Stewart Longman

Of the various methods and rules-of-thumb for deciding the 4correct" number of components to retain in principal components analysis, parallel analysis is arguably the most useful. Recently, researchers have become interested in developing alternative methods of implementing parallel analysis and of comparing their accuracy. The accuracy of three methods of implementing parallel analysis with mean eigenvalues (regression, interpolation, and computation with three samples of random data) was compared. The index of accuracy was the proportion of agreement on the number of components for extraction suggested by each of these three procedures and those suggested by implementing parallel analysis with 40 runs of random data, in a sample of 28 published correlation matrices. Moreover, the accuracy of two methods of implementing parallel analysis with 95th percentile eigenvalues (regression and interpolation) was compared using the aforementioned index of accuracy. In separate analyses for mean and 95th percentile eigenvalue strategies, no evidence of differential accuracy emerged. Implications for implementing parallel analysis are discussed.

The Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; Wechsler, 1997b) provides factor-based index scores but allows only for pairwise comparison of these scores, producing inflated Type I error rates and reducing profile interpretability. This article provides tables for simultaneous comparison to the overall mean index score, thus reducing error rates and aiding interpretation. The Working Memory Index or Processing Speed Index can also be specifically compared when an individual is believed to have a condition, such as a learning disability or traumatic brain injury, associated with the selective depression of these indexes. Tables for the infrequency of specific differences are also provided, allowing the practitioner to note how unusual an obtained difference is in the general population.

Group cohesion is an important construct in understanding the behavior of different types of groups. However, controversy exists about how to conceptualize and measure cohesion, and a central issue is its dimensionality. Consequently, researchers have used factor analysis to examine the structure of the construct of cohesion and measures of it. Our goals in writing this article were to review critically how factor analysis has been used to understand group cohesion, make some recommendations for future factor analytic work, and point out some weaknesses and strengths in using factor analysis to explore cohesion.

... parallel analysis as a method for determining the "correct" number of factors in factor analysis (Humphreys & ... Also, in practical applications of the parallel analysis method, predicted means for the last two ... because there is no variability in the value of p after the 33rd ordinal value ...

Both behavior disorder (BD) and learning disability (LD) are frequently diagnosed in the same children. This study comprises 2 parts. First, previously published data were examined to compare the Wechsler Intelligence Scale for Children–Revised (WISC–R) profiles of groups of children diagnosed as BD and to assess the fit of their scores to the Learning Disability Index (LDI). Second, new data

This is an expanded and revised version of the 1989 text, Introduction to Cognitive Rehabilitation, and like its predecessor, it is based strongly on the authors’ personal experience, particularly in the emphasis on traumatic brain injury (TBI) and stroke. It is aimed at practitioners (particularly psychologists, occupational therapists, and speech-language pathologists) working with inpatients and outpatients, and continues to emphasize the practical aspects of rehabilitation. Sohlberg and Mateer have done a commendable job in presenting a package, including their conceptual framework and a continued emphasis on the interplay of previous skills, current techniques, and generalizing skills from treatment to practical application. The section on needs assessment for the specific individual is a useful reminder for all therapists involved in rehabilitation. The rehabilitation approach appears to try and balance both restorative and compensatory approaches, particularly in attention training (as expected from the authors of Attention Process Training). This is a change in emphasis from the earlier edition, which emphasized a restorative approach. The list of topics is broader than the previous edition, reflecting the variety of research and increased consideration of applications. For example, mild TBI now has a complete chapter, rather than a few pages. In apparent contradiction of the first part of the title, but appropriately for the clinician, there is greater emphasis on addressing behavioral and psychosocial concerns, as well as the more purely cognitive issues of memory, attention, and executive functioning. The authors also spend more time addressing the role of emotional factors in treatment, but might have benefited from greater emphasis on identifying and developing healthy and useful emotional appraisals, as well as identifying dysfunctional emotions. Other welcome changes include a greater consideration and discussion of outcome assessment (important when we must convince payers that the service is worthwhile, or identify if a particular approach has helped a particular individual), some discussion of the empirical evidence, and increased emphasis on generalization. The technological changes of the past decade are also apparent in the section on external aids, including the role of paging systems, electronic planners and PDAs, and wristwatch computers. In terms of patient level, this work spans a variety of concerns, including patients with severe impairments (where the work on priming and errorless learning and behavioral contingencies is important), to patients with little objective finding but continued impact (as seen in the chapter on mild TBI). There is also a basic presentation on pediatric applications, including the school setting, although workers with this group are likely to benefit from consulting more comprehensive resources (e.g., Ylvisaker, 1998). The chapter on working with families, although identifying familiar issues for most clinical psychologists, should be reviewed every time a “difficult family” is being seen. Similarly, the section on premorbid personality styles, although brief, may be particularly useful for nonpsychologist therapists in identifying some of the issues that clients bring to their rehabilitation. To my mind, there are several areas that could have been revised and considered. For example, a complete chapter devoted to the empirical basis for cognitive rehabilitation, and evidence for specific components or approaches, would have been appropriate (e.g., Park & Ingles, 2001). Another area that could have been addressed is cognitive rehabilitation in schizophrenia, as there is a growing literature here and evidence that these techniques may produce meaningful changes in function (e.g., Hodel & Brenner, 1998). The chapter on neuropsychological disorders associated with cognitive impairments is somewhat uneven, with a great deal of emphasis on TBI, but much less detail on other causes of injury. This chapter may be an excellent primer for a student or clinician who is new to the neurorehabilitation setting, but is less useful for those who are familiar with the most common causes of referral, but need information about a less common

Deciding how many components to retain is a crucial step in principal components analysis. Evidence (Zwick & Velicer, 1986) suggests that parallel analysis of random data matrices (Horn, 1965) provides an excellent guideline for selecting the appropriate number of components. Allen and Hubbard (1986) developed regression equations for estimating mean eigenvalues from random data matrices. Longman, Cota, Holden, and Fekken (in press) also developed regression procedures for predicting

Introduction: Transient ischemic attack (TIA) greatly increases the risk of developing dementia later in life. Measurement of microstructural changes in white matter (WM) using diffusion tensor imaging (DTI) tractography has potential for identifying those at greatest risk of cognitive decline. We hypothesized that patients presenting with TIA have abnormal DTI measures in major WM tracts. Our objective was to determine changes in DTI measures for fractional anisotropy (FA) and medial diffusivity (MD) in frontoparietal (Superior Longitudinal Fasciculus; SF) and medial temporal (Uncinate Fasciculus; UF) WM tracts for TIA patients and healthy controls. Methods: Patients presenting with symptoms of high risk TIA but free of dementia, and healthy volunteer controls were recruited acutely. Structural MRI, inclusive of DTI sequences (31 directions b1000) was performed. FA and MD values were collected in the left and right SLF and UF. Multiple linear regression was performed to determine p...

Accelerated trajectories of cognitive decline in older adults may increase the risk of developing Alzheimer disease and related dementias (ADRD). Physical activity has potential modifying effects on these changes that could prevent and/or delay ADRD. This review explores the hypothesis that multiple, mutually complimentary and interacting factors explain the positive association between exercise and the optimization of cognition in older adults.

Background There remains no effective intervention capable of reversing most cases of dementia. Current research is focused on prevention by addressing risk factors that are shared between cardiovascular disease and dementia (e.g., hypertension) before the cognitive, functional, and behavioural symptoms of dementia manifest. A promising preventive treatment is exercise. This study describes the methods of a randomized controlled trial (RCT) that assesses the effects of aerobic exercise and behavioural support interventions in older adults at increased risk of dementia due to genetic and/or cardiovascular risk factors. The specific aims are to determine the effect of aerobic exercise on cognitive performance, explore the biological mechanisms that influence cognitive performance after exercise training, and determine if changes in cerebrovascular physiology and function persist 1 year after a 6-month aerobic exercise intervention followed by a 1-year behavioural support programme (at...

The 2019 update of the <i>Canadian Stroke Best Practice Recommendations (CSBPR) for Mood, Cognition and Fatigue following Stroke</i> is a comprehensive set of evidence-based guidelines addressing three important issues that can negatively impact the lives of people who have had a stroke. These include post-stroke depression and anxiety, vascular cognitive impairment, and post-stroke fatigue. Following stroke, approximately 20% to 50% of all persons may be affected by at least one of these conditions. There may also be overlap between conditions, particularly fatigue and depression. If not recognized and treated in a timely matter, these conditions can lead to worse long-term outcomes. The theme of this edition of the CSBPR is <i>Partnerships and Collaborations,</i> which stresses the importance of integration and coordination across the healthcare system to ensure timely and seamless care to optimize recovery and outcomes. Accordingly, these recommendations p...

ObjectiveTo test the hypothesis that aerobic exercise is associated with improvements in cognition and cerebrovascular regulation, we enrolled 206 healthy low-active middle-aged and older adults (mean ± SD age 65.9 ± 6.4 years) in a supervised 6-month aerobic exercise intervention and assessed them before and after the intervention.MethodsThe study is a quasi-experimental single group pre/postintervention study. Neuropsychological tests were used to assess cognition before and after the intervention. Transcranial Doppler ultrasound was used to measure cerebral blood flow velocity. Cerebrovascular regulation was assessed at rest, during euoxic hypercapnia, and in response to submaximal exercise. Multiple linear regression was used to examine the association between changes in cognition and changes in cerebrovascular function.ResultsThe intervention was associated with improvements in some cognitive domains, cardiorespiratory fitness, and cerebrovascular regulation. Changes in executi...

The Attention Network Test (ANT) is a frequently used computer-based tool for measuring the three attention networks (alerting, orienting, and executive control). We examined the psychometric properties of performance on a variant of the ANT, the Attention Network Test-Interaction (ANT-I) in healthy older adults (N = 173; mean age = 65.4, SD = 6.5; obtained from the Brain in Motion Study, Tyndall et al. BMC Geriatr 13:21, 2013. doi: 10.1186/1471-2318-13-21) to evaluate its usefulness as a measurement tool in both aging and clinical research. In terms of test reliability, split-half correlation analyses showed that all network scores were significantly reliable, although the strength of the correlations varied across networks as seen before (r = 0.29, 0.70, and 0.68, for alerting, orienting, and executive networks, respectively, p's < 0.05). In terms of construct validity, ANOVAs confirmed that each network score was significant (18.3, 59.4, and 109.2 ms for the alerting, orienting, and executive networks, respectively, p's < 0.01) and that these scores were generally independent from each other. Importantly, for criterion validity, a series of hierarchical linear regressions showed that the executive network score, in addition to demographic information, was a significant predictor of performance on tests of conflict resolution as well as verbal memory and retrieval (β = -0.165 and -0.184, p's < 0.05, respectively). These results provide new information regarding the reliability and validity of ANT-I test performance in a healthy older adult population. The results provide insights into the psychometrics of the ANT-I and its potential utility in clinical research settings.

Group cohesion is an important construct in understanding the behavior of groups. However, there has been ongoing controversy on how to define and measure this construct. Central to this debate is the structure of cohesion. The authors critically review the literature on unidimensional and multidimensional models of cohesion and describe cohesion as a multidimensional construct with primary and secondary dimensions. Primary dimensions are applicable to describing the cohesiveness of all or most types of groups, whereas secondary dimensions are applicable to describing the cohesiveness of specific types of groups. Viewing group cohesion as consisting of primary and secondary dimensions is discussed.

Selecting the "correct" number of components to retain in principal components analysis is crucial. Parallel analysis, which requires a comparison of eigenvalues from observed and random data, is a highly promising strategy for making this decision. This paper focuses on linear interpolation, which has been shown to be an accurate method of implementing parallel analysis. Specifically, this article contains tables of 95th percentile eigenvalues from random data that can be used when the sample size is between 50 and 500 and when the number of variables is between 5 and 50. An empirical example is provided illustrating linear interpolation, direct computation, and regression methods for obtaining 95th percentile eigenvalues from random data. The tables of eigenvalues given in this report will hopefully enable more researchers to use parallel analysis because interpolation is an accurate and simple method of obviating the Monte Carlo requirements of parallel analysis.

Of the various methods and rules-of-thumb for deciding the 4correct" number of components to retain in principal components analysis, parallel analysis is arguably the most useful. Recently, researchers have become interested in developing alternative methods of implementing parallel analysis and of comparing their accuracy. The accuracy of three methods of implementing parallel analysis with mean eigenvalues (regression, interpolation, and computation with three samples of random data) was compared. The index of accuracy was the proportion of agreement on the number of components for extraction suggested by each of these three procedures and those suggested by implementing parallel analysis with 40 runs of random data, in a sample of 28 published correlation matrices. Moreover, the accuracy of two methods of implementing parallel analysis with 95th percentile eigenvalues (regression and interpolation) was compared using the aforementioned index of accuracy. In separate analyse...

Tables are presented for the Wechsler Adult Intelligence Scale—Third Edition (WAIS-III) IQ and index scores by education level for both the U.S. and Canadian normative samples. This allows clinicians to provide more accurate identification of relative strengths or weaknesses, compared to expectations from an individual's background, rather than the general population. Because sex di ferences are notable on the Processing Speed Index, data for this measure are presented separately. The similarities and di ferences between the two national samples are noted, with particular reference to the relatively weaker demographic e fects found in the Canadian sample.

Studies of the effects of physical fitness on cognition suggest that exercise can improve cognitive abilities in healthy older adults, as well as delay the onset of age-related cognitive decline. The mechanisms for the positive benefit of exercise and how these effects interact with other variables known to influence cognitive function (e.g., involvement in cognitive activities) are less well understood. The current study examined the associations between the physical fitness, cerebrovascular blood flow regulation and involvement in cognitive activities with neuropsychological function in healthy post-menopausal women. Methods: Forty-two healthy women between the ages of 55 and 90 were recruited. Physical fitness (V˙O2 max), cerebrovascular reserve (cerebral blood flow during rest and response to an increase in end-tidal (i.e., arterial) PCO2), and cognitive activity (self-reported number and hours of involvement in cognitive activities) were assessed. The association of these varia...

Every year, approximately 62 000 people with stroke and transient ischemic attack are treated in Canadian hospitals. The 2014 update of the Canadian Secondary Prevention of Stroke guideline is a comprehensive summary of current evidence-based recommendations for clinicians in a range of settings, who provide care to patients following stroke. Notable changes in this 5th edition include an emphasis on treating the highest risk patients who present within 48 h of symptom onset with transient or persistent motor or speech symptoms, who need to be transported to the closest emergency department with capacity for advanced stroke care; a recommendation for brain and vascular imaging (of the intra- and extracranial vessels) to be completed urgently using computed tomography/computed tomography angiography; prolonged cardiac monitoring for patients with suspective cardioembolic stroke but without evidence for atrial fibrillation on electrocardiogram or holter monitoring; and de-emphasizing ...

Impaired glucose tolerance is a risk factor for non-age-related cognitive decline and is also associated with measures of physical activity (PA) and cardiorespiratory fitness (CRF). A low glycemic load (GL) diet can aid in the management of blood glucose levels, but little is known about its effect on cognition with poor glucoregulation. We assessed the relation between GL and cognitive function by glucoregulation and possible mediatory effects by CRF and PA in older adults from the Brain in Motion Study. A cross-sectional analysis of 194 cognitively healthy adults aged ≥55 years (mean = 65.7, SD = 6.1) was conducted. GL was assessed using a quantitative food frequency questionnaire, and glucoregulation was characterized on the HOMA-IR index. Subjects also completed a cognitive assessment, CRF testing, a validated self-reported PA questionnaire, and a blood draw. Multiple linear regression models adjusted for significant covariates were used to evaluate the relation between GL and c...

Better physical fitness in later life is associated positively with cognitive functioning. Novel data suggest that this association is mediated, in part, by increases in brain perfusion and the ability of cerebral blood vessels to respond to demand. This review presents evidence on the beneficial effects of exercise on cerebrovascular and cognitive health with aging and explores potential underlying vascular-related mechanisms.

Background Carcinoid syndrome (CS) is characterized by symptoms of diarrhea, flushing, bronchospasm, and valvular heart disease. It has been our impression that patients with CS also exhibit features of cognitive impairment. The purpose of this pilot study was ...

To determine the relationship between sleep spindle characteristics (density, power and frequency), executive functioning and cognitive decline in older adults, we studied a convenience subsample of healthy middle‐aged and older participants of the Brain in Motion study. Participants underwent a single night of unattended in‐home polysomnography with neurocognitive testing carried out shortly afterwards. Spectral analysis of the EEG was performed to derive spindle characteristics in both central and frontal derivations during non‐rapid eye movement (NREM) Stage 2 and 3. Multiple linear regressions were used to examine associations between spindle characteristics and cognitive outcomes, with age, body mass index (BMI), periodic limb movements index (PLMI) and apnea hypopnea index (AHI) as covariates. NREM Stage 2 total spindle density was significantly associated with executive functioning (central: β = .363, p = .016; frontal: β = .408, p = .004). NREM Stage 2 fast spindle density was associated with executive functioning (central: β = .351, p = .022; frontal: β = .380, p = .009) and Montreal Cognitive Assessment score (MoCA, central: β = .285, p = .037; frontal: β = .279, p = .032). NREM Stage 2 spindle frequency was also associated with MoCA score (central: β = .337, p = .013). Greater spindle density and fast spindle density were associated with better executive functioning and less cognitive decline in our study population. Our cross‐sectional design cannot infer causality. Longitudinal studies will be required to assess the ability of spindle characteristics to predict future cognitive status.

Amidst a growing concern regarding concussion in sports, there is an emerging link between sport concussion and mental health outcomes. This review summarizes the current literature addressing long-term psychiatric sequelae associated with sport concussion in adults. Several databases were searched using a broad list of keywords for each of concussion, sports, and mental health, with a resultant 311 studies for initial review. After limiting studies based on duplication, appropriateness of data, and relevance, 21 studies remained pertaining to depression, anxiety, substance use, and behavioural changes, including those highlighting chronic traumatic encephalopathy (CTE). Most studies identified suggested an increased prevalence of depressive symptoms related to concussion history. A conference abstract and qualitative study suggested increasing anxiety related to concussion history; however, a PhD dissertation found no relationship. In reviewing substance use, several studies mentio...

Allen and Hubbard (1986) increased the accessi bility of parallel analysis for principal components applications by developing an equation to predict mean eigenvalues of random data matrices with unities in the diagonals. Two recent studies have shown, however, that Allen and Hubbard's proce dure may yield degenerate solutions—that is, solu tions in which succeeding eigenvalues are larger than preceding eigenvalues. The parameters of sample size and number of variables within which the Allen and Hubbard equation degenerates are documented. Implications for the use of this procedure are discussed.

To develop supplementary methods for the analysis of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) in neuropsychological assessment. Psychometric. The following methods are made available: (a) provision of traditional confidence intervals (CIs) on index scores, (b) expression of the endpoints of CIs as percentile ranks; (c) quantification of the number of abnormally low index scores exhibited by a case and accompanying estimate of the percentage of the normative population expected to exhibit at least this number of low scores; (d) quantification of the reliability and abnormality of index score deviations from an individual's index score mean (thereby offering an alternative to the pairwise approach to index score comparisons available in the WAIS-IV manual); (e) provision of CIs on an individual's deviation scores or pairwise difference scores, (f) estimation of the percentage of the normative population expected to exhibit at least as many abnormal deviations or abnormal pairwise differences as a case; and (g) calculation of a case's Mahalanobis distance index (MDI), thereby providing a multivariate estimate of the overall abnormality of an index score profile. With the exception of the MDI, all the methods can be applied using tables provided in this paper. However, for ease and speed of application, and to reduce the possibility of clerical error, all the methods have also been implemented in a computer program. The methods are useful for neuropsychological interpretation of the WAIS-IV.

The Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; Wechsler, 1997b) provides factor-based index scores but allows only for pairwise comparison of these scores, producing inflated Type I error rates and reducing profile interpretability. This article provides tables for simultaneous comparison to the overall mean index score, thus reducing error rates and aiding interpretation. The Working Memory Index or Processing Speed Index can also be specifically compared when an individual is believed to have a condition, such as a learning disability or traumatic brain injury, associated with the selective depression of these indexes. Tables for the infrequency of specific differences are also provided, allowing the practitioner to note how unusual an obtained difference is in the general population.

ABSTRACT The Canadian standardization of the Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; Wechsler, 1997a, 2001) provides factor-based index scores, giving an intermediate level of analysis between IQ scores and individual subtests. This article provides tables for comparing all indices to the mean index score, and for identifying the statistical significance and relative frequency of obtained differences. This simultaneous or ipsative approach can avoid some of the statistical and logical pitfalls of multiple pairwise comparisons, such as decreased interpretability and inflated risk of Type I errors. (PsycINFO Database Record (c) 2012 APA, all rights reserved)