A novel approach to intra-individual performance variability in ADHD.
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ABSTRACT:
SUBMITTER: Bluschke A
PROVIDER: S-EPMC8060200 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundCognitive deficits contribute to disability in Parkinson's disease (PD). Cognitive intra-individual variability (IIV) is associated with cognitive decline in age-related disorders, but IIV has not been related to functional ability in PD. We examined IIV in predicting functional ability in participants with PD.MethodsDe-identified National Alzheimer's Coordinating Center data (N = 1,228) from baseline and follow-up visits included participants with PD propensity score matched to control participants at baseline on age (M = 72), education (M = 15), and gender (28% female). PD symptom duration averaged 6 years. Outcome measures included the Functional Ability Questionnaire (FAQ), overall test battery mean (OTBM) of ten cognitive variables, IIV calculated as the standard deviation of cognitive data for each participant, Geriatric Depression Scale (GDS), and Unified PD Rating Scale gait and posture items. Baseline FAQ status in the PD group was predicted using logistic regression with age, education, cognition, GDS, and motor function as predictors. We compared baseline characteristics of PD participants with and without functional impairment at follow up.ResultsPD participants showed lower OTBM and greater IIV, GDS, and motor dysfunction than controls (p < .0001). Education, OTBM, IIV, GDS, and gait predicted functional status (77% overall classification; AUC = .84). PD participants with functional impairment at follow up showed significantly lower OTBM and greater IIV, GDS, and motor dysfunction at baseline (p < .001).ConclusionIIV independently predicts functional status in participants with PD while controlling for other variables. PD participants with functional impairment at follow up showed greater IIV than those without functional impairment at follow up.
| S-EPMC10330935 | biostudies-literature
Project description:ObjectivesRecent studies suggest that intraindividual variability (IIV) of neuropsychological performance may be sensitive to HIV-associated neurologic compromise. IIV may be particularly dependent upon the integrity of frontal-subcortical systems, and therefore may be a meaningful phenotype in HIV. We examined the relationship between change in IIV and white matter integrity among HIV seropositive (HIV+) and HIV seronegative (HIV-) individuals.MethodThe sample consisted of 38 HIV+ participants and 26 HIV- control participants who underwent neuroimaging and a neuropsychological evaluation at baseline and at 2-year follow-up evaluation.ResultsAmong HIV+ participants, increases in IIV (greater dispersion) were related to lower fractional anisotropy (FA) values in the anterior thalamic radiations (ATR) and the superior longitudinal fasciculus (SLF). Changes in mean-level global cognitive functioning were not significantly related to white matter integrity. Additionally, there was a significant Group × IIV interaction effect in the SLF demonstrating that the relationship between IIV and white matter integrity was specific to HIV.ConclusionsOverall, findings suggest that IIV may be more sensitive, relative to mean-level global cognitive functioning, in the detection of neurologic compromise among HIV+ individuals. (PsycINFO Database Record
| S-EPMC5845766 | biostudies-literature
Project description:ObjectivesLittle is known about how much variability exists in free-living sitting time within individuals. The purpose of this study was to examine intra-individual variability of objectively determined daily sitting time and to determine if this variability was related to weekly averages of sitting duration or recommended moderate-vigorous physical activity (MVPA). Also, this study determined the reliability of free-living sitting and MVPA time as it useful for guiding researchers in determining how many days of monitoring are needed.DesignAn activPAL monitor was worn for 7 consecutive days by 68 women (52±8 years).MethodsIntra-individual range of daily sitting time was calculated. Generalizability theory analysis determined the reliability of daily sitting and recommended MVPA.ResultsMean sitting time was 9.0±1.8h/day and the within individual weekly mean range was 4.5±1.7h/day. Similarly, there was a 4.5h/day difference in sitting time between the mean of the lowest sitting (6.7±0.8) and highest sitting (11.3±1.1h/day) quartiles. The intra-individual range in daily sitting did not differ among quartiles of sitting time (i.e., 4.9±1.9, 4.1±1.9, 5.1±1.5, 3.9±1.1h/day for the 1st-4th quartiles) nor among quartiles of MVPA (i.e., 4.2±1.8, 4.7±2.0, 4.6±1.5, 4.4±1.3h/day for the 1st-4th quartiles). A reliability coefficient of 0.80 was achieved with 4 days of objectively measured sitting time and 7 days for MVPA.ConclusionsThe findings suggest exposure to relatively high levels of sedentary time may occur in people regardless of weekly averages in sitting and regular exercise due to the high day-to-day variation in daily sitting time (4.5h/d range within a week).
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Project description:The potential benefits and mechanistic effects of working memory training (WMT) in children are the subject of much research and debate. We show that after five weeks of school-based, adaptive WMT 6-9 year-old primary school children had greater activity in prefrontal and striatal brain regions, higher task accuracy, and reduced intra-individual variability in response times compared to controls. Using a sequential sampling decision model, we demonstrate that this reduction in intra-individual variability can be explained by changes to the evidence accumulation rates and thresholds. Critically, intra-individual variability is useful in quantifying the immediate impact of cognitive training interventions, being a better predictor of academic skills and well-being 6-12 months after the end of training than task accuracy. Taken together, our results suggest that attention control is the initial mechanism that leads to the long-run benefits from adaptive WMT. Selective and sustained attention abilities may serve as a scaffold for subsequent changes in higher cognitive processes, academic skills, and general well-being. Furthermore, these results highlight that the selection of outcome measures and the timing of the assessments play a crucial role in detecting training efficacy. Thus, evaluating intra-individual variability, during or directly after training could allow for the early tailoring of training interventions in terms of duration or content to maximise their impact.
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Project description:When individuals are measured more than once in the same context they do not behave in exactly the same way each time. The degree of predictability differs between individuals, with some individuals showing low levels of variation around their behavioural mean while others show high levels of variation. This intra-individual variability in behaviour has received much less attention than between-individual variability in behaviour, and very little is known about the underlying mechanisms that affect this potentially large but understudied component of behavioural variation. In this study, we combine standardized behavioural tests in a chicken intercross to estimate intra-individual behavioural variability with a large-scale genomics analysis to identify genes affecting intra-individual behavioural variability in an avian population. We used a variety of different anxiety-related behavioural phenotypes for this purpose. Our study shows that intra-individual variability in behaviour has a direct genetic basis that is largely unique compared to the genetic architecture for the standard behavioural measures they are based on (at least in the detected quantitative trait locus). We identify six suggestive candidate genes that may underpin differences in intra-individual behavioural variability, with several of these candidates having previously been linked to behaviour and mental health. These findings demonstrate that intra-individual variability in behaviour appears to be a heritable trait in and of itself on which evolution can act.
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Project description:This study examined whether the recurrent difficulty to replicate results obtained with paradigms measuring distractor processing as a function of perceptual load is due to individual differences. We first reanalyzed, at the individual level, the data of eight previously reported experiments. These reanalyses revealed substantial inter-individual differences, with particularly low percentage of participants whose performance matched the load theory's predictions (i.e., larger distractor interference with low than high levels of load). Moreover, frequently the results were opposite to the theory's predictions-larger interference in the high than low load condition; and often a reversed compatibility effect emerged-better performance in the incompatible than neutral condition. Subsequently, seven observers participated in five identical experimental sessions. If the observed inter-individual differences are due to some stable trait or perceptual capacity, similar results should have emerged in all sessions of a given participant. However, all seven participants showed large between-sessions variations with similar patterns to those found between participants. These findings question the theoretical foundation implemented with these paradigms, as none of the theories suggested thus far can account for such inter- and intra-individual differences. Thus, these paradigms should be used with caution until further research will provide better understanding of what they actually measure.
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Project description:Studies reporting on biomarkers aiming to predict adverse renal outcomes in patients with type 2 diabetes and kidney disease (DKD) conventionally define a surrogate endpoint either as a percentage of decrease of eGFR (e.g. ≥ 30%) or an absolute decline (e.g. ≥ 5 ml/min/year). The application of those study results in clinical practise however relies on the assumption of a linear and intra-individually stable progression of DKD. We studied 860 patients of the PROVALID study and 178 of an independent population with a relatively preserved eGFR at baseline and at least 5 years of follow up. Individuals with a detrimental prognosis were identified using various thresholds of a percentage or absolute decline of eGFR after each year of follow up. Next, we determined how many of the patients met the same criteria at other points in time. Interindividual eGFR decline was highly variable but in addition intra-individual eGFR trajectories also were frequently non-linear. For example, of all subjects reaching an endpoint defined as a decrease of eGFR by ≥ 30% between baseline and 3 years of follow up, only 60.3 and 45.2% lost at least the same amount between baseline and year 4 or 5. The results were similar when only patients on stable medication or subpopulations based on baseline eGFR or albuminuria status were analyzed or an eGFR decline of ≥ 5 ml/min/1.73m2/year was used. Identification of reliable biomarkers predicting adverse prognosis is a strong clinical need given the large interindividual variability of DKD progression. However, it is conceptually challenging in early DKD because of non-linear intra-individual eGFR trajectories. As a result, the performance of a prognostic biomarker may be accurate after a specific time of follow-up in a single population only.
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Project description:Intra-individual response time variability (IIRTV) is proposed as a viable endophenotype for many psychiatric disorders, particularly attention-deficit hyperactivity disorder (ADHD). Here we assessed whether IIRTV was associated with common DNA variation genome-wide and whether IIRTV mediated the relationship between any associated loci and self-reported ADHD symptoms. A final data set from 857 Australian young adults (489 females and 368 males; Mage = 22.14 years, SDage = 4.82 years) who completed five response time tasks and self-reported symptoms of ADHD using the Conners' Adult ADHD Rating Scale was used. Principal components analysis (PCA) on these response time measures (standard deviation of reaction times and the intra-individual coefficient of variation) produced two variability factors (labelled response selection and selective attention). To understand the genetic drivers of IIRTV we performed a genome-wide association analysis (GWAS) on these PCA-derived indices of IIRTV. For the selective attention variability factor, we identified one single-nucleotide polymorphism (SNP) attaining genome-wide significance; rs62182100 in the HDAC4 gene located on chromosome 2q37. A bootstrapping mediation analysis demonstrated that the selective attention variability factor mediated the relationship between rs62182100 and self-reported ADHD symptoms. Our findings provide the first evidence of a genome-wide significant SNP association with IIRTV and support the potential utility of IIRTV as a valid endophenotype for ADHD symptoms. However, limitations of this study suggest that these observations should be interpreted with caution until replication samples become available.
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Project description:Several studies have sought to identify novel transcriptional biomarkers in normal breast or breast microenvironment to predict tumor risk and prognosis. However, systematic efforts to evaluate intra-individual variability of gene expression within normal breast have not been reported. This study analyzed the microarray gene expression data of 288 samples from 170 women in the Normal Breast Study (NBS), wherein multiple histologically normal breast samples were collected from different block regions and different sections at a given region. Intra-individual differences in global gene expression and selected gene expression signatures were quantified and evaluated in association with other patient-level factors. We found that intra-individual reliability was relatively high in global gene expression, but differed by signatures, with composition-related signatures (i.e., stroma) having higher intra-individual variability and tumorigenesis-related signatures (i.e., proliferation) having lower intra-individual variability. Histological stroma composition was the only factor significantly associated with heterogeneous breast tissue (defined as > median intra-individual variation; high nuclear density, odds ratio [OR] = 3.42, 95% confidence interval [CI] = 1.15-10.15; low area, OR = 0.29, 95% CI = 0.10-0.86). Other factors suggestively influencing the variability included age, BMI, and adipose nuclear density. Our results underscore the importance of considering intra-individual variability in tissue-based biomarker development, and have important implications for normal breast research.
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Project description:The variability of electromyographic (EMG) recordings between and within participants is a complex problem, rarely studied in swimming. The importance of signal normalization has long been recognized, but the method used might influence variability. The aims of this study were to: (i) assess the intra-individual variability of the EMG signal in highly skilled front crawl swimmers, (ii) determine the influence of two methods of both amplitude and time normalization of the EMG signal on intra-individual variability and of time normalization on muscle activity level and (iii) describe the muscle activity, normalized using MVIC, in relation to upper limb crawl stroke movements. Muscle activity of rectus abdominis and deltoideus medialis was recorded using wireless surface EMG in 15 adult male competitive swimmers during three trials of 12.5 m front crawl at maximal speed without breathing. Two full upper limb cycles were analyzed from each of the swimming trials, resulting in six full cycles used for the intra-individual variability assessment, quantified with the coefficient of variation (CV), coefficient of quartile variation (CQV) and the variance ratio (VR). The results of this study support previous findings on EMG patterns of deltoideus medialis and rectus abdominis as prime mover during the recovery (45% activity relative to MVIC), and stabilizer of the trunk during the pull (14.5% activity) respectively. The intra-individual variability was lower (VR of 0.34-0.47) when compared to other cyclic movements. No meaningful differences were found between variability measures CV or VR when applying either of the amplitude or the time normalization methods. In addition to reporting the mean amplitude and standard deviation, future EMG studies in swimming should also report the intra-individual variability, preferably using VR as it is independent of peak amplitude, provides a good measure of repeatability and is insensitive to mean EMG amplitude and the degree of smoothing applied.
| S-EPMC4682934 | biostudies-literature