects on frontal functions.

This study aimed to determine whether age differentially affects performance on tasks tapping orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC). We administered prefrontal measures to healthy younger ( n=23; age= 28.4+/-5.9, education = 15.7+/-2.6, MMSE=29.5+/-0.6 ) and older participants ( n=20; age=69.1+/-5.0, education =15.5+/-3.4, MMSE =28.9+/-1.5). Groups did not differ on education or mental status, P>0.05. Tasks thought to involve greater OFC processing included the Iowa Gambling Task and Delayed Match and Non-Match to Sample Tasks. Tasks requiring greater DLPFC processing included Petrides' Self-Ordered Pointing, WAIS-R Digit Span Backward, Letter Fluency, and Months Backward from the Boston Revision of WMS-Mental Control. Composite z-scores were calculated for OFC and DLPFC tasks. A 2 x 2 ANOVA revealed a Group x Task interaction: F(1,41) =5.55, P=0.02, and a Group main effect: F(1,41)= 12.16, P=0.001. Follow-up analyses revealed younger adults outperformed older adults on OFC tasks only ( younger = 0.37+/-0.46, older= -0.43+/-0.70; t(41) =4.5, P<0.001 ). Post-hoc analyses of individual tasks confirmed that despite age differences on Petrides' Self-Ordered Pointing, measures requiring relatively greater OFC involvement showed larger effect sizes for age differences. Thus, tasks emphasizing OFC functions appear more sensitive to age effects when directly compared to measures of DLPFC functioning. Reasons for this difference in magnitude may stem from differential aging of prefrontal cortex or differential recruitment of alternative brain regions for successful task completion.

Purpose: Types of medication misunderstanding among community-dwelling elderly people were studied., Methods: Community-dwelling people who were at least 65 years of age and who volunteered to participate in a medication-review program were recruited for the study. A structured interview including a background interview, attitudinal questions, and questions related to dosage, frequency, timing, and what to do if a dose was missed was conducted., Results: A total of 375 people were included in the study. Of these, 232 (62%) showed perfect understanding of their medication regimens. Twenty-eight (7.5%) of the subjects with less than perfect understanding misunderstood a limited aspect of their regimens across multiple medications, most frequently what to do if a dose was missed. These subjects had the least complex regimens, could name their medications and describe their purpose, and rated themselves as having few medical problems. Their lack of knowledge was not attributed to cognitive problems. Twenty-seven subjects (7%) did not know multiple aspects of at least one medication and appeared to be at high risk for nonadherence. These individuals had the most complex regimens, had difficulty naming and explaining the purpose of their medications, and rated themselves as less adherent. Eighty-eight subjects (23.5%) demonstrated mixed problems with understanding; they did not show a defined pattern attributable to cognitive or noncognitive factors., Conclusion: A majority of people over the age of 65 years had good understanding of the drugs they were taking.

Differential patterns of executive function deficits (EFD) exist in cortical and subcortical dementia; however, little work exists attempting to integrate these findings into a conceptual framework. The current study aimed to characterize EFD in cortical and subcortical dementia. Patients with Alzheimer's disease (AD; n = 65), subcortical ischemic vascular dementia (IVD; n = 64), or Parkinson's disease with dementia (dPD; n = 21) completed a variety of measures purported to require executive systems. We extracted variables of interest from measures shown in a growing body of literature to be associated with EFD in dementia. These measures included the Boston Revision of the WMS Mental Control subtest, letter fluency, WAIS-R Similarities subtest, CVLT, the Graphical Sequence Test-Dementia version, and Clock Drawing. When submitted to a PCA with varimax rotation, these variables produced a four-component solution (62% of the variance). Component 1 appeared to reflect adequacy of working memory, Component 2 irrelevant or context nonspecific interference, Component 3 reflected response preparation and Component 4 relevant or context-specific interference. Post hoc analyses of z-transformed composite scores revealed that AD differentially affected context-specific interference, IVD and dPD disrupted working memory and response preparation while IVD differentially affected context non-specific interference. EFD in dementia can be divided into specific components that are differentially impaired by cortical and subcortical dementias. Implications for an overall conceptual framework of EFD in dementia are discussed.

Clinical methods used to determine unawareness in dementia exist; however, their applicability to empirical research is limited. The authors present a statistically derived approach to determining unawareness that addresses these limitations. Dementia patients (n=32) completed an awareness questionnaire. On an identical questionnaire, collateral sources (relatives or friends; n=32) provided their best estimate of participants' abilities. The authors compared cluster analysis, the proposed empirical approach, to a currently used standard deviation cutoff score approach. Cluster analysis included all participants, displayed sound statistical properties, and was more sensitive to between-group differences in psychotic symptoms than standard deviation cutoff. Cluster analysis appears more appropriate for understanding the overall spectrum of unawareness in dementia research.

The current study investigated executive function measures emphasizing Alpha Span (ASp) to understand relationships among executive and nonexecutive tasks. Nondemented older participants (N = 417) received a comprehensive cognitive battery. Age and vocabulary adjusted correlations revealed associations among ASp, Wechsler Adult Intelligence Scale--Revised (D. Wechsler, 1981) Digit Span subtests, and fluency tasks. Principal-components analysis with varimax rotation revealed a 4 component solution (86.4% of the variance) with executive variables contributing to all loadings. Calculated component indices were submitted to a regression analysis predicting ASp performance. After accounting for age (6.3% of the variance), Component 3 reflecting brief attention-mental manipulation accounted for 13.4% of ASp variance; Component 1, verbal language ability, 11.5%; Component 2, sustained attention-mental tracking, 1.9%; and Component 4, visuoperceptual spatial organization-planning, 0.9%. Results stress the importance of considering executive and nonexecutive aspects of cognition when conceptualizing executive functioning.

Most patients with neglect demonstrate a crossover effect on line bisection. Crossover refers to a pattern of performance in which long lines (>10 cm) are bisected ipsilateral to brain injury and short lines (<2 cm) are bisected contralateral to brain injury. Crossover bisections on short lines are of interest because they are not predicted by contemporary theories concerning neglect. However, we propose that the effect depends on two independent factors that normally influence bisection performance but are merely exaggerated in neglect--a tendency to overestimate the length of short lines and underestimate long lines and a tendency to orient attention preferentially in one spatial direction. We predicted that both patients with unilateral left and right hemisphere injury would demonstrate crossover on line bisection and that they would overestimate short lines and underestimate long lines upon direct visual inspection. Further, the 2 groups were predicted to demonstrate crossover in opposite directions owing to different lesion-induced biases in attentional orientation. Testing 5 patients with right hemisphere injury and 7 patients with left hemisphere injury confirmed each prediction. Additionally, errors in length estimation were exaggerated among patients with right hemisphere injury, most of whom had neglect. It is concluded that while crossover is accentuated in cases of neglect, it is not a consequence of neglect per se. As such, crossover bisections are not at odds with contemporary neglect theory.

Visuoconstructional ability was assessed by asking patients diagnosed with Alzheimer's disease (AD), ischaemic vascular dementia (IVD), and Parkinson's disease (PD) and a normal control group (NC) to copy a modification of the Rey-Osterrieth Complex Figure (M-ROCF). The drawings of the NC group were superior to all dementia participants. AD patients generally outperformed IVD and PD patients; however, there were few differences between IVD and PD groups. Nonetheless, the drawings of IVD and PD patients were very fragmented and contained numerous perseverations and omissions. Despite these errors, patients with IVD and PD obtained higher delayed recognition memory scores than AD patients. Correlational analyses among dementia patients between neuropsychological tests and the copy of the M-ROCF found that accurate figure copy was most consistently correlated with tests of working memory, that is, tests requiring patients to monitor their behavior and sustain a complex mental set while performing mental manipulations. By contrast, no relationship between executive function tests related to measures of response selection/inhibition or other domains of neuropsychological functioning was found.

Objective: This study tested the hypothesis that a standardized dose of jelly beans could be used as an alternative sugar source to the 50-g glucose beverage to screen for gestational diabetes mellitus., Study Design: One hundred sixty pregnant women at 24 to 28 weeks' gestation were recruited for a prospective study to compare 2 sugar sources for serum glucose response, side effects, preference, and ability to detect gestational diabetes mellitus. Patients were randomly assigned to consume 50-g glucose beverage or 28 jelly beans (50 g simple carbohydrate). Serum glucose values were determined 1 hour later. The test was later repeated with the other sugar source. Finally, a 100-g 3-hour oral glucose tolerance test was performed. Participants completed a questionnaire recording subjective outcome variables. American Diabetes Association criteria were used to interpret all test results., Results: Among 136 participants completing the study no significant differences were found between 1-hour serum glucose values (116.5 +/- 27 mg/dL with 50-g glucose beverage, 116.9 +/- 23.6 mg/dL with jelly beans; P =.84), frequency of discrepant results (P =.47), sensitivity, specificity, or predictive value. Jelly beans yielded fewer side effects (38% with 50-g glucose beverage, 20% with jelly beans; P <.001) and were preferred by 76% of participants (P <.001). Five cases (3.7% incidence) of gestational diabetes mellitus were diagnosed, 3 with 50-g glucose beverage alone, 1 with jelly beans alone, and 1 with both sugar sources., Conclusions: Jelly beans may be used as an alternative to the 50-g glucose beverage as a sugar source for gestational diabetes mellitus screening. The 2 sources provoke similar serum glucose responses. Patients report fewer side effects after a jelly bean challenge than after a 50-g glucose beverage challenge.

Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

The underlying mechanisms for impaired output on letter (F, A, and S) and category (e.g., animal) word list generation (WLG) tasks in subcortical ischemic vascular dementia (IVD) were investigated. Normal control (NC) and Alzheimer's disease (AD) participants were also studied. IVD and NC participants performed better on category than letter WLG tasks, whereas the opposite was observed among AD participants. IVD participants produced fewer responses than AD participants on letter WLG tasks, but there was no difference between AD and IVD participants on the "animal" WLG task. AD participants scored lower than IVD and NC participants on animal WLG indexes measuring semantic knowledge. There were few differences between IVD and NC participants. The reduced output on the animal WLG task for IVD participants is consistent with search-retrieval deficits. The reduced output of AD participants may be caused by degraded semantic knowledge.