Identifying psychosis spectrum disorder from experience sampling data using machine learning approaches

The ubiquity of smartphones have opened up the possibility of widespread use of the Experience Sampling Method (ESM). The method is used to collect longitudinal data of participants' daily life experiences and is ideal to capture fluctuations in emotions (momentary mental states) as an indicator for later mental ill-health. In this study, ESM data of patients with psychosis spectrum disorder and controls were used to examine daily life emotions and higher order patterns thereof. We attempted to determine whether aggregated ESM data, in which statistical measures represent the distribution and dynamics of the original data, were able to distinguish patients from controls in a predictive modelling framework. Variable importance, recursive feature elimination, and ReliefF methods were used for feature selection. Model training, tuning, and testing were performed in nested cross-validation, based on algorithms such as Random Forests, Support Vector Machines, Gaussian Processes, Logistic Regression and Neural Networks. ROC analysis was used to post-process these models. Stability of model performance was studied using Monte Carlo simulations. The results provide evidence that patterns in emotion changes can be captured by applying a combination of these techniques. Acceleration in the variables anxious and insecure was particularly successful in adding further predictive power to the models. The best results were achieved by Support Vector Machines with radial kernel (accuracy=82% and sensitivity=82%). This proof-of-concept work demonstrates that synergistic machine learning and statistical modeling may be used to harness the power of ESM data in the future

CH06 Psychotic exacerbation and emotional dampening in the daily life of patients with schizophrenia switched to aripiprazole therapy: a collection of standardized case reports

<b>Background:</b> Blockade of the dopamine D2 receptor is a key mechanism in the antipsychotic treatment of patients with a psychotic disorder, but may also induce emotional deficits. The partial D2 agonistic profile of aripiprazole has, therefore, been suggested to favor emotional wellbeing compared with the pure dopamine antagonistic properties of traditional antipsychotics. <b>Method:</b> The current study used the experience sampling method (a structured diary technique) to assess the effects of switching from treatment with traditional dopamine antagonist antipsychotics to treatment with the partial dopamine agonist aripiprazole on emotional wellbeing in the daily life of 13 patients with a diagnosis of schizophrenia. <b>Results:</b> More than half of all patients experienced exacerbation of psychotic symptoms after they had switched to the aripiprazole medication regime, consequently resulting in dropout of the study. Furthermore, switching to aripiprazole treatment, when effective in terms of symptom reduction, was accompanied by decreased feelings of both positive and negative affect in daily life, suggestive of a general state of emotional dampening. <b>Conclusions:</b> Although the scale of the current study and the 54% dropout rate call for careful interpretation of the data, implementation of ecological monitoring in psychopharmacological research may open up new avenues for untangling the working mechanisms of compounds with regard to their impact on mental states.<div><br></div><div>see also:</div><div>Lataster, J., Myin-Germeys, I., Wichers, M., Delespaul, P. A., van Os, J., & Bak, M. (2011). Psychotic exacerbation and emotional dampening in the daily life of patients with schizophrenia switched to aripiprazole therapy: a collection of standardized case reports. <i>Therapeutic advances in psychopharmacology</i>, <i>1</i>(5), 145-151.<br></div><div><br></div><div><b>DOI: 10.1177/2045125311419552</b><br></div

CH05-1 Emotional experience and estimates of D2 receptor occupancy in psychotic patients treated with haloperidol, risperidone, or olanzapine: an experience sampling study

Blockade of dopamine D(2) receptors is thought to mediate the therapeutic effects of antipsychotic medication but may also induce social indifference. As antipsychotic drugs differ in D(2) receptor binding, "tight" and "loose" binding drugs may be hypothesized to differentially affect emotional experience. The present study investigates the differential effects of relatively tight versus looser binding drugs on the experience of emotions in the realm of daily life.We assessed positive and negative affect in the daily life of 109 patients with a DSM-IV diagnosis of psychotic disorder who were currently taking antipsychotic medication by using the experience sampling method (a structured diary technique). Antipsychotic medication was classified as loose (olanzapine; n = 35) or tight (haloperidol, risperidone; n = 74) binding, based on the drug's dissociation constants at the D(2) receptor. The study was conducted from 2007 to 2008.Multilevel analyses showed a significant interaction between binding group (loose vs tight) and D(2) receptor occupancy estimates with regard to the experience of positive (P = .008) and negative (P = .019) affect. For tight-binding-agent users, a significant association was found between D(2) receptor binding estimates and both positive affect (P = .040) and negative affect (P = .0001) in the flow of daily life, with increasing levels of estimated D(2) receptor occupancy being associated with decreased feelings of positive affect and increased feelings of negative affect. For loose-binding-agent users, no such association was apparent. These associations were only partly mediated by clinical symptoms.These findings add ecological validity to previous laboratory findings showing an association between D(2) receptor occupancy and emotional experience.<div><br></div><div>see also:</div><div>Lataster, J., van Os, J., de Haan, L., Thewissen, V., Bak, M., Lataster, T., ... & Myin-Germeys, I. (2011). Emotional experience and estimates of D2 receptor occupancy in psychotic patients treated with haloperidol, risperidone, or olanzapine: an experience sampling study. <i>The Journal of clinical psychiatry</i>, <i>72</i>(10), 1397-1404.<br></div><div><br></div><div><b>DOI: 10.4088/JCP.09m05466yel</b><br></div