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.
Genetic association studies have identified 44 common genome-wide significant risk loci for late-onset Alzheimer's disease (LOAD). However, LOAD genetic architecture and prediction are unclear. Here ...we estimate the optimal P-threshold (P
) of a genetic risk score (GRS) for prediction of LOAD in three independent datasets comprising 676 cases and 35,675 family history proxy cases. We show that the discriminative ability of GRS in LOAD prediction is maximised when selecting a small number of SNPs. Both simulation results and direct estimation indicate that the number of causal common SNPs for LOAD may be less than 100, suggesting LOAD is more oligogenic than polygenic. The best GRS explains approximately 75% of SNP-heritability, and individuals in the top decile of GRS have ten-fold increased odds when compared to those in the bottom decile. In addition, 14 variants are identified that contribute to both LOAD risk and age at onset of LOAD.
Purpose: Our purpose was to create a comprehensive review of speech impairment in frontotemporal dementia (FTD), primary progressive aphasia (PPA), and progressive apraxia of speech in order to ...identify the most effective measures for diagnosis and monitoring, and to elucidate associations between speech and neuroimaging. Method: Speech and neuroimaging data described in studies of FTD and PPA were systematically reviewed. A meta-analysis was conducted for speech measures that were used consistently in multiple studies. Results: The methods and nomenclature used to describe speech in these disorders varied between studies. Our meta-analysis identified 3 speech measures which differentiate variants or healthy control-group participants (e.g., nonfluent and logopenic variants of PPA from all other groups, behavioral-variant FTD from a control group). Deficits within the frontal-lobe speech networks are linked to motor speech profiles of the nonfluent variant of PPA and progressive apraxia of speech. Motor speech impairment is rarely reported in semantic and logopenic variants of PPA. Limited data are available on motor speech impairment in the behavioral variant of FTD. Conclusions: Our review identified several measures of speech which may assist with diagnosis and classification, and consolidated the brain-behavior associations relating to speech in FTD, PPA, and progressive apraxia of speech.
Natural History of Concussion in Sport Makdissi, Michael; Darby, David; Maruff, Paul ...
The American journal of sports medicine,
03/2010, Letnik:
38, Številka:
3
Journal Article
Recenzirano
Background Evidence-based clinical data are required for safe return to play after concussion in sport.
Purpose The objective of this study was to describe the natural history of concussion in sport ...and identify clinical features associated
with more severe concussive injury, using return-to-sport decisions as a surrogate measure of injury severity.
Study Design Cohort study (prognosis); Level of evidence, 3.
Methods Male elite senior, elite junior, and community-based Australian Rules football players had preseason baseline cognitive testing
(Digit Symbol Substitution Test, Trail-Making TestâPart B, and CogSport computerized test battery). Players were recruited
into the study after a concussive injury sustained while playing football. Concussed players were tested serially until all
clinical features of their injury had resolved.
Results Of 1015 players, 88 concussions were observed in 78 players. Concussion-associated symptoms lasted an average of 48.6 hours
(95% confidence interval, 39.5â57.7 hours) with delayed return to sport correlated with â¥4 symptoms, headache lasting â¥60
hours, or self-reported âfatigue/fogginess.â Cognitive deficits using the Digit Symbol Substitution Test and Trail-Making
Testâpart B recovered concomitantly with symptoms, but computerized test results recovered 2 to 3 days later and remained
impaired in 35% of concussed players after symptom resolution.
Conclusion Delayed return to sport was associated with initially greater symptom load, prolonged headache, or subjective concentration
deficits. Cognitive testing recovery varied, taking 2 to 3 days longer for computerized tests, suggesting greater sensitivity
to impairment. Therefore, symptom assessment alone may be predictive of but may underestimate time to complete recovery, which
may be better estimated with computerized cognitive testing.
Socio-emotional skills, including social competence and social cognition, form the basis for robust relationships and wellbeing. Despite their importance, these skills are poorly defined and ...measured, particularly in children with developmental vulnerabilities. As a consequence, targets for effective management and treatment remain unclear. We aimed to i) phenotype social competence and social cognition in typically developing children (TDC) and in children with neurodevelopmental or mental health disorders (clinical groups) and ii) establish the relationships between these child-direct measures and parent ratings of social competence and behavior. Using a multi-site, cross-sectional study design, we recruited 513 TDC and 136 children with neurodevelopmental (autism spectrum disorder ASD, attention deficit hyperactivity disorder ADHD) or mental health (Anxiety Disorder ANX) diagnoses (age range 5-15 years). We administered the Paediatric Evaluation of Emotions, Relationships and Socialisation (PEERS) to children, and parents completed standardised questionnaires rating children's socio-emotional function. Standardised parent questionnaires revealed a global pattern of everyday socio-emotional impairment that was common to all clinical groups, while PEERS identified disorder-specific socio-cognitive profiles for children with ASD, ADHD and ANX. Compared to TDCs, children with ASD demonstrated global socio-cognitive impairment. Children with ADHD were impulsive, demonstrating difficulties managing speed accuracy trade-offs. Children with ANX exhibited slowed social decision-making, but otherwise intact skills. Standardized parent questionnaires of child socio-emotional function reveal differences between children with typical and atypical development, but do not yield disorder-specific, socio-emotional profiles. In contrast, findings from the PEERS objective assessment suggest that that ASD, ADHD and ANX are associated with distinct socio-cognitive phenotypes, to more accurately guide and target management and treatment of impaired social competence.
Concussion-related cognitive impairments are typically evaluated with repeated neuropsychological assessments where post-injury performances are compared with pre-injury baseline data (baseline ...method). Many cases of concussions, however, are evaluated in the absence of baseline data by comparing post-injury performances with normative data (normative method). This study aimed to compare the sensitivity and specificity of these two methods using the CogSport/Axon test battery. Normative data and reliable change indices were computed from a non-injured athlete sample (n = 235). Test-retest data from non-injured (n = 260) and recently concussed (n = 29) athlete samples were then used to compare the two methods. The baseline method was found to be more sensitive than the normative method, and both methods had high specificity and overall correct classification rates. This suggests that while the normative method identifies most cases of recent concussions, the baseline method remains a more precise approach to assessing concussion-related cognitive impairments.
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 Australian Imaging, Biomarkers and Lifestyle (AIBL) flagship study of aging aimed to recruit 1000 individuals aged over 60 to assist with prospective research into Alzheimer's disease (AD). This ...paper describes the recruitment of the cohort and gives information about the study methodology, baseline demography, diagnoses, medical comorbidities, medication use, and cognitive function of the participants.
Volunteers underwent a screening interview, had comprehensive cognitive testing, gave 80 ml of blood, and completed health and lifestyle questionnaires. One quarter of the sample also underwent amyloid PET brain imaging with Pittsburgh compound B (PiB PET) and MRI brain imaging, and a subgroup of 10% had ActiGraph activity monitoring and body composition scanning.
A total of 1166 volunteers were recruited, 54 of whom were excluded from further study due to comorbid disorders which could affect cognition or because of withdrawal of consent. Participants with AD (211) had neuropsychological profiles which were consistent with AD, and were more impaired than participants with mild cognitive impairment (133) or healthy controls (768), who performed within expected norms for age on neuropsychological testing. PiB PET scans were performed on 287 participants, 100 had DEXA scans and 91 participated in ActiGraph monitoring.
The participants comprising the AIBL cohort represent a group of highly motivated and well-characterized individuals who represent a unique resource for the study of AD. They will be reassessed at 18-month intervals in order to determine the predictive utility of various biomarkers, cognitive parameters and lifestyle factors as indicators of AD, and as predictors of future cognitive decline.
This study investigated alterations in heart rate variability (HRV) and cognitive performance before and after physical effort, for 30 high-level track and field athletes (23 males and 7 females). ...Interbeat intervals were assessed at the baseline and during each task of a CogState cognitive battery (simple reaction time, choice reaction time, working memory, short-term memory and sustained attention). Time and frequency domain measures of HRV were compared between conditions and between tasks. The results indicated differences in HRV between executive and non-executive tasks. There was a significant increase in sympathetic-modulation-related indices after physical effort. The differences between executive and non-executive tasks were the same in post-test. Correlations were found between HRV and cognitive performance, which differed by speed and accuracy. We conclude that HRV is related to cognitive demand and that the correlation between HRV and cognitive performance seems to be stronger after physical exercise. The results raise questions about the psychophysiological meaning of different HRV signals and this has implications for future research about the relationship between HRV and cognition.
Controversy exists whether acute hyperglycemia is causally associated with worse stroke outcome or simply reflects a more severe stroke. In reversible ischemia models, hyperglycemia is associated ...with lactic acidosis and conversion of penumbral tissue to infarction. However, the relationship between hyperglycemia, lactic acidosis, and stroke outcome has not been explored in humans. Sixty‐three acute stroke patients were prospectively evaluated with serial diffusion‐weighted and perfusion‐weighted magnetic resonance imaging and acute blood glucose measurements. Patients with hypoperfused at‐risk tissue were identified by acute perfusion‐diffusion lesion mismatch. As a substudy, acute and subacute magnetic resonance spectroscopy was performed in the 33 most recent patients to assess the relationship between acute blood glucose and lactate production in the ischemic region. In 40 of 63 patients with acute perfusion‐diffusion mismatch, acute hyperglycemia was correlated with reduced salvage of mismatch tissue from infarction, greater final infarct size, and worse functional outcome. These correlations were independent of baseline stroke severity, lesion size, and diabetic status. Furthermore, higher acute blood glucose in patients with perfusion‐diffusion mismatch was associated with greater acute‐subacute lactate production, which, in turn, was independently associated with reduced salvage of mismatch tissue. In contrast, acute blood glucose levels in nonmismatch patients did not independently correlate with outcome measures, nor was there any acute‐subacute increase in lactate in this group. Acute hyperglycemia increases brain lactate production and facilitates conversion of hypoperfused at‐risk tissue into infarction, which may adversely affect stroke outcome. These findings support the need for randomized controlled trials of aggressive glycemic control in acute stroke.
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