The Role of Cognitive Reserve in Recovery From Traumatic Brain Injury.

OBJECTIVE: To examine whether cognitive reserve (CR) attenuates the initial impact of traumatic brain injury (TBI) on cognitive performance (neural reserve) and results in faster cognitive recovery rates in the first year postinjury (neural compensation), and whether the advantage of CR differs on the basis of the severity of TBI. SETTING: Inpatient/outpatient clinics at an academic medical center. PARTICIPANTS: Adults with mild TBI (mTBI; n = 28), complicated mild TBI (cmTBI; n = 24), and moderate to severe TBI (msevTBI; n = 57), and demographically matched controls (n = 66). DESIGN: Retrospective, longitudinal cohort assessed at 1, 6, and 12 months postinjury. MAIN MEASURES: Outcomes were 3 cognitive domains: processing speed/executive function, verbal fluency, and memory. Premorbid IQ, estimated with the Wechsler Test of Adult Reading, served as CR proxy. RESULTS: Higher premorbid IQ was associated with better performance on cognitive domains at 1 month postinjury, and the effect of IQ was similarly beneficial for all groups. Cognitive recovery rate was moderated only by TBI severity; those with more severe TBI had faster recovery in the first year. CONCLUSION: Results support only the neural reserve theory of CR within a TBI population and indicate that CR is neuroprotective, regardless of the degree of TBI. Higher premorbid CR does not allow for more rapid adaptation and recovery from injury.

Mild Cognitive Impairment and Changes in Everyday Function Over Time: The Importance of Evaluating Both Speed and Accuracy.

OBJECTIVES: Research estimates that a significant percentage of individuals with mild cognitive impairment (MCI) experience functional difficulties. In addition to reduced accuracy on measures of everyday function, cross-sectional research has demonstrated that speed of performing instrumental activities of daily living (IADLs) is slowed in individuals with MCI. The present study investigated whether baseline and longitudinal changes in speed and accuracy of IADL performance differed between persons with MCI and cognitively normal peers. DESIGN: Linear mixed models were used to estimate the group differences in longitudinal performance on measures of IADLs. SETTING: Assessments were conducted at university and medical research centers. PARTICIPANTS: The sample consisted of 80 participants with MCI and 80 control participants who were enrolled in the Alzheimer's Disease Research Center's Measuring Independent Living in the Elderly Study. MEASUREMENTS: Instrumental activities of daily living speed and accuracy were directly assessed using selected domains of the Financial Capacity Instrument, the Timed IADL assessment, and driving-related assessments (Useful Field of View, Road Sign Test). RESULTS: Individuals with MCI performed worse on speed and accuracy measures of IADLs in comparison to cognitively normal peers and demonstrated significantly steeper rates of decline over three years in either speed or accuracy in all domains assessed. CONCLUSION: Both speed and accuracy of performance on measures of IADL are valuable indices for early detection of functional change in MCI. The performance pattern may reflect a trade-off between speed and accuracy that can guide clinical recommendations for maintaining patient independence.

Higher visceral fat is associated with lower cerebral N-acetyl-aspartate ratios in middle-aged adults.

Excessive adipose tissue, particularly with a central distribution, consists of visceral fat, which is metabolically active and could impinge upon central nervous system functioning. The aim of the current study was to examine levels of visceral adiposity in relation to key cerebral metabolite ratios localized in the occipitoparietal grey matter. Seventy-three adults, aged between 40 and 60 years, underwent structural magnetic resonance imaging and single voxel 1H Magnetic Resonance Spectroscopy (1H MRS). Visceral fat was assessed using Dual Energy X Ray Absorptiometry (DXA). Individuals with higher visceral fat mass and volume had significantly lower ratios of N-acetyl-aspartate to total creatine (phosphocreatine + creatine, PCr + Cr) (NAA/PCr + Cr) (ß = -0.29, p = 0.03, ß = -0.28, p = 0.04). They also had significantly higher ratios of myo-inositol to total creatine (mI/PCr + Cr ) (ß = 0.36, p = 0.01, ß = 0.36, p = 0.01). Visceral fat mass and volume were not significantly related to ratios of glutamate to total creatine (Glu/PCr + Cr). While future studies are necessary, these results indicate central adiposity is associated with metabolic changes that could impinge upon the central nervous system in middle age.

Specificity of Embedded Performance Validity Tests in Elderly Veterans with Mild and Major Neurocognitive Disorder.

OBJECTIVE: This study explored the specificity of four embedded performance validity tests (PVTs) derived from common neuropsychological tasks in a sample of older veterans with verified cognitive decline and whose performance was deemed valid by licensed psychologists. METHOD: Participants were 180 veterans who underwent comprehensive neuropsychological evaluation, were determined to have valid performance following profile analysis/conceptualization, and were diagnosed with mild neurocognitive disorder (i.e., MCI; n = 64) or major neurocognitive disorder (i.e., Dementia; n = 116). All participants completed at least one of four embedded PVTs: Reliable Digit Span (RDS), California Verbal Learning Test-2nd ed. Short Form (CVLT-II SF) Forced choice, Trails B:A, and Delis-Kaplan Executive Function System (DKEFS) Letter and Category Fluency. RESULTS: Adequate specificity (i.e., ≥90%) was achieved at modified cut-scores for all embedded PVTs across MCI and Dementia groups. Trails B:A demonstrated near perfect specificity at its traditional cut-score (Trails B:A < 1.5). RDS ≤ 5 and CVLT-II SF Forced Choice ≤7 led to <10% false positive classification errors across MCI and dementia groups. DKEFS Letter and Category Fluency achieved 90% specificity at extremely low normative cut-scores. CONCLUSIONS: RDS, Trails B:A, and CVLT-II SF Forced Choice reflect promising embedded PVTs in the context of dementia evaluations. DKEFS Letter and Category Fluency appear too sensitive to genuine neurocognitive decline and, therefore, are inappropriate PVTs in adults with MCI or dementia. Additional research into embedded PVT sensitivity (via known-groups or analogue designs) in MCI and dementia is needed.

Anosognosia in moderate-to-severe traumatic brain injury: A review of prevalence, clinical correlates, and diversity considerations.

METHOD: A comprehensive search of peer-reviewed articles was conducted from September to November 2020 using Google Scholar and PubMed databases. Key terms included "anosognosia," "self-awareness," "traumatic brain injury," and variants thereof. Our search was restricted to articles published in English within the last 25 years, although a few historical articles were included due to scientific merit. Articles were chosen based on methodological quality, inclusion of solely or predominantly msevTBI sample, and relevance to the current topic. CONCLUSIONS: Anosognosia is a multifaceted and domain-specific construct that affects the majority of those with msevTBI. It is related to TBI severity, injuries in right-hemispheric and cortical midline regions, specific aspects of executive function, psychological function, and cultural factors. We offer pragmatic advice for clinicians working with this population and discuss implications for the field regarding "best practices" of anosognosia assessment and intervention.

Obstructive sleep apnea is associated with worse cognitive outcomes in acute moderate-to-severe traumatic brain injury: A TBI Model Systems study.

OBJECTIVE: To examine the relationship between polysomnography-classified obstructive sleep apnea (OSA) severity and cognitive performance in acute moderate-to-severe traumatic brain injury (TBI). METHOD: This was a cross-sectional, secondary analysis leveraging data from a clinical trial (NCT03033901) and TBI Model Systems. Sixty participants (mean age = 50 ± 18y, 72% male, 67% white) with moderate-to-severe TBI from five civilian rehabilitation hospitals were assessed at one-month post-injury. Participants underwent Level 1 polysomnography. OSA severity was classified as mild, moderate, and severe using the Apnea-Hypopnea Index (AHI). Associations between OSA metrics of hypoxemia (nadir and total time spent below 90%) and AHI with cognition were examined. Cognition was assessed with the Brief Test of Adult Cognition by Telephone (BTACT), which is comprised of six subtests assessing verbal memory, attention/working memory, processing speed, language, and executive function. RESULTS: Over three-quarters of this acute TBI sample (76.7%) were diagnosed with OSA (no OSA n = 14; mild OSA n = 19; moderate/severe OSA n = 27). After adjustment for age, gender, and education, those with OSA had worse processing speed, working memory, and executive functioning compared to those without OSA. Compared to those with moderate/severe OSA, those with mild OSA had worse working memory and executive function. CONCLUSIONS: OSA is highly prevalent during acute stages of TBI recovery, and even in mild cases is related to poorer cognitive performance, particularly in the domains of attention/working memory and executive functioning. Our results support the incorporation of OSA diagnostic tools and interventions into routine clinical care in rehabilitation settings.

Neuropsychology of COVID-19: Anticipated cognitive and mental health outcomes.

OBJECTIVE: Discuss anticipated patterns of cognitive and emotional dysfunction, prognostic indicators, and treatment considerations based on review of (a) neuroinvasive properties of prior human coronaviruses and (b) extensively researched disorders which share similar neurological mechanisms. METHOD: A web-based comprehensive search of peer-reviewed journals was conducted based on a variety of key terms (and variants of) including coronavirus, neuroinvasion, cognitive dysfunction, viral pandemics, respiratory illness, critical illness, and metabolic disease. Articles were chosen based on relevance to the current topic and ability to provide unique thematic information. Historical articles were included if these added scientific merit to recent literature. Review of information in widely disseminated news articles was followed-up with direct review of cited scientific literature. Databases searched included Google Scholar, PubMed, and Ovid Medline. RESULTS: Based on neuroinvasive properties of prior coronaviruses and existing research on similar neurophysiological conditions with detrimental cognitive effects, COVID-19-especially those with severe symptoms-are at risk for cognitive decline and significant psychiatric/behavioral sequela. CONCLUSIONS: There are few studies examining cognitive outcomes in COVID-19. This review argues that neuropsychological sequelae are to be expected in patients with COVID-19. Considerations for clinicians working with this unique population are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Cognitive Processing Speed Is Strongly Related to Driving Skills, Financial Abilities, and Other Instrumental Activities of Daily Living in Persons With Mild Cognitive Impairment and Mild Dementia.

BACKGROUND: Cognitive processing speed is important for performing everyday activities in persons with mild cognitive impairment (MCI). However, its role in daily function has not been examined while simultaneously accounting for contributions of Alzheimer's disease (AD) risk biomarkers. We examine the relationships of processing speed and genetic and neuroimaging biomarkers to composites of daily function, mobility, and driving. METHOD: We used baseline data from 103 participants on the MCI/mild dementia spectrum from the Applying Programs to Preserve Skills trial. Linear regression models examined relationships of processing speed, structural magnetic resonance imaging (MRI), and genetic risk alleles for AD to composites of performance-based instrumental activities of daily living (IADLs), community mobility, and on-road driving evaluations. RESULTS: In multivariable models, processing speed and the brain MRI neurodegeneration biomarker Spatial Pattern of Abnormality for Recognition of Early Alzheimer's disease (SPARE-AD) were significantly associated with functional and mobility composite performance. Better processing speed and younger age were associated with on-road driving ratings. Genetic risk markers, left hippocampal atrophy, and white matter lesion volumes were not significant correlates of these abilities. Processing speed had a strong positive association with IADL function (p < .001), mobility (p < .001), and driving (p = .002). CONCLUSIONS: Cognitive processing speed is strongly and consistently associated with critical daily functions in persons with MCI in models including genetic and neuroimaging biomarkers of AD risk. SPARE-AD scores also significantly correlate with IADL performance and mobility. Results highlight the central role of processing speed in everyday task performance among persons with MCI/mild dementia.

Neuropsychological Correlates of Anosognosia for Objective Functional Difficulties in Older Adults on the Mild Cognitive Impairment Spectrum.

OBJECTIVE: To examine the neuropsychological correlates of anosognosia for instrumental activities of daily living (IADLs) in older adults with mild cognitive impairment (MCI) and mild dementia. METHOD: Participants (n = 103; age range = 54-88, 52% female) with MCI and mild dementia were recruited from neurology and geriatrics clinics for cross-sectional analysis. They completed neuropsychological tests along with subjective and performance-based assessments of six IADLs: financial management, driving, grocery shopping, nutrition evaluation, telephone use, and medication management. For each IADL, participants were classified as having anosognosia when there was objective difficulty but no subjective complaints. RESULTS: Depending on functional domain, 13-39% of the sample had objective IADL difficulty, and of those, 65-93% lacked insight into these deficits. Binomial logistic regression models controlling for demographic variables revealed that measures of global cognition, executive function, visual attention, and verbal memory predicted classification of anosognosia, and these relationships varied across IADLs. In contrast, basic auditory attention, working memory, depressive symptoms, nor cognitive reserve were significantly related to anosognosia for any IADL. CONCLUSION: Results support the Conscious Awareness Model, which theorizes that accurate metacognitive output is reliant on attentional, memory, and executive functioning systems. Findings from this study suggest that anosognosia for different IADLs may arise from breakdowns at varying points in this model, explaining both inter- and intra-patient variability in self-awareness of functional deficits.

Differences in self-awareness of functional deficits between amnestic single- and multidomain mild cognitive impairment.

INTRODUCTION: Prior research examining self-awareness of deficits in those with mild cognitive impairment (MCI) has been inconsistent, suggesting that preservation of insight at this disease stage may be conditional on the domain(s) examined as well as individual characteristics. The current study is the first to examine differences in objective performance and self-awareness of difficulties between older adults with amnestic single- (MCI-ASD) and multidomain MCI (MCI-AMD) across six instrumental activities of daily living (IADLs). METHOD: Seventy-five individuals (Mage = 73.9 years, range = 55-88 years; 56% female) with MCI-ASD (n = 30) and MCI-AMD (n = 45) were recruited primarily from a hospital-based memory disorders clinic. Participants were administered self-report and objective measures assessing six functional domains: financial management, driving, telephone use, nutrition evaluation, grocery shopping, and medication management. Self-awareness discrepancy scores were calculated for each of these IADLs, and participants were classified as either "overestimating ability" or "accurately/underestimating ability." RESULTS: Individuals with MCI-AMD performed significantly worse on objective measures of financial management, driving, and nutrition evaluation than those with MCI-ASD. Across MCI subtypes, participants were most likely to lack awareness of their difficulties in nutrition evaluation (31%), financial management (25%), and driving (23%) domains. Individuals with MCI-AMD were significantly more likely than those with MCI-ASD to overestimate performance on driving and telephone use domains. CONCLUSION: Individuals with MCI-AMD are more likely than those with MCI-ASD to have impairment in their everyday function and to lack awareness into their IADL difficulties. When possible, clinicians should obtain objective measures in combination with detailed informant reports of functional abilities in order to evaluate capacity to independently engage in various daily activities. Finally, level of self-awareness varies across IADL domains, providing further evidence that insight is not a unitary construct.

Poor awareness of IADL deficits is associated with reduced regional brain volume in older adults with cognitive impairment.

Performance of instrumental activities of daily living (IADLs) can become compromised in older adults with mild cognitive impairment (MCI). Patients' level of insight into their everyday functioning varies both amongst individuals and across domains assessed, with some individuals exhibiting complete unawareness of deficits. The current cross-sectional study examined the neuroanatomical substrates of self-awareness in order to help explain the variability in this phenomenon in older adults across a continuum of cognitive impairment. Eighty-five participants (ages 54-88, mean age = 73 years, 57% female, 89% Caucasian) diagnosed with MCI or mild probable dementia underwent structural magnetic resonance imaging. Level of self-awareness was assessed by calculating the discrepancy between objective and subjective performance across six IADLs (Financial Management, Driving, Grocery Shopping, Nutrition Evaluation, Medication Management, and Telephone Use). Over-estimation of current abilities occurred in 13-31% of the sample depending on which IADL was evaluated. Poor awareness was significantly related to reduced volume in the bilateral medial prefrontal cortex, middle and posterior cingulate cortex, right insular cortex, and cerebellum. No associations were found with total white matter lesion load. These findings were broadly consistent across all functional domains assessed, supporting the theory that cortical midline and cerebellar structures are involved in self-referential processing across a variety of different cognitive and behavioral skills. Longitudinal studies are needed to confirm this association.

Performance-based measures and behavioral ratings of executive function in diagnosing attention-deficit/hyperactivity disorder in children.

Deficits in real-world executive functioning (EF) are a frequent characteristic of attention-deficit/hyperactivity disorder (ADHD). However, the predictive value of using performance-based and behavioral rating measures of EF when diagnosing ADHD remains unclear. The current study investigates the use of performance-based EF measures and a parent-report questionnaire with established ecological validity and clinical utility when diagnosing ADHD. Participants included 21 healthy controls, 21 ADHD-primary inattentive, and 21 ADHD-combined type subjects aged 6-15 years. A brief neuropsychological battery was administered to each subject including common EF assessment measures. Significant differences were not found between groups on most performance-based EF measures, whereas significant differences (p < 0.05) were found on most parent-report behavioral rating scales. Furthermore, performance-based measures did not predict group membership above chance levels. Results further support differences in predictive value of EF performance-based measures compared to parent-report questionnaires when diagnosing ADHD. Further research must investigate the relationship between performance-based and behavioral rating measures when assessing EF in ADHD.

Self-Awareness of Executive Functioning Deficits in Adolescents With ADHD.

OBJECTIVE: Children with ADHD lack self-awareness of their social and academic deficits, frequently rating themselves more favorably than external sources. The purpose of the current study was to assess whether adolescents with ADHD also hold a positive bias toward their executive functioning (EF). METHOD: Participants include 22 control and 35 ADHD subjects, aged 11 to 16. Participants and their parents completed the Behavior Rating Inventory of Executive Functioning (BRIEF) Self and Parent forms, respectively. Discrepancy scores were calculated for each domain by subtracting the adolescents' T-score from the parents' T-score. RESULTS: Discrepancy scores were significantly higher in the ADHD group than controls within the Inhibit, Shift, Monitor, Emotional Control, Working Memory, and Plan/Organization domains (all p < .05). CONCLUSION: As compared with controls, adolescents with ADHD tend to endorse fewer EF difficulties than what parents report. This is the first study to demonstrate that those with ADHD may overestimate their EF ability.

The Wechsler Test of Adult Reading as a Measure of Premorbid Intelligence Following Traumatic Brain Injury.

OBJECTIVE: The current study sought to determine whether the Wechsler Test of Adult Reading (WTAR) provides a stable estimate of premorbid intellectual ability in acutely injured patients recovering from traumatic brain injury (TBI). METHOD: A total of 135 participants (43 mild TBI [mTBI], 40 moderate/severe TBI [msevTBI], 52 healthy controls) were administered the WTAR at 1 and 12 months post-injury. RESULTS: Despite similar demographic profiles, participants with msevTBI performed significantly worse than controls on the WTAR at both time points. Moreover, the msevTBI group had a significant improvement in WTAR performance over the 1-year period. In contrast, those participants with mTBI did not significantly differ from healthy controls and both the mTBI and control groups demonstrated stability on the WTAR over time. CONCLUSIONS: Results indicate that word-reading tests may underestimate premorbid intelligence during the immediate recovery period for patients with msevTBI. Clinicians should consider alternative estimation measures in this TBI subpopulation.

Twelve-month recovery of medical decision-making capacity following traumatic brain injury.

OBJECTIVE: To investigate recovery of medical decision-making capacity (MDC) over the first year following traumatic brain injury (TBI). METHODS: A total of 177 participants (111 persons with TBI and 66 healthy controls) were recruited from an inpatient/outpatient TBI rehabilitation unit and outpatient neurology department. Participants with TBI were classified by injury severity into subgroups: mild TBI (mTBI; n = 28), complicated mild TBI (cmTBI; n = 23), and moderate/severe TBI (msevTBI; n = 60). Control and TBI groups were compared at 1 month (t1), 6 months (t2), and 12 months (t3) postinjury using the Capacity to Consent to Treatment Instrument (CCTI), which evaluates MDC using 5 consent standards: expressing choice, reasonable choice, appreciation, reasoning, and understanding. RESULTS: Relative to controls, no TBI group displayed impairment on CCTI expressing choice or reasonable choice at any timepoint. Those with mTBI had reduced appreciation and understanding at t1, which resolved by t2. The cmTBI and msevTBI groups were impaired on all 3 complex consent standards at t1. While patients with cmTBI improved to a level similar to controls by t3, those with msevTBI remained impaired on reasoning and understanding. Across all TBI groups, notable MDC improvement only occurred over the first 6 months postinjury. CONCLUSIONS: Over 1 year, most individuals with mTBI or cmTBI regain MDC, while many individuals with msevTBI have lingering deficits in reasoning and comprehension of treatment information. Clinical recovery of MDC occurs primarily during the first 6 months post-TBI regardless of injury severity. Clinicians can therefore identify MDC outcomes in TBI at 6 months postinjury.