Intra-individual Dynamics Research Articles

Bayesian estimation and comparison of idiographic network models.

Idiographic network models are estimated on time series data of a single individual and allow researchers to investigate person-specific associations between multiple variables over time. The most common approach for fitting graphical vector autoregressive (GVAR) models uses least absolute shrinkage and selection operator (LASSO) regularization to estimate a contemporaneous and a temporal network. However, estimation of idiographic networks can be unstable in relatively small data sets typical for psychological research. This bears the risk of misinterpreting differences in estimated networks as spurious heterogeneity between individuals. As a remedy, we evaluate the performance of a Bayesian alternative for fitting GVAR models that allows for regularization of parameters while accounting for estimation uncertainty. We also develop a novel test, implemented in the tsnet package in R, which assesses whether differences between estimated networks are reliable based on matrix norms. We first compare Bayesian and LASSO approaches across a range of conditions in a simulation study. Overall, LASSO estimation performs well, while a Bayesian GVAR without edge selection may perform better when the true network is dense. In an additional simulation study, the novel test is conservative and shows good false-positive rates. Finally, we apply Bayesian estimation and testing in an empirical example using daily data on clinical symptoms for 40 individuals. We additionally provide functionality to estimate Bayesian GVAR models in Stan within tsnet. Overall, Bayesian GVAR modeling facilitates the assessment of estimation uncertainty which is important for studying interindividual differences of intraindividual dynamics. In doing so, the novel test serves as a safeguard against premature conclusions of heterogeneity. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Two-Year Study on the Intra-Individual Dynamics of Gut Microbiota and Short-Chain Fatty Acids Profiles in Healthy Adults.

While the gut microbiome has been intensively investigated for more than twenty years already, its role in various disorders remains to be unraveled. At the same time, questions about what changes in the gut microbiota can be considered as normal or pathological and whether communities are able to recover after exposure to negative factors (diseases, medications, environmental factors) are still unclear. Here, we describe changes in the gut microbiota composition and the content of short-chain fatty acids in adult healthy volunteers (n = 15) over a 24 month-period. Intraindividual variability in gut microbial composition was 40%, whereas the short chain fatty acids profile remained relatively stable (2-year variability 20%, inter-individual 26%). The changes tend to accumulate over time. Nevertheless, both short-term and long-term changes in the gut microbiome composition were significantly smaller within individuals than interindividual differences (two-year interindividual variability was 75%). Seasonal changes in gut microbiota were found more often in autumn and spring involving the content of minor representatives (less than 1.5% of the community in average) in the phyla Actinobacteriota, Firmicutes and Proteobacteria.

The intraindividual dynamics of university students' motivation and emotions: The role of autonomy-supportive learning climates and learning activities.

The motivation and emotions of students are context dependent. There are specific moments when students may find their coursework more or less motivating, resulting in stronger or milder emotional responses. Identifying factors directly controllable by teachers empowers them to effectively address challenging situations characterized by lower motivation and increased negative emotions. We aimed to investigate how learning activities and students' perception of teaching practices fostering autonomy relate to competence and value beliefs, and emotions in the context of course participation within higher education. Seventy-seven Taiwanese university students provided 762 learning reports associated with their course participation experiences. The experience sampling method (ESM) was used. Participants responded to ESM surveys on their phones for 14 days, reporting motivational beliefs, emotions and contextual characteristics of the course if they indicated active participation in a course upon receiving notifications from their phones. A significant portion of the variation is attributed to situational fluctuation, suggesting that academic emotions and competence and value beliefs vary within students across measurements. An increase in students' perception of an autonomy-supportive learning climate correlates with higher competence beliefs, intrinsic value and positive emotions, coupled with reduced perceived costs and negative emotions. In contrast to lectures, engaging in independent hands-on work, participating in group collaborative projects or interactive discussions appear to inspire motivation or evoke stronger emotional responses in students. Teachers' teaching practices and classroom learning activities play a pivotal role in shaping students' situational motivation and emotions.

A precision-mapping approach to physical exercise interventions targeting cognitive function.

Physical exercise confers numerous benefits to brain structure, function and cognition, however, considerable individual variability exists in these effects. Emerging paradigms focused on intraindividual dynamics provide novel opportunities to map and leverage individualized neural architectures underlying exercise-cognition relationships. Progress at the intersection of psychometrics, structural and functional neuroimaging, electrophysiology, and genetics can be integrated to elucidate each individual's potential for improvement, as well as the specific abilities that are most likely to benefit from exercise regimens. These personalized profiles can then guide targeted exercise programs tailored to effectively modulate the pathways identified as most promising for that individual. Such mapping-guided exercise interventions tailored to a person's neurocognitive profile allows optimizing cognitive improvements compared to results elicited by generic regimens. While still in its infancy, precision interventions represent an innovative future direction to advance exercise in support of brain health, toward potent, truly personalized cognitive enhancement.

Variability in the energy reserves of swordfish (Xiphias gladius) of the southeastern Pacific Ocean: A temporal and intra-individual perspective

The temporal dynamics of energy reserves are associated with the physiological processes (i.e., reproduction) in marine fishes, in which storage organs play a key role for efficient energy investment. We evaluated the temporal (i.e., seasons) and intra-individual (i.e., organs) dynamics of adult female swordfish (Xiphias gladius) during its feeding period off the Chilean coast in the southeastern Pacific Ocean (SEPO). The biochemical composition (i.e., lipids, proteins, and glucose), energy content and fatty acid profile of the muscle, liver and gonad were evaluated during the austral autumn, winter, and spring. Our results showed principally an intra-individual effect in both the muscle and liver in the autumn and spring. Herein, a trend of higher amounts of lipids and total energy were found in the muscle, while the liver showed greater protein and glucose contents. Consequently, the muscle showed a higher saturated, monounsaturated, and polyunsaturated fatty acid contents than the liver. Although the gonad showed no significant temporal effect in the lipids and proteins contents, an increasing trend of each biochemical constituent, fatty acid group and gonadosomatic index were found from autumn to winter. Consistently, the glucose and total energy content as well Fulton's condition factor were significantly higher in winter. These findings reflect the spatial-temporal physiological dynamic of swordfish based on the storage of energy reserves in different organs during its feeding period. In this way, the products obtained from swordfish could have an added value depending on the season and capture zone, which could benefit the exploitation and regulation measures of this resource under an ecological approach of conservation and sustainability in the SEPO.

Friendly-user score assessing gut dysbiosis and resistance to immune checkpoint inhibitors (ICI).

103 Background: Accumulating evidence pointed to the impact of the intestinal microbiota on ICI outcomes across various cancers. Although specific gut microbial species have been associated with beneficial responses ( i.e. Akkermansia muciniphila (Akk)), no consensus exists on a gut fingerprint predicting immunoresistance to clinical routine use. Methods: NCT04567446 provided whole genome sequencing (WGS) of longitudinal fecal samples from patients (pts) with advanced non-small cell lung cancer (NSCLC) during ICI (alone or with chemotherapy) in France and Canada. Topological Pearson networks clustered into species interacting groups (SIG) correlating with overall survival (OS; OS<12=NR; OS>12=R). Forty harmful (SIG1) and thirty-four beneficial (SIG2) WGS species were associated with NR and R to ICI. A monodimensional score (TOPOSCORE) based on SIG1/SIG2 ratio combined with Akk relative abundance was calculated and compared to machine-learning (ML) algorithms. Multivariate Cox analysis (MVA) adjusted for established risk factors (ATB, gender, age, ECOG, PD-L1, LIPI score). Intraindividual dynamics of the TOPOSCORE was evaluated in pts with at least two fecal samples. Three independent cohorts of NSCLC and genitourinary (GU) cancers pts validated the data. Results: In n=245 and n=148 NSCLC pts, we could classify pts into dysbiotic (SIG1+,33%) and eubiotic (SIG2+, 67%), using the TOPOSCORE. Pts falling within the SIG2+ exhibited a significantly prolonged OS than pts falling into SIG1+ (HR: (95% CI), 0.50 (0.36-0.71), p<0.0001). TOPOSCORE also predicted OS in 277 ICI-treated NSCLC and GU pts and compared to the state-of-the-art ML algorithms, held the highest percentage of correct predictions (63%). At MVA, TOPOSCORE was independently associated with OS (HR: 0.56 (0.39-0.81), p=0.002). Analyzing the intraindividual dynamics of the TOPOSCORE (n=67), we found that 74% of SIG2+ and 68% of SIG1+ individuals remained in their initial classification during ICI treatment. We finally scaled the calculation of the TOPOSCORE down to 24WGS (instead 75WGS) and set up a qPCR-based friendly-user test capable of accurately identifying the fecal presence of the bacteria of interest within 48 hrs. We confirmed (n=323) that OS was superior in those pts harboring a 24-bacteria-qPCR-based TOPOSCORE falling within the SIG2+ category (HR: 0.65 (0.48 to 0.87), p=0.0005). Conclusions: TOPOSCORE represents a robust biomarker predicting and following the dynamic of the immunoresistance to ICI across cancers on an individual basis. By converting the WGS TOPOSCORE to a qPCR-based test with a rapid turnaround time, it will be possible to adopt this score in routine clinical practice to improve pts stratification and ICI success rates guiding the selection of dysbiotic pts amenable to microbiota-centered interventions and eubiotic fecal microbiota transplantation donors. Clinical trial information: NCT04567446 .

Predictors of post-stroke depression: Validation of established risk factors and introduction of a dynamic perspective in two longitudinal studies.

Cerebral insults lead in many cases not only to cognitive impairment but also to disturbed emotionality. After stroke, one in three survivors develops a depression which impacts quality of life and rehabilitation. Meta-analyses have identified five main predictors of post-stroke depression (PSD): history of mental disorder, stroke severity, physical disability, cognitive impairment, and social support. However, these five established variables have never been conjointly investigated in a sample of stroke survivors. Therefore, their independent predictive values remain unclear. Moreover, predictors are most often used as time-invariant factors (status scores), neglecting the intraindividual dynamics after stroke. Our study analyses the data of two prospective longitudinal studies, investigating stroke survivors from two rehabilitation hospitals (N 1 = 273) and one acute care hospital (N 2 = 226). Baseline assessments included the five established predictors and depressive symptoms. After 6 months, depressive symptoms were reassessed in both studies (n 1 = 176, n 2 = 183), and physical disability and social support were reassessed in study 2. The predictivity of the five predictors and the additional predictivity of intraindividual dynamics for PSD were examined in multiple linear regression analyses. History of mental disorder was a risk factor for depressive symptoms after stroke at all measurement times (B = 3.32 to 3.97; p < 0.01). Physical disability was a risk factor at all measurement times (B = -0.09 to -0.03; p < 0.05) except 6 months after rehabilitation. Social support was a protective factor (B = -2.69 to -1.91; p < 0.01) outside the acute phase (R 2 = 0.15-0.39). Intraindividual changes in physical disability and perceived social support were independent predictors of PSD 6 months after the acute phase (B = -0.08/-0.14; p < 0.01), in addition to status scores on established variables (ΔR 2 = 0.08, p < 0.001). History of mental disorder, physical disability, and social support are independent predictors of depressive symptoms in the first year post-stroke, also when considered conjointly. Future studies should control for these variables when investigating new predictors of PSD. In addition, intraindividual changes in known predictors after stroke play a relevant role in the pathogenesis of PSD and should be considered in clinical practice and future research.

Call for new measures suitable for intensive longitudinal studies: Ideas and suggestions

The intensive longitudinal studies (ILS) has recently gained prominence as one of the most developing and promising approaches in psychological research. It is suitable for studying intraindividual dynamics, since it collects many repeated measurements for multiple persons. However many existing psychometric scales that are suitable for cross-sectional studies cannot be used successfully in ILS. That is why it would be advisable to develop them. This article presents potential solutions and future directions that may be helpful in developing such tools. It focuses on and discusses three issues: (1) appropriate tool length, so that the person completing them multiple times does not feel too tired; (2) parallel forms of questionnaires to reduce the problem of remembering previous answers; (3) complementary types of measure, that would allow approaching certain characteristics in slightly different ways.

The within-person dynamics of affect, meaning in life, and perceived stress

ABSTRACT While the relationship between meaning in life and affect has been examined extensively in individual differences and experimental studies, we know little about the intraindividual dynamics of the naturally occurring relationships between these constructs. We examined meaning in life, positive/negative affect, and perceived stress across 13 weekly assessments in a sample of 50–95 year-olds (N = 226). Overall, there was qualitative similarity across between-individual and within-individual analyses, each showing unique relationships between positive affect and meaning in life, as well as between positive affect, negative affect, meaning in life, and perceived stress. Moreover, cross-lagged panel analyses confirmed that positive, but not negative affect, may have a causal and unidirectional effect on meaning in life, and that positive affect, negative affect, and meaning in life each have unique lagged, week-to-week effects on stress. These results suggest that each of these related constructs plays a unique functional role in individuals’ mental health and well-being.

Advancing the Study of Resilience to Daily Stressors

Historically, studies of childhood and adult resilience have typically focused on adaptation to chronic life adversities, such as poverty and maltreatment, or isolated and potentially traumatic events, such as bereavement and serious illness. Here, we present a complementary view and suggest that stressors experienced in daily life may also forecast individual health and well-being. We argue that daily process approaches that incorporate intensive sampling of individuals in natural settings can provide powerful insights into unfolding adaptational processes. In making this argument, we review studies that link intraindividual dynamics with diverse health-related phenomena. Findings from this research provide support for a multiple-levels-analysis perspective that embraces greater unity in pivotal resilience constructs invoked across childhood and adult literatures. Drawing on insights and principles derived from life-span theory, we conclude by outlining promising directions for future work and considering their broader implications for the field of resilience.

GPS2space: An Open-source Python Library for Spatial Measure Extraction from GPS Data.

Global Positioning System (GPS) data have become one of the routine data streams collected by wearable devices, cell phones, and social media platforms in this digital age. Such data provide research opportunities in that they may provide contextual information to elucidate where, when, and why individuals engage in and sustain particular behavioral patterns. However, raw GPS data consisting of densely sampled time series of latitude and longitude coordinate pairs do not readily convey meaningful information concerning intra-individual dynamics and inter-individual differences; substantial data processing is required. Raw GPS data need to be integrated into a Geographic Information System (GIS) and analyzed, from which the mobility and activity patterns of individuals can be derived, a process that is unfamiliar to many behavioral scientists. In this tutorial article, we introduced GPS2space, a free and open-source Python library that we developed to facilitate the processing of GPS data, integration with GIS to derive distances from landmarks of interest, as well as extraction of two spatial features: activity space of individuals and shared space between individuals, such as members of the same family. We demonstrated functions available in the library using data from the Colorado Online Twin Study to explore seasonal and age-related changes in individuals' activity space and twin siblings' shared space, as well as gender, zygosity and baseline age-related differences in their initial levels and/or changes over time. We concluded with discussions of other potential usages, caveats, and future developments of GPS2space.

Intraindividual dynamics between alliance and symptom severity in long-term psychotherapy: Why time matters.

Objective: The association between alliance and therapy outcome is one of the most investigated factors in psychotherapy research. However, even studies using advanced methods estimate effects over a specific time period (interval) between measurement occasions. Thus, it remains unknown how the magnitude and direction of effects depend on the considered time interval, resulting in limited comparability across studies. The current study examines the influence of time on the within-person relationship between alliance and symptom severity. Method: Alliance (WAI-SR) and symptom severity (SCL-K11) were assessed every fifth session in N = 650 patients receiving up to 100 weekly sessions (mode = 55; M = 41.03; SD = 27.23) of individual psychotherapy in a German outpatient clinic. Bivariate continuous-time (CT) structural equation modeling (SEM) was used to estimate within-person cross- and auto-effects. Results: Analysis revealed significant reciprocal within-person cross-effects with stronger relative effects of SCL-K11 on WAI-SR (a₂₁) than vice versa (a₁₂). CT analysis showed that both cross-lagged effects increased for longer time intervals with strongest effects for time intervals of about 40 sessions (a₂₁ = -.47; a₁₂ = -.19). Conclusions: Alliance and symptom severity showed a reciprocal relationship. Expanding current evidence, our analysis showed how the magnitude of these effects depends on the considered time interval. Applying CT-SEM on longitudinal data of the alliance outcome association complements current cross-lagged panel analysis and allows to compare results of studies which are based on different time intervals between measurement occasions. Methodological, theoretical, and clinical implications are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Short-term effects of fluctuations in self-esteem, perceived stress and loneliness in depressive states

Depression depends on risk factors such as loneliness, low self-esteem, and perceived stress when inter-individual differences are investigated in the long run. Depression, however, oscillates within-person over short-time periods as well, but there is a lack of evidence on its temporary correlates. The present study explored how transitory feelings of depression covariate with states of loneliness, stress, and self-esteem at the within-person level, further inspecting how inter-individual differences contribute to understanding intra-individual dynamics. Seventy-four adults (M = 33 years) took part in the study and reported on daily depression, stress, loneliness, and self-esteem for eight successive evenings. The main results showed that within-person fluctuations in depression depended on transient changes in loneliness, self-esteem, and stress, with stress further moderating the depression-self-esteem association; the link between depression and its predictors was reciprocal; inter-individual differences in depression instability across the assessment occasions enhanced the effect of transitory loneliness on feelings of depression. The present findings revealed that within-person associations for depression reflect correlation patterns between people, further highlighting how an individual’s instability in depressive states is relevant for understanding who is more vulnerable to transitory depressive states, which might develop into trait-like conditions over longer time periods.

Supplemental Material for Intraindividual Dynamics Between Alliance and Symptom Severity in Long-Term Psychotherapy: Why Time Matters

Supplemental Material for Intraindividual Dynamics Between Alliance and Symptom Severity in Long-Term Psychotherapy: Why Time Matters

Responsivity to light in familial hemiplegic migraine type 1 mutant mice reveals frequency-dependent enhancement of visual network excitability.

Migraine patients often report (inter)ictal hypersensitivity to light, but the underlying mechanisms remain an enigma. Both hypo‐ and hyperresponsivity of the visual network have been reported, which may reflect either intra‐individual dynamics of the network or large inter‐individual variation in the measurement of human visual evoked potential data. Therefore, we studied visual system responsivity in freely behaving mice using combined epidural electroencephalography and intracortical multi‐unit activity to reduce variation in recordings and gain insight into visual cortex dynamics. For better clinical translation, we investigated transgenic mice that carry the human pathogenic R192Q missense mutation in the α1A subunit of voltage‐gated CaV2.1 Ca2+ channels leading to enhanced neurotransmission and familial hemiplegic migraine type 1 in patients. Visual evoked potentials were studied in response to visual stimulation paradigms with flashes of light. Following intensity‐dependent visual stimulation, FHM1 mutant mice displayed faster visual evoked potential responses, with lower initial amplitude, followed by less pronounced neuronal suppression compared to wild‐type mice. Similar to what was reported for migraine patients, frequency‐dependent stimulation in mutant mice revealed enhanced photic drive in the EEG beta‐gamma band. The frequency‐dependent increases in visual network responses in mutant mice may reflect the context‐dependent enhancement of visual cortex excitability, which could contribute to our understanding of sensory hypersensitivity in migraine.

Intraindividual Dynamics of Leaders in Change Processes

Although a growing body of research links leadership behavior to follower well-being in change situations, comparatively little is known about leaders’ experience and behavior during organizational change processes. This weekly diary study of 57 leaders examined the personal and organizational resources and demands of leaders in change processes, their effect on irritation and engagement and how the job demands-resources model theoretically informs this dynamic. This paper is the first to examine the role of change self-efficacy and change-commitment of leaders and their specific effects of strain and engagement. Main theoretical implications lie in the finding that—in line with job demands–resources theory – especially for engagement intraindividual factors are of importance. For practitioners, our results offer valuable insights regarding the specific support of leaders for organizational change implementation.

Using the time-varying autoregressive model to study dynamic changes in situation perceptions and emotional reactions.

Assuming personality to be a system of intra-individual processes emerging over time in interaction with the environment, we propose an idiographic approach to investigate potential changes of intra-individual dynamics in the perception of situations and emotions of individuals varying in personality traits. We compared the semiparametric time-varying autoregressive model (TV-AR) that takes into account the non-stationarity of psychological processes at the individual level, with the standard AR model. We conducted analyses of individual time series to assess intra-individual changes in mean levels and inertia on data from two adolescents who completed measures of personality and indicated their situation perceptions and emotions five times a day for 19days. For the less honest, emotional, extraverted, and more agreeable adolescent, the TV-AR model detected reliable changes in the intra-individual dynamics of situation perceptions and emotions whereas, for the other individual, the standard AR model was more preferred, given the lack of changes in the intra-individual dynamics. Psychological processes dynamics in situation perception and emotions may vary from person to person depending on their personality. This work constitutes a first step in demonstrating that an idiographic approach has advantages in identifying changes in individuals' perceptions and reactions to situations.

INTEGRATION OF OBJECTIVE AND SUBJECTIVE EXPERIENCES OF HEALTH IN OLD AGE

Life-span perspectives on adult development and aging highlight the processes of understanding and acting to support one’s own health and well-being. Within this framework, subjective measures offer insight into the experience of objective measures of health. This symposium brings together four papers that highlight the overlap and discrepancy between subjective and objective measures of health and how these are shaped by individual development in different contexts and phases of adult development over various timescales. Mejía and colleagues consider the intraindividual dynamics of older adults’ perceived and actual fall risk. Using 30 days of subjective and objective balance assessment, they illustrate individual differences in how awareness of fall-risk relates to physical activity on that day. Koffer and Kamarck use data from the Pittsburgh Healthy Heart Project to examine how reactivity of cardiovascular response and affective experience to daily experiences of stress changes with age. Drewelies and colleagues consider how objective aging feels. Using data from the Berlin Aging Study II, they examine how chronological and subjective age are linked to biological age in older adults. Gonzalez and colleagues use self-reported and behavioral data from an in-context biosocial research lab to comment on the theoretical and methodological implications of integrating objective and subjective measures of experience. The discussion by Berg integrates the four papers, highlights their theoretical and methodological contributions, and considers challenges and opportunities for subjective and objective inquiries of older adults’ experiences of health.

THE DAILY BALANCE PROJECT: AN INQUIRY INTO THE INTRAINDIVIDUAL DYNAMICS OF PERCEIVED AND ACTUAL FALL RISK

An accurate understanding of one’s abilities and limitations allows adaptive response to the challenges that are faced in daily life. However, older adults may over or under estimate their actual abilities. The Daily Balance Project examined the intraindividual dynamics of older adults’ perceived balance with objective measures of balance and physical activity. For 30 consecutive days, following a comprehensive fall risk assessment, 20 older adults rated their balance confidence (Activities Balance Confidence scale) at that moment and then performed five standardized balance assessments measured via smartphone accelerometer held to their chest. Physical activity was measured with an activity monitor. Baseline measurements of fall risk differentiated the extent of intraindividual variation and co-variation of balance and physical activity. For some participants, actual and perceived balance became more closely aligned as the study progressed. The implications of the findings for life-span perspectives on aging and fall prevention are discussed.

Is there a direct relation between the development of vocabulary and grammar?

Previous studies of individual differences have revealed strong correlations between children's vocabulary and grammatical abilities, and these data have been used to support theoretical accounts positing direct developmental relations between these two areas of language. However, between-person differences do not necessarily reflect intra-individual dynamics. Thus, in the present study, we analysed longitudinal data from three annual assessments of vocabulary and grammar in 217 children (Mage = 4 years and 3 months at first assessment) using a modelling strategy with some utility in distinguishing relations at the between- and within-person levels. The results revealed strong correlations between grammar and vocabulary at the between-person level, but the evidence of direct dependencies between the variables at the within-person level was rather limited. Specifically, we found a small direct contribution from grammar to vocabulary for children between the ages of 4 and 5, but there was no evidence of any direct contributions from vocabulary to grammar. Further analyses suggested that the home literacy environment may represent a common source of individual differences in children's vocabulary and grammatical skills. In light of these results, we argue that the evidence of direct relations between vocabulary and grammatical development in preschool-aged children may not be as strong as previously assumed.