Moderating effects of positive symptoms of psychosis in suicidal ideation among adults diagnosed with schizophrenia

Exploring the interplay between core and mood symptoms in schizophrenia: A network analysis

BACKGROUND

Schizophrenia is a complex neuropsychiatric disorder characterized by positive symptoms, negative symptoms, cognitive deficits, and co-occurring mood symptoms. Network analysis offers a novel approach to investigate the intricate relationships between these symptom dimensions, potentially informing personalized treatment strategies.

METHODS

A cross-sectional study was conducted from November 2019 to October 2021, involving 1285 inpatients with schizophrenia in Liaoning Province, China. Symptom severity was assessed using the Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Rating Scale (HAMA-14), and Montreal Cognitive Assessment (MoCA). Network analysis was conducted to investigate the network structure, central symptoms, and bridge symptoms.

RESULTS

The network analysis uncovered profound interconnectivity between core symptoms and the anxiety-depression community. Central symptoms, such as psychic anxiety, poor rapport, delusions, and attention, were identified as potential therapeutic targets. Bridge symptoms, including insomnia, depressed mood, anxiety-somatic, conceptual disorganization, and stereotyped thinking, emerged as key nodes facilitating interactions between symptom communities. The stability and reliability of the networks were confirmed through bootstrapping procedures.

DISCUSSION

The findings highlight the complex interplay between schizophrenia symptoms, emphasizing the importance of targeting affective symptoms and cognitive impairment in treatment. The identification of central and bridge symptoms suggests potential pathways for personalized interventions aimed at disrupting self-reinforcing symptom cycles. The study underscores the need for a transdiagnostic, personalized approach to schizophrenia treatment.

Can neurocognition, brain neurotrophic factor, triglyceride, and total cholesterol predict suicidal ideation in first-episode Han Chinese patients with schizophrenia?

OBJECTIVE

Previous studies have suggested that the suicide rate of patients with schizophrenia is high. This study investigates factors influencing suicidal ideation in first-episode schizophrenia patients, focusing on cognitive function, brain-derived neurotrophic factor (BDNF), triglyceride (TG), and total cholesterol (TC) in patients with first-episode schizophrenia.

METHODS

A total of 123 patients with first-episode schizophrenia and 38 healthy controls were included in the study. The patients were divided into suicidal and nonsuicidal ideation groups based on the Beck Scale for Suicidal Ideation, and they were assessed with Positive and Negative Syndrome Scale (PANSS). Cognitive function was assessed using the Chinese version of the MATRICS consensus cognitive battery (MCCB) and the serum BDNF, TG, and TC were detected. The main statistical methods include t-test, χ2 test, multivariate logistic regression analysis, receiver operating characteristic (ROC) curve analysis, and the DeLong test.

RESULTS

26.02% of patients exhibited suicidal ideation. Higher PANSS and TC levels were risk factors, while higher MCCB scores and BDNF levels were protective factors. ROC analysis indicated AUCs of 0.630, 0.724, and 0.762 for serum BDNF, PANSS, and MCCB, respectively, with a combined AUC of 0.870.

CONCLUSION

Serum BDNF level, PANSS score, and MCCB score can be used as auxiliary predictors of suicidal ideation in schizophrenic patients. Combining these three indicators can effectively predict suicidal ideation in schizophrenic patients.

Suicidal ideation in Chinese patients with chronic schizophrenia: prevalence, clinical correlates, and relationship with alexithymia

Suicidal ideation (SI) is common among people with schizophrenia. However, it has received less attention than suicide attempts (SA), especially in the Chinese population. Alexithymia is a well-established risk factor for SI across different populations. Nevertheless, very few studies evaluated their relationship in schizophrenia patients. We aimed to determine the prevalence and clinical correlates of SI and its relationship with alexithymia in 812 Chinese chronic schizophrenia inpatients. We assessed SI, clinical symptoms, and alexithymia by the Beck Scale for Suicidal Ideation, the Positive and Negative Syndrome Scale (PANSS), and the Toronto Alexithymia Scale, respectively. A multiple logistic regression model was conducted to identify independent correlates of SI. Receiver operating characteristic (ROC) curves and area under the curve (AUC) were performed to determine the ability of our model to distinguish between patients with and without SI. 10% (n = 84) reported current SI. Lifetime SA (OR, 4.68; 95% CI 2.76-7.94, p < 0.001), PANSS depressive factor (OR, 1.24; 95% CI 1.12-1.38, p < 0.001), PANSS positive subscale (OR, 1.055; 95% CI 1.004-1.108, p = 0.035), and difficulty identifying emotions (OR, 1.07; 95% CI 1.03-1.12, p = 0.002) were associated with SI. The AUC value was 0.80, indicating excellent distinguishing capabilities. Timely assessments of these factors may help identify schizophrenia patients who are at risk for SI.

The Relationship between the Therapeutic Alliance and Suicidal Experiences in People with Psychosis Receiving Therapy

Few studies have examined the relationship between the therapeutic alliance in therapy and suicidal experiences. No studies have examined this relationship with people with non-affective psychosis. The present study sought to redress this gap in the literature. Sixty-four participants with non-affective psychosis and suicidal experiences who were receiving a suicide-focused cognitive therapy were recruited. Self-reported suicidal ideation, suicide plans, suicide attempts, depression, and hopelessness were collected from participants prior to starting therapy. Suicidal experience measures were collected again post-therapy at 6 months. Therapeutic alliance ratings were completed by clients and therapists at session 4 of therapy. Dose of therapy was documented in number of minutes of therapy. Data were analyzed using correlation coefficients, independent samples t-tests, a multiple hierarchical regression, and a moderated linear regression. There was no significant relationship found between suicidal ideation prior to therapy and the therapeutic alliance at session 4, rated by both client and therapist. However, there was a significant negative relationship between the client-rated therapeutic alliance at session 4 and suicidal ideation at 6 months, after controlling for pre-therapy suicidal ideation, depression, and hopelessness. Furthermore, the negative relationship between the client-rated alliance and suicidal ideation was the strongest when number of minutes of therapy was 15 h or below. A stronger therapeutic alliance developed in the first few sessions of therapy is important in ameliorating suicidal thoughts in people with psychosis. Nevertheless, it is not necessarily the case that more hours in therapy equates to a cumulative decrease in suicidal ideation of which therapists could be mindful. A limitation of the current study was that the alliance was analyzed only at session 4 of therapy, which future studies could seek to redress.

Prevalence and predictors of suicidality and non-suicidal self-harm among individuals at clinical high-risk for psychosis: Results from a community-recruited sample

AIM

Suicidal thoughts and behaviours are prevalent in individuals with schizophrenia. However, research examining the prevalence and predictors of suicidality and self-harm in participants at clinical high-risk for psychosis (CHR-P) is limited and mostly focuses on help-seeking participants recruited through clinical pathways. The current study sought to assess the prevalence of suicidality and self-harm and identify predictors of current suicidal ideation in community-recruited CHR-P participants.

METHODS

Data were available for 130 CHR-P participants, 15 participants with first-episode psychosis (FEP), 47 participants not fulfilling CHR-P criteria (CHR-Ns) and 53 healthy controls. Current and lifetime suicidality and self-harm were assessed using the Mini-International Neuropsychiatric Interview and the Comprehensive Assessment of At-Risk Mental States (CAARMS). Multivariable logistic regression analysis was used to determine predictors of current suicidal ideation in the CHR-P group.

RESULTS

A considerable proportion of CHR-P participants disclosed current suicidal ideation (34.6%). Overall, FEP individuals were at greatest risk, with considerably high prevalence rates for current suicidal ideation (73.3%), lifetime self-harm behaviour (60.0%) and lifetime suicide attempt (60.0%). In the CHR-P sample, current suicidal ideation was predicted by lifetime suicide attempts, lower CAARMS severity, impaired social functioning and greater comorbidity.

CONCLUSIONS

Our findings suggest that suicidality and self-harm are highly prevalent in community-recruited CHR-P and FEP individuals. Accordingly, these results highlight the importance of further research into the determinants of suicidality and self-harm during at-risk and early stages of psychosis, and the implementation of intervention strategies to reduce adverse outcomes in these populations.

Longitudinal predictors of stigma in first-episode psychosis: Mediating effects of depression

AIM

Stigma is commonly experienced among individuals with schizophrenia spectrum disorders and has been shown to be a barrier to help-seeking and behavioural service utilization. Given the established relationships between stigma, barriers to treatment, and poorer psychiatric outcomes including depression and psychotic symptoms, we examined the relationships between symptoms of depression, positive and negative symptoms, and the emergence of stigma longitudinally among a sample of first-episode of psychosis (FEP) participants in the United States.

METHODS

Data were obtained from the Recovery After an Initial Schizophrenia Episode project of National Institute of Mental Health's Early Treatment Program. Participants (n = 404) included adults between ages 15 and 40 with schizophrenia or other psychotic disorders based on the DSM-IV. Data were analysed using structural equation modelling (SEM).

RESULTS

Findings indicated that increased positive and negative symptoms independently related to greater symptoms of depression at baseline. Furthermore, increased positive symptoms and symptoms of depression at baseline independently related to the emergence of greater stigma being experienced over time.

CONCLUSIONS

Considering the role that symptoms of depression played as a factor explaining the relationships between positive and negative symptoms and emergence of stigma over time among individuals in FEP, and symptoms of depression is important predictor of stigma and may furthermore present as a viable and less stigmatizing initial treatment target in the early course of a psychotic disorder.

Suicidal ideation in first-episode psychosis: Considerations for depression, positive symptoms, clinical insight, and cognition

BACKGROUND

Suicide is a leading cause of death for individuals with psychosis. Although factors influencing suicide risk have been studied in schizophrenia, far less is known about factors that protect against or trigger increased risk during early-stage and first episode of psychosis. This study examined whether depression, psychotic symptoms, clinical insight, and cognition were associated with suicide ideation among individuals with first-episode psychosis.

METHODS

Data were obtained from the Recovery After an Initial Schizophrenia Episode (RAISE) project. Participants (n = 404) included adults between ages 15 and 40 in a first episode of psychosis. Measurement included the Positive and Negative Syndrome Scale, Brief Assessment of Cognition in Schizophrenia, and Calgary Depression Scale for Schizophrenia. A logistic regression model evaluated clinical and cognitive variables as predictors of suicidal ideation.

RESULTS

Greater positive symptoms (OR = 1.085, p < .01) and depression (OR = 1.258, p < .001) were associated with increased likelihood of experiencing suicidal ideation during the RAISE project. Meanwhile, stronger working memory (OR = 0.922, p < .05) and impaired clinical insight (OR = 0.734, p < .05) were associated with a decreased likelihood of experiencing suicidal ideation.

CONCLUSION

The likelihood of experiencing suicidal ideation was significantly increased when positive and depressive symptoms were present, and significantly decreased when clinical insight was poorer and working memory stronger. These findings have important implications for the role of cognition and insight in risk for suicide ideation in early-stage psychosis, which may aid in improving the prediction of suicide behaviors and inform clinical decision-making over the course of the illness.

Mediating Effect of Hope on the Relationship Between Depression and Recovery in Persons With Schizophrenia

Background: Depression and hope are considered pivotal variables in the recovery process of people with schizophrenia. Aim: This study examined the moderating effect of depression on the relationship between hope and recovery, and the mediating effect of hope on the relationship between depression and recovery in persons with schizophrenia. Methods: The model was tested empirically using the data of 115 persons with schizophrenia from Central Java Province, Indonesia. The Calgary Depression Scale for Schizophrenia, Schizophrenia Hope Scale-9, and Recovery Assessment Scale were used to measure participants' depression, hope, and recovery, respectively. Results: The findings supported the hypothesis that depression moderates the relationship between hope and recovery, and hope mediates the relationship between depression and recovery. Conclusions: The findings suggest that mental health professionals need to focus on instilling hope and reducing depression to help improve the recovery of persons with schizophrenia. Furthermore, mental health professionals should actively develop and implement programs to instill hope and continuously evaluate the effectiveness of the interventions, particularly in community-based and in-patient mental health settings.

Effectiveness of Suicide-Focused Psychosocial Interventions in Psychosis: A Systematic Review and Meta-Analysis

OBJECTIVE

Suicide ideation, plan, attempt, and death are significant and prevalent concerns among individuals with psychosis. Previous studies have focused on risk factors, but few have systematically evaluated the effect of psychosocial interventions on these experiences among individuals with psychosis. This study evaluated the effectiveness of psychosocial interventions in reducing suicide ideation, plan, attempt, and death among individuals with psychotic symptoms.

METHODS

Eight electronic databases were systematically searched from inception until June 30, 2019. Identified studies included both randomized controlled trials and controlled trials without randomization that examined psychosocial interventions for suicide ideation, plan, attempt, and death among individuals with psychotic symptoms. A random-effects model was used to pool the effect sizes for synthesis.

RESULTS

Eleven studies with 14 effect sizes (N=4,829 participants) were analyzed. The average age of participants ranged from 21 to 51, and most participants identified as male and non-Hispanic Caucasian or Chinese and were in an early or first-episode stage of illness. On average, participants who received psychosocial interventions were less likely than their counterparts in the control group to report suicide ideation, plan, and attempt and die by suicide (odds ratio [OR]=0.57, 95% confidence interval [CI]=0.41-0.78). Subgroup analyses further revealed significant reductions in suicide ideation (OR=0.73, 95% CI=0.55-0.97) and suicide death (OR=0.45, 95% CI=0.30-0.68) among intervention participants.

CONCLUSIONS

Preliminary evidence indicated that psychosocial interventions are effective in reducing suicide ideation, plan, attempt, and death among individuals with psychotic symptoms. Intervention characteristics, however, varied across studies, which suggests a lack of consensus on best clinical practices.

Potential metabolic monitoring indicators of suicide attempts in first episode and drug naive young patients with major depressive disorder: a cross-sectional study

BACKGROUNDS

Major depressive disorder is an ordinary mental disorder, and suicide is considered to be a major concern among patients with MDD. Previous studies focused on the relationship between suicide attempts and metabolism in elderly patients with MDD, while ignore the young people. The aim of this study is to find the potential relationship between suicide attempts and metabolism in young patients with MDD to find a way to prevent and ultimately reduce suicide in young patients with MDD.

METHODS

Cross-sectional design was employed in the study.740 patients aged between 18 and 45 years old with MDD had been consecutively recruited in this study between 2011 and 2017, 128 of whom had suicide attempts. Their serum samples used to monitor fasting blood glucose, serum lipids as well as socio-demographic characteristics were collected. Besides, some clinical scales were also employed to measure symptoms of anxiety, depression and other conditions.

RESULTS

This study indicated that compared with non-suicide attempters, suicide attempters in young patients with MDD showed higher levels of FBG, TC, LDL-C (all p <  0.05) and lower levels of HDL-C(p <  0.001). Further logistic regression analysis suggested that suicide attempts were associated with increased FBG, decreased HDL-C, the course of disease, HAMD scores and obvious anxiety.

CONCLUSIONS

Suicide attempts in young patients with MDD may be predicted by metabolic levels in the future. And our findings suggested that the level of FBG and HDL-C can be promising biomarkers to predict the occurrence of this event.

Suicidal ideation in individuals at ultra-high risk for psychosis and its association with suspiciousness independent of depression

AIM

Psychotic experiences, including delusions and hallucinations, and their attenuated forms have been recently suggested as a significant but under-recognized marker of suicide risk. However, the relationship between attenuated positive symptoms and suicide has not yet been clearly demonstrated in individuals at ultra-high risk (UHR) for psychosis. Here, we investigated the effect of attenuated positive symptoms on suicidal ideation in UHR individuals.

METHODS

Fifty-three healthy controls (HCs) and 74 UHR individuals participated in the present study. All participants were assessed for the intensity of suicidal ideation and depressive symptoms at baseline. The effect of attenuated positive symptoms on suicidal ideation in the UHR group was examined using a multiple linear regression analysis after adjustment for concurrent depressive symptoms.

RESULTS

UHR participants were found to have significantly greater suicidal ideation and more severe depressive symptoms compared to those of HCs. The regression model demonstrated that suspiciousness significantly increased suicidal ideation in UHR participants, independent of the severity of depressive symptoms.

CONCLUSION

The findings of the present study suggest that suspiciousness may serve as a risk indicator for suicide in clinical practice for UHR individuals. It is crucial to focus on the risk of suicide in the UHR population, as they require sufficient clinical attention and proper management for crises related to their unusual and confusing experiences.

Childhood trauma and the likelihood of increased suicidal risk in schizophrenia

The aims of the present study were to investigate the dimensions of childhood trauma (CT) in patients with schizophrenia, and to predict suicidal risk (e.g., current suicidal ideation and lifetime suicide attempts) by CT dimensions and clinical factors (positive and negative symptoms and depression). Eighty-two inpatients with schizophrenia completed the Childhood Trauma Questionnaire-Short Form (CTQ-SF), the Beck Depression Inventory-II (BDI-II), and the Beck Scale for Suicide Ideation (BSSI); they were also administered the Positive and Negative Syndrome Scale (PANSS).The presence of lifetime suicide attempts was assessed by structured diagnostic clinical interview. Patients with lifetime suicide attempts scored higher on sexual abuse than those without attempts after controlling for depression severity. Patients with high suicidal risk had higher scores on physical neglect than those without high risk after controlling for depression severity. Patients with high CT had higher scores on negative and positive symptoms, current suicidal ideation, and depression than those with low CT. Logistic regression analyses indicated that sexual abuse was a unique predictor of lifetime suicide attempts, and that physical neglect and depression were unique predictors of current suicidal ideation. These findings indicate that patients with schizophrenia who have experienced CT may be at increased risk for suicide.

Identification of risk factors for suicidal ideation in patients with schizophrenia

Patients with schizophrenia have a high risk for suicide, and therefore, identification of risk factors for suicidal ideation (SI) may be helpful to reduce suicide rate. This study aimed to detect which clinical symptoms and biochemical parameters were most strongly associated with SI. A total of 174 patients and 35 healthy controls were enrolled in our study. Patients were evaluated by the Positive and Negative Syndrome Scale (PANSS), Scale of Assessment Negative Symptoms (SANS) and the Calgary Depression Scale for Schizophrenia (CDSS) for psychiatric and depressive symptoms, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) for cognitive function. We examined the levels of prolactin (PRL) and metabolic parameters in all participants. Our results showed a significantly increased level of PRL in patients compared to the controls before (t = 10.414, P < 0.001) and after (F = 31.308, P < 0.001) covariates were controlled for. In addition, we found that patients with SI had significantly higher PRL levels than those without SI (t = 2.586, P = 0.011). And there were positive correlations between serum PRL levels (r = 0.194, P = 0.010), serum fasting triglyceride levels (TG) (r = 0.188, P = 0.013), and RBANS visuospatial skill subscores (r = 0.162, P = 0.036) and SI severity. Finally, the stepwise multiple linear regression analysis revealed that SI severity was significantly associated with PRL levels, fasting TG levels and RBANS visuospatial skill subscores. This study provides support that greater cognitive ability, specifically visuospatial skill, PRL and TG, may confer an elevated risk for more severe SI in schizophrenia patients.

Self-Stigma Mediates the Impact of Insight on Current Suicide Ideation in Suicide Attempters with Schizophrenia: Results of a Moderated Mediation Approach

This study examined the relationships among insight, self-stigma, self-esteem, hope, quality of life, and suicidal behavior in individuals diagnosed as having schizophrenia. Hypotheses concerning mediating and moderating effects were examined. A total of 170 community-dwelling patients with schizophrenia participated in the study. The results revealed a negative association between insight and suicide ideation, which was partially mediated by self-stigma. Moreover, this indirect link was stronger among patients with suicide attempts than among those without attempts. We discuss the implications of these results for preventing or reducing the considerable risks of suicide in this population.

Association of auditory hallucination and anxiety symptoms with depressive symptoms in patients with schizophrenia: A three-month follow-up

This study was to investigate the association of auditory hallucinations and anxiety symptoms with depressive symptoms in patients with schizophrenia for three months. The participants (N = 189) were evaluated using Characteristics of Auditory Hallucination Questionnaire (CAHQ), Beck Anxiety Inventory (BAI), and Beck Depression Inventory-II. Forty-two participants suffered from depressive symptoms at both baseline and 3-month follow-up. Higher CAHQ and BAI at both periods predicted depressive symptoms at three-month end. Being male, increased severity of CAHQ and BAI were risk factors of depressive symptoms. Psychiatric professionals must educate patients to manage auditory hallucinations and anxiety symptoms to decrease depressive symptoms.

A state-independent network of depressive, negative and positive symptoms in male patients with schizophrenia spectrum disorders

Depressive symptoms occur frequently in patients with schizophrenia. Several factor analytical studies investigated the associations between positive, negative and depressive symptoms and reported difficulties differentiating between these symptom domains. Here, we argue that a network approach may offer insights into these associations, by exploring interrelations between symptoms. The aims of current study were to I) construct a network of positive, negative and depressive symptoms in male patients with schizophrenia to investigate interactions between individual symptoms; II) identify the most central symptoms within this network and III) examine group-level differences in network connectivity between remitted and non-remitted patients. We computed a network of depressive, positive and negative symptoms in a sample of 470 male patients diagnosed with a psychotic disorder. Depressive symptoms were assessed with the Calgary Depression Rating Scale for Schizophrenia, while psychotic symptoms were assessed with the Positive and Negative Syndrome Scale. Networks of male patients who fulfilled remission criteria (Andreasen et al., 2005) and non-remitters for psychosis were compared. Our results indicate that depressive symptoms are mostly associated with suicidality and may act as moderator between psychotic symptoms and suicidality. In addition, 'depressed mood', 'observed depression', 'poor rapport', 'stereotyped thinking' and 'delusions' were central symptoms within the network. Finally, although remitted male patients had a similar network structure compared to non-remitters the networks differed significantly in terms of global strength. In conclusion, clinical symptoms of schizophrenia were linked in a stable way, independent of symptomatic remission while the number of connections appears to be dependent on remission status.

Associations Among Suicidal Ideation, White Matter Integrity and Cognitive Deficit in First-Episode Schizophrenia

Objective: The study was aimed to investigate the possible associations among suicidal ideation, brain white matter (WM) integrity and cognitive deficit in first-episode schizophrenia (FES) using diffusion tensor imaging. Methods: The sample contained 18 FES patients with suicidal ideation (SI+), 45 FES patients without suicidal ideation (SI-) and 44 healthy controls. The Calgary Depression Scale for Schizophrenia was used to measure the suicidal ideation and depression symptoms. The whole brain WM integrity and three domains of cognitive function: working memory, verbal comprehension as well as processing speed were compared between the three groups. Results: Compared with SI-, SI+ showed preserved WM integrity as indicated by significantly higher factional anisotropy (FA) or lower mean diffusivity (MD) in multiple WM tracts, and higher FA coupled with lower MD in bilateral posterior corona radiata. Compared with SI-, SI+ were more depressed and had less cognitive deficit in working memory and verbal comprehension. The fiber tracts in bilateral posterior corona radiata connect to the precuneus as shown by probabilistic tractography, and their WM integrity disruptions were found to be positively associated with the cognitive deficits in the FES patients. Discussion: Preserved WM integrity may be a risk factor for suicidal ideation in FES patients. One possible explanation is that it contributes to preserved cognitive function, especially in working memory and verbal comprehension, which may be associated with greater insight and could lead to increased depression and suicidal ideation. The posterior corona radiata and the precuneus may be linked to the related biological processes.

A symptom network structure of the psychosis spectrum

Current diagnostic systems mainly focus on symptoms needed to classify patients with a specific mental disorder and do not take into account the variation in co-occurring symptoms and the interaction between the symptoms themselves. The innovative network approach aims to further our understanding of mental disorders by focusing on meaningful connections between individual symptoms of a disorder and has thus far proven valuable insights to psychopathology. The aims of current study were to I) construct a symptom network and investigate interactions between a wide array of psychotic symptoms; II) identify the most important symptoms within this network and III) perform an explorative shortest pathway analysis between depressive and delusional symptoms. We analyzed interview data from n=408 male patients with non-affective psychosis using the Comprehensive Assessment of Symptoms and History (CASH). A network structure of 79 symptoms was computed to explore partial correlations between positive, negative, catatonia and affective symptoms. The resulting network showed strong connectivity between individual symptoms of the CASH, both within- and between-domains. Most central symptoms included 'loss of interest', 'chaotic speech', 'inability to enjoy recreational interest in activities', 'inability to form or maintain relationships with friends' and 'poverty of content of speech'. The shortest pathway analysis between depressive and delusional symptoms displayed an important role for 'persecutory delusions'. In conclusion, this study showed that individual psychotic symptoms are meaningfully related to each other not only within their own cluster, but also between different clusters and that important information may be acquired by investigating interactions at a symptom level.