scholarly journals The Lindy effect in psychology: Network dynamics reinforce depression over time

2021 ◽  
Author(s):  
Eren Asena
Keyword(s):  
Mental Disorders ◽  
Time Distribution ◽  
Hazard Function ◽  
Network Dynamics ◽  
Stopping Time ◽  
Lifetime Distribution ◽  
Pathological State ◽  
Stable States ◽  
Over Time ◽  
Time Point

This paper studies the factors that sustain mental disorders by taking a network approach. The network theory suggests that mental disorders are networks of symptoms that causally interact (Borsboom, 2017). Symptom networks share certain dynamics with other complex systems: abrupt transitions between stable states, critical slowing down and hysteresis (Cramer et al., 2016). These findings suggest that symptom networks that have transitioned to a pathological state tend to remain that state. We argue that this tendency leads to the Lindy effect in symptom networks. The Lindy effect means that the conditional probability of surviving beyond a time point, given survival until that time point, increases over time (Taleb, 2014). In other words, time benefits future survival. A symptom network is considered to have survived until a time point if it has remained in a pathological state until that point. We first show how the Lindy effect is formalised by examining the stopping time distribution of Brownian motion with an absorbing barrier (Cook, 2012; Taleb, 2018). Specifically, we describe the hazard function of the stopping time distribution and make a distinction between "strong Lindy" and "weak Lindy". Strong Lindy is a monotonically decreasing hazard function whereas weak Lindy means an inverted-U shaped hazard function. Then, major depressive disorder (MDD) networks were simulated, manipulating the level of symptom connectivity. As before, the presence of the Lindy effect in these networks were tested using hazard functions, and in addition, survival probabilities conditioned on time. Afterwards, we fit a distribution to the network lifetimes. The lifetime distribution of strongly connected networks were heavy tailed and showed the Lindy effect; the longer a network had been depressed, the more likely it was to remain depressed. The lifetime distribution of weakly connected networks were light tailed and did not show the Lindy effect. After discussing caveats and alternative explanations of the findings, we conclude that network dynamics and the resulting Lindy effect can explain several findings in psychology such as the chronicity of depression (Swaminath, 2009) and the frequency distribution of remission times (Simon, 2000; Patten et al., 2010).

Modeling the probability of occurrence of events

2021 ◽  
pp. 096228022110224
Author(s):  
Matteo Bottai ◽  
Andrea Discacciati ◽  
Giola Santoni
Keyword(s):  
Clinical Trial ◽  
Hazard Function ◽  
Renal Carcinoma ◽  
Probability Function ◽  
Survival Functions ◽  
Event Probability ◽  
Proportional Odds Models ◽  
Computational Aspects ◽  
Over Time ◽  
Time Point

This paper introduces the event-probability function, a measure of occurrence of an event of interest over time, defined as the instantaneous probability of an event at a given time point conditional on having survived until that point. Unlike the hazard function, the event-probability function is a proper probability. This paper describes properties and interpretation of the event-probability function, presents its connection with other popular functions, such as the hazard and survival functions, proposes practical flexible proportional-odds models for estimating conditional event-probabilities given covariates with possibly censored and truncated observations, discusses the theoretical and computational aspects of parameter estimation, and applies the proposed models for assessing mortality in patients with metastatic renal carcinoma from a randomized clinical trial.

scholarly journals Levels of physical activity in four domains and affective wellbeing before and during the Covid-19 pandemic

2021 ◽  
Vol 79 (1) ◽  
Author(s):  
Eliane S. Engels ◽  
Michael Mutz ◽  
Yolanda Demetriou ◽  
Anne K. Reimers
Keyword(s):  
Mental Health ◽  
Physical Activity ◽  
Protective Factor ◽  
Total Sample ◽  
Poor Mental Health ◽  
German Population ◽  
Time Points ◽  
Sport And Exercise ◽  
Over Time ◽  
Time Point

Abstract Background Latest studies indicated that the general mental health level is low during the pandemic. Probably, this deterioration of the mental health situation is partly due to declines in physical activity. The aim of this study was to investigate differences in and the association between affective wellbeing and levels of different domains of physical activity at three time points before and during the pandemic. Method We used a nationwide online panel with a trend data design encompassing a total sample of N = 3517, representing the German population (> 14 years). Four different activity domains (sport and exercise, light outdoor activity, housework/gardening, active travel) and affective wellbeing (positive and negative affect) were assessed at three time points before and during the Covid-19 pandemic (October 2019, March 2020, October 2020). Results Multivariate analyses of variance (MANOVA) indicate differences regarding affective wellbeing over the three time points with the lowest values at the second time point. Levels of activity in the four domains differed significantly over time with the strongest decrease for sport and exercise from the first to the second time point. Partial correlations indicated that the relationships between sport and exercise and positive affect were most consistent over time. Conclusions Overall, our findings suggest that physical activity plays a particularly important role in the pandemic period as a protective factor against poor mental health. Especially sports and exercise seem to be supportive and should be encouraged, e.g. by providing additional support in finding adequate outdoor, home-based or digital substitutes.

scholarly journals Knee Muscle Strength Recovery in the Early Period After ACL Reconstruction

2014 ◽  
Vol 2 (11_suppl3) ◽  
pp. 2325967114S0014
Author(s):  
Gulcan Harput ◽  
Hasan Erkan Kılınc ◽  
Hamza Özer ◽  
Gül Baltacı ◽  
Carl G. Mattacola
Keyword(s):  
Acl Reconstruction ◽  
Early Period ◽  
Quadriceps Strength ◽  
Isometric Strength ◽  
Time Points ◽  
Hamstring Muscles ◽  
Significant Difference ◽  
Isometric Torque ◽  
Over Time ◽  
Time Point

Objectives: The aim of this study was to investigate quadriceps and hamstrings isometric strength at 4, 8 and 12 week time points following ACL Reconstruction (ACLR) and to document the strength changes of these muscles over time. The primary hypothesis was that there would be significant increases in quadriceps and hamstring muscle strengths between the 4th, 8th and 12th weeks following ACLR. The secondary hypothesis was that the quadriceps index would be higher than hamstring index at 12th week after ACLR. Methods: Thirty patients (Mean ± SD [age, 29.1±2.3yrs; weight, 77.3±13.2kg; height, 172.1±7.1cm; BMI, 21.2±3.5kg/m2, time to surgery: 7.1±7.2 months]) who underwent ACLR with Hamstring Tendon Autograft (HTG) were enrolled in this study. The isometric strength of quadriceps and hamstring muscles was measured on an isokinetic dynamometer at 60° knee flexion angle at 4th, 8th and 12th weeks after surgery. The recovery of quadriceps and hamstring muscles strength following rehabilitation was expressed as a Quadriceps Index (QI) and Hamstring Index (HI) and calculated with the following formula:[(maximum voluntary isometric torque of the involved limb / maximum voluntary isometric torque by uninvolved limb) × 100]. Torque output of the involved and uninvolved limbs and quadriceps and hamstring indexes were used for the statistical analysis. A repeated measures of ANOVA was used to determine the strength changes of quadriceps and hamstrings over time. Results: Quadriceps and Hamstrings strengths significantly increased over time for both involved (Quadriceps: F (2,46)=58.3, p<0.001, Hamstring: F (2,46)=35.7, p<0.001) and uninvolved limb (Quadriceps: F(2,46)=17.9, p<0.001, Hamstring: F(2,46)=56.9, p=0.001 ). Quadriceps strength was higher at 12th week when compared to the 8 and 4 week time points for the involved limb (p<0.001), and it was higher at 8th week when compared to 4 week time point for the involved limb (p<0.001). For the uninvolved limb, quadriceps strength was also higher at 12th week when compared to the 8 (p=0.02) and 4 week time point (p<0.001), and higher at 8 week when compared to the 4 week time point (p=0.02). Hamstring strength was higher at 12 week when compared to the 8 and 4 week time points (p<0.001) and it was higher at 8 week when compared to 4 week time point for the involved limb (p<0.001). For the uninvolved limb hamstring strength was also higher at 12 week when compared to 4 week time point (p=0.01). There was no significant difference between the 4 and 8 week time points (p>0.05) or between the 8 and 12 week time points (p=0.07). Quadriceps and hamstring indexes significantly changed from 4th weeks (QI:57.9, HI:54.4 ) to 8th weeks (QI:78.8, HI:69.9 ) and from 8th weeks to 12th weeks (QI:82, HI:75.7 ) (p<0.001); however, there was no difference between indexes at the 12-week time point (p=0.17). Conclusion: Isometric strength of quadriceps and hamstring muscles for the involved and uninvolved limb increased during the early period of ACLR. The results of this study could be a baseline for clinicians while prescribing a rehabilitation protocol for ACLR patients with HTG to better appreciate expected strength changes of the muscles in the early phase.

scholarly journals Nitrogenous metabolism in Thoroughbred and Arabian foals from birth to five months of age

2006 ◽  
Vol 58 (4) ◽  
pp. 525-529 ◽  
Author(s):  
G. Piccione ◽  
A. Costa ◽  
F. Fazio ◽  
F. Grasso ◽  
G. Caola
Keyword(s):  
Uric Acid ◽  
Serum Concentration ◽  
Nitrogen Metabolism ◽  
Rectal Temperature ◽  
Total Protein ◽  
Critical Period ◽  
Critical Period Of Development ◽  
Over Time ◽  
Time Point ◽  
Nitrogenous Metabolism

The maturation of nitrogen metabolism was studied in six Thoroughbred and six Arabian foals. Rectal temperature, heart and respiratory rates and serum concentration of several hematochemical parameters (total protein, urea, uric acid, creatinine, and albumine) were monitored from birth to 5 months of age. In both breeds, all the parameters except albumine showed significant differences over time (P<0.05). The two breeds did not differ from each other at any time point. Statistically significant decreases in urea and creatinine concentrations were related to the growth needs of foals during this critical period of development.

The Influence of Social Factors on Common Mental Disorders

1990 ◽  
Vol 156 (5) ◽  
pp. 704-713 ◽  
Author(s):  
David Goldberg ◽  
Keith Bridges ◽  
Diane Cook ◽  
Barbara Evans ◽  
David Grayson
Keyword(s):  
Mental Disorders ◽  
Social Factors ◽  
Common Mental Disorders ◽  
Anxiety And Depression ◽  
Symptom Dimensions ◽  
Personality Variables ◽  
Over Time

This study distinguishes between processes that cause individuals to experience symptoms – destabilisation – and those that are associated with loss of symptoms over time – restitution. It is shown that different clinical, social, and personality variables are associated with each of these processes. Where destabilisation is concerned, it is shown that different variables were associated with the development of symptoms of anxiety and those of depression. Different variables were associated with restitution, and they did not show the same relationship with the symptom dimensions of anxiety and depression as those which were associated with destabilisation.

scholarly journals Assessing and predicting adolescent and early adulthood common mental disorders using electronic primary care data: analysis of a prospective cohort study (ALSPAC) in Southwest England

BMJ Open ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. e053624
Author(s):  
Daniel Smith ◽  
Kathryn Willan ◽  
Stephanie L Prady ◽  
Josie Dickerson ◽  
Gillian Santorelli ◽  
...  
Keyword(s):  
Primary Care ◽  
Cohort Study ◽  
Mental Disorders ◽  
Outcome Measures ◽  
Prospective Cohort Study ◽  
Prospective Cohort ◽  
Common Mental Disorders ◽  
Free Text ◽  
Primary Care Data ◽  
Time Point

ObjectivesWe aimed to examine agreement between common mental disorders (CMDs) from primary care records and repeated CMD questionnaire data from ALSPAC (the Avon Longitudinal Study of Parents and Children) over adolescence and young adulthood, explore factors affecting CMD identification in primary care records, and construct models predicting ALSPAC-derived CMDs using only primary care data.Design and settingProspective cohort study (ALSPAC) in Southwest England with linkage to electronic primary care records.ParticipantsPrimary care records were extracted for 11 807 participants (80% of 14 731 eligible). Between 31% (3633; age 15/16) and 11% (1298; age 21/22) of participants had both primary care and ALSPAC CMD data.Outcome measuresALSPAC outcome measures were diagnoses of suspected depression and/or CMDs. Primary care outcome measure were Read codes for diagnosis, symptoms and treatment of depression/CMDs. For each time point, sensitivities and specificities for primary care CMD diagnoses were calculated for predicting ALSPAC-derived measures of CMDs, and the factors associated with identification of primary care-based CMDs in those with suspected ALSPAC-derived CMDs explored. Lasso (least absolute selection and shrinkage operator) models were used at each time point to predict ALSPAC-derived CMDs using only primary care data, with internal validation by randomly splitting data into 60% training and 40% validation samples.ResultsSensitivities for primary care diagnoses were low for CMDs (range: 3.5%–19.1%) and depression (range: 1.6%–34.0%), while specificities were high (nearly all >95%). The strongest predictors of identification in the primary care data for those with ALSPAC-derived CMDs were symptom severity indices. The lasso models had relatively low prediction rates, especially in the validation sample (deviance ratio range: −1.3 to 12.6%), but improved with age.ConclusionsPrimary care data underestimate CMDs compared to population-based studies. Improving general practitioner identification, and using free-text or secondary care data, is needed to improve the accuracy of models using clinical data.

Delirium superimposed on dementia: defining disease states and course from longitudinal measurements of a multivariate index using latent class analysis and hidden Markov chains

2011 ◽  
Vol 23 (10) ◽  
pp. 1659-1670 ◽  
Author(s):  
Antonio Ciampi ◽  
Alina Dyachenko ◽  
Martin Cole ◽  
Jane McCusker
Keyword(s):  
Mental Disorders ◽  
Markov Chains ◽  
Latent Class Analysis ◽  
Latent Class ◽  
Hidden Markov ◽  
The Elderly ◽  
Population Heterogeneity ◽  
Class Analysis ◽  
Hidden Markov Chains ◽  
Time Point

ABSTRACTBackground: The study of mental disorders in the elderly presents substantial challenges due to population heterogeneity, coexistence of different mental disorders, and diagnostic uncertainty. While reliable tools have been developed to collect relevant data, new approaches to study design and analysis are needed. We focus on a new analytic approach.Methods: Our framework is based on latent class analysis and hidden Markov chains. From repeated measurements of a multivariate disease index, we extract the notion of underlying state of a patient at a time point. The course of the disorder is then a sequence of transitions among states. States and transitions are not observable; however, the probability of being in a state at a time point, and the transition probabilities from one state to another over time can be estimated.Results: Data from 444 patients with and without diagnosis of delirium and dementia were available from a previous study. The Delirium Index was measured at diagnosis, and at 2 and 6 months from diagnosis. Four latent classes were identified: fairly healthy, moderately ill, clearly sick, and very sick. Dementia and delirium could not be separated on the basis of these data alone. Indeed, as the probability of delirium increased, so did the probability of decline of mental functions. Eight most probable courses were identified, including good and poor stable courses, and courses exhibiting various patterns of improvement.Conclusion: Latent class analysis and hidden Markov chains offer a promising tool for studying mental disorders in the elderly. Its use may show its full potential as new data become available.

Grazer-epilithon interactions in an Australian upland stream

1996 ◽  
Vol 47 (6) ◽  
pp. 831 ◽  
Author(s):  
J Jordan ◽  
PS Lake
Keyword(s):  
Organic Matter ◽  
Algal Biomass ◽  
Food Resource ◽  
Organic Matter Content ◽  
Treatment Patterns ◽  
Matter Content ◽  
Abiotic Conditions ◽  
Diatom Density ◽  
Over Time ◽  
Time Point

Effects of macroinvertebrate grazers on the distribution of their food resource, epilithon, were examined in a south-eastern Australian stream. The hypothesis that grazers would significantly alter the development of epilithon was tested experimentally: macroinvertebrates were excluded from some experimental substrata and allowed to colonize others. Epilithic chlorophyll a concentration, organic matter content and total diatom density were used to monitor the effects of the grazer assemblage over 35 days. As predicted, epilithon density was higher on bricks with exclusion barriers than on bricks open to colonization by grazers. Similarly, diatom densities were significantly higher on bricks from the grazer-exclusion treatment. Patterns in the development of epilithon over time point to the importance of prevailing abiotic conditions in determining the outcome of macroinvertebrate grazing. Differences in total epilithon biomass, algal biomass and diatom density between treatments clearly indicate the independent importance of macroinvertebrate grazing to the microdistribution of epilithon in upland streams.

scholarly journals Tissue Distribution Comparison of Six Active Ingredients from an Eucommiae Cortex Extract between Normal and Spontaneously Hypertensive Rats

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Hejia Hu ◽  
Hongqin Xiao ◽  
Hongsong Bao ◽  
Mei Li ◽  
Cun Xue ◽  
...  
Keyword(s):  
Tissue Distribution ◽  
Spontaneously Hypertensive Rats ◽  
Normal Group ◽  
Good Effect ◽  
Pathological State ◽  
Hypertensive Rats ◽  
Active Components ◽  
Spontaneously Hypertensive ◽  
Liquid Chromatography Tandem Mass ◽  
Time Point

Eucommiae Cortex (EC), a rare, nourishing medicinal herb that is native in China, has good effect in the treatment of hypertension. In this study, we compared tissue distribution of six representative active components of EC extract—genipinic acid (GA), protocatechuic acid (PCA), neochlorogenic acid (NCA), chlorogenic acid (CA), (+)-pinoresinol di-O-β-D-glucopyranoside (PDG), and (+)-pinoresinol 4′-O-β-D-glucopyranoside (PG)—between normal rats and spontaneously hypertensive rats (SHRs). Each rat was intragastrically given EC extract at a dose of 5.4 g/kg. Rats were sacrificed at 10 min, 30 min, 2 h, and 8 h after administration; six rats were sacrificed at each time point. Then, we quickly harvested their major organs, including heart, liver, spleen, lungs, kidneys, and brain. Using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), we determined the levels of the above mentioned six components in the organs of both types of rats and then analyzed differences in the tissue distribution. The results showed that levels of each component differed between SHRs and the normal group at each time point. As time progressed, the number of organs in which GA distribution in each tissue of SHRs differed from that of the normal group gradually increased: SHRs showed lower GA levels than normal rats. Levels of PG and PDG in both groups at 10 and 30 min were similar. NCA and CA in the SHR group and the normal group at 10 min, 30 min, and 2 h were also similar to some extent. The results indicated that the pathological state of spontaneous hypertension could affect tissue distribution of EC active components in rats.

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