Greater Intra-individual Variability Research Articles

91 Intraindividual Variability and Executive Functioning Differences in Pedophilic and Non-Pedophilic Child Molesters and Non-Sexual Offenders

Objective:Research has found that child molesters (both pedophilic and non-pedophilic) tend to have poorer executive functioning (EF), particularly inhibition, as compared to other types of criminal offenders (Eastvold, Suchy, Strassberg, & 2011; Suchy, Whittaker, Strassberg, & Eastvold, 2009). Poorer performance on measures of inhibition may have different mechanisms for pedophilic child molesters (PCM; i.e., those offenders who are sexually attracted only to children) than non-pedophilic child molesters (N-PCM; i.e., those offenders whose sexual attraction is not limited to children). Specifically, poor inhibition in PCM may be explained by slower processing speed (Suchy, et al., 2009; Suchy, Eastvold, Strassberg, & Franchow, 2014), whereas it may be explained by impulsive errors in N-PCM (Eastvold, Suchy, & Strassberg, 2011). Intraindividual variability (IIV) refers to transient, short-term fluctuations in performance (Nesselroade, 1991). IIV is sometimes interpreted as a measure of cognitive control, an aspect of EF that could impact performance speed and accuracy due to poorer focus.Greater IIV also appreas to be associated with greater vulnerability to EF depletion after behavioral inhibition (DesRuisseaux, Suchy, & Franchow, 2021), which could represent a mechanism whereby vulnerability to EF depletion could be a precursor of offense. However, given that poor performance on measures of inhibition seem to have different underlying mechanisms for PCM and N-PCM, it is unclear whether both groups would exhibit greater IIV compared to non-sexual offenders.Participants and Methods:Participants were PCM (n = 76, M age = 33.61(7.74), Range = 1947; 92.1% White, 2.6% Hispanic/Latino, 2.6% Native American, 1.3% Black, 1.3% Other), N-PCM (n = 52, M age = 30-88(6.37), Range = 2045; 73.1% White, 13.5% Hispanic/Latino, 7.7% Other, 3.8% Native American, 1.9% Black), and non-sexual offenders (n = 25, M age = 29.96(8.16), Range = 22-45; 80% White, 8% Hispanic/Latino, 8% Other, 8% Asian) recruited as part of two larger studies examining cognition in sex offenders. IIV was assessed using the Push-Turn-Tap-Tap (PTT) task, an experimental computerized measure of EF from which IIV can be calculated (DesRuisseaux et al., 2021).Results:Independent samples t-tests found that both PCM and N-PCM had greater IIV than nonsexual offenders (t(99) = 2.13, p = .04; t(75) = 2.23, p = .03, respectively). Even on their fastest responses, PCM had greater time elapsed between correct sequences (i.e., slower response style; t(126) = 2.23, p = .03) than N-PCM. There were no significant differences in error rates between any groups (p > .05).Conclusions:These results suggest that IIV varies between sexual and non-sexual offenders but does not vary between PCM and N-PCM. This is consistent with prior research suggesting that both PCM and N-PCM have poorer EF than non-sexual offenders. Additionally, consistent with prior research, PCM had a slower response style than N-PCM and non-sexual offenders. Unlike prior research that has found significant differences in accuracy rates between PCM and N-PCM, the present results did not find a significant difference. Since IIV has been associated with increased likelihood of EF depletion (likely increasing risk of lapses), future research could examine whether CM with greater IIV have an increased likelihood of reoffending.

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.

Epigenetic Age Acceleration and Chronological Age: Associations With Cognitive Performance in Daily Life.

DNA methylation-derived epigenetic clocks offer the opportunity to examine aspects of age acceleration (ie, the difference between an individual's biological age and chronological age), which vary among individuals and may better account for age-related changes in cognitive function than chronological age. Leveraging existing ambulatory cognitive assessments in daily life from a genetically diverse sample of 142 adults in midlife, we examined associations between 5 measures of epigenetic age acceleration and performance on tasks of processing speed and working memory. Covarying for chronological age, we used multilevel models to examine associations of epigenetic age acceleration (Horvath 1, Horvath 2, Hannum, PhenoAge, and GrimAge clocks) with both average level and variability of cognitive performance. Positive age acceleration (ie, epigenetic age greater than chronological age) was associated with poorer mean processing speed (Horvath 1 and 2) and working memory (GrimAge). Higher chronological age was also associated with poorer mean processing speed and working memory performance. Further, positive age acceleration was generally associated with greater intraindividual variability in working memory and processing speed tasks, whereas being chronologically older was associated with less intraindividual variability. Although further work is needed, our results indicate age acceleration effects have comparable or greater size as those for chronological age differences, suggesting that epigenetic age acceleration may account for additional risk and interindividual variation in cognitive performance above chronological age.

Modeling Risk Factors for Intraindividual Variability: A Mixed-Effects Beta-Binomial Model Applied to Cognitive Function in Older People in the English Longitudinal Study of Ageing.

Cognitive functioning in older age profoundly impacts quality of life and health. While most research on cognition in older age has focused on mean levels, intraindividual variability (IIV) around this may have risk factors and outcomes independent of the mean value. Investigating risk factors associated with IIV has typically involved deriving a summary statistic for each person from residual error around a fitted mean. However, this ignores uncertainty in the estimates, prohibits exploring associations with time-varying factors, and is biased by floor/ceiling effects. To address this, we propose a mixed-effects location scale beta-binomial model for estimating average probability and IIV in a word recall test in the English Longitudinal Study of Ageing. After adjusting for mean performance, an analysis of 9,873 individuals across 7 (mean=3.4) waves (2002-2015) found IIV to be greater at older ages, with lower education, in females, with more difficulties in activities of daily living, in later birth cohorts, and when interviewers recorded issues potentially affecting test performance. Our study introduces a novel method for identifying groups with greater IIV in bounded discrete outcomes. Our findings have implications for daily functioning and care, and further work is needed to identify the impact for future health outcomes.

Intra-individual variability adaptively increases following inhibition training during middle childhood

There is ongoing debate on the relationship between intra-individual variability (IIV) of cognitive processes and task performance. While psychological research has traditionally assumed that lower intra-individual variability (IIV) aids consistent task performance, some studies suggest that greater IIV can also be adaptive, especially when flexible responding is required. Here we selectively manipulate inhibitory control (Stopping) and response speed (Going) by means of a training paradigm to 1) assess how this manipulation impacts Stopping IIV and its relationship to task performance, and 2) replicate previous findings showing that reductions in Going IIV are adaptive. A group of 208 6–13-year-old children were randomly allocated to an 8-week training targeting Stopping (experimental group) or Going (control group). The stop signal task was administered before and after training. Training Stopping led to adaptive increases in Stopping IIV, where greater flexibility in cognitive processing may be required to meet higher task demands. In line with previous studies, training Going led to adaptive reductions in Going IIV, which allows more consistent and efficient Going performance. These findings provide systematic and causal evidence of the process-dependent relationship of IIV and task performance in the context of Stopping and Going, suggesting a more nuanced perspective on IIV with implications for developmental, ageing and intervention studies.

Intra-individual variability in cognitive performance predicts functional decline in Parkinson’s disease

Background Cognitive 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. Methods De-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. Results PD 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). Conclusion IIV 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.

Sleep health, its intraindividuality, and perceived stress in college students during the COVID-19 pandemic

Objective: To describe the changes in sleep health domains and examine the associations between the repeated measures and intraindividual variability (IIV) of these domains and perceived stress. Participants: A diverse racial and ethnic group of first-year college students (N = 23, 78.3% female, aged 17–18) attending in-person classes during the COVID-19 pandemic. Methods: Sleep health domains were determined using 7-day wrist actigraph and daily sleep diaries, and perceived stress scale was completed at 1-month intervals across 3 months. Results: Sleep timing, regularity, and alertness during daytime demonstrated statistically significant changes between three timepoints. Greater stress was associated with more irregularity (B = 2.25 [.87–3.62], p < .001), more dissatisfaction in sleep (B = .04 [.02–.19], p < .01), alertness during daytime (B = .18 [.05–.31], p < .001), and greater IIV (ie, fluctuations) in sleep satisfaction (B = .083 [.02, .15], p < .01). Conclusion: These findings offer insights for future researchers to facilitate intervention development to promote mental and sleep health among college students.

Intraindividual variability in neuropsychological performance predicts longitudinal cortical volume loss in early Parkinson's disease.

Cognitive impairment is common among individuals with Parkinson's disease (PD). Intraindividual variability (IIV) is a measure of variability across multiple tasks of cognitive functioning. Due to the limited amount of research, particularly among individuals with PD, IIV has been an underutilized metric of cognitive functioning both in research and clinical practice. Previous research demonstrated that individuals with PD have greater variability in cognitive performance relative to controls, and that IIV is predictive of future cognitive impairments. The aim of this study is to investigate the association between baseline IIV and change in cortical and subcortical volumes among individuals with PD. The present study used data from 80 newly diagnosed PD patients who were part of a longitudinal cohort study (Parkinson progression marker initiative [PPMI]). Participants completed neuropsychological measures and underwent T1 structural magnetic resonance imaging (MRI) at baseline and the first annual follow-up. Neuropsychological tests assessed attention, processing speed, visuospatial functioning, verbal fluency learning, and memory. T1 scans were processed using standard Freesurfer protocols for extraction of regional volumes. Greater IIV at baseline was predictive of change in cortical volume in posterior temporal/parietal regions over the 1-year period. Baseline IIV predicted cortical volume changes above and beyond the main effect of motor severity and the baseline statistical mean/global cognition score. Our results provide initial evidence that IIV is a marker of longitudinal cortical volume loss. Evidence is building that IIV is a sensitive marker of cognitive impairment and the underlying neurodegeneration among individuals with PD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Racial/ethnic variations in inflammatory markers: exploring the role of sleep duration and sleep efficiency.

Individuals from minoritized racial/ethnic groups have higher levels of circulating inflammatory markers. However, the mechanisms underlying these differences remain understudied. The objective of this study was to examine racial/ethnic variations in multiple markers of inflammation and whether impaired sleep contributes to these racial/ethnic differences. Nurses from two regional hospitals in Texas (n = 377; 71.62% White; 6.90% Black; 11.14% Hispanic, 10.34% Asian; mean age = 39.46; 91.78% female) completed seven days of sleep diaries and actigraphy to assess mean and variability in total sleep time (TST) and sleep efficiency (SE). On day 7, blood was drawn to assess 4 inflammatory markers: C-reactive protein (CRP), Interleukin-6 (IL-6), Interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α). Results from regression models showed differences in inflammatory markers by race/ethnicity, adjusting for age and gender. The associations between sleep parameters and inflammatory markers also varied by race/ethnicity. Among White nurses, lower mean and greater variability in actigraphy-determined TST and greater variability in diary-determined TST were associated with higher levels of IL-6. Among Black nurses, lower mean diary-determined SE was associated with higher levels of IL-6 and IL-1β. Among Hispanic nurses, greater diary-determined mean TST was associated with higher CRP. Among Asian nurses, greater intraindividual variability in actigraphy-determined SE was associated with lower CRP. Among nurses, we did not find racial/ethnic disparities in levels of inflammation. However, analyses revealed differential relationships between sleep and inflammatory markers by race/ethnicity. Results highlight the importance of using a within-group approach to understand predictors of inflammatory markers.

Longitudinal Intraindividual Cognitive Variability Is Associated With Reduction in Regional Cerebral Blood Flow Among Alzheimer's Disease Biomarker-Positive Older Adults.

Intraindividual variability (IIV) across neuropsychological measures within a single testing session is a promising marker predictive of cognitive decline and development of Alzheimer’s disease (AD). We have previously shown that greater IIV is cross-sectionally associated with reduced cerebral blood flow (CBF), but not with cortical thickness or brain volume, in older adults without dementia who were amyloid beta (Aβ) positive. However, there is little known about the association between change in IIV and CBF over time. Therefore, we examined 12-month longitudinal change in IIV and interactions of IIV and AD biomarker status on changes in regional CBF. Fifty-three non-demented Alzheimer’s Disease Neuroimaging Initiative (ADNI) participants underwent lumbar puncture to obtain cerebrospinal fluid (CSF) at baseline and neuropsychological testing and magnetic resonance imaging (MRI) exams at baseline and 12-month follow-up evaluation. IIV was calculated as the intraindividual standard deviation across 6 demographically-corrected neuropsychological measures. Pulsed arterial spin labeling (ASL) MRI was acquired to quantify CBF and FreeSurfer-derived a priori CBF regions of interest (ROIs) were examined. AD biomarker positivity was determined using a published CSF p-tau/Aβ ratio cut-score. Change scores were calculated for IIV, CBF, and mean neuropsychological performance from baseline to 12 months. Hierarchical linear regression models showed that after adjusting for age and gender, there was a significant interaction between IIV change and biomarker-positivity (p-tau/Aβ+) for change in entorhinal and hippocampal CBF but not for the other ROIs. Specifically, increases in IIV were associated with reductions in entorhinal and hippocampal CBF among individuals who were biomarker-positive (n = 21). In contrast, there were no significant associations between change in IIV and CBF among those who were biomarker-negative (n = 32). Findings remained similar when analyses were performed adjusting for change in mean level of neuropsychological performance. Changes in IIV may be sensitive to changes in regional hypoperfusion in AD-vulnerable regions among AD biomarker-positive individuals, above and beyond demographics and mean neuropsychological performance. These findings provide further evidence supporting IIV as a potential marker of cerebrovascular brain changes in individuals at risk for dementia.

0242 Intraindividual Variability in Sleep Duration Blunts Response to Academic Stressors

Abstract Introduction Cross-sectional studies indicate that greater intra-individual variability (IIV) in sleep is correlated with poorer cognitive-emotional outcomes. Yet, the causal direction of these relationships is unclear. Therefore, we conducted an experimental study to compare cognitive and stress outcomes following random assignment to normal sleep, sleep restriction, and irregular/IIV sleep conditions. Methods Ninety college students (mean age=19.16, SD=0.98; 77.78% female) completed an Organic Chemistry virtual lecture during session 1. Then, for the next five days, participants were randomly assigned to the following conditions: normal sleep (8h in bed every night), sleep restriction (6h in bed every night), or IIV sleep (nightly oscillation between 6.5h and 9.5h in bed, with mean of 8h/night). Adherence was confirmed using actigraphy. On the sixth day (session 2), participants took a test on the Organic Chemistry lecture (retention measure) and then completed a new lecture and test (acquisition measure). Participants reported their stress levels across the lectures and tests. Results ANCOVA tests showed that sleep condition did not affect retention (F=0.50, p=.611) or acquisition of Organic Chemistry knowledge (F=1.33, p=.275; adjusted for Grade Point Average). Interestingly, participants in the IIV condition reported lower stress levels throughout session 2 than students in the normal sleep condition, adjusting for baseline stress levels (p=.025). Furthermore, when collapsing across conditions, correlation analyses confirmed that greater IIV in TST predicted lower stress throughout session 2, after adjusting for mean TST and baseline stress level (r=-.33, p=.014). This “blunted” stress response following nightly sleep fluctuations was in contrast to the heightened stress levels that were associated with shorter mean TST (r=-.22, p=.051). Conclusion Brief sleep variability and mild sleep restriction had minimal impact on laboratory measures of STEM knowledge retention and acquisition. However, greater sleep IIV blunted reactivity to academic stressors, which may reflect altered hypothalamic–pituitary–adrenal axis functions and have implications for student metacognition and course persistence. Future research should investigate the chronic effect of maintaining irregular sleep patterns and whether improving regularity of sleep across longer time intervals promotes cognitive and emotional functioning. Support (If Any) American Psychological Association, APAGS, Psi Chi, National Science Foundation (1920730, 1943323)

0232 An Intraindividual Variability of Sleep Health and Perceived Stress in College Students During the COVID-19 Pandemic

Abstract Introduction Pandemic-related societal response and uncertainty have generated marked changes in sleep-wake patterns and psycho-social well-being especially among first year college students. The current study sough to describe the changes in the sleep health domains determined from Actigraph and self-report, and examine the associations between the repeated-measure and intraindividual variability (IIV) of these domains and perceived stress in young college students over the course of a semester in the midst of an on-going COVID-19 pandemic (i.e., Fall, 2020). Methods A repeated measure design at 1-month interval across a 3-month period was conducted among a group of diverse racial and ethnic groups of college students (N=23, 78.3% female, age range 17-18). Participants completed a 7-days of wrist Actigraph, daily sleep diaries, and other surveys at each interval. A multidimensional sleep health was determined using Actigraph and daily sleep diary measures of sleep duration, efficiency, timing and regularity, and self-reported surveys of sleep satisfaction and alertness during daytime. Participants also completed the Perceived Stress Scale. Non-parametric tests were used to assess the changes in sleep health across 3 intervals, and a series of linear mixed effects model and regression analysis were conducted to assess associations between stress and subjective sleep health, adjusting for sex. Results Actigraph-determined sleep timing and regularity, and sleep diary-determined sleep timing and alertness during daytime demonstrated statistically significant changes between given timepoints. Among the sleep diary-determined sleep health domains, greater perceived stress was associated with more irregular (B=2.25 [.87–3.62], p&amp;lt;.001), more dissatisfied (B=.04 [.02–.19], p&amp;lt;.01), and sleepier during daytime (B=.18 [.05–.31], p&amp;lt;.001), across 3 timepoints. Moreover, greater perceived stress was associated with greater IIV (i.e., fluctuations) in sleep satisfaction, but no significance was found among IIV of other domains. Conclusion This study aids understanding of the relationship between stress and sleep health in this population, and offers insight to future research questions that can facilitate intervention development to promote both mental and sleep health among young college students. Support (If Any)

0611 Intraindividual Variability in Subjective Sleep and Average Fatigue in Parents of Children on the Autism Spectrum

Abstract Introduction Fatigue is related to various adverse health outcomes. Mean levels of some common sleep variables, such as total sleep time (TST), sleep onset latency (SOL), and wake after sleep onset (WASO), have been associated with fatigue. However, intraindividual variability (IIV) of sleep parameters might play an independent role in sleep’s relationship with fatigue. Understanding fatigue is particularly important for parents of children with autism spectrum disorder (ASD) given fatigue's negative associations with positive parenting and implementation of child interventions. This preliminary study examined linear associations between subjective sleep IIV and mean fatigue levels in parents of children on the autism spectrum. Methods The sample included 66 parents who expressed interest in a behavioral treatment sleep study for their school-aged children diagnosed with ASD (6-12 years old; NCT04545606). All parents (Mage=37.03, SD=6.53; 91% female) completed daily electronic diaries over a two-week baseline period. Daily fatigue rating was collected using a visual analog scale (0-100) and averaged within individuals. Within-individual standard deviations of subjective TST, SOL, and WASO were calculated to estimate IIV. Data were analyzed in R (v4.1.2) using multiple linear regression models controlling for participant age, gender, and individual sleep parameter means. Results Bivariate correlations between sleep variable IIV and average fatigue indicated a positive association between TST variability and average fatigue, r(64)=0.33, p&amp;lt;0.01. Multiple regression analyses showed that greater IIV of TST was associated with higher average fatigue (β=0.14, 95%CI [0.01, 0.27], sr2=0.06, p=0.041). No significant associations were found between average fatigue level and IIV of WASO or SOL. Conclusion Results suggest that greater TST variability may be one factor independently contributing to higher fatigue levels in parents of children on the autism spectrum, which warrants further examination of sleep variability in this population. Future research could explore IIV of additional sleep parameters, fatigue IIV as an outcome, alternative methods of sleep measurement, and study designs that address causation. Increased insight into these connections might inform the importance of considering sleep interventions for both children and parents, and potential subsequent treatment benefits. Support (If Any) MU Research Board Grant (McCrae, PI); Department of Defense Autism Research Program (McCrae, PI; W81XWH2010399).

Recreational Marijuana Use, Adolescent Cognitive Development, and Schizophrenia Susceptibility

BackgroundWe investigated how low marijuana (MJ) use levels, the typical use pattern in most adolescent users, affect cognitive maturation and schizophrenia risk. MethodsIn two complementary adolescent samples where the majority reported minimal MJ use, we compared cognitive performances before and after MJ use initiation. The Iowa sample (40 first-degree relatives and 54 second-degree relatives of patients with schizophrenia and 117 control subjects with no schizophrenia family history) underwent a battery of standardized neuropsychological tests at 0, 18, and 36 months. Based on self-administered Timeline Followback interviews, 26.5% of adolescents had emergent MJ use (eMJ) during follow-up. The second sample (n = 3463), derived from a birth cohort, received substance use and sustained attention assessments between ages 10 and 15 years. Mixed linear models and regression analyses tested the effects of eMJ on longitudinal changes in cognitive performance. ResultsIn the Iowa sample, longitudinal changes in 5 of 8 cognitive domains were significantly associated with eMJ. On sustained attention, visuospatial working memory, and executive sequencing, adolescents with eMJ showed less age-expected improved performance. In addition, first-degree relatives with eMJ were less improved on processing speed and executive reasoning than first-degree relatives without eMJ. In the birth cohort, greater intraindividual variability in reaction times (indicative of poorer sustained attention) was significantly associated with more frequent MJ use and with recreational use levels. ConclusionsNonheavy MJ use disrupts normal adolescent maturation and compounds aberrant adolescent maturation associated with familial schizophrenia risk. These findings underscore the importance of reducing adolescent MJ access in the context of increased availability to high-potency MJ.

Awareness of Balance as an Intraindividual Dynamic of Objective and Subjective Experiences of Fall Risk in Daily Life

Falls are life-changing events in older adulthood. With an accurate understanding of balance, older adults can adapt to age-related changes in physical ability without prematurely restricting physical activity. The Daily Balance Project examines the implications of older adults’ awareness of fall risk in daily life. For 30-consecutive days, following a fall-risk assessment, 40 older adults used a smartphone to report balance confidence and then perform four balance assessment and a 30-second sit-to-stand task to measure postural sway and fall-risk. Measures of postural sway showed greater intraindividual variability than balance confidence and fall risk. Multilevel models showed that awareness of balance fluctuated during the study and varied across individual differences in baseline fall-risk. Baseline fall risk also differentiated how balance confidence and postural sway were linked to subsequent momentary fall risk assessments. The findings are discussed within the framework of action-perspectives of adult development and awareness of aging.

Cognitive Intra-individual Variability in HIV: an Integrative Review.

Nearly 30-50% of people living with HIV experience HIV-Associated Neurocognitive Disorder (HAND). HAND indicates performance at least one standard deviation below the normative mean on any two cognitive domains. This method for diagnosing or classifying cognitive impairment has utility, however, cognitive intraindividual variability provides a different way to understand cognitive impairment. Cognitive intraindividual variability refers to the scatter in cognitive performance within repeated measures of the same cognitive test (i.e., inconsistency) or across different cognitive tests (i.e., dispersion). Cognitive intraindividual variability is associated with cognitive impairment and cognitive decline in various clinical populations. This integrative review of 13 articles examined two types of cognitive intraindividual variability in people living with HIV, inconsistency and dispersion. Cognitive intraindividual variability appears to be a promising approach to detect subtle cognitive impairments that are not captured by traditional mean-based neuropsychological testing. Greater intraindividual variability in people living with HIV has been associated with: 1) poorer cognitive performance and cognitive decline, 2) cortical atrophy, both gray and white matter volume, 3) poorer everyday functioning (i.e., driving simulation performance), specifically medication adherence, and 4) even mortality. This inspires future directions for research. First, greater cognitive intraindividual variability may reflect a greater task demand on executive control to harness and regulate cognitive control over time. By improving executive functioning through cognitive training, it may reduce cognitive intraindividual variability which could slow down cognitive decline. Second, cognitive intraindividual variability may be reconsidered in prior cognitive intervention studies in which only mean-based cognitive outcomes were used. It is possible that such cognitive interventions may actually improve cognitive intraindividual variability, which could have clinical relevance.

Intraindividual variability in executive and motor control tasks in children with attention deficit hyperactivity disorder

ABSTRACT Objective Emerging evidence highlights intraindividual variability (IIV) during executive function (EF) tasks as a reliable endophenotype of Attention Deficit/Hyperactivity Disorder (ADHD) and as contributing to motor dysregulation and hyperactive-impulsive behaviors. This study examined the relationship between EF and motor control in children with and without ADHD. Method Ninety-seven children (6–13 years) completed standardized and experimental tasks of executive and motor control. Primary caregivers completed a semi-structured interview, and behavioral rating forms for ADHD symptoms and EF. Results Children with ADHD demonstrated lower performance on motor dexterity and sequencing tasks, and greater IIV during EF tasks with lower cognitive demand. IIV accounted for ADHD symptoms of hyperactivity, beyond age and motor dexterity. IIV from EF measures with lower cognitive demand was also sensitive to ADHD symptoms. Conclusion IIV metrics may tap into the motor regulation challenges associated with ADHD, as well as attentional lapsing at lower levels of cognitive demand.

Reward-Seeking Deficits in Major Depression: Unpacking Appetitive Task Performance with Ex-Gaussian Response Time Variability Analysis.

Major depressive disorder (MDD) has extensive ties to motivation, including impaired response time (RT) performance. Average RT, however, conflates response speed and variability, so RT differences can be complex. Because recent studies have shown inconsistent effects of MDD on RT variability, the present research sought to unpack RT performance with several key improvements: (1) a sample of adults (n = 78; 18 MDD, 60 Control) free of antidepressant medication; (2) an unambiguously appetitive task with appealing incentives at stake; and (3) ex-Gaussian RT modeling, which can unconfound speed and variability by estimating parameters for the mean (Mu) and standard deviation (Sigma) of the normal component and the mean of the exponential component (Tau). The groups had comparable Mu and Sigma parameters, but the MDD group had a significantly larger Tau, reflecting greater intraindividual RT variability. The findings suggest that MDD's effect on average RT can stem from greater intraindividual variability, not from overall slowness. Possible mechanisms, such as impaired executive processes in MDD and difficulties maintaining stable mental representations of incentives, are considered.

Behavioral and Social Considerations

Cognitive, behavioral and social dimensions also demonstrate increasing heterogeneity with aging. For example, a longitudinal study of over 1,000 clergy revealed increasing heterogeneity in cognitive function and rate of decline with aging. Moreover, studies of individuals with probable Alzheimer’s disease have shown heterogeneity in terms of clinical manifestations and rates of cognitive decline. Older adults also demonstrate greater heterogeneity in mood, anxiety, and the nature and patterns of symptoms over time. Heterogeneity of overall health status increases with aging, as does reported quality of life. Health and Retirement Study (HRS) data have shown that low socioeconomic status or being an underrepresented minority are both associated with greater intra-individual variability in health status in old age, with greatest differences seen in Hispanics. Finally, early life adversity can contribute to heterogeneity of multidimensional health trajectories even in late life.

Day-to-Day Variability in Loneliness: Associations With Age, Sleep Duration, and Health Symptoms

Research has suggested that high day-to-day intraindividual variability (IIV) in positive emotions has negative impacts on well-being. Little research has explored the impact of IIV in negative emotions, particularly loneliness - a known risk-factor for poorer health in old age. With an estimated 25-29% of older adults reporting feelings of loneliness, it is imperative to examine age differences in the presence of IIV in loneliness and how this relates to sleep and physical health symptoms. Using data from the National Study of Daily Experiences (N=2022, Mage=56.24, Range=33-84), we examined whether (1) age was associated with IIV in loneliness, (2) greater IIV in loneliness was associated with lower average sleep duration and more physical health symptoms, and (3) age differences moderate the extent to which IIV in loneliness impacted the previous outcomes. Preliminary results indicated that age was associated with decreased IIV in loneliness (p<.001). Additionally, increased IIV in loneliness and age was associated with significantly fewer physical health symptoms (ps<.05) but was not reliably associated with sleep duration. Finally, age and IIV in loneliness did not interact to predict either physical health symptoms or sleep duration. Older participants diminished IIV in loneliness – and lack of differential vulnerability to IIV in loneliness – is consistent with theoretical models of older adults’ socioemotional regulation (i.e., socioemotional selectivity theory). Contrary to expectations, a higher variability in loneliness was related to lower average physical health symptoms. Discussion will focus on the meaning and importance of IIV in loneliness for older adults’ health.