Applying a Dynamical Systems Model and Network Theory to Major Depressive Disorder

Mental disorders like major depressive disorder can be seen as complex dynamical systems. In this study we investigate the dynamic behaviour of individuals to see whether or not we can expect a transition to another mood state. We introduce a mean field model to a binomial process, where we reduce a dynamic multidimensional system (stochastic cellular automaton) to a one-dimensional system to analyse the dynamics. Using maximum likelihood estimation, we can estimate the parameter of interest which, in combination with a bifurcation diagram, reflects the expectancy that someone has to transition to another mood state. After validating the proposed method with simulated data, we apply this method to two empirical examples, where we show its use in a clinical sample consisting of patients diagnosed with major depressive disorder, and a general population sample. Results showed that the majority of the clinical sample was categorized as having an expectancy for a transition, while the majority of the general population sample did not have this expectancy. We conclude that the mean field model has great potential in assessing the expectancy for a transition between mood states. With some extensions it could, in the future, aid clinical therapists in the treatment of depressed patients.Comment: arXiv admin note: text overlap with arXiv:1610.0504

Environmental influences on adult neuroticism:A systematic review

Behavioral-genetic studies show substantial non-genetic influences on variance of neuroticism within a population. Longitudinal studies show a small but steady drop in testretest correlations with increasing time intervals. This suggest environmental effects on neuroticism, but a systematic overview of which environmental determinants account for change in neuroticism is lacking. We review (specific or unique) environmental influences that modify the neuroticism setpoint in adulthood and therewith individual life trajectories. Results are interpreted in light of the so-called ‘mixed model’ in which within-person changes in neuroticism are subdivided over short term perturbations around the setpoint of neuroticism versus more persistent changes in the setpoint itself. To account for genetic confounding and shared environmental influences studies of monozygotic (MZ) twin pairs discordant for neuroticism and longitudinal studies that report on environmental factors that predict within-individual change in neuroticism are reviewed. Our results indicate that the neuroticism setpoint is consistently touched by experiences that affect central aspects of one’s identity and status, mainly role transitions as partner (marriage/divorce) and employee (job loss/promotion). Especially interpersonal stress, conflict, and major events that were unpredictable, uncontrollable, unexpected, undesirable, and ‘off time’ from a life history perspective were followed by changes in neuroticism that persisted more than six months, which suggest setpoint change. Most change after severe SLEs persisted over a decade. Long-term and detailed studies are required to elucidate the details of the ‘mixed model’ of change in neuroticism. An understanding of the specifics of the events that lead to persistent changes in neuroticism may enable us to craft prevention strategies to tackle the vulnerability for mental disorders inherent in high neuroticism, rather than to wait for their manifestation

Cross-instrument feasibility, validity, and reproducibility of wireless heart rate monitors:Novel opportunities for extended daily life monitoring

Wired ambulatory monitoring of the electrocardiogram (ECG) is an established method used by researchers and clinicians. Recently, a new generation of wireless, compact, and relatively inexpensive heart rate monitors have become available. However, before these monitors can be used in scientific research and clinical practice, their feasibility, validity, and reproducibility characteristics have to be investigated. Therefore, we tested how two wireless heart rate monitors (i.e., the Ithlete photoplethysmography (PPG) finger sensor and the Cortrium C3 ECG monitor perform against an established wired reference method (the VU-AMS ambulatory ECG monitor). Monitors were tested on cross-instrument and test-retest reproducibility in a controlled laboratory setting, while feasibility was evaluated in protocolled ambulatory settings at home. We found that the Cortrium and the Ithlete monitors showed acceptable agreement with the VU-AMS reference in laboratory setting. In ambulatory settings, assessments were feasible with both wireless devices although more valid data were obtained with the Cortrium than with the Ithlete. We conclude that both monitors have their merits under controlled laboratory settings where motion artefacts are minimized and stationarity of the ECG signal is optimized by design. These findings are promising for long-term ambulatory ECG measurements, although more research is needed to test whether the wireless devices' feasibility, validity, and reproducibility characteristics also hold in unprotocolled daily life settings with natural variations in posture and activities

Rejection sensitivity relates to hypocortisolism and depressed mood state in young women

Rejection sensitivity and the associated fear of negative social evaluation (FNSE) trait are characteristics of hypocortisolemic syndromes such as atypical depression. However, a meta-analysis showed that acute FNSE evokes strong cortisol responses in humans. This is consistent with suggestions that hypocortisolism reflects a protective adaptation to a history of high cortisol responses. This leads us to hypothesize that measures of trait FNSE relate to hypocortisotism. Moreover, because FNSE relates positively to depressed mood state, but negatively to cortisol, we expect that the positive relationship between depressed mood state and cortisol will show up most clearly when controlling for the confounding effect of FNSE on this relationship. In the present study we measured salivary cortisol awakening response and psychological variables in 194 community women aged 18-30 years. The results confirmed our hypotheses. We propose that dispositional FNSE is associated with a history of frequent high cortisol responses, leading to long-term protective inhibition of further cortisol and energy mobilization. The present results have special relevance for mental health problems that have high prevalence among young women. (C) 2008 Elsevier Ltd. All rights reserved.</p

Using person-specific networks in psychotherapy:challenges, limitations, and how we could use them anyway

Background The complexity of psychopathology is evident from its multifactorial etiology and diversity of symptom profiles and hampers effective treatment. In psychotherapy, therapists approach this complexity by using case conceptualization. During this process, patients and therapists closely collaborate on a personalized working theory of the patient’s psychopathology. This is a challenging process and shows low reliability between therapists. With the experience sampling method (ESM), time-series data—valuable for case conceptualization—can be systematically gathered in a patient’s normal daily life. These data can be analyzed and visualized in person-specific networks (PSNs). PSNs may support case conceptualization by providing a schematic representation of association patterns between affective, cognitive, behavioral, and context variables. Main text We adopt a clinical perspective in considering how PSNs might be implemented to serve case conceptualization and what their role could be in psychotherapy. We suggest PSNs to be based on personalized ESM assessment to capture the unique constellation of variables in each patient. We reflect on the lack of a gold standard for creating PSNs, which may result in substantially different PSNs and thereby disparate information for case conceptualization. Moreover, even if PSNs are created in a consistent manner, results remain ambiguous as they are subject to multiple interpretations. Therefore, associations in PSNs do not allow for firm conclusions about a patient’s psychopathology, but they may nevertheless be valuable in the process of case conceptualization. PSNs are based on systematically gathered, ecologically valid ESM data and provide a unique personalized perspective. When used responsibly, PSNs may be able to support case conceptualization by generating questions that serve as a starting point for a dialog between therapists and patients. Well-targeted questions are an essential tool for therapists to gain insight into the patients’ psychopathology patterns and improve the quality of case conceptualization. Conclusions PSNs have limitations in terms of the reliability of the insights they provide directly. However, taking these challenges into account, we believe they have potential as a tool to help therapists and patients in their collaborative exploration of a patient’s psychopathology. Clearly, this would need to be validated in future clinical research

ACTman:Automated preprocessing and analysis of actigraphy data

Objectives: To introduce a novel software-library called Actigraphy Manager (ACTman) which automates labor-intensive actigraphy data preprocessing and analyses steps while improving transparency, reproducibility, and scalability over software suites traditionally used in actigraphy research practice. Design: Descriptive. Methods: Use cases are described for performing a common actigraphy task in ACTman and alternative actigraphy software. Important inefficiencies in actigraphy workflow are identified and their consequences are described. We explain how these hinder the feasibility of conducting studies with large groups of athletes and/or longer data collection periods. Thereafter, the information flow through the ACTman software is described and we explain how it alleviates aforementioned inefficiencies. Furthermore, transparency, reproducibility, and scalability issues of commonly used actigraphy software packages are discussed and compared with the ACTman package. Results: It is shown that from an end-user perspective ACTman offers a compact workflow as it automates many preprocessing and analysis steps that otherwise have to be performed manually. When considering transparency, reproducibility, and scalability the design of the ACTman software is found to outperform proprietary and open-source actigraphy software suites. As such, ACTman alleviates important bottlenecks within actigraphy research practice. Conclusions: ACTman facilitates the current transition towards larger datasets containing data of multiple athletes by automating labor-intensive preprocessing and analyses steps within actigraphy research. Furthermore, ACTman offers many features which enhance user-convenience and analysis customization, such as moving window functionality and period selection options. ACTman is open-source and thus fully verifiable, in contrast with many proprietary software packages which remain a black box for researchers

Transitions in Depression (TRANS-ID) Recovery: Study protocol for a repeated intensive longitudinal n = 1 study design to search for personalized early warning signals of critical transitions towards improvement in depression

Aim. The Transitions in Depression (TRANS-ID) Recovery study has gathered intensive longitudinal data in a group of individuals with depression during psychological therapy.The study was designed to gather high-resolution time series to monitor individual change processes in great detail, to allow for personalized predictions of shifts in depressive symptoms.Method. The data collection combined experience sampling methods to assess momentary affect and behavior (five 27-item questionnaires a day, for four months), ambulatory assessment of physical activity and heart rate (continuous, for four months), and depression symptom assessments (weekly for six months, and monthly for the six months thereafter, twelve months total). In addition to a baseline diagnostic interview, baseline questionnaires covered a range of constructs, including overall psychopathology symptoms, medication use, psychological treatment history, alexithymia, life events, quality of life, and chronotype. After the four-month ambulatory assessment period, a personal report of the experience sampling data was given to each participant, and a semi-structured qualitative interview was conducted to evaluate participants’ own retrospective experience of symptom changes during the research period. Conclusion. The TRANS-ID Recovery study procedures and materials are described in detail in this document. The study protocol was approved by the Medical Ethical Committee of the University Medical Center Groningen (reg. number: NL58848.04.16)