SEARCH · PubMed Health

Results for “Cognitive function”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources

PubMed2005

Effects of ovarian hormones on cognitive function in nonhuman primates.

Several studies have suggested that estrogen benefits verbal memory and lowers the risk of Alzheimer's disease in women, and improves cognitive function in animal models. However, the negative outcome of the Women's Health Initiative Memory Study has challenged the rationale for using estrogen as a protective agent against age-related cognitive decline. In view of the limitations of the Women's Health Initiative Memory Study, it is clear that our understanding of estrogen effects would greatly benefit from further interactions between clinical and basic science. Animal models of menopause can provide crucial information regarding the consequences of estrogen loss and replacement on several systems, including cognition. In this paper, I review the evidence that nonhuman primates, who share numerous cognitive and physiological characteristics with humans, can substantially contribute to our understanding of estrogen influences on the brain and cognition. Studies in young adult females suggest that some aspects of cognition fluctuate with the menstrual cycle, but that ovariectomy and estrogen replacement have only modest effects on cognitive function. In contrast, data in aged, naturally or surgically menopausal monkeys indicate that estrogen modulates a broad range of cognitive domains. Neurobiological data are consistent with the cognitive findings and demonstrate an array of morphological and physiological changes in brain areas important for cognition following ovariectomy and/or estrogen replacement. It is concluded that nonhuman primates, by providing a bridge between rodent and human data, constitute invaluable models to further our understanding of hormonal actions on the brain and cognition and to develop effective hormonal interventions against brain and cognitive aging.

Adult↗

PubMed1995

Interrelationships of peak expiratory flow rate with physical and cognitive function in the elderly: MacArthur Foundation studies of aging.

BACKGROUND: Peak expiratory flow rate (PEFR) is correlated with several measures of health in the elderly, including physical and cognitive function. It is unclear, however, whether these relationships persist among the non-frail. METHODS: The Community-based Studies of the MacArthur Foundation Research Network on Successful Aging included measures of PEFR using a mini-Wright peak flow meter on a sample of 1,354 subjects selected from those aged 70-79 in three population samples. Subjects were chosen on the basis of simple measures of physical and cognitive function (high = 1192; medium = 80; low = 82), and were given a series of more detailed tests. RESULTS: Residual PEFR, adjusted for age, sex, height, weight, and smoking, was highly correlated (p < .001) with several physical performance measures, including number of steps in a tandem walk, number of seconds in a single leg stand, times to turn in a circle, write one's name, and walk 10 feet at a fast pace, foot-tapping (time per tap), and hand grip strength. The strongest association was evident for a combination of six physical function items. Residual PEFR was also correlated with cognitive performance, including tests of similarities, naming, spatial recognition, memory, and figure drawing. The strongest association was present for a combined measure. These associations persisted in analyses restricted to those in the "high" function group as well as with no history of previous myocardial infarction, stroke, or cancer. Residual PEFR also exhibited a strong independent association with urinary norepinephrine, as measured in 12-hour overnight urine specimens. This relation did not appear to be mediated by smoking or medication use.

Aged↗

PubMed2002

Relationship between cognitive function and regional cerebral blood flow in Alzheimer's disease.

The Mini-Mental State examination (MMSE) is frequently used to assess the cognitive function of neurological patients. The purpose of this study was to investigate associations between regional cerebral blood flow (rCBF) and MMSE scores in Alzheimer's disease (AD) and localization of cognitive functions. Fifty-nine patients with probable AD (21 males and 38 females; mean age 74 years) and 12 normal volunteers (five males and seven females; mean age 73 years) were studied. CBF was measured by SPECT using the N-isopropyl-p-[(123)I]iodoamphetamine autoradiography method. The CBF images were reconstructed in parallel with the orbitomeatal line and parallel to the long axis of the temporal cortex. Regions of interest were set in the cerebral and cerebellar cortex. Multivariate analysis was performed by the step-wise method, using each section of the MMSE as the dependent variable and the rCBF ratio as the independent variable. The decline in rCBF in the parietal cortex and hippocampus reflected disorientation, and the most significant cortex affecting scores on each section of the MMSE were found to be the anterior temporal cortex for registration, the frontal cortex for attention and calculation, the medial temporal cortex for recall, and the posterior temporal cortex for language.

Aged↗

PubMed1998

The effect of a 50 Hz magnetic field on cognitive function in humans.

OBJECTIVES: To examine whether the power frequency magnetic field of 0.6mT applied to humans has an effect on cognitive function as has been suggested by animal studies. These fields are less than the suggested intervention level in the UK of 1.6mT and are similar to those found close to some domestic appliances. METHOD AND MATERIALS: A randomized three-way cross-over design using a battery of computerized cognitive function tests were used in the presence or absence of a 50Hz or static magnetic field. Sixteen healthy volunteers undertook two training and three test sessions with a 50Hz or static 0.6 mT magnetic field from a set of coils centred on the head. RESULTS: In response to the 50 Hz field, disruptions of accuracy were seen from an attentional task (the ability to correctly recognize words shown 20min previously and the ability to maintain a string of digits in working memory). There was no similar response to comparable levels of static magnetic field. CONCLUSIONS: These tests indicated at least temporary deterioration in attention, and working and secondary memory performance while a 50 Hz field is applied. There were no adverse effects on speed from any of the tasks. It was not possible in this study to be sure if these effects were persistent.

Adult↗

PubMed2003

The relationship between stressful life events and cognitive function in HIV-infected men.

Previous studies have demonstrated an impact of stress on immune function, and recent studies have suggested an adverse effect of stress on the brain. However, no previous study has examined the impact of stress on cognitive function. This article examines the relationship between stress and cognitive function in 82 HIV-negative subjects and 251 HIV-positive subjects. Subjects completed a comprehensive neuropsychological examination, measures of anxiety and depression, and a measure of stressful life events. After controlling for the impact of anxiety, depression, age, and education, stressful life events were related to cognitive impairment only among the HIV-positive subjects. The data were interpreted in the context of previous studies that have demonstrated an adverse effect of stress on the brain and suggest that this adverse impact may be expressed in the setting of a compromised immune system. Furthermore, this analysis suggests several implications for patient management.

Adult↗

PubMed2006

The effects of blood pressure reduction on cognitive function: a review of effects based on pooled data from clinical trials.

OBJECTIVE: To review systematically and synthesize quantitatively the evidence from completed randomized, controlled trials of blood pressure reduction on cognitive performance. METHODS: MEDLINE, EMBASE and Cochrane databases were searched to identify randomized, controlled trials that measured the effect of blood pressure reduction on cognitive performance. Additional studies were identified by searching bibliographies of retrieved articles and contacting experts in the field. Data were extracted on study quality, blood pressure, performance on cognitive function tests, antihypertensive treatment regimens and the duration of treatment. Studies were reviewed and abstracted independently by two trained researchers. RESULTS: Sixteen studies with 19 501 subjects were identified. Modest reductions in blood pressure (< 5/3 mmHg) in 13 860 subjects were associated with improvements in Mini Mental State Examination score [weighted mean difference (WMD) = 0.19; 95% confidence interval (CI) = 0.19-0.19] and performance on immediate (WMD = 0.62; 95% CI = 0.21-1.02) and delayed (WMD = 0.67; 95% CI = 0.23-1.11) logical memory tasks. However, studies in 2380 subjects that included tests of perceptual processing and learning capacity (trail making test-A, paired associated learning test) showed impaired performance (WMD = -1.12 s; 95% CI = -1.22 to -1.02 and WMD = -0.04; 95% CI = -0.04 to -0.04) on these tests. CONCLUSION: Blood pressure lowering may have a heterogeneous effect on different aspects of cognitive function. Future studies with specific cognitive end-points are needed for greater clarity to guide practice.

Antihypertensive Agents↗

PubMed2003

50-60 Hz electric and magnetic field effects on cognitive function in humans: a review.

This paper reviews the effect of 50-60 Hz weak electric, magnetic and combined electric and magnetic field exposure on cognitive functions such as memory, attention, information processing and time perception, as determined by electroencephalographic methods and performance measures. Overall, laboratory studies that have investigated the acute effects of power frequency fields on cognitive functioning in humans are heterogeneous, in terms of both electric and magnetic field (EMF) exposure and the experimental design and measures used. Results are inconsistent and difficult to interpret with regard to functional relevance for possible health risks. Statistically significant differences between field and control exposure, when they are found, are small, subtle, transitory, without any clear dose-response relationship and difficult to reproduce. The human performance or event related potentials (ERPs) measures that might specifically be affected by EMF exposure, as well as a possible cerebral structure or function that could be more sensitive to EMF, cannot be better determined.

Brain↗

PubMed2004

Maturation of white matter is associated with the development of cognitive functions during childhood.

In the human brain, myelination of axons continues until early adulthood and is thought to be important for the development of cognitive functions during childhood. We used diffusion tensor MR imaging and calculated fractional anisotropy, an indicator of myelination and axonal thickness, in children aged between 8 and 18 years. Development of working memory capacity was positively correlated with fractional anisotropy in two regions in the left frontal lobe, including a region between the superior frontal and parietal cortices. Reading ability, on the other hand, was only correlated with fractional anisotropy in the left temporal lobe, in the same white matter region where adults with reading disability are known to have lower fractional anisotropy. Both the temporal and the frontal regions were also correlated with age. These results show that maturation of white matter is an important part of brain maturation during childhood, and that maturation of relatively restricted regions of white matter is correlated with development of specific cognitive functions.

Adolescent↗

PubMed2003

Older adults and withdrawal from benzodiazepine hypnotics in general practice: effects on cognitive function, sleep, mood and quality of life.

BACKGROUND: Older adults are the main recipients of repeat prescriptions for benzodiazepine (BZD) hypnotics. BZDs can impair cognitive function and may not aid sleep when taken continuously for years. This study therefore aimed to determine if withdrawing from BZDs leads to changes in patients' cognitive function, quality of life, mood and sleep. METHOD: One hundred and ninety-two long-term users of BZD hypnotics, aged > or = 65 years, were identified in 25 general practices. One hundred and four who wished to withdraw were randomly allocated to one of two groups under double-blind, placebo controlled conditions: group A's BZD dose was tapered from week 1 of the trial; group B were given their usual dose for 12 weeks and then it was tapered. An additional group (C) of 35 patients who did not wish to withdraw from BZDs participated as 'continuers'. All patients were assessed at 0, 12 and 24 weeks and 50% were reassessed at 52 weeks. RESULTS: Sixty per cent of patients had taken BZDs continuously for > 10 years; 27% for > 20 years. Of all patients beginning the trial, 80% had successfully withdrawn 6 months later. There was little difference between groups A and B, but these groups differed from continuers (C) in that the performance of the withdrawers on several cognitive/psychomotor tasks showed relative improvements at 24 or 52 weeks. Withdrawers and continuers did not differ in sleep or BZD withdrawal symptoms. CONCLUSIONS: These results have clear implications for clinical practice. Withdrawal from BZDs produces some subtle cognitive advantages for older people, yet little in the way of withdrawal symptoms or emergent sleep difficulties. These findings also suggest that, taken long-term, BZDs do not aid sleep.

Affect↗

PubMed1997

Effects of HIV seropositivity and drug abuse on cognitive function.

Fifty-eight HIV-positive drug abusers and 22 HIV-positive nondrug abusers at stages II-III and IV of the Centers for Disease Control classification were evaluated neuropsychologically. The study confirmed previous findings that drug abuse has a negative influence on cognitive function. It also emerges that seropositivity affects cognitive function, although the poor performance of group II-III patients compared to group IV may be explained by factors related to seropositivity (anxiety and panic) rather than the disease itself. It is concluded that disease-related factors probably determine cognitive performance in the earlier stages of HIV infection.

AIDS Dementia Complex↗

PubMed2005

Memory, executive cognitive function, and readiness to change drinking behavior.

The transtheoretical model of Prochaska and DiClemente [Psychother. Theory Res. Prac. 19 (1982) 276] postulates that cognitive skills are critical for drinking behavior change. Memory and executive cognitive function likely influence the execution of skills that are implicated for both motivating and sustaining drinking behavior change. Participants who met criteria for alcohol abuse or dependence (N=117) were administered a battery of standardized memory and executive cognitive function tests that included the Wechsler Memory Scale-Revised (WMS-R), Controlled Oral Word Association Test (COWAT), Ruff Figural Fluency Test (RFFT), and Wisconsin Card Sort Test (WCST). Lower verbal and higher delayed recall memory score at baseline significantly predicted precontemplation, higher verbal memory scores predicted contemplation, and better attention-concentration at baseline significantly predicted reduced drinking at 3-month follow-up, after controlling for baseline alcohol consumption. The study findings indicate that explicit memory processes may have utility for predicting readiness to change drinking behavior.

Adolescent↗

PubMed1997

Risk and resilience in the cognitive functioning of children born to HIV-1-infected mothers: a preliminary report.

Although biologic and environmental risk factors show an age-dependent effect on children's cognitive development, outcome studies have yet to consider the role such factors play in the development of children born to HIV-1-infected women. This study explored the age-dependent differential impact of such risk factors on the cognitive functioning of children exposed in utero to HIV-1. Eighty-two children were administered a standardized measure of cognitive functioning and divided into two groups depending on their age when tested. Group 1 included children age 2 to 29 months (n = 46); Group 2 included children age 30 to 101 months (n = 36). Correlations between cognitive test scores and specific risk factors revealed an age-related double-dissociation. Serostatus and percent of CD4 cells correlated moderately with cognitive test scores in Group 1; however, these correlations were attenuated and nonsignificant in Group 2. Conversely, caregiver status and cognitive test scores were uncorrelated in Group 1, but were correlated in Group 2. These findings support a risk and resilience model of development. That is, in the context of biologic risk factors, aspects of the child's environment may either facilitate or hinder cognitive development.

AIDS Dementia Complex↗

PubMed2004

Heart rate variability and its relation to prefrontal cognitive function: the effects of training and detraining.

The aim of the present study was to investigate the relationship between physical fitness, heart rate variability (HRV) and cognitive function in 37 male sailors from the Royal Norwegian Navy. All subjects participated in an 8-week training program, after which the subjects completed the initial cognitive testing (pretest). The subjects were assigned into a detrained group (DG) and a trained group (TG) based on their application for further duty. The DG withdrew from the training program for 4 weeks after which all subjects then completed the cognitive testing again (post-test). Physical fitness, measured as maximum oxygen consumption (VO2(max)), resting HRV, and cognitive function, measured using a continuous performance task (CPT) and a working memory test (WMT), were recorded during the pre-test and the post-test, and the data presented as the means and standard deviations. The results showed no between-group differences in VO2(max) or HRV at the pre-test. The DG showed a significant decrease in VO2(max) from the pre- to the post-test and a lower resting HRV than the TG on the post-test. Whereas there were no between-group differences on the CPT or WMT at the pre-test, the TG had faster reaction times and more true positive responses on tests of executive function at the post-test compared to the pre-test. The DG showed faster reaction times on non-executive tasks at the post-test compared to the pre-test. The results are discussed within a neurovisceral integration framework linking parasympathetic outflow to the heart to prefrontal neural functions.

Adolescent↗

PubMed2005

Subcortical hyperintensities impact cognitive function among a select subset of healthy elderly.

Previous studies have examined the impact of subcortical hyperintensities (SH), a proxy measure of cerebrovascular disease, on the cognitive abilities of otherwise healthy older adults. However, there remains a limited understanding as to what extent this MRI marker of pathological processes explains the decline in specific cognitive functions that occur nearly ubiquitously with advanced age, especially in relation to other age-related imaging markers. In the present study we compared cognitive abilities between a sample of 53 older healthy adults (age range=50-79) and a sample of 53 younger adults (age range=21-40). As expected, the older group performed significantly worse on most cognitive measures compared to the younger group. Frontal volume and total grey matter volume were also significantly reduced among the older individuals compared to the younger individuals. SH volume was consistently associated with cognitive function in older adults, though, this relationship was evident only for a relatively small subset of older individuals with the most severe SH. These data suggest that the relationship between SH and cognition in the elderly is driven by a subset of individuals who may be in the earliest stages of vascular cognitive impairment. Further, the findings suggest that cognitive aging is largely determined by factors other than SH for most older adults.

Adolescent↗

PubMed2000

Impact of asymptomatic malaria parasitaemia on cognitive function and school achievement of schoolchildren in the Yemen Republic.

Asymptomatic malaria parasitaemia is prevalent among schoolchildren in many countries. The relationship between asymptomatic parasitaemia and children's cognitive functions was examined in a case control study and then in a natural experiment. A group (n = 445) of asymptomatic parasitaemic boys were compared with a group of non-parasitaemic boys (n = 142) matched for grade and school on their performance on a battery of cognitive tests. Two weeks later the parasitaemic children were re-screened and 150 children of those who remained parasitaemic were matched for grade and school with 150 children who were no longer parasitaemic. These children were then re-tested and their cognitive function compared. Initially, after controlling for age, socio-economic background and nutritional status the parasitaemic children performed worse than the non-parasitaemic children in fine motor function tests. There was no difference in change in cognitive test scores between those who became non-parasitaemic and those who remained parasitaemic. However, children who initially had the highest parasite density improved the most in 2 fine motor tests and a picture memory test. We were unable to show a benefit from losing parasitaemia over a 2 week period, but it remains possible that parasitaemia may affect cognition and longer term trials should be conducted.

Child↗

PubMedDate not supplied

A survey of cognitive functioning at difference glucose levels in diabetic persons.

Cognitive functioning was assessed in diabetic patients during hypoglycemia (60 mg/dl), euglycemia/control (110 mg/dl), and hyperglycemia (300 mg/dl). Blood glucose levels were set and maintained to within 4% of targeted levels by an artificial insulin/glucose infusion system (Biostator). Attention and fine motor skills, assessed by visual reaction time, was slowed at altered glucose levels. Performance was less impaired during hyperglycemia than hypoglycemia when a longer interstimulus interval was used, although it was still slower than normal. The time required to solve simple addition problems was increased during hypoglycemia, although reading comprehension was not affected. The possibility that some automatic brain skills are disrupted at altered glucose concentrations is discussed, while associative or inferential skills may be less affected.

Attention↗

PubMed2000

Interstrain differences in cognitive functions in rats in relation to status epilepticus.

Cognitive functions of Long Evans (N=30) and Wistar rats (N=32) were compared using a Morris water maze. Under control conditions the Long Evans rats were more efficient in this test, their average escape latency after 5 days of training (6.4+/-0.1 s, mean+/-S.E.M.) was significantly shorter than that of the Wistar rats (11.0+/-0.1 s). When the training was completed seizures were induced by an intraperitoneal injection of pilocarpine (330 mg/kg in the Long Evans strain and 350 mg/kg in the Wistar rats) 30 min after pretreatment with N-methylscopolamine (1 mg/kg i.p.). Clonazepam (1 mg/kg i.p.) was used to interrupt clonic seizures after 2 hours of continuous activity. Approximately one quarter of rats in both strains did not develop seizures. Severe convulsive status epilepticus was common in Long Evans rats (23 out of 30). In contrast, only 12 Wistar rats generated convulsive status epilepticus and the same number of animals exhibited only bursts of motor seizures separated by periods without convulsions (temporary seizures). Mortality after pilocarpine-induced status epilepticus was considerably higher in the Long Evans rats than in the Wistar rats. After a latency of 2-3 weeks spontaneous recurrent seizures appeared in all animals surviving status. Cognitive memory was tested during the 'silent period' between status and recurrent seizures. The Long Evans rats were unable to find the platform at the 3rd and 6th day after status but then their performance rapidly improved. The performance of the Wistar rats undergoing status epilepticus was seriously deteriorated and it never normalized, whereas the animals with temporary seizures exhibited only a transitory marginal prolongation of latencies. The hippocampal formation was damaged by status epilepticus in rats of both strains - the Long Evans rats exhibited more extensive damage of subfields CA1 and CA3, whereas in the Wistar rats a complete destruction of hilar neurons was observed in addition to partial CA1 and CA3 damage.

Animals↗

PubMed2004

Abnormal cognitive function in treated congenital hypopituitarism.

AIMS: To assess cognitive function in school age children with congenital pituitary hormone deficiency (PHD). METHODS: Ten children with PHD (aged 6.0-15.6 years, mean 11.5 years) and sibling controls (aged 8.7-14.9 years, mean 12.1 years) were assessed using the Wechsler Intelligence Scale for Children (WISC-III UK). RESULTS: The patients' full scale IQ scores were all below average (mean 75, 95% CI 70-80), but were not significantly different to those of sibling controls (mean 82, 95% CI 75-89). There was no difference in verbal IQ between patients and siblings, but performance IQ was significantly reduced (mean 75, 95% CI 68-82 in patients; mean 88, 95% CI 80-96 in sibling controls). The reduced performance IQ reflected a poorer performance in tasks assessing perceptual organisational skills. CONCLUSIONS: Data suggest that children with PHD have an IQ that is below average when compared to the population norm and a reduced performance IQ when compared to sibling controls. This may reflect abnormal brain development or could be linked to the impact of hypoglycaemia or low thyroxine concentrations in early life. This information is of value when counselling parents and planning a child's care and education, although further, more extensive studies of patients and siblings are required.

Adolescent↗