Alex Collie

The effects of practice on the cognitive test performance of neurologically normal individuals assessed at brief test-retest intervals.

Performance on many cognitive and neuropsychological tests may be improved by prior exposure to testing stimuli and procedures. These beneficial practice effects can have a significant impact on test performance when conventional neuropsychological tests are administered at test-retest intervals of weeks, months or years. Many recent investigations have sought to determine changes in cognitive function over periods of minutes or hours (e.g., before and after anesthesia) using computerized tests. However, the effects of practice at such brief test-retest intervals has not been reported. The current study sought to determine the magnitude of practice effects in a group of 113 individuals assessed with an automated cognitive test battery on 4 occasions in 1 day. Practice effects were evident both between and within assessments, and also within individual tests. However, these effects occurred mostly between the 1st and 2nd administration of the test battery, with smaller, nonsignificant improvements observed between the 2nd, 3rd, and 4th administrations. On the basis of these results, methodological and statistical strategies that may aid in the differentiation of practice effects from drug-induced cognitive changes are proposed.

The neuropsychology of preclinical Alzheimer's disease and mild cognitive impairment.

Subjects in the preclinical stages of Alzheimers disease (AD) typically record neuropsychological performance between that of healthy older individuals and demented patients. More specifically, deficits on measures of verbal episodic memory are commonly reported in these patients, while other cognitive functions (e.g. language, praxis and executive function) seem to be spared. A similar neuropsychological profile is observed in elderly subjects with mild cognitive impairment (MCI), a disorder that is attracting increasing research interest. Evidence from lesion and functional imaging studies, as well as volumetric imaging in probable AD and MCI patients, suggests that the cognitive deficits observed in these disorders may be related to medial temporal lobe dysfunction. An issue currently under investigation is whether MCI represents the preclinical stages of AD or a distinct and static cognitive aetiology. In an attempt to address this issue, present investigations are adopting a convergent approach to the detection of preclinical AD, where multiple risk factors are considered when making a diagnosis.

Validity of the CogState Brief Battery: Relationship to Standardized Tests and Sensitivity to Cognitive Impairment in Mild Traumatic Brain Injury, Schizophrenia, and AIDS Dementia Complex

This study examined the validity of the four standard psychological paradigms that have been operationally defined within the CogState brief computerized cognitive assessment battery. Construct validity was determined in a large group of healthy adults. CogState measures of processing speed, attention, working memory, and learning showed strong correlations with conventional neuropsychological measures of these same constructs (rs = .49 to .83). Criterion validity was determined by examining patterns of performance on the CogState tasks in groups of individuals with mild head injury, schizophrenia, and AIDS dementia complex. Each of these groups was impaired on the CogState performance measures (Cohens ds = -.60 to -1.80) and the magnitude and nature of this impairment was qualitatively and quantitatively similar in each group. Taken together, the results suggest that the cognitive paradigms operationally defined in the CogState brief battery have acceptable construct and criterion validity in a neuropsychological context.

Practice Effects Associated with the Repeated Assessment of Cognitive Function Using the CogState Battery at 10-minute, One Week and One Month Test-retest Intervals

There are many situations in which cognitive tests need to be administered on more than two occasions and at very brief test-retest intervals to detect change in group performance. However, previous literature has not specifically addressed these important issues. The main aim of the current study was to examine these two factors by using a computerized cognitive battery designed specifically for the repeated assessment of cognition (i.e., CogState) in healthy young adult individuals. A further aim of the study was to examine how many times the battery needed to be completed before performance, as measured by the battery, stabilized. Forty-five adults (age range: 18–40 years) completed the battery four times at 10-minute test-retest intervals, and a fifth time at an interval of one week. The results illustrated that when brief test-retest intervals were used (i.e., 10 minutes), performance stabilized after the second assessment, as significant practice effects were generally observed between the first and the second assessments. Practice effects were also observed on some of the tasks at a one-week test-retest interval. Due to these findings, 55 adults (age range: 18–40 years) completed the battery twice at 10-minute test-retest intervals (i.e., to eliminate the initial practice effect), and a third time at an interval of one month. No practice effects were observed. The implications of the results are discussed in terms of methods that can be adopted in order to minimize practice effects when this particular cognitive battery is used.

CogSport: reliability and correlation with conventional cognitive tests used in postconcussion medical evaluations.

ObjectiveTo determine the repeatability of a computerized cognitive test designed to monitor recovery from concussion and assist team physicians make return to play decisions (CogSport™). To determine the correlation between CogSport and two conventional neuropsychological tests. DesignProspective, serial investigation of cognitive function. SettingProfessional and semi-professional Australian Football clubs and a university affiliated research institute in Melbourne, Australia. ParticipantsThree-hundred healthy young adults, including 240 elite athletes. Main Outcome MeasuresIntra-class correlation (ICC) coefficients for CogSport performance measures administered serially. ICC between CogSport performance measures and conventional neuropsychological tests. Normative data for CogSport performance measures. ResultsMeasures of psychomotor function, decision making, working memory and learning were highly reliable. Some measures also displayed high correlations with conventional neuropsychological tests of information processing and attention. Preliminary normative data is described. ConclusionsCogSport is a highly reliable cognitive function test when administered to healthy young adults and elite athletes. CogSport measures similar cognitive functions as conventional tests used commonly in concussion research.

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 athletes 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.

A validation of the post concussion symptom scale in the assessment of complex concussion using cognitive testing and functional MRI

Background: Clinical assessment of cerebral concussion relies on the presence and duration of post concussive symptoms (PCS). Given that these PCS are subjective reports and not always specific to concussion, their usefulness remains to be validated. Objective: To evaluate the usefulness of self-reported PCS by means of cognitive tests and functional MRI (fMRI). Method: 28 male athletes with and without concussion were grouped according to their PCS score. They were then administered a computerised cognitive test battery and submitted to an fMRI session where cerebral activations associated with verbal and non-verbal working memory tasks were analysed. Results: Behaviourally, response accuracy and speed on the cognitive test battery were comparable for the control and low PCS group. The moderate PCS group showed significantly slower response times than the control group on the matching (p<0.05) and one-back tasks (p<0.05). The functional MRI study showed reduced task related activation patterns in the dorsolateral prefrontal cortex for both low and moderate PCS groups. Activation peaks outside the regions of interest, not seen in the control group, were also noted for both PCS groups. Regression analyses indicated an inverse relationship between PCS scores and performances on several CogSport subtests. Severity of PCS also predicted fMRI blood oxygen level dependent signal changes in cerebral prefrontal regions. Conclusion: Self-reported PCS is associated with an ongoing cerebral haemodynamic abnormality as well as with mild cognitive impairment. These results support the use of the PCS scale in the assessment of cerebral concussion and in monitoring recovery.

Can we manage sport related concussion in children the same as in adults

Evidence based guidelines are required for the management of concussive injury in children Consensus guidelines for managing sport related concussion in adults have been increasingly widely implemented.1 So far, there are no guidelines that enable clinicians to manage similar sporting concussive injuries in children. Furthermore, there are a number of important anatomical, physiological, and behavioural differences between adults and children that suggest that adult guidelines will need to be either modified or rewritten to manage injuries in this age group. The annual incidence of traumatic brain injury (TBI) in adults is remarkably constant worldwide and has been estimated at between 180 and 300 cases per 100 000 population.2–5 This is believed to be an underestimate of the true incidence as an equivalent number of mild injuries are treated by general practitioners and do not result in hospital admission.6 Direct sport participation accounts for approximately 15–20% of all such TBI3,7 and in children a further smaller percentage of TBI is associated with play activities.8 In children aged 15 years and under, the estimated incidence rate of TBI is 180 per 100 000 children per year of which approximately 85% are categorised as mild injuries.7 In the US, it has been estimated that more than 1 million children sustain a TBI annually and that TBI accounts for more than 250 000 paediatric hospital admissions as well as more than 10% of all visits to emergency service settings.9 In child and adolescent populations, few well controlled studies exist to identify the age specific frequency and outcome of sport related concussive injuries. The most common cognitive sequelae of concussive injuries in children are the same as for adults, namely reduced speed of information processing, poor attention, and impaired executive function.10–14 Concussion may also have a significant …

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. MethodsThis 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.

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.