The role of life events in onset and recurrent episodes of schizophrenia and schizoaffective disorder

Dynamic interplay between life events and course of psychotic disorders: 10-year longitudinal study following first admission

BACKGROUND

Life events (LEs) are a risk factor for first onset and relapse of psychotic disorders. However, the impact of LEs on specific symptoms - namely reality distortion, disorganization, negative symptoms, depression, and mania - remains unclear. Moreover, the differential effects of negative v. positive LEs are poorly understood.

METHODS

The present study utilizes an epidemiologic cohort of patients (N = 428) ascertained at first-admission for psychosis and followed for a decade thereafter. Symptoms were assessed at 6-, 24-, 48-, and 120-month follow-ups.

RESULTS

We examined symptom change within-person and found that negative events in the previous 6 months predicted an increase in reality distortion (β = 0.07), disorganized (β = 0.07), manic (β = 0.08), and depressive symptoms (β = 0.06), and a decrease in negative symptoms (β = -0.08). Conversely, positive LEs predicted fewer reality distortion (β = -0.04), disorganized (β = -0.04), and negative (β = -0.13) symptoms, and were unrelated to mood symptoms. A between-person approach to the same hypotheses confirmed that negative LEs predicted change in all symptoms, while positive LEs predicted change only in negative symptoms. In contrast, symptoms rarely predicted future LEs.

CONCLUSIONS

These findings confirm that LEs have an effect on symptoms, and thus contribute to the burden of psychotic disorders. That LEs increase positive symptoms and decrease negative symptoms suggest at least two different mechanisms underlying the relationship between LEs and symptoms. Our findings underscore the need for increased symptom monitoring following negative LEs, as symptoms may worsen during that time.

Are adult stressful life events associated with psychotic relapse? A systematic review of 23 studies

Relapse rates among individuals with psychotic disorders are high. In addition to the financial burden placed on clinical services, relapse is associated with worse long-term prognosis and poorer quality of life. Robust evidence indicates that stressful life events commonly precede the onset of the first psychotic episode; however, the extent to which they are associated with relapse remains unclear. The aim of this systematic review is to summarize available research investigating the association between recent stressful life events and psychotic relapse or relapse of bipolar disorder if the diagnosis included psychotic symptoms. PsycINFO, Medline and EMBASE were searched for cross-sectional, retrospective and prospective studies published between 01/01/1970 and 08/01/2020 that investigated the association between adult stressful life events and relapse of psychosis. Study quality was assessed using the Effective Public Health Practice Project guidelines. Twenty-three studies met eligibility criteria (prospective studies: 14; retrospective studies: 6; cross-sectional: 3) providing data on 2046 participants in total (sample size range: 14-240 participants). Relapse was defined as a return of psychotic symptoms (n = 20), a return of symptoms requiring hospitalization (n = 2) and a return of symptoms or hospitalization (n = 1). Adult stressful life events were defined as life events occurring after the onset of psychosis. Stressful life events included but were not limited to adult trauma, bereavement, financial problems and conflict. Eighteen studies found a significant positive association between adult stressful life events and psychotic relapse and five studies found a non-significant association. We conclude that adult stressful life events, occurring after psychosis onset, appear to be associated with psychotic relapse.

Transcriptional changes in the stress pathway are related to symptoms in schizophrenia and to mood in schizoaffective disorder

Altered levels of stress-signalling transcripts have been identified in post-mortem brains of people with schizophrenia, and since stress effects may be expressed throughout the body, there should be similar changes in peripheral cells. However, the extent to which these markers are altered in peripheral white blood cells of people with schizophrenia is not known. Furthermore, how peripheral cortisol and stress-related mRNA are associated with negative symptom severity and emotional states in people with schizophrenia versus schizoaffective disorder has not been determined. Whole blood samples were collected from 86 patients with either schizophrenia or schizoaffective disorder (56 people with schizophrenia and 30 people with schizoaffective disorder), and 77 healthy controls. Total RNA was isolated, cDNA was synthesized, and stress-signalling mRNA levels (for NR3C1, FKBP5, FKBP4, PTGES3 and BAG1) were determined. Stress and symptom severity scores were measured by the Depression, Anxiety and Stress Scale, and the Positive and Negative Syndrome Scale, respectively. We found increased FKBP5 mRNA, Z(156) = 2.5, p = 0.01, decreased FKBP4 mRNA, t(155) = 3.5, p ≤ 0.001, and decreased PTGES3 mRNA, t(153) = 3.0, p ≤ 0.01, in schizophrenia and schizoaffective disorder cohorts combined compared to healthy controls. Stress-related peripheral mRNA levels were differentially correlated with negative emotional states and symptom severity in schizoaffective disorder (β's = -0.45-0.56, p's = 0.05-0.001) and schizophrenia (β's = -0.34-0.38, p's = 0.04-0.03), respectively. Therefore, molecules of the stress-signalling pathway appear to differentially contribute to clinical features of schizophrenia versus schizoaffective disorder.

An improved method for counting stressful life events (SLEs) when predicting mental health and wellness

OBJECTIVE

Checklists for registering stressful life events (SLEs) generally correlate negatively, but weakly, with mental health outcome measures. Thus, the present study examined various methodological approaches for improving these relationships.

DESIGN

A total of 1679 participants (women = 943, men = 736, M age-39.8) were randomly drawn from the general Norwegian population (response rate 34%). This prospective cohort study included two follow-ups at 10 (n = 1181) and 23 months (n = 942).

MAIN OUTCOME MEASURES

Satisfaction with life and absence of psychological distress (i.e. anxiety and depression) represented a joint measure for indexing 'mental wellness' (MW).

RESULTS

A simple count of SLEs weakly predicted MW, as expected, whereas the addition of a moderator (i.e. manageability of the event) substantially improved predictive power. Four additional moderators were examined: duration, impact, help-seeking and time since onset, but these were non-significant after inserting manageability into the model. This SLE counting method also retained its predictive power after including multiple criterion-related variables that substantially adjusted the longitudinal statistical model.

CONCLUSION

This new SLE counting method exhibited a considerable improvement to predicting mental health and well-being. It is well suited for use in epidemiological research requiring a short SLE checklist format with high predictive power.

Life events in schizoaffective disorder: A systematic review

BACKGROUND

Life events play a central role in the development of psychiatric disorders and impact course and outcome. We present a systematic review of the literature on the relationship of life events with the onset and long-term course of schizoaffective disorder.

METHODS

MEDLINE was searched with the combination of the key words: 'life events' plus 'schizoaffective'. The PRISMA method was followed in the review process.

RESULTS

From the identified 66 papers only 12 were considered to be of relevance to the current study and 6 more papers were identified by inspecting the reference lists of the identified papers.

LIMITATIONS

There are very few studies focusing on the role of life events in schizoaffective disorder indicating insufficient data concerning the relationship of life events with onset and long-term course of schizoaffective disorder. Reported effects are not generic but concern specific events like the loss of mother, and females seem to be more vulnerable. Patients with schizoaffective disorder manifest high rates of PTSD.

CONCLUSION

The literature on life events with the development and course of schizoaffective disorder is limited and precludes solid conclusions.

Recent life events and psychosis: The role of childhood adversities

Life events are commonly reported to be related to psychosis. However, less attention has been given to the role that recent events play on psychosis, in relation to exposure to childhood adversity. The current study aimed to evaluate the relationship between recent events and psychosis, taking into account the role of early adversities. 78 psychotic patients and 156 controls were enrolled. Childhood adversity was evaluated using a validated semi-structured interview and the Childhood Experience of Care and Abuse Questionnaire. Recent events were recorded using a semi-structured interview with a normative and contextual approach. The diagnosis of psychosis was made according to Jablenski's criteria. Chi-square, t-test, odds ratio, and binary logistic regression statistical analyses were performed. Psychotic patients reported an excess of recent events. The occurrence of more than one recent event increased the risk of psychosis; there was a cumulative effect between recent and childhood events on psychosis. Recent events were significantly related to psychosis, even in the absence of childhood adversity or when adjusted for it. Our findings suggested that the effect of recent events on psychosis may be amplified by previous exposure to early adversity. Recent events alone, could be also linked to psychosis independently of childhood adversity.

The role of vulnerability factors in individuals with an at-risk mental state of psychosis

BACKGROUND

Several indicators of heightened vulnerability to psychosis and relevant stressors have been identified. However, it has rarely been studied prospectively to what extent these vulnerability factors are in fact more frequently present in individuals with an at-risk mental state for psychosis. Moreover, it remains unknown whether any of these contribute to the prediction of psychosis onset in at-risk mental state individuals.

METHODS

There were 28 healthy controls, 86 first-episode psychosis patients and 127 at-risk mental state individuals recruited within the Basel "Früherkennung von Psychosen" project. Relative frequencies of selected vulnerability factors for psychosis were compared between healthy controls, psychosis patients, those at-risk mental state individuals with subsequent psychosis onset (n = 31) and those without subsequent psychosis onset (n = 55). Survival analyses were applied to determine associations between time to transition to psychosis and vulnerability factors in all 127 at-risk mental state individuals.

RESULTS

The vulnerability factors/indicators such as "difficulties during school education or vocational training", "difficulties during employment", "being single", "difficulties with intimate relationships" and "being burdened with specific stressful situations" were more commonly found in the at-risk mental state and first-episode psychosis group than in healthy controls.

CONCLUSIONS

At-risk mental state and first-episode psychosis individuals more frequently present with vulnerability factors. Individual vulnerability factors appear, however, not to be predictive for an onset of psychosis.

Violence Affects Physical and Mental Health Differently: The General Population Based Tromsø Study

This general population-based study examined associations between violence and mental health, musculoskeletal pain, and early disability pension. The prevalence and consequences of good vs. poor adjustment (resilience vs. vulnerability) following encounters with violence were also examined. Data were based on the sixth wave of the "Tromsø Study" (N = 12,981; 65.7% response rate, 53.4% women, M-age = 57.5 years, SD-age = 12.7 years). Self-reported data on psychological (threats) and physical violence (beaten/kicked), mental health (anxiety/depression), musculoskeletal pain (MSP), and granting of disability pension (DP) were collected. Men suffered more violent events during childhood than women did, and vice versa during adulthood. Psychological violence implied poorer mental health and slightly more MSP than physical violence. The risk of MSP was highest for violence occurring during childhood in women and during the last year for men. A dose-response relationship between an increasing number of violent encounters and poorer health was observed. About 58% of individuals reported no negative impact of violence (hence, resilience group), whereas 42% considered themselves as more vulnerable following encounters with violence. Regression analyses indicated comparable mental health but slightly more MSP in the resilience group compared to the unexposed group, whereas the vulnerable group had significantly worse health overall and a higher risk of early granting of DP. Resilience is not an all-or-nothing matter, as physical ailments may characterize individuals adapting well following encounters with violence.

Stress exposure and sensitivity in the clinical high-risk syndrome: initial findings from the North American Prodrome Longitudinal Study (NAPLS)

There is inconsistent evidence for increased stress exposure among individuals at clinical high risk (CHR) for psychosis. Yet similar to patients with a diagnosed psychotic illness, the preponderance of evidence suggests that CHR individuals tend to experience stressful life events (LE) and daily hassles (DH) as more subjectively stressful than healthy individuals. The present study utilizes data from the North American Prodrome Longitudinal Study Phase 2 (NAPLS-2) to test the hypotheses that (1) CHR individuals manifest higher self-reported stress in response to both LE and DH when compared to healthy controls (HC), (2) group differences in self-reported stress increase with age, (3) baseline self-reported stress is associated with follow-up clinical status, and (4) there is a sensitization effect of LE on the response to DH. In contrast to some previous research, the present findings indicate that the CHR group (N=314) reported exposure to more LE when compared to the HC group (N=162). As predicted, CHR participants rated events as more stressful, and those who progressed to psychosis reported a greater frequency of LE and greater stress from events compared to those whose prodromal symptoms remitted. There was also some evidence of stress-sensitization; those who experienced more stress from LE rated current DH as more stressful. The results indicate that the "prodromal" phase is a period of heightened stress and stress sensitivity, and elevated cumulative lifetime exposure to stressful events may increase reactions to current stressors.

Stressful life events, social class and symptoms of schizophrenia

We test to see if severe stressful life events precede onset of specific symptoms of schizophrenia. Our analyses extend to possible variations in the effect by socioeconomic status (SES) of origin. The medical records of 431 schizophrenic patients were categorized into negative and positive subtypes by application of SANS, SAPS and PANS scales. SES was bifurcated into low SES and high SES groups. Stressful life events were classified into four domains. The study variables were tested by the use of chi-square analysis. Our results show that there is an elevated rate of positive symptoms among low SES patients who underwent a stressful life event before symptom onset. Significance is confirmed with a X2 value of 5.418, p=.020. The finding does not hold true for high SES patients and is not related to type of stressful life event. Thus, we conclude that environmental stressors frequently precede onset of positive symptoms of schizophrenia. This is only true for patients of low SES of origin. We hypothesize that low SES patients have a heightened reactivity to stressors, a reactivity that is incubated by the human toll of impoverishment.

Effects of the adverse life events and Disrupted in Schizophrenia-1 (DISC1) gene polymorphisms on acute symptoms of schizophrenia

The aim of this study was to evaluate the effects of traumatic childhood events and recent adverse life events, as well as the Disrupted in Schizophrenia-1 (DISC1) gene polymorphisms on types of last acute symptoms of patients with schizophrenia. Hundred patients with schizophrenia were given the Childhood Trauma Questionnaire, the Social Readjustment Rating Scale, Scale for Assessment of Positive Symptoms (SAPS), Scale for Assessment of Negative Symptoms (SANS), Brief Psychiatric Rating Scale (BPRS), and Calgary Depression Scale for Schizophrenia (CDSS). The patients' and healthy controls' DISC1 gene was evaluated for the -274G>C, c.791G>A, and c.2110A>T polymorphisms. There was no statistically significant difference with regard to the DISC1 gene polymorphisms between patient and healthy control groups. No significant relationship was found between the -274G>C, c.791G>A, and c.2110A>T haplotypes and development of different acute symptoms of schizophrenia. Having a recent stressful life event significantly affected SAPS (95% confidence interval [CI]=-67.547, -21.473; p=0.00) and BPRS-1 scores (95% CI=-51.405, -6.885; p=0.01), whereas emotional abuse at childhood significantly affected SANS scores (95% CI=-37.300, -10.401; p=0.00). This study shows that features of acute symptoms in schizophrenia are not influenced by the polymorphisms on the DISC1 gene, but are influenced by recent adverse life events and emotional abuse at childhood.

Longitudinal study of stressful life events and daily stressors among adolescents at high risk for psychotic disorders

Psychosocial stress preceding the onset or recurrence of psychotic symptoms has been identified in patients with schizophrenia; yet there is limited understanding of the effects of stress in typically developing adolescents or those who show behavioral signs of risk for schizophrenia spectrum disorders. This study examined the developmental course of symptom progression as a function of stressful life events and daily hassles in adolescents with schizotypal personality disorder (SPD), other personality disorders, or no Axis II disorder. In this prospective longitudinal study, life events and daily stressors were assessed in adolescents aged 12 to 18 years. Results revealed that adolescents with SPD and other personality disorders reported significantly greater total, independent, and undesirable life events than individuals with no Axis II disorders. Youth with SPD report daily hassles to cause more distress compared to peers. Correlational analyses and hierarchal linear regression was used to evaluate the relationship of life events and daily stressors with psychiatric symptoms measured concurrently and 1 year later. Across diagnostic groups, the incidence of independent and undesirable life events were associated with current prodromal symptoms, while the frequency of daily stressors predicted a significant increment in positive, but not negative, prodromal symptoms over time. Therefore, adolescents who report greater daily stressors exhibit an increase in prodromal symptoms over a 1 year period. Psychosocial stress has been implicated in the etiology of schizophrenia, and these findings suggest the importance of life events and daily hassles as potential risk factors in the onset of psychotic symptoms during adolescence.

The role of intrusive and other recent life events on symptomatology in relapses of schizophrenia: a community nursing investigation

This study aimed to identify the impact of life events on psychotic relapse in individuals with an established diagnosis of schizophrenia to explore their proneness to experience life events, to examine if any effect of life events was cumulative or triggering in nature and to explore if specific types of events influence subsequent symptom formation. An association between adverse life events and relapse in people with schizophrenia has been reported in several studies; however, the nature of the association remains unclear. Some studies suggest that intrusive events promote the formation of paranoid psychotic symptoms. Using well-validated semi-structured interview schedules the author interviewed participants during or shortly after relapse. The severity and intrusiveness of life events was rated and relationships between events and symptoms were explored. Increasing numbers of patients experienced life events especially moderately threatening life events in the last 4 weeks prior to relapse; however, no relationship was discovered between life events in general or specifically intrusive life events and the specific content of psychotic symptoms. An increased frequency of milder life events occurred in the 2 months prior to relapse, suggesting that chronic illness is not associated with absence of mild or moderately severe life events or with diminished sensitivity to them.

Life events; their role in onset and relapse in psychosis, research utilizing semi-structured interview methods: a literature review

This literature review explores the findings of studies that adopted semi-structured interviewing methods to assess the impact of life events on the course of psychotic illness. It begins by discussing the historical context and theoretical underpinnings of the use of semi-structured approaches to measure the role and impact of life events in the onset and course of psychotic illness. The review then focuses on the main findings of the studies commencing by focusing on causality by specifically discussing the time frame from life event to relapse and whether life events have a triggering role or cumulative effect in onset. The review examines the sample populations studied and asks whether they are homogenous and comparable or heterogeneous, therefore making comparisons between studies less valid. Issues concerning the number of episodes of illness and sensitivity to relapse are explored. The review concludes that despite a general acceptance in the literature that life events have an impact on psychotic illness the findings of life events studies provide contradictory and inconclusive results and that this is at least partly attributable to the differing methodologies utilized. Continued methodological refinements may generate a 'gold standard' methodology that with repeated use will provide consistency in findings.

Stress and psychosis: towards the development of new models of investigation

The experience of stress is commonly implicated in the onset and maintenance of psychotic disorders such as schizophrenia. Previous studies that have addressed this relationship have had mixed results and serious methodological flaws associated with study design are common. One central limitation is the over-reliance on the experience of life events as a measure of the experience of stress. Research in the general stress literature suggest that attention also needs to be paid to the experience of other types of stressful events (such as 'hassles') as well as qualitative appraisals of events to fully understand the relationship between stressful experiences and mental health problems such as psychosis. Investigation of the experiences of stress by young people who are identified as being at heightened risk of developing a psychotic disorder would also result in a more complete understanding of the relationship between the experience of stress and the onset of psychotic disorder.

Mapping of hippocampal gene clusters regulated by the amygdala to nonlinkage sites for schizophrenia

A recent study using a 'partial' rodent model of schizophrenia has employed amygdalar activation to induce reported changes in the expression of hippocampal genes associated with metabolic and signaling pathways in response to amygdalar activation. The amygdalo-hippocampal pathway plays a central role in the regulation of the stress response and emotional learning. In the current study, we have performed a chromosome mapping analysis to determine whether genes showing changes in response to environmental stress may form clusters and, if so, whether they might show a topographical association with linkage sites for schizophrenia. When the hippocampal genes showing changes in expression were topographically mapped on specific rat chromosomes, significant clustering was observed on chromosomes 1, 4 and 8, although chromosome 1 showed the largest amount of clustering. When these same rodent genes were mapped to human chromosomes, most of the genes found on chromosome 1 in rat mapped to chromosome 11 in human. The vast majority of the genes showing changes in regulation were excluded from known linkage sites for schizophrenia. Based on these findings, we postulate that environmental factors may contribute to the endophenotype for schizophrenia through the activation and/or deactivation of specific genetic clusters, ones that do not appear to be directly associated with susceptibility genes for this disorder.

Environmental risk factors for psychosis

Genetic factors are clearly important in the etiology of schizophrenia, but the environment in which an individual's genes find expression is also crucial to the development of the illness. In this review of environmental risk factors for schizophrenia, we consider risks operating prenatally and perinatally, during childhood, and then later in life prior to illness onset. Some of these risk factors have been well documented, for example, early hazards causing fetal growth retardation or hypoxia, and hazards nearer the onset of illness like drug abuse and migration. Others are much less certain. The importance of interaction between genetic and environmental risk is, however, undoubtedly important and there is emerging evidence for this from a range of sources. As the etiology of schiz-ophrenia is unraveled, the picture becomes more complex, but also more obviously relevant to the plight of the individual patient.

Psychotic disorders in Prader-Willi syndrome

The Prader-Willi syndrome (PWS) is a genetically determined developmental disorder caused by abnormalities of the proximal region of chromosome 15q11-13. In a previous study, we reported that psychotic episodes, occurring in 16% of persons with PWS, had an onset in adolescence, never occurred in persons with paternal deletion, and were exclusively associated with maternal uniparental disomy (UPD) or imprinting abnormalities (IM). In order to gain a better understanding of the psychopathology and to further refine the psychiatric diagnosis, we describe in more detail the psychopathological manifestations of six adults with a history of psychotic episodes. All these individuals had a detailed psychiatric examination, including the use of the operational criteria (OPCRIT) checklist. An identifiable subtype of psychotic disorder was associated with PWS. Characteristics include early age of onset, acute onset, polymorphous, and shifting symptomatology and a need for psychiatric hospitalization. The presence of precipitating stress factors and a prodromal phase with physiological symptoms was reported in all patients. Current diagnostic categories do not allow an unequivocal psychiatric diagnosis.

Psychiatric admissions for psychosis in Malmö during the NATO bombing of Kosovo

Little is known about the possible mechanisms contributing to increased risk for psychosis found among immigrants. We used the NATO bombing campaign of Kosovo as a naturalistic experiment to explore the role of potentially stressful aspects of minority group status. We examined all patient admissions to the psychiatric clinic in Malmö during the months of the NATO campaign in Kosovo in 1999 and during control months in 1997. Admission rates showed significantly differing trends over time, with an increasing proportion of immigrant patients with psychosis admitted during the NATO campaign months and a decreasing proportion of such patients admitted during control months. A significantly greater proportion of the immigrant patients admitted for psychosis during the NATO campaign months versus control months had been exposed to extreme duress before migration. Cumulative adversity, either solely or in combination with current stress, may possibly contribute to increased risk for psychosis among immigrants.

The causes of schizophrenia: neurodevelopment and other risk factors

Understanding the etiology of schizophrenia has been a considerable challenge. The neurodevelopmental hypothesis has held sway in recent years, focusing our attention on biological causes acting in early life. Much evidence supports this hypothesis and risk factors operating in early life (e.g., obstetric complications) have been shown to be associated with the later development of schizophrenia. Indicators of abnormal neurodevelopment that characterize individuals vulnerable to later developing schizophrenia have also been identified. For example, as a group, children who will later develop schizophrenia subtly differ from their peers in terms of their motor, cognitive, and social functioning. However, there is much that cannot be explained in purely neurodevelopmental terms. There is growing evidence of associations between the risk of schizophrenia and factors such as drug misuse, ethnicity/migration, life events, and urbanicity. A multifactorial model of causation that encompasses biological, social, and psychological elements is arguably both a better representation of current research findings and a more appropriate model for clinical practice.

On episode sensitization in recurrent affective disorders: the role of noise

Episode sensitization is postulated as a key mechanism underlying the long-term course of recurrent affective disorders. Functionally, episode sensitization represents positive feedback between a disease process and its disease episodes resulting in a transition from externally triggered to autonomous episode generation. Recently, we introduced computational approaches to elucidate the functional properties of sensitization. Specifically, we considered the dynamics of episode sensitization with a simple computational model. The present study extends this work by investigating how naturally occurring, internal or external, random influences ("noise") affect episode sensitization. Our simulations demonstrate that actions of noise differ qualitatively in dependence on both the model's activity state as well as the noise intensity. Thereby induction as well as suppression of sensitization can be observed. Most interestingly, externally triggered sensitization development can be minimized by tuning the noise to intermediate intensities. Our findings contribute to the conceptual understanding of the clinical kindling model for affective disorders and also indicate interesting roles for random fluctuations in kindling and sensitization at the neuronal level.

Effects of noise on different disease states of recurrent affective disorders

BACKGROUND

Nonlinear dynamics are currently proposed to explain the course of recurrent affective disorders. Such a nonlinear disease model predicts complex interactions with stochastic influences, in particular, because both disease dynamics and stochastic influences, such as psychosocial stressors, will vary during the course of the disease. We approach this problem by investigating general effects of noise intensity on different disease states of a nonlinear model for recurrent affective disorders.

METHODS

A recently developed neurodynamic model is studied numerically.

RESULTS

Noise can cause unstructured randomness or can maximize periodic order. The frequency of episode occurrence can increase with noise but it can also remain unaffected or even can decrease. The observed effects, thereby, depend critically on both the noise intensity and the internal nonlinear dynamics of the disease model.

CONCLUSIONS

Our findings indicate that altered stochastic influences can significantly affect the outcome of a dynamic disease. To evaluate the effects of noise, it is essential to know about the underlying dynamics of respective disease states. Therefore, characterization of low-dimensional dynamics might become valuable for disease prediction and control.