Indices Of Intra-individual Variability Research Articles

44 Cognitive Intraindividual Variability as a Predictor of Functional Outcomes in a Sample of Precariously Housed Individuals

Objective:Precariously housed individuals are exposed to multiple adverse factors negatively impacting neurocognitive functioning. Additionally, this population is subjected to poor life outcomes, such as impaired psychosocial functioning. Neurocognitive functioning plays an important role in psychosocial functioning and may be especially critical for precariously housed individuals who face numerous barriers in their daily lives. However, few studies have explicitly examined the cognitive determinants of functional outcomes in this population. Cognitive intraindividual variability (IIV) involves the study of within-person differences in neurocognitive functioning and has been used as marker of frontal system pathology. Increased IIV has been associated with worse cognitive performance, cognitive decline, and poorer everyday functioning. Hence, IIV may add to the predictive utility of commonly used neuropsychological measures and may serve as an emergent predictor of poor outcomes in at-risk populations. The objective of the current study was to examine IIV as a unique index of the neurocognitive contributions to functional outcomes within a large sample of precariously housed individuals. It was hypothesized that greater IIV would be associated with poorer current (i.e., baseline) and long-term (i.e., up to 12 years) psychosocial functioning.Participants and Methods:Four hundred and thirty-seven adults were recruited from single-room occupancy hotels located in the Downtown Eastside of Vancouver, Canada (Mage = 44 years, 78% male) between November 2008 and November 2021. Baseline neurocognitive functioning was assessed at study enrolment. Scores from the Social and Occupational Functioning Assessment Scale (SOFAS), the Role Functioning Scale (RFS), the physical component score (PCS) and the mental component score (MCS) of the 36-Item Short Form Survey Instrument were obtained at participants’ baseline assessments and at their last available follow-up assessment to represent baseline and long-term psychosocial functioning, respectively. Using an established formula, an index of IIV was derived using a battery of standardized tests that broadly assessed verbal learning and memory, sustained attention, mental flexibility, and cognitive control. A series of multiple linear regressions were conducted to predict baseline and long-term social and role functioning (average across SOFAS and RFS scores), and PCS and MCS scores from IIV. In each of the models, we also included common predictors of functioning, including a global cognitive composite score, age, and years of education.Results:The IIV index and the global composite score did not explain a significant proportion of the variance in baseline and long-term social and role functioning (p > .05). However, IIV was a significant predictor of baseline (B = -3.84, p = .021) and long-term (B = -3.58, p = .037) PCS scores, but not MCS scores (p > .05). The global composite score did not predict baseline or long-term PCS scores.Conclusions:IIV significantly predicted baseline and long-term physical functioning, but not mental functioning or social and role functioning, suggesting that IIV may be a sensitive marker for limitations in everyday functioning due to physical health problems in precariously housed individuals. Critically, the present study is the first to show that IIV may be a useful index for predicting poor long-term health-related outcomes in this population compared to traditional neuropsychological measures.

Reversal learning in young and middle-age neurotypicals: Individual difference reaction time considerations

ABSTRACT Reversal learning is frequently used to assess components of executive function that contribute to understanding age-related cognitive differences. Reaction time (RT) is less characterized in the reversal learning literature, perhaps due to the daunting task of analyzing the entire RT distribution, but has been deemed a generally sensitive measure of cognitive aging. The current study extends our prior work to further characterize distributional properties of the reversal RT distribution and to distinguish groups of individuals with fractionated profiles of performance, which may be of clinical importance within the context of cognitive aging. Participant sample included young (n = 43) and community-dwelling, healthy, middle-aged (n = 139) adults. To explore individual differences, recursive partitioning analysis achieved a high classification rate by specifying decision tree rules that split participants into young and middle-aged groups. Mu (μ, efficient RT) was the most successful parameter in distinguishing age groups while sigma ( and tau (, ex-Gaussian indices of intra-individual variability) revealed more subtle individual differences. Accuracy measures did not contribute to separating the groups, suggesting that fractionated components of RT, as opposed to accuracy, can distinguish differences between young and middle-aged participants.

Individual variability in attention and language performance in aphasia: a study using Conner’s Continuous Performance Test

ABSTRACTBackground: Individual variability in attention in aphasia is important because moment-to-moment fluctuations in attention could might influence language performance.Aims: Moment-to-moment variability in performance has been considered a feature of aphasia. The aim of the current work is to study the possible relationship between moment-to-moment intraindividual fluctuations in attention and their possible relationship with language disorders in people with aphasia (PWA).Methods & Procedures: 24 controls and 21 PWA matched by age and sex took part in the study. Language assessment included phonological processing (phonological discrimination, word and pseudoword repetition), lexical access (auditory lexical decision, spoken word-to-picture matching and naming), and semantic association (object–action association, semantic association, and odd-one-out). Attention assessment employed a comprehensive test of basic attention functions (Conner’s Continuous Performance Test II). We studied the association between indices of intraindividual variability in response time in Conner’s Continuous Performance Test and linguistic performance in both groups.Outcomes & Results: PWA showed increased response times and also increased intraindividual variability in response speed. Moreover, only in this group, response speed variability was significantly associated with speech discrimination and with performance in semantic association tasks. Indices of intraindividual variability predicted performance in linguistic tasks in PWA, even after accounting for language performance in related tasks.Conclusion: The current results provide additional support to evidence suggesting a relationship between attention skills and some aspects of linguistic performance in PWA, and draw attention to the putative importance of processing speed instability.

Growth Trajectories and Detrended Intraindividual Variability to Assess Case Managers' Competency in Continuing Education.

Tracking the effectiveness of CE over time beyond simply confirming its efficacy in continuing education (CE) in nursing is crucial. However, research evidence on the analysis of change of the effectiveness of CE over time is limited, particularly in the context of case management. This methodological study aimed to introduce both a growth curve modeling and an intra-individual variability index and demonstrate step-by-step procedures and interpretations of those analyses to assess case manager competency over time, using secondary data analysis. Data were collected from 22 case managers affiliated with the Korean National Health Insurance Corporation who attended three series of CE to improve their competency between May 2008 and August 2009. Unexpected results revealed a negative fixed effect of education level in the overall estimation of case managers' competency trajectory and a negative correlation between education level and case managers' intra-individual competency inconsistency over time. J Contin Nurs Educ. 2017;48(5):230-238.

Performance variability during a multitrial list-learning task as a predictor of future cognitive decline in healthy elders

Introduction: In clinical settings, neuropsychological test performance is traditionally evaluated with total summary scores (TSS). However, recent studies demonstrated that indices of intraindividual variability (IIV) yielded unique information complementing TSS. This 18-month longitudinal study sought to determine whether IIV indices derived from a multitrial list-learning test (the Rey Auditory Verbal Learning Test) provided incremental utility in predicting cognitive decline in older adults compared to TSS. Method: Ninety-nine cognitively intact older adults (aged 65 to 89 years) underwent neuropsychological testing (including the Rey Auditory Verbal Learning Test) at baseline and 18-month follow-up. Participants were classified as cognitively stable (n = 65) or declining (n = 34) based on changes in their neuropsychological test performance. Logistic regression modeling tested the ability of baseline TSS indices (sum of Trials 1–5, immediate recall, and delayed recall) and IIV indices (lost access and gained access) to discriminate between stable and declining individuals. Results: Higher values of both lost access and gained access at baseline were associated with an increased risk for decline at 18-month follow-up. Further, the IIV indices provided predictive utility above and beyond the TSS indices. Conclusion: These results highlight the value of analyzing IIV in addition to TSS during neuropsychological evaluation in older adults. High levels of IIV may reflect impairment in anterograde memory systems and/or executive dysfunction that may serve as a prognostic indicator of cognitive decline.

Parental attachment and its relationship to contextualised trait expression and mean-corrected cross-context trait variability

The study explored relationships between attachment to parents, personality traits and cross-context trait variability in adulthood. The 209 adult participants completed the Parental Attachment Questionnaire (PAQ), and rated themselves on a Big Five trait inventory to describe their personality as it manifests when with parents, friends and work colleagues. Indices of intra-individual variability were corrected to negate correlations between trait variability and trait means. It was found that weaker parental attachment was related to higher levels of cross-context variability in Agreeableness, Openness to Experience and Emotional Stability (Neuroticism). Correlations between an overall index of cross-context personality variability and trait means were moderated by context. PAQ scores were linked to all five trait means in the parent context, but not to trait means in other contexts. The findings support a link between the attachment bond with parents and particular personality traits in respect to both cross-context variability and mean level.

Believing in paranormal phenomena: Relations to asymmetry of body and brain

The goal of this study was to investigate the possible relationship between established measures of body and brain asymmetries and individual differences in paranormal beliefs. In addition to behavioural measures of cerebral laterality, measures of facial features and finger length were taken to calculate body asymmetry scores and indicators of fluctuating asymmetry (average absolute differences between left and right body features). Both the direction and degree of laterality measures were used. In addition to that, quantitative measures of inconsistency of cerebral lateralization were obtained. Results indicated that a stronger belief in paranormal phenomena was associated with fluctuating asymmetry of finger length, and that this aspect of body asymmetry may be related to greater intraindividual variability in the degree of ‘atypical’ functional lateralization. This intraindividual variability index, in turn, significantly predicted strength of belief in the paranormal. Belief in the paranormal was also higher in women than men and it was negatively correlated with the education level. In sum, these findings suggest that a part of the variance of strength of belief in paranormal phenomena can be explained by patterns of functional hemispheric asymmetry that may be related to perturbations during fetal development.