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Biomedical subjects

A Collie

Publications and source records attributed to A Collie.

At least 19 recordsLinked to original sources
PubMed2006

Mild memory impairment in healthy older adults is distinct from normal aging.

Mild memory impairment was detected in 28% of a sample of healthy community-dwelling older adults using the delayed recall trial of a word list learning task. Statistical analysis revealed that individuals with memory impairment also demonstrated relative deficits on other measures of memory, and tests of executive function, processing speed and global cognition, as measured by the CERAD and CogState batteries and CANTAB paired associate learning task. These relative deficits cannot be explained by age-related changes, education, intelligence, mood, health-related factors, or the individuals' ApoEepsilon4 status. Memory-impaired individuals (n = 30) did not recognize the extent of their memory and cognitive difficulties beyond the general complaints expressed by normal elderly (n = 77) within the study and their apparent difficulties did not appear to impact on their participation in life activities. These findings suggest it is unlikely that the memory and cognitive difficulties demonstrated by individuals with mild memory impairment reflect normal aging. Rather it is possible that such impairment may signal early neurodegenerative processes worthy of further investigation.

Aged↗
PubMed2006

Cognitive deterioration associated with an expedition in an extreme desert environment.

BACKGROUND: Prolonged exposure to extreme environments may result in cognitive changes that may influence decision making ability and increasing risk of injury or death. OBJECTIVE: To measure the cognitive performance of a healthy man as he completed a 17 day desert expedition. METHOD: A computer based cognitive test battery, subjective cognitive rating scale, and measures of physical characteristics were used. Objective cognitive performance was compared with the performance of eight age matched men who remained in their own homes. RESULTS: The speed of psychomotor, attentional, and executive functions decreased as the expedition progressed, but the accuracy of performance remained unaffected. Although some impairments were large, they resolved completely once the expedition was completed. Subjective ratings indicated that the subject had insight into his failing cognitive performance during the expedition. CONCLUSIONS: Cognitive performance can be measured repeatedly throughout an expedition in an extreme environment. Cognitive impairment may occur.

Adult↗
PubMed2006

Does history of concussion affect current cognitive status?

The association between self reported history of concussion and current neurocognitive status is controversial. Some football studies suggest that athletes with a history of concussion display cognitive impairment relative to athletes with no history of concussion, but other studies have not been able to reproduce such findings. This study shows that there is no relation between the number of previous self reported episodes of concussion and current cognitive state, directly contradicting the findings of previous research.

Adult↗
PubMed2006

Concussion history is not a predictor of computerised neurocognitive performance.

BACKGROUND: The long term effects of self reported concussion on neurocognitive functioning have been found to be variable. OBJECTIVES: To evaluate cognitive performance on the Headminder concussion resolution index (CRI) and ImPACT assessment tests of subjects with and without a history of self reported concussion. METHODS: A retrospective analysis was completed on 235 Headminder CRI baseline assessments and 264 ImPACT baseline assessments. Participants were divided into four groups on the basis of reported number of concussions (zero, one, two, or three). Multivariate analysis of variance was used to evaluate differences between the concussion history groups on the two computer based concussion assessment programs. RESULTS: Multivariate analysis of variance indicated no significant difference between those with and without a history of concussion on the CRI (Lambda = 0.963, F((15, 627.05)) = 0.57, p = 0.898). It also revealed no significant differences between groups on the ImPACT test (Lambda = 0.951, F((12, 672.31)) = 1.07, p = 0.381). CONCLUSIONS: The results suggest that either long term cognitive decrements may not be associated with a history of concussion or the decrements may be subtle and undetectable by these computer programs.

Adult↗
PubMed2006

Cognition in the days following concussion: comparison of symptomatic versus asymptomatic athletes.

BACKGROUND: Concussion is a common neurological injury occurring during contact sport. Current guidelines recommend that no athlete should return to play while symptomatic or displaying cognitive dysfunction. This study compared post-concussion cognitive function in recently concussed athletes who were symptomatic/asymptomatic at the time of assessment with that of non-injured (control) athletes. METHODS: Prospective study of 615 male Australian Rules footballers. Before the season, all participants (while healthy) completed a battery of baseline computerised (CogSport) and paper and pencil cognitive tasks. Sixty one injured athletes (symptomatic = 25 and asymptomatic = 36) were reassessed within 11 days of being concussed; 84 controls were also reassessed. The serial cognitive function of the three groups was compared using analysis of variance. RESULTS: The performance of the symptomatic group declined at the post-concussion assessment on computerised tests of simple, choice, and complex reaction times compared with the asymptomatic and control groups. The magnitude of changes was large according to conventional statistical criteria. On paper and pencil tests, the symptomatic group displayed no change at reassessment, whereas large improvements were seen in the other two groups. CONCLUSION: Injured athletes experiencing symptoms of concussion displayed impaired motor function and attention, although their learning and memory were preserved. These athletes displayed no change in performance on paper and pencil tests in contrast with the improvement observed in asymptomatic and non-injured athletes. Athletes experiencing symptoms of concussion should be withheld from training and competition until both symptoms and cognitive dysfunction have resolved.

Adult↗
PubMed2005

Value of neuropsychological testing after head injuries in football.

This paper reviews the pros and cons of the traditional paper and pencil and the newer computerised neuropsychological tests in the management of sports concussion. The differences between diagnosing concussion on the field and neuropsychological assessment at follow up and decision making with regard to return to play are described. The authors also discuss the issues involved in interpreting the results of neuropsychological testing (comparison with population norms versus player's own baseline test results) and potential problems of such testing in football. Finally, suggested recommendations for neuropsychological testing in football are given.

Brain Concussion↗
PubMed2004

Subtle memory decline over 12 months in mild cognitive impairment.

OBJECTIVE: Screening of normal older persons for progressive memory decline is a worthwhile strategy in the pursuit of the earliest possible stages of pre-clinical Alzheimer's disease (AD) or mild cognitive impairment (MCI). Reliable tests are needed to both detect MCI and measure the natural history of decline over months rather than years. We aimed to detect memory decline over 1 year in a group of older individuals with well-characterised amnestic MCI. METHODS: The continuous learning task (CLT) from the CogState test battery was administered 8 times in 12 months to 15 individuals with MCI and 35 controls matched for age, education, IQ and gender. All subjects were recruited from an ongoing aging study. The rate of change in CLT performance over the year was compared between groups and also compared to that detected with a word list learning task and a computerised paired associate learning task. RESULTS: At baseline, memory performance in the amnestic MCI group was significantly worse than controls on all memory tests. However, at 12 months the magnitude of the difference between the groups had increased significantly on the CLT due to decline in memory accuracy in the MCI group. No decline over 12 months was detectable on the routine memory tests. CONCLUSIONS: Subtle memory decline is detectable in amnestic MCI using reliable and sensitive tests of memory. Such measures may assist in the early identification of AD and also in trials of putative disease-modifying therapies to be conducted over as little as 12 months.

Aged↗
PubMed2004

A prospective controlled study of cognitive function during an amateur boxing tournament.

BACKGROUND: Few studies have reported acute postbout cognitive function in amateur boxers, and none have documented the effects of repeated boxing bouts within a short time frame. OBJECTIVE: To determine whether participation in a 7-day amateur boxing tournament is associated with acute deterioration in cognitive test performance. METHODS: A prospective study was done of 82 collegiate amateur boxers participating in a 7-day single elimination tournament and a group of 30 matched nonboxing control participants. No participants had a history of recent concussion or past history of brain injury. For boxers, cognitive assessment using a computerized test battery was performed before the tournament and within 2 hours of completing each bout. Tests of simple and choice reaction time, working memory, and learning were administered. Analysis of variance was conducted to compare the serial performance of control participants with that of boxers participating in one, two, and three bouts. RESULTS: The 82 boxers fought 159 times. Cognitive testing was performed after 142 of these bouts. On simple reaction time, choice reaction time, and working memory tasks, the serial performance of boxers participating in three bouts (n = 22) was equivalent to that of boxers participating in two bouts (n = 22) and one bout (n = 32) and to nonboxing control participants (n = 30). An improvement in performance was observed on the learning task in boxers participating in three bouts. Boxers whose bout was stopped by the referee (n = 7) displayed significant slowing in simple and choice reaction time. CONCLUSIONS: With the exception of boxers whose contest is stopped by the referee, amateur boxers participating in multiple bouts during a 7-day tournament display no evidence of cognitive dysfunction in the immediate postbout period.

Adult↗
PubMed2004

Statistical procedures for determining the extent of cognitive change following concussion.

Neuropsychological (NP) testing is now often used to help to determine if the cognitive function of a concussed athlete has declined. The NP test score after concussion is compared with the baseline test score. Many clinicians simply subtract one from the other and make a clinical decision about the significance or otherwise of the resulting "difference score". Such techniques are inadequate, as they fail to account for the many factors that may confound interpretation of serially acquired cognitive test scores. This is a review of a number of alternative approaches used in other areas of medicine for differentiating "true" changes from changes caused by these confounding factors. A case example is used to illustrate the effect that the statistical approach may have on clinical decision making.

Adult↗
PubMed2003

Health effects of kava use in an eastern Arnhem Land Aboriginal community.

BACKGROUND: Heavy kava use in Aboriginal communities has been linked to various health effects, including anecdotes of sudden cardiac deaths. AIMS: To examine associations between kava use and potential health effects. METHODS: A cross-sectional study was carried out within a kava-using east Arnhem Land Aboriginal community in tropical northern Australia. One-hundred-and-one adults who were current, recent or non-users of kava were enrolled in March 2000. Main outcome measures were physical, anthropometric, biochemical, haematological, immunological and neurocognitive assessments. RESULTS: Kava users more frequently showed a characteristic dermopathy (P<0.001). They had increased levels of gamma-glutamyl transferase and alkaline phosphatase (P<0.001). Lymphocyte counts were significantly lower in kava users (P<0.001). Fibrinogen, plasminogen activator inhibitor-1 and neurocognitive tests were not different between kava use categories. IgE and IgG antibodies were elevated across the whole group, as were C-reactive protein and homocysteine. CONCLUSIONS: Kava use was associated with dermopathy, liver function abnormalities and decreased lymphocytes. If kava continues to be used by Aboriginal populations, monitoring should focus on the health consequences of these findings, including a possible increase in serious infections. The interaction between kava, alcohol and other substances requires further study. Although markers of cardiovascular risk are increased across the population, these were not higher in kava users, and this increase may be linked to the large infectious pathogen burden reflective of the socioeconomic disadvantage seen in many remote Aboriginal communities.

Adult↗
PubMed2002

Mild cognitive impairment can be detected by multiple assessments in a single day.

BACKGROUND: Reliable detection of mild cognitive impairment (MCI), in many cases preceding AD, is important in determining the efficacy of emerging treatments. The operational definition of MCI is currently imprecise and would be improved by objective criteria. Inherent in the transition from MCI to AD is cognitive decline, which can be detected using multiple assessments over several years. OBJECTIVE: To determine whether multiple assessments on the same day could also differentiate well-studied subjects with very mild MCI from normal control subjects. METHODS: This study utilized a novel 15- to 18-minute computerized cognitive battery designed for frequent serial use, administered four times within 3 hours. Subjects were participants in a longitudinal healthy aging study (20 with MCI, 40 control subjects matched for age, gender, and education). RESULTS: The MCI group showed significantly attenuated learning performance with repetition on accuracy and reaction time tasks. Discriminant function analysis correctly classified 95% of subjects and 80% of those with MCI. CONCLUSIONS: Multiple assessments with standardized, repeatable cognitive measures is a promising method for reliably differentiating patients with early MCI in a single test session and deserves further study for refining patient selection in trials of therapeutic agents for MCI.

Analysis of Variance↗
PubMed2002

Impairments of response conflict monitoring and resolution in schizophrenia.

BACKGROUND: It has been argued recently that the attentional dysfunction in schizophrenia occurs as a result of an inability to inhibit automatic attentional shifts to compelling external stimuli. However, this hypothesis is based on performance on paradigms that require overt or covert shifts of spatial attention. METHOD: We investigated responses to foveally presented stimuli in patients with schizophrenia and healthy controls as they performed unidimensional and bidimensional versions of the flanker task. In both tasks, centrally presented target stimuli were flanked by peripheral stimuli that were either congruent or incongruent with the behavioural goal of the subject. In the bidimensional task, the flanking stimuli could be congruent and incongruent on multiple stimulus characteristics. RESULTS: On the unidimensional flanker task, the behavioural goal modulated the responses of the schizophrenia group such that response times (RTs) to target stimuli that were flanked by congruent stimuli were faster than RTs to target stimuli flanked by incongruent stimuli. However, on the bidimensional flanker task, the responses of schizophrenia patients were no longer constrained by the behavioural goal and RTs to both congruent and incongruent stimuli were equivalent. CONCLUSIONS: It appears that the attentional dysfunction in schizophrenia may reflect difficulty in resolving multiple and simultaneous response conflicts. These findings suggest a possible role for the anterior cingulate cortex in the attentional impairments associated with schizophrenia.

Adult↗
PubMed2001

Memory decline in healthy older people: implications for identifying mild cognitive impairment.

BACKGROUND: Criteria for mild cognitive impairment require objective evidence of a memory deficit but do not require objective evidence of memory decline. Application of these criteria may therefore result in the misclassification of older patients with memory decline as normal because their neuropsychological test performance at a single point in time may be within normal limits. This study aimed to identify and characterize older people with memory decline. METHOD: Word list delayed recall (WLDR) test performance was assessed on five occasions during a 2-year period in a cohort of healthy older individuals. Older people with declining (n = 35) and nondeclining (n = 66) WLDR scores were identified. Both subgroups were then compared on apoE genotype, Clinical Dementia Rating, and neuropsychological test performance at the fifth assessment. RESULTS: Thirty-four percent of the group with declining memory recorded a Clinical Dementia Rating of 0.5, compared with 5% of the nondeclining memory group. No between-group differences were observed in cognitive domains other than memory, self-reported cognitive failures, or the proportion of each group carrying the apoE epsilon 4 allele. CONCLUSIONS: A large proportion of healthy older individuals show memory decline, which may represent the early stages of a potentially more severe cognitive impairment. Further investigation is necessary to determine the relationship between apoE genotype, self-reported cognitive impairment, and memory decline in older people.

Aged↗
PubMed2001

Computerised cognitive assessment of athletes with sports related head injury.

Professional and amateur participants in many sports are at risk of brain injury caused by impact with other players or objects. In many cases, mild cognitive deficits may persist after the common neurological signs of brain injury have passed. In recent years, the athlete's cognitive status after concussion has been measured with conventional "paper and pencil" neuropsychological tests. However, such tests are not ideal for sporting settings, as they are designed for the detection of gross cognitive impairments at a single assessment, not for the identification of mild cognitive deficits on repeated assessment. A number of computerised cognitive assessment tests and test batteries have been developed over the past two decades. These batteries offer major scientific and practical advantages over conventional neuropsychological tests which make them ideal for the assessment of cognitive function in sportspeople. This review first describes the problems associated with cognitive assessment of people with sports related cognitive deficits, and then critically examines the utility of conventional neuropsychological and computerised cognitive tests in sporting settings.

Athletic Injuries↗