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Results for “Cognitive Reserve”

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PubMed2000

Factors associated with neuropsychological performance in HIV-seropositive subjects without AIDS.

BACKGROUND: Previous research has suggested that several factors may influence the presence of cognitive impairment in human immunodeficiency virus (HIV) infection. The objective of this study was to assess the impact of cognitive reserve capacity and other variables on neuropsychological performance in early HIV infection. METHODS: The neuropsychological performance of 100 HIV-seropositive subjects without AIDS (71 men and 29 women) was compared with that of 63 seronegative controls (51 men and 12 women). Measures included a neuropsychological battery, a medical examination and a psychiatric assessment. Cognitive reserve scores were based on a combination of years in school, a measure of educational achievement, and an estimate of pre-morbid intelligence. RESULTS: HIV-positive subjects had longer reaction time latencies than HIV-negative subjects. Those in the HIV-positive group with low cerebral reserve scores showed the poorest performance on the neuropsychological tests. The prevalence of cognitive impairment was significantly higher in the HIV-positive group (27%) than in the controls (32%). Multiple regression analysis and logistic regression analysis were used to identify factors associated with global neuropsychological performance and cognitive impairment. Older age, lower cerebral reserve scores and not being on zidovudine treatment were associated with lower global neuropsychological scores and with the presence of cognitive impairment. CONCLUSIONS: Our results suggest that although cognitive impairment is not characteristic of early HIV infection, there is a subgroup of subjects who perform more poorly than expected. A lower reserve capacity, older age and not being on zidovudine treatment are factors that lower the threshold for neuropsychological abnormalities in cases of early HIV infection.

Adult↗
PubMed1998

The link between knowledge and remembering in Alzheimer's disease.

Current research on the influence of cognitive support (e.g., activation of task-relevant prior knowledge, item organizability, retrieval cues) on episodic remembering in normal aging and Alzheimer's disease (AD) is reviewed. Examining the effects of cognitive support on memory may shed light on the relationship between knowledge and remembering, and also provides relevant information pertaining to the development of cognitive intervention procedures. A series of studies from our own and other laboratories reveal a number of interesting empirical regularities. First, AD results in problems in utilizing cognitive support for improving memory. Conceivably, this reduction in cognitive reserve capacity is due to both the overall severity of the episodic memory impairment in AD, as well as to dementia-related deficits in the semantic network that guides encoding and retrieval of information. Nevertheless, AD patients are able to utilize cognitive support in episodic memory tasks, although they typically need more support than their healthy aged counterparts to show memory facilitation. Specifically, it is critical to provide support at both encoding and retrieval in order to demonstrate performance gains in AD. Moreover, successful utilization of retrieval support in this disease is most likely to occur when the encoding requirements force the individual to engage in elaborative cognitive activity (e.g., generation of task-relevant knowledge, categorical organization). Finally, a reduction in cognitive reserve capacity occurs later in the pathogenesis of AD than a generalized episodic memory impairment. This observation reflects the insidious nature of AD, and suggests that the transition from normal aging to AD may be continuous rather than discrete.

Aged↗
PubMedDate not supplied

Early-life risk factors for Alzheimer disease.

Research findings obtained over the past 20 years suggest that Alzheimer disease (AD) may have its origins in early life. In this review, we consider the evidence for early-life risk factors for this illness. We propose that risk factors that predict neuropathology are largely distinct from those related to the clinical expression of Alzheimer disease. Early-life risk factors for pathology include genes, chromosomal abnormalities, head injury, insulin resistance, and inflammation. With regard to risk factors for clinical expression of Alzheimer disease, six general groups of childhood exposures are reviewed: (1) perinatal conditions, (2) early-life brain development, (3) early-life body growth, (4) early-life socioeconomic conditions, (5) environmental enrichment, and (6) cognitive reserve. The literature reviewed suggests that risk of Alzheimer disease is probably not determined in any single time period but results from the complex interplay between genetic and environmental exposures throughout the life course. Enhancement or preservation of brain or cognitive reserve could delay the onset of Alzheimer disease and in some cases prevent the disease from occurring altogether.

Alzheimer Disease↗
PubMed2026

Role of Polygenic Risk Scores in Predicting Cognitive Functioning after Mild Traumatic Brain Injury: A TRACK-TBI Study.

Patients with traumatic brain injury (TBI) and Glasgow Coma Scale scores of 13-15 (historically called mild TBI [mTBI]) commonly experience changes in cognitive functioning, including processing speed, memory, and executive functioning. In a prospective sample (N = 523) of individuals of European descent who had been treated in a U.S. level 1 trauma center for mTBI, we examined the prognostic value of four polygenic risk scores (PRS) for cognitive outcomes at 6-months postinjury. To estimate the impact of mTBI on cognition, primary cognitive outcomes were scaled as z-scores reflecting changes in performance relative to predicted preinjury performance. The PRS examined were previously developed and validated to predict cognition-related outcomes of educational attainment (Education-PRS), intelligence (Intelligence-PRS), and Alzheimer's disease (AD-mild traumatic brain injury (APOE)-PRS and AD + APOE-PRS). Both the Education-PRS and Intelligence-PRS displayed bivariate associations with all four cognitive outcomes (β = 0.19-0.32), whereas neither Alzheimer's disease PRS was significantly associated with any outcome. After controlling for other factors known to predict cognitive outcomes of TBI (e.g., sex, education, mTBI severity defined by a combination of Glasgow Coma Scale scores and the presence/absence of acute intracranial findings on clinical neuroimaging), the Education-PRS and Intelligence-PRS remained independently predictive of verbal episodic memory (β = 0.10-0.16), whereas their associations with processing speed and executive functioning were mostly nonsignificant and were mediated through educational attainment. Looking across primary z-score and secondary raw score outcomes, cognitive outcomes 6 months post-mTBI were good on average, and PRS made small independent contributions to outcome prediction. The mediation model findings may support theories of cognitive reserve, which propose that individuals with stronger preinjury cognitive processing abilities (often estimated by educational history) can better compensate for TBI. Moreover, findings indicate that PRS may contribute modestly to multivariable models predicting cognitive function after TBI.

Humans↗
PubMed2025

Premorbid functioning trajectories and the one-year course of cognitive performance in first-episode psychosis: a cluster analysis in PSYSCAN.

BACKGROUND: We examined the course of cognitive performance in first-episode psychosis (FEP) compared to healthy controls (HC), and whether this varied across subgroups of patients defined by premorbid functioning (PMF) trajectories, using a clustering approach. METHODS: Data were collected in 302 FEP and 136 HC subjects participating in PSYSCAN (HEALTH.2013.2.2.1-2-FEP). K-means clustering (Euclidean distance) was used to cluster longitudinal trajectories of different PMF domains simultaneously. Since PMF was assessed retrospectively using the Premorbid Adjustment Scale (PAS), findings should be interpreted with caution, although PAS ratings have shown reasonable validity against prospective data. RESULTS: As expected, FEP showed impaired performance across all cognitive domains compared to HC. We identified four trajectories of PMF: a normal premorbid developmental trajectory (globally-normal, 21 %), stable intermediate PMF across domains (stable-intermediate, 29 %), stable poor or deteriorating PMF in the academic domain (normal-social/poor-academic, 29 %), and a globally impaired group with poor/deteriorating PMF across domains (globally-poor, 21 %). These clusters showed distinct levels of post-onset impairments in sustained visual attention, visual working memory and emotion recognition. CONCLUSIONS: This study confirms a positive association between PMF and cognitive performance in the early years following psychosis onset. It aligns with findings that individuals later diagnosed with schizophrenia already show developmental deficits/lags from childhood to early adolescence compared to normally developing children. As PMF can be considered a proxy for cognitive reserve, our results suggest that higher reserve acts as a buffer against cognitive decline and supports better performance on sustained visual attention, complex visual working memory, and aspects of emotion recognition.

Clustering↗
PubMed1998

Normal and pathological aging--findings of positron-emission-tomography.

Normal aging of the brain is predominantly characterized by metabolic changes in the prefrontal cortex. While in middle age there is a trend to hyperfrontality, PET demonstrates in old age a decline of regional cerebral glucose metabolism in frontal areas. In progeric diseases, clinically apparent as premature aging, the metabolic pattern is similar like in normal aging but qualitatively more severe. In patients with the diagnosis of probable Alzheimer's disease (AD) hypometabolism in early dementia is typically present in heteromodal association areas. Hypometabolism then spreads to other cortical and subcortical regions suggesting a characteristic pattern of degeneration that reflects selective vulnerability within limbic-cortical networks. Synaptic plasticity, clinically apparent as cognitive reserve capacity, can be assessed by PET under specific cognitive activation. In AD it is reduced in comparison to age-matched normals and may be influenced by drugs giving trophic support to neurochemical systems.

Aging↗
PubMed2001

Cognitive performance and cerebrohemodynamics associated with the Persian Gulf Syndrome.

The Persian Gulf Syndrome generally manifests as a set of nonspecific complaints with emphasis on central nervous system impairment. The purpose of this study was to determine if cognitive performance and middle cerebral artery blood flow velocity (MCABFV) were altered in symptomatic Gulf War veterans (sGWVs) and asymptomatic Gulf War veterans (aGWVs) by exposure to low levels of acetone. MCABFV was assessed in male aGWVs (n = 8) and sGWVs (n = 8) during cognitive challenges while breathing 1) clean air, 2) a clean air placebo, and 3) a mixture of air and 40 parts per million (ppm) acetone. Pulmonary function was also evaluated. Pulmonary function tests showed no statistical differences between aGWVs and sGWVs while breathing clean air or 40 ppm acetone in air. Cognitive performance was similar during the clean air, placebo, and acetone test conditions for sGWVs and aGWVs. Data pooled across test conditions for each group indicated a statistically significant (P < 0.05) poorer performance primarily in memory and executive function tasks by sGWVs. sGWVs had a 34.2% higher baseline MCABFV than aGWVs (P < 0.05). Increases in MCABFV for aGWVs (averaged over all cognitive tasks for each test condition) ranged between 7.8% and 8.8%, and were not statistically significant. Increases for sGWVs ranged between 0.3% and 4.8%, averaged over all cognitive tasks for each test condition. No significant differences were noted between the clean air and placebo test conditions but both were significantly different to the acetone condition. Differences in MCABFV increases for each of the test conditions between aGWVs and sGWVs were also statistically significant. sGWV did not appear to demonstrate pulmonary dysfunction following exposure to acetone. They did, however, appear to have generally lower cognitive function as compared to aGWVs. sGWVs appeared to have a significant degree of autoregulatory disruption in cerebral perfusion, resulting in reduced cognitive reserve capacity and potentially impaired ability to handle complex cognitive tasks.

Acetone↗
PubMed2002

Memory functioning following traumatic brain injury in children with premorbid learning problems.

This study examines the memory functioning of 25 children who sustained a traumatic brain injury (TBI) and who had prior learning problems, 48 children with TBI who did not have prior learning problems, and 23 noninjured controls. The children with TBI and prior learning problems displayed significantly worse memory abilities than both the control participants and the children with TBI and no prior learning problems. They differed significantly from these 2 groups on measures of general memory, verbal memory, sound-symbol learning, and attention. The results suggest that children with premorbid learning problems who sustain TBI have less cognitive reserve and a lower threshold for the expression of cognitive impairments in areas that reflect preexisting learning and language problems, compared to children without premorbid learning problems.

Adolescent↗
PubMed2006

The effect of education and occupational complexity on rate of cognitive decline in Alzheimer's patients.

We explored the effect of education and occupational complexity on the rate of cognitive decline (as measured by the Mini-Mental State Examination) in 171 patients with a confirmed Alzheimer's disease (AD) diagnosis. Complexity was measured as substantive complexity of work and complexity of work with data, people, and things. Average lifetime occupational complexity was calculated based on years at each occupation. Participants were followed for an average of 2.5 years and 3.7 visits. In multivariate mixed-effects models, high education, high substantive complexity, and high complexity of work with data and people predicted faster rates of cognitive decline, controlling for age, gender, native language, dementia severity, and entry into the analyses at initial versus follow-up testing. These results provide support for the concept of cognitive reserve according to which greater reserve may postpone clinical onset of AD but also accelerate cognitive decline after the onset.

Age of Onset↗
PubMed2005

Cognitive decline and literacy among ethnically diverse elders.

Researchers on genetic and environmental influences on risk for Alzheimer's disease must be prepared for the growing ethnic and racial diversity of our participants. Within the investigation, years of education has typically served as a proxy for cognitive reserve, which may be one factor in influencing risk of cognitive decline among aging people. However, among ethnic minorities, years of education is a poor reflection of the value of educational experience and native ability. This study was conducted among 1002 ethnically diverse English-speaking residents of Northern Manhattan who were cognitively and functionally normal at a baseline evaluation. We found that literacy level was a better predictor of decline in memory, executive function, and language skills than was years of education. The results of this study suggest that in an ethnically diverse cohort, literacy level should be considered as a mediator of the interactions of biological and environmental factors on cognitive decline.

Aged↗
PubMed2004

Incidence and prevalence of dementia in elderly adults with mental retardation without down syndrome.

Rates of dementia in adults with mental retardation without Down syndrome were equivalent to or lower than would be expected compared to general population rates, whereas prevalence rates of other chronic health concerns varied as a function of condition. Given that individual differences in vulnerability to Alzheimer's disease have been hypothesized to be due to variation in cognitive reserve, adults with mental retardation, who have long-standing intellectual and cognitive impairments, should be at increased risk. This suggests that factors determining intelligence may have little or no direct relationship to risk for dementia and that dementia risk for individuals with mental retardation will be comparable to that of adults without mental retardation unless predisposing risk factors for dementia are also present.

Aged↗
PubMedDate not supplied

The relation of white matter hyperintensities to cognitive performance in the normal old: education matters.

This study examined whether the severity of cerebral white matter abnormalities (evident on MR images as white matter hyperintensities (WMH)) was related to the cognitive performance of 141 high-functioning older adults. The elderly showed the typical age decrement on measures of processing speed, working memory, and inhibition; however WMH severity was significantly related only to processing speed. The strength of this relationship was, however, influenced by the educational level of the participants, such that processing speed was more associated with WMH severity in less-educated than in well-educated participants. This is consistent with recent concepts of cognitive reserve, but does raise a question as to the underlying source of the cognitive decrement found in the sort of well-educated elders typically used in cognitive-aging studies.

Adolescent↗
PubMedDate not supplied

Experienced and less-experienced nurses' diagnostic reasoning: implications for fostering students' critical thinking.

PURPOSE: To compare the use of mental representations (heuristics) in diagnostic reasoning of expert (> or = 5 years' experience) and novice (< 5 years' experience) emergency nurses. METHODS: Clinical simulations were completed by a nationwide randomly selected sample of 173 experienced and 46 less-experienced emergency nurses (N = 219). FINDINGS: Experienced nurses used the heuristic, Judging by Causal Systems (diagnostic inferences deduced from systems of causal factors) significantly more did than less-experienced nurses. PRACTICE IMPLICATIONS: Standardized nursing diagnoses may cut short the time needed to develop representational thinking and spare cognitive reserves for reasoning needed for complex patients. Faculty need to promote student's cognitive development through strategies that promote active, reflective, and integrative learning.

Adult↗
PubMed2006

From bedside to bench: does mental and physical activity promote cognitive vitality in late life?

A wide range of animal and human studies provide evidence for the potential of physical and cognitive exercise in promoting cognitive health later in life. The effects of such activities on intermediate outcomes, such as cognitive performance, are becoming clearer, as are the molecular mechanisms involved. Physical and cognitive exercise might increase "cognitive reserve" and increase the overall health of the brain, thereby reducing or delaying cognitive impairment and dementia. However, conclusive evidence for such benefits is not yet established. The third annual Bedside to Bench conference, cosponsored by The American Geriatrics Society and the National Institutes of Health's National Institute on Aging, reviewed current knowledge regarding the role of physical and cognitive exercise in promoting cognitive vitality. Conference attendees identified gaps in our current understanding of these processes and recommended next steps for research. In particular, researchers will need to explore clinical issues related to the timing, intensity, and duration of various types and combinations of physical and cognitive activities in animal models to elucidate the mechanisms involved and inform the design of future human studies. The concept of the enriched environment currently employed in animal studies to promote physical activity, socialization, and problem solving should be explored in human studies.

Aged↗
PubMed2005

Very early detection of Alzheimer neuropathology and the role of brain reserve in modifying its clinical expression.

Numerous studies show that the pathology of Alzheimer's disease is present decades before a clinical diagnosis of dementia can be made. Given the likelihood that agents will become available that reliably delay onset and/or slow progression of Alzheimer's disease, it will be important to detect preclinical Alzheimer's disease as early as possible for maximal treatment effect. Detection of individuals by sensitive cognitive measures provides one way to identify people who are at high risk of developing clinical Alzheimer's disease. However, it is likely that those with considerable brain or cognitive reserve will be able to mask cognitive deficits until very close to the onset of the dementia, rendering such cognitive measures insensitive. Optimum biomarkers for Alzheimer's disease therefore need to target the severity of underlying brain pathology independently of brain reserve. Findings are presented showing the importance of higher education and larger brain size in masking the underlying disease pathology.

Aged↗
PubMed2003

Assessment of lifetime participation in cognitively stimulating activities.

Cognitively stimulating experience is thought to contribute to cognitive reserve. We constructed a questionnaire consisting of 25 items about frequency of participation in cognitive activities across the life span and administered it to two groups of older persons. The total score on the scale had high internal consistency (coefficient alpha = 0.88) and temporal stability over a 4-week re-test interval (r = 0.79), and it was positively correlated with education. In analyses controlling for age, sex, and education, more frequent cognitive activity was related to better perceptual speed, visuospatial ability, and semantic memory but not to episodic memory or working memory. The results suggest that the scale provides a psychometrically sound measure of frequency of cognitive activity across the life span.

Aged↗
PubMed2006

Physical fitness and lifetime cognitive change.

OBJECTIVE: To test the hypothesis that physical fitness is associated with more successful cognitive aging. METHODS: Surviving participants (N = 460) of the Scottish Mental Survey of 1932 were tested on the same general cognitive test at age 11 and 79 years. Measures of grip strength, 6-meter walk time, and lung function (forced expiratory volume from the lungs in 1 second [FEV1]) were assessed at age 79 years. RESULTS: A latent physical fitness trait, derived by principal components analysis of the three fitness measures, was significantly associated with successful cognitive aging. Cognitive score at age 11, sex, social class, and APOE-epsilon4 genotype were included as covariables. Higher childhood IQ was associated with better lung function in old age. CONCLUSIONS: Physical fitness is associated with cognitive reserve. Intervention studies aimed at making older people fitter are good candidates to improve cognitive aging.

Adaptation, Physiological↗
PubMed2003

Early life physical activity and cognition at old age.

Physical activity has shown to be inversely associated with cognitive decline in older people. Whether this association is already present in early life has not been investigated previously. The association between early life physical activity and cognition was studied in 1,241 subjects aged 62-85 years, in a prospective population-based study. Physical activity between ages 15 and 25 years was asked retrospectively. The findings suggest a positive association between regular physical activity early in life and level of information processing speed at older age in men, not in women. The association could not be explained by current physical activity or other lifestyle factors. This finding supports the cognitive reserve hypothesis, and might suggest that early life physical activity may delay late-life cognitive deficits.

Aged↗