Differences In Cognitive Test Scores Research Articles

24 Demographic Adjustment Is Not Demographic Correction: A Simulation Study

Objective:Prior studies have presented demographic adjustment as beneficial because it helps equalize, across demographic groups, the percentage of participants (recruited from the general population without prior diagnosis) who fell beneath the test impairment cutoff (e.g., Smith, et al., 2008). This methodology ignores the possibility that group differences in those falling beneath an impairment cutoff could reflect cognitive impairment prevalence differences between demographic groups in the undiagnosed general population. Demographic group differences in cognitive test scores reflect a mixture of two categories of influences: measurement bias (item/test/examiner bias, language/cultural bias, stereotype threat, etc.) and factors which differentially increase the number of low scores in one group by increasing relative risk (RR) for cognitive impairment (biological aging processes, cognitive reserve, social determinants of health [SDoH], etc.). The current simulation study examined how the effect of demographic adjustment on the diagnostic accuracy of a hypothetical test (operationalized as the area under the curve [AUC] in an ROC analysis) varied as the mixture of influences which caused demographic differences in scores were varied.Participants and Methods:215,040 samples were randomly generated. Each sample consisted of two demographic groups, with Group 0 always representing the lower scoring group. Across samples, Group 1's baseline risk of impairment and Group 0's relative risk were varied, and these determined the prevalence of cognitive impairment in the groups. Three facets of measurement bias were varied in the simulation: how much lower Group 0's average score was than Group 1's, the degree of non-homogeneity of variance between groups, and how much less reliable the measure was for Group 0. Additional parameters were included and varied to ensure the robustness of findings across a variety of situations. Samples reflected all possible combinations of all varied parameters. For each sample, a baseline AUC was calculated when impairment was regressed on the unadjusted test score. Then, test scores were adjusted for demographic group and difference in adjusted and unadjusted AUC was calculated. This adjusted/unadjusted AUC difference was then regressed on the simulation parameters to quantify their relative influence.Results:The more Group 0's average score was reduced by measurement bias, the more improvement in AUC was seen after adjustment (ß = 1.76). Trivial but significant main effects of variance non-homogeneity (ß = .09), increased relative risk (ß = -.08), and reduced reliability (ß = .02) were also found, but more importantly, each of these predictors significantly interacted with Group 0 mean score reduction, such that higher relative risks (ß = -1.22), lower reliability (ß = .36), and higher variance (ß = -.15) in Group 0 compared to Group 1 each reduced the association between Group 0 mean score reduction and improvement in AUC.Conclusions:Demographic adjustment only improves AUC when the mean reduction in scores due to measurement bias is sufficiently high while risk for impairment, test reliability and test score variances are sufficiently equivalent among the demographic groups. When this is not the case, demographic adjustment can be counter-productive, reducing the AUC of the test. We conclude by proposing a novel method for adjusting test scores.

Amyloid-PET Levels in the Precuneus and Posterior Cingulate Cortices Are Associated with Executive Function Scores in Preclinical Alzheimer's Disease Prior to Overt Global Amyloid Positivity.

Global amyloid-β (Aβ) deposition in the brain can be quantified by Aβ-PET scans to support or refute a diagnosis of preclinical Alzheimer's disease (pAD). Yet, Aβ-PET scans enable quantitative evaluation of regional Aβ elevations in pAD, potentially allowing even earlier detection of pAD, long before global positivity is achieved. It remains unclear as to whether such regional changes are clinically meaningful. Test the hypothesis that early focal regional amyloid deposition in the brain is associated with cognitive performance in specific cognitive domain scores in pAD. Global and regional standardized uptake value ratios (SUVr) from 18F-florbetapir PET/CT scanning were determined using the Siemens Syngo.via® Neurology software package across a sample of 99 clinically normal participants with Montreal Cognitive Assessment (MoCA) scores≥23. Relationships between regional SUVr and cognitive test scores were analyzed using linear regression models adjusted for age, sex, and education. Participants were divided into two groups based on SUVr in the posterior cingulate and precuneus gyri (SUVR≥1.17). Between group differences in cognitive test scores were analyzed using ANCOVA models. Executive function performance was associated with increased regional SUVr in the precuneus and posterior cingulate regions only (p < 0.05). There were no significant associations between memory and Aβ-PET SUVr in any regions of the brain. These data demonstrate that increased Aβ deposition in the precuneus and posterior cingulate (the earliest brain regions affected with Aβ pathology) is associated with changes in executive function that may precede memory decline in pAD.

Self-administered Web-Based Tests of Executive Functioning and Perceptual Speed: Measurement Development Study With a Large Probability-Based Survey Panel.

BackgroundCognitive testing in large population surveys is frequently used to describe cognitive aging and determine the incidence rates, risk factors, and long-term trajectories of the development of cognitive impairment. As these surveys are increasingly administered on internet-based platforms, web-based and self-administered cognitive testing calls for close investigation.ObjectiveWeb-based, self-administered versions of 2 age-sensitive cognitive tests, the Stop and Go Switching Task for executive functioning and the Figure Identification test for perceptual speed, were developed and administered to adult participants in the Understanding America Study. We examined differences in cognitive test scores across internet device types and the extent to which the scores were associated with self-reported distractions in everyday environments in which the participants took the tests. In addition, national norms were provided for the US population.MethodsData were collected from a probability-based internet panel representative of the US adult population—the Understanding America Study. Participants with access to both a keyboard- and mouse-based device and a touch screen–based device were asked to complete the cognitive tests twice in a randomized order across device types, whereas participants with access to only 1 type of device were asked to complete the tests twice on the same device. At the end of each test, the participants answered questions about interruptions and potential distractions that occurred during the test.ResultsOf the 7410 (Stop and Go) and 7216 (Figure Identification) participants who completed the device ownership survey, 6129 (82.71% for Stop and Go) and 6717 (93.08% for Figure Identification) participants completed the first session and correctly responded to at least 70% of the trials. On average, the standardized differences across device types were small, with the absolute value of Cohen d ranging from 0.05 (for the switch score in Stop and Go and the Figure Identification score) to 0.13 (for the nonswitch score in Stop and Go). Poorer cognitive performance was moderately associated with older age (the absolute value of r ranged from 0.32 to 0.61), and this relationship was comparable across device types (the absolute value of Cohen q ranged from 0.01 to 0.17). Approximately 12.72% (779/6123 for Stop and Go) and 12.32% (828/6721 for Figure Identification) of participants were interrupted during the test. Interruptions predicted poorer cognitive performance (P<.01 for all scores). Specific distractions (eg, watching television and listening to music) were inconsistently related to cognitive performance. National norms, calculated as weighted average scores using sampling weights, suggested poorer cognitive performance as age increased.ConclusionsCognitive scores assessed by self-administered web-based tests were sensitive to age differences in cognitive performance and were comparable across the keyboard- and touch screen–based internet devices. Distraction in everyday environments, especially when interrupted during the test, may result in a nontrivial bias in cognitive testing.

A Consideration of Racism in Pediatric Epidemiologic Studies

A Consideration of Racism in Pediatric Epidemiologic Studies

Digital Technology Differentiates Graphomotor and Information Processing Speed Patterns of Behavior.

Coupling digital technology with traditional neuropsychological test performance allows collection of high-precision metrics that can clarify and/or define underlying constructs related to brain and cognition. To identify graphomotor and information processing trajectories using a digitally administered version of the Digit Symbol Substitution Test (DSST). A subset of Long Life Family Study participants (n = 1,594) completed the DSST. Total time to draw each symbol was divided into 'writing' and non-writing or 'thinking' time. Bayesian clustering grouped participants by change in median time over intervals of eight consecutively drawn symbols across the 90 s test. Clusters were characterized based on sociodemographic characteristics, health and physical function data, APOE genotype, and neuropsychological test scores. Clustering revealed four 'thinking' time trajectories, with two clusters showing significant changes within the test. Participants in these clusters obtained lower episodic memory scores but were similar in other health and functional characteristics. Clustering of 'writing' time also revealed four performance trajectories where one cluster of participants showed progressively slower writing time. These participants had weaker grip strength, slower gait speed, and greater perceived physical fatigability, but no differences in cognitive test scores. Digital data identified previously unrecognized patterns of 'writing' and 'thinking' time that cannot be detected without digital technology. These patterns of performance were differentially associated with measures of cognitive and physical function and may constitute specific neurocognitive biomarkers signaling the presence of subtle to mild dysfunction. Such information could inform the selection and timing of in-depth neuropsychological assessments and help target interventions.

Associations of family income with cognition and brain structure in USA children: prevention implications

Poverty, as assessed by several socioeconomic (SES) factors, has been linked to worse cognitive performance and reduced cortical brain volumes in children. However, the relative contributions of the various SES factors on brain development and the mediating effects between cognition and brain morphometry have not been investigated. Here we used cross-sectional data from the ABCD Study to evaluate associations among various SES and demographic factors, brain morphometrics, and cognition and their reproducibility in two independent subsamples of 3892 children. Among the SES factors, family income (FI) best explained individual differences in cognitive test scores (stronger for crystallized than for fluid cognition), cortical volume (CV), and thickness (CT). Other SES factors that showed significant associations with cognition and brain morphometrics included parental education and neighborhood deprivation, but when controlling for FI, their effect sizes were negligible and their regional brain patterns were not reproducible. Mediation analyses showed that cognitive scores, which we used as surrogate markers of the children’s level of cognitive stimulation, partially mediated the association of FI and CT, whereas the mediations of brain morphometrics on the association of FI and cognition were not significant. These results suggest that lack of supportive/educational stimulation in children from low-income families might drive the reduced CV and CT. Thus, strategies to enhance parental supportive stimulation and the quality of education for children in low-income families could help counteract the negative effects of poverty on children’s brain development.

Cognitive characteristics of older adults with history of concussion

AbstractBackgroundConcussion is a common injury, and among older adults often results from falls (Thompson, McCormick, &amp; Kagan, 2006). There is some evidence to suggest that older adults with a history of concussion show higher mortality rates than their younger counterparts, as well as increased risk for developing neurodegenerative diseases (such as Alzheimer’s Disease [AD]; Becker, Kapogiannis, &amp; Greig, 2018; Thompson et al., 2006). However, the literature on risk for neurocognitive decline in those with concussion history is limited, and the available evidence is conflicting (Abner et al., 2014). The current study aims to add to the literature regarding the cognitive differences between older adults with and without concussion in a well‐characterized cohort of patients with AD.MethodThis retrospective study investigated cognitive differences in individuals with and without self‐reported concussion history [CH] taking into account age and education level. Participants were enrolled in the Center for Neurodegeneration and Translational Neuroscience and included 52 cognitively normal controls (13 with CH), 68 mild cognitive impairment [MCI] (24 with CH), and 24 mild AD (8 with CH). Cognitive domains assessed included: Global cognitive (MoCA); verbal memory (WMS‐IV Logical Memory; RAVLT); non‐verbal memory (BVMT‐R); attention/working memory (WAIS‐IV Digit Span); verbal set‐shifting (DKEFS Verbal Fluency); and processing speed (SDMT).ResultOmnibus tests did not reveal a significant difference between those with and without CH in the CN, MCI, or AD, groups after taking into account age at time of evaluation and education [CN – F(14,35)=1.20, p&gt;.05; MCI – F(14,46)=0.50, p&gt;.05; AD – F(9,1)=0.66, p&gt;.05, respectively]. Effect sizes (Cohen’s d) for the CN group ranged from small to medium (min=0.1, max=0.7). For MCI, effect sizes were small (min=0.0, max=0.3). For AD, effect sizes ranged from small to medium (min=0.0, max= ‐0.7).ConclusionResults suggest that there are no meaningful differences in cognitive test scores between individuals with and without history of self‐reported concussion after accounting for influences of age and education. Effect sizes were medium despite non‐significant ANCOVAs, suggesting that these results are under‐powered and that future research would find significant results with larger samples. Small sample size and uncertainties regarding self‐report of concussion are limitations of this study.

Effect of computer-assisted-learning and simulation clinics on dental students' cognitive and performance skills: panoramic image errors related to patient's head position.

To assess dental students' ability to recognize head positioning errors in panoramic (PAN) images after individual learning via computer-assisted-learning (CAL) and in a simulation clinic (SIM). Both cognitive skills and performance in patient examination were assessed. 60 students (mean age 23.25 years) participated in lectures on the relation between PAN-image errors and patient's head position. Immediately after they took a test, based on which they were randomized to three groups: control (CON) group, CAL group, and SIM group (both CAL and training in a simulation clinic with a phantom). 4-5 weeks after intervention/no intervention, all students individually examined a patient with PAN-exposure. A blinded rater, not knowing group allocation, supervised patient exposure and assessed student's performance (correct/incorrect head position in three planes). 1-2 weeks after, the students scored positioning errors in 40 PAN-images. Differences in cognitive test scores between groups were evaluated by ANOVA and in patient examination by χ2 tests, and within-group differences by sign-tests. No statistically significant difference in cognitive test scores was seen between the SIM and CAL group, while the CON group scored lower (p < 0.003). In all groups, several students positioned the patient incorrectly in the Frankfort horizontal plane. All students performed well in the sagittal plane. Students in SIM group positioned the patient more correctly in the coronal plane. Training with CAL increased students' cognitive skills compared with a control group. Simulated patient exposure with a phantom increased to some extent their performance skills in examination of patients.

Cognitive differences between older adult instrumental musicians: Benefits of continuing to play

Previous research suggests that ongoing cognitive engagement in late life may help maintain cognitive functioning. We assessed cognition across all major domains in older adult instrumental musicians (active vs. former) and non-musicians using a standardized neuropsychological battery and collected self-report information on levels of physical activity, social activity, and overall health. We used ANCOVAs to determine if there were differences in cognitive test scores among groups. Results showed that all musicians (active and former) had higher scores on a test of language (Boston Naming Test) and of language and executive functioning (Controlled Oral Word Association) compared to non-musicians. However, active musicians scored higher than both non-musicians and former musicians on a version of the Stroop task (Delis-Kaplan Executive Function System: Color Word Interference). These findings suggest that, in some types of executive functions, there may be continued benefit to participating in musical activities later in life. However, in the domain of language, gains from playing an instrument are sustained even if a musician stops playing. We discuss these results in the contexts of cognitive reserve and crystallized and fluid intelligence, including cognitive benefits of early life music lessons that remain in late life.

Thromboprophylaxis in atrial fibrillation and association with cognitive decline: systematic review.

atrial fibrillation (AF) is associated with dementia. If AF-related cognitive decline is driven by cerebral embolic events, thromboprophylaxis may impact on this. This systematic review assessed the association between cognitive impairment and AF thromboprophylaxis. two independent reviewers searched CINAHL, EMBASE, MEDLINE, PsycINFO, Web of Science Core Collection and Cochrane Library from inception until 12 November 2014. Eligible studies compared AF thromboprophylaxis to control with an outcome measure of cognition or dementia. Where data allowed, meta-analyses describing between-group differences in cognitive test scores or rates of incident dementia were performed. nineteen studies were eligible. For two prospective studies (one randomised controlled trial, RCT) comparing anticoagulation against antiplatelet therapy, change in Mini-Mental Score Examination (MMSE) score from baseline to last follow-up (maximal duration: 5.9 years) suggested a difference favouring anticoagulation (mean difference: 0.90, 95% CI: 0.29-1.51), in keeping with a trend seen in the single RCT (mean difference MMSE: 0.80, 95% CI: -0.07 to 1.67). Pooled odds ratio (OR) suggested no association with incident dementia, comparing anticoagulant to antiplatelet therapy (two studies, OR: 1.23, 95% CI: 0.80-1.91) or no treatment (three studies, OR: 0.89, 95% CI: 0.47-1.69). our analyses show no definitive evidence of cognitive benefit or harm from anticoagulation. We demonstrated a potential benefit of anticoagulation in comparison to antiplatelet over time. Larger scale studies with longer follow-up are needed to determine the true cognitive impact of AF thromboprophylaxis.

Testing Spearman's hypothesis with advanced placement examination data

The nature, source, and meaning of average group score differences between demographic groups on cognitive tests has been a source of controversy for decades. One possible explanation is “Spearman's hypothesis,” which states that the magnitude of score differences across demographic groups is a direct function of how strongly the test measures g. To test this hypothesis, Jensen (1985, 1998) developed the method of correlated vectors. In this study I used the method of correlated vectors to examine the relationship between racial/ethnic group differences of Advanced Placement (AP) exam scores and the correlation between those AP exam scores and a test of general cognitive ability, the PSAT. Results are consistent with Spearman's hypothesis for White-Black and White-Hispanic comparisons, but not for White-Asian comparisons. Comparisons of White examinees and Native Americans are inconclusive. This study shows that academic achievement tests can be used to test Spearman's hypothesis. Additionally, Spearman's hypothesis is not a unique characteristic of White-Black differences in cognitive test scores, but it may not universal either.

Explaining the black-white gap in cognitive test scores: Toward a theory of adverse impact.

In understanding the causes of adverse impact, a key parameter is the Black-White difference in cognitive test scores. To advance theory on why Black-White cognitive ability/knowledge test score gaps exist, and on how these gaps develop over time, the current article proposes an inductive explanatory model derived from past empirical findings. According to this theoretical model, Black-White group mean differences in cognitive test scores arise from the following racially disparate conditions: family income, maternal education, maternal verbal ability/knowledge, learning materials in the home, parenting factors (maternal sensitivity, maternal warmth and acceptance, and safe physical environment), child birth order, and child birth weight. Results from a 5-wave longitudinal growth model estimated on children in the NICHD Study of Early Child Care and Youth Development from ages 4 through 15 years show significant Black-White cognitive test score gaps throughout early development that did not grow significantly over time (i.e., significant intercept differences, but not slope differences). Importantly, the racially disparate conditions listed above can account for the relation between race and cognitive test scores. We propose a parsimonious 3-Step Model that explains how cognitive test score gaps arise, in which race relates to maternal disadvantage, which in turn relates to parenting factors, which in turn relate to cognitive test scores. This model and results offer to fill a need for theory on the etiology of the Black-White ethnic group gap in cognitive test scores, and attempt to address a missing link in the theory of adverse impact.

Infections and Brain Development.

Several different bodies of evidence support a link between infection and altered brain development. Maternal infections, such as influenza and human immunodeficiency virus, have been linked to the development of autism spectrum disorders, differences in cognitive test scores, and bipolar disorder; an association that has been shown in both epidemiologic and retrospective studies. Several viral, bacterial, and parasitic illnesses are associated with alterations in fetal brain structural anomalies including brain calcifications and hydrocephalus. The process of infection can activate inflammatory pathways causing the release of various proinflammatory biomarkers and histological changes consistent with an infectious intrauterine environment (chorioamnionitis) or umbilical cord (funisitis). Elevations in inflammatory cytokines are correlated with cerebral palsy, schizophrenias, and autism. Animal studies indicate that the balance of proinflammatory and anti-inflammatory cytokines is critical to the effect prenatal inflammation plays in neurodevelopment. Finally, chorioamnionitis is associated with cerebral palsy and other abnormal neurodevelopmental outcomes. In conclusion, a plethora of evidence supports, albeit with various degrees of certainty, the theory that maternal infection and inflammation that occur during critical periods of fetal development could theoretically alter brain structure and function in a time-sensitive manner.

Cognitive function in women with polycystic ovary syndrome (PCOS): impact of reproductive and metabolic factors

Cognitive function in women with polycystic ovary syndrome (PCOS): impact of reproductive and metabolic factors

Specific Subjective Memory Complaints in Older Persons May Indicate Poor Cognitive Function

To examine the association between the type and number of subjective memory complaints (SMCs) and performance on objective cognitive tests. Cross-sectional. Nurses' Health Study. Sixteen thousand nine hundred sixty-four women (mean age 74) who provided information on SMCs. Telephone cognitive assessments and seven questions regarding SMCs were administered. Cognitive impairment was defined as a score of less than 31 on the Telephone Interview for Cognitive Status (TICS) and below the 10th percentile on other cognitive measures. To assess associations with SMCs, multivariable logistic regression was used to calculate odds ratios for cognitive impairment and multivariable linear regression to calculate mean differences in cognitive test scores, adjusting for age and depressive symptoms. Some SMCs, such as trouble following a group conversation or finding one's way around familiar streets, were more highly associated than others with odds of cognitive impairment. The complaint of forgetting things from one second to the next, generally considered part of normal aging, was not associated with cognitive impairment. In addition, there were strong, linear trends of increasingly worse scores on cognitive tests with increasing numbers of memory complaints. For each additional SMC endorsed, the odds of cognitive impairment increased approximately 20% when each SMC was weighted equally. SMCs are associated with objective cognitive status and may be considered by primary care physicians in determining whether follow-up is warranted.

Neuropsychological Functioning in PLS: A Comparison with ALS

In order to characterize the nature and extent of neuropsychological dysfunction in primary lateral sclerosis (PLS), we studied prospectively cognitive, emotional, and behavioral functioning in PLS, and compared performances to functioning in amyotrophic lateral sclerosis (ALS). Eighteen patients with PLS and 13 patients with ALS completed a neuropsychological test battery assessing both cognitive skills and emotional/behavioral functioning. Both PLS and ALS groups scored broadly within normal limits (mean T-scores greater than 40) on all cognitive measures and no significant between-group differences were found with the exception of one variable. However, when examined on a case by case basis, the data revealed considerable heterogeneity amongst patients in both groups. Overall, 39% of PLS patients and 31% of ALS patients were considered cognitively impaired. Ahigher than expected frequency of abnormal scores was noted for several tests of executive function in both groups, and a majority of PLS patients also exhibited abnormal behavioural symptoms. There was no relationship in PLS or ALS groups between cognitive functioning and disease duration, current site of disease, site of onset, functional status, and respiratory variables. Comparison between the PLS and ALS groups indicated virtually no differences in cognitive test scores and overall emotional/behavioural symptoms. We observed deficits in cognition and behaviour in a significant proportion of PLS patients which were comparable to those observed in ALS cases. Although deficits were not in the range of frontotemporal dementia, both ALS and PLS cases demonstrated deficits most prominently on tests of executive functioning.

Rugby versus Soccer in South Africa: Content familiarity contributes to cross-cultural differences in cognitive test scores

In this study, cross-cultural differences in cognitive test scores are hypothesized to depend on a test's cultural complexity (Cultural Complexity Hypothesis: CCH), here conceptualized as its content familiarity, rather than on its cognitive complexity (Spearman's Hypothesis: SH). The content familiarity of tests assessing short-term memory, attention, working memory, and figural and verbal fluid reasoning, was manipulated by constructing test versions with an item content derived from either Afrikaans or Tswana culture in South Africa. Both test versions were administered to children of both cultures. The sample consisted of 161 urban Afrikaans, 181 urban, and 159 rural Tswana children ( M age = 9.37 years). Children generally performed best on the test version that was designed for their own group, particularly on the cognitively and culturally complex working memory and figural fluid reasoning tests. This relation between content familiarity and cognitive test performance supports CCH and disconfirms SH.

Smoking and cognitive function in Parkinson's disease

The risk of dementia among Parkinson's disease (PD) patients is greatly elevated compared to controls, yet little is known about determinants of cognitive function among PD patients. We assessed the relation between cigarette smoking prior to disease onset and later cognitive function among PD patients (n = 286) and age- and sex-matched controls (n = 1144) participating in the Nurses' Health Study and Health Professionals Follow-up Study. Both groups completed telephone-administered assessments of cognitive function. We used linear regression to calculate mean differences in cognitive test scores across smoking categories, adjusted for age, education, sex, age at onset of PD, and years since diagnosis. PD patients scored significantly worse on all tests than their matched controls. In analyses only among PD cases, but not among controls, current smokers at PD onset scored worse than never smokers on the Telephone Interview for Cognitive Status (difference = -0.82, 95% CI: -1.33, -0.30, P = 0.002) as well as on a global score combining results of all tests (difference = -0.36, 95% CI: -0.72, 0.01, P = 0.06). This difference was equivalent to the difference in global score observed among controls approximately 10 years apart in age. Analyses of pack-years of smoking prior to disease onset gave similar results. These findings, nested in prospective cohort studies, suggest that cigarette smoking prior to disease onset is associated with worse cognitive function in PD.

Neurocognitive Outcomes in Off-Pump Versus On-Pump Bypass Surgery: A Randomized Controlled Trial

Cognitive difficulties have been reported after coronary artery bypass graft surgery using cardiopulmonary bypass. However, the cognitive benefit of off-pump surgery remains unclear. Consecutively listed candidates for elective bypass were randomly assigned to either off-pump or on-pump techniques (n = 107). A battery of 11 standardized neuropsychological tests was administered before surgery, and again at 2 and 6 months after surgery. The two groups were compared using a range of statistical procedures, including growth modeling. There were no significant differences in cognitive test scores between the off-pump and on-pump groups using t tests at any of the time points. There were no differences between off-pump and on-pump groups in the incidence of cognitive deficits at 2 months or 6 months, with the exception that fewer off-pump patients showed impairment on one test of verbal fluency at 6 months. When the pattern of cognitive change over time between the two groups was compared using sophisticated modeling techniques, the two groups were again comparable, except for results on the test of verbal fluency, in which the off-pump group showed more rapid postsurgical cognitive gains than the on-pump group. The off-pump group appears to be generally comparable to the on-pump group in terms of short-term and long-term postsurgical neurocognitive outcomes.

Mixed Dementia

The prevalence of mixed dementia, defined as the coexistence of Alzheimer disease (AD) and vascular dementia (VaD), is likely to increase as the population ages. To provide an overview of the diagnosis, pathophysiology, and interaction of AD and VaD in mixed dementia, and to provide a systematic literature review of the current evidence for the pharmacologic therapy of mixed dementia. The Cochrane Database of Systematic Reviews was searched using the keyword dementia. MEDLINE was searched for English-language articles published within the last 10 years using the keywords mixed dementia, the combination of keywords Alzheimer disease, cerebrovascular disorders, and drug therapy, and the combination of keywords vascular dementia and drug therapy. Dementia is more likely to be present when vascular and AD lesions coexist, a situation that is especially common with increasing age. The measured benefits in clinical trials for the treatment of mixed dementia are best described as statistically significant differences in cognitive test scores and clinician and caregiver impressions of change. In these studies, the control groups' scores typically decline while the treatment groups improve slightly or decline to a lesser degree over the study period. Nevertheless, even the patients who experience treatment benefits eventually decline. Cholinesterase inhibitor (ChI) therapy for mixed dementia shows modest clinical benefits that are similar to those found for ChI treatment of AD. The N-methyl-D-aspartate (NMDA) antagonist memantine also shows modest clinical benefits for the treatment of moderate to severe AD and mild to moderate VaD, but it has not been studied specifically in mixed dementia. The treatment of cardiovascular risk factors, especially hypertension, may be a more effective way to protect brain function as primary, secondary, and tertiary prevention for mixed dementia. Currently available medications provide only modest clinical benefits once a patient has developed mixed dementia. Cardiovascular risk factor control, especially for hypertension and hyperlipidemia, as well as other interventions to prevent recurrent stroke, likely represent important strategies for preventing or slowing the progression of mixed dementia. Additional research is needed to define better what individuals and families hope to achieve from dementia treatment and to determine the most appropriate use of medication to achieve these goals.