A narrative review of digital biomarkers in the management of major depressive disorder and treatment-resistant forms

IntroductionDepression is the leading cause of worldwide disability, until now only 3% of patients with major depressive disorder (MDD) experiences full recovery or remission. Different studies have tried to better understand MDD pathophysiology and its resistant forms (TRD), focusing on the identification of candidate biomarkers that would be able to reflect the patients’ state and the effects of therapy. Development of digital technologies can generate useful digital biomarkers in a real-world setting. This review aims to focus on the use of digital technologies measuring symptom severity and predicting treatment outcomes for individuals with mood disorders.MethodsTwo databases (PubMed and APA PsycINFO) were searched to retrieve papers published from January 1, 2013, to July 30, 2023, on the use of digital devices in persons with MDD. All papers had to meet specific inclusion criteria, which resulted in the inclusion of 12 articles.ResultsResearch on digital biomarkers confronts four core aspects: (I) predicting diagnostic status, (II) assessing symptom severity and progression, (III) identifying treatment response and (IV) monitoring real-word and ecological validity. Different wearable technologies have been applied to collect physiological, activity/sleep, or subjective data to explore their relationships with depression.DiscussionDepression’s stable rates and high relapse risk necessitate innovative approaches. Wearable devices hold promise for continuous monitoring and data collection in real world setting.ConclusionMore studies are needed to translate these digital biomarkers into actionable interventions to improve depression diagnosis, monitoring and management. Future challenges will be the applications of wearable devices routinely in personalized medicine

Social cognition in people with schizophrenia: A cluster-analytic approach

Background The study aimed to subtype patients with schizophrenia on the basis of social cognition (SC), and to identify cut-offs that best discriminate among subtypes in 809 out-patients recruited in the context of the Italian Network for Research on Psychoses. Method A two-step cluster analysis of The Awareness of Social Inference Test (TASIT), the Facial Emotion Identification Test and Mayer-Salovey-Caruso Emotional Intelligence Test scores was performed. Classification and regression tree analysis was used to identify the cut-offs of variables that best discriminated among clusters. Results We identified three clusters, characterized by unimpaired (42%), impaired (50.4%) and very impaired (7.5%) SC. Three theory-of-mind domains were more important for the cluster definition as compared with emotion perception and emotional intelligence. Patients more able to understand simple sarcasm (14 for TASIT-SS) were very likely to belong to the unimpaired SC cluster. Compared with patients in the impaired SC cluster, those in the very impaired SC cluster performed significantly worse in lie scenes (TASIT-LI <10), but not in simple sarcasm. Moreover, functioning, neurocognition, disorganization and SC had a linear relationship across the three clusters, while positive symptoms were significantly lower in patients with unimpaired SC as compared with patients with impaired and very impaired SC. On the other hand, negative symptoms were highest in patients with impaired levels of SC. Conclusions If replicated, the identification of such subtypes in clinical practice may help in tailoring rehabilitation efforts to the person's strengths to gain more benefit to the person

Avolition domain of negative symptoms: electrophysiological correlates

Objective Negative symptoms of schizophrenia constitute an important predictor for poor outcome, but remain a multi-factorial construct that requires additional neurobiological support. Thus, we tested whether different sub-dimensions of negative symptoms have specific brain functional correlates, as assessed by the distribution of subsecond global functional brain states (microstates). Methods EEG microstate features (duration, frequency of occurrence and time covered) of 142 schizophrenia patients were correlated with the negative symptom domains of avolition and expressive deficits. Results The time spend in and occurrence of a particular microstate class (class A) was positively associated with avolition, but not expressive deficits, Further analyses limited this association to anticipatory anhedonia, apathy and asociality. In addition, asociality was negatively associated with time spent in microstate class D. Conclusion Our results indicate that negative symptoms is a biologically heterogeneous construct that needs to be further subdivided to identify the underlying dysfunctional brain systems

Impact of Reward and Loss Anticipation on Cognitive Control: An Event-Related Potential Study in Subjects With Schizophrenia and Healthy Controls

Introduction. Deficits of cognitive functions and motivation are core aspects of schizophrenia. The interaction of these deficits might contribute to impair the ability to flexibly adjust behavior in accordance with oneâ\u80\u99s intentions and goals. Many studies have focused on the anterior N2 as a correlate of cognitive control based on motivational value. Aims. Given the key role of motivation impairment in schizophrenia as a predictor of functional outcome, we aimed to study the impact of reward- and avoidance-based motivation on cognitive control using N2. Method. Event-related potentials were recorded during the execution of the â\u80\u9cMonetary Incentive Delay (MID)â\u80\u9d task in 34 patients with schizophrenia (SCZ) stabilized on second-generation antipsychotics and 22 healthy controls (HC). Cognitive domains were assessed using the MATRICS Consensus Cognitive Battery. Negative symptom domains (Avolition/apathy and Expressive deficit), as well as positive and disorganization dimensions were also assessed in SCZ. Results. We did not observe any group difference in N2 amplitude or latency. In HC, N2 amplitude was significantly larger for anticipation of large loss with regard to all reward conditions and for all incentive versus neutral conditions. In SCZ, N2 amplitude did not discriminate between large loss and reward or between incentive and neutral conditions. N2 amplitude was not correlated with psychopathological dimensions or MCCB-assessed cognitive deficits in SCZ. Conclusion. Our data in HC are in line with the hypothesis that N2 amplitude reflects the impact of motivational salience on cognitive control. Our results in SCZ indicate a deficit in the discrimination of motivational salience to the service of cognitive control, independently of psychopathology and other cognitive deficits

Avolition-Apathy and White Matter Connectivity in Schizophrenia: Reduced Fractional Anisotropy Between Amygdala and Insular Cortex

The avolition/apathy domain of negative symptoms includes motivation- and pleasure-related impairments. In people with schizophrenia, structural and functional abnormalities were reported in key regions within the motivational reward system, including ventral-tegmental area (VTA), striatum (especially at the level of the nucleus accumbens, NAcc), orbitofrontal cortex (OFC), as well as amygdala (Amy) and insular cortex (IC). However, the association of the reported abnormalities with avoliton-apathy is still controversial. In the present study, we investigated white matter connectivity patterns within these regions, using a probabilistic analysis of diffusion tensor imaging (DTI) data, in male subjects with schizophrenia. Thirty-five male subjects with schizophrenia (SCZ) and 17 male healthy controls (HC) matched for age, underwent DTI. SCZ were evaluated using the Schedule for Deficit Syndrome (SDS), the Positive and Negative Syndrome Scale (PANSS), and the MATRICS Consensus Cognitive Battery (MCCB). Probabilistic tractography was applied to investigate pathways connecting the Amy and the NAcc with the OFC and IC. Reduced fractional anisotropy (FA) was observed in left Amyâ\u80\u93ventral anterior IC connections, in SCZ compared with controls. This abnormality was negatively correlated with avolition/apathy but not with expressive deficit scores. SCZ showed also a reduced connectivity index between right NAcc and medial OFC, as compared with controls. Finally, the left NAcc-dorsal anterior IC connectivity index was negatively correlated with working memory scores. Our results indicate that only the avolition/apathy domain of negative symptoms is related to abnormal connectivity in the motivation-related circuits. The findings also demonstrate that distinct alterations underlie cognitive impairment and avolition/apathy

Neurophysiological correlates of Avolition-apathy in schizophrenia: A resting-EEG microstates study

Background: The “Avolition-apathy” domain of the negative symptoms was found to include different symptoms by factor analytic studies on ratings derived by different scales. In particular, the relationship of anhedonia with this domain is controversial. Recently introduced negative symptom rating scales provide a better assessment of anhedonia, allowing the distinction of anticipatory and consummatory aspects, which might be related to different psychopathological dimensions. The study of associations with external validators, such as electrophysiological, brain imaging or cognitive indices, might shed further light on the status of anhedonia within the Avolition-apathy domain. Objectives: We used brain electrical microstates (MSs), which represent subsecond periods of quasi-stable scalp electrical field, associated with resting-state neural networks (and thus with global patterns of functional connectivity), to test whether the component symptoms of Avolition-apathy share the same correlates. Method: We analyzed multichannel resting EEGs in 142 individuals with schizophrenia (SCZ) and in 64 healthy controls (HC), recruited within the add-on EEG study of the Italian Network for Research on Psychoses. Relative time contribution, duration and occurrence of four MS classes (MS-A/-B/-C/−D) were calculated. Group differences on MS parameters (contribution and duration) and their associations with negative symptom domains (assessed using the Brief Negative Symptoms Scale) were investigated. Results: SCZ, in comparison to HC, showed increased contribution and duration of MS-C. The contribution of MS-A positively correlated with Avolition-apathy, but not with Expressive deficit. Within the Avolition-apathy domain, anticipatory anhedonia, avolition and asociality, but not consummatory anhedonia, showed the same correlations with MS-A contribution. Conclusion: Our findings support the existence of distinct electrophysiological correlates of Avolition-apathy with respect to Expressive deficit, and lend support to the hypothesis that only the anticipatory component of anhedonia shares the same pathophysiological underpinnings of the Avolition-apathy domain. Keywords: Schizophrenia, Avolition-apathy, Anhedonia, Resting-EEG, Brain electrical microstate

Persistent negative symptoms in recent-onset psychosis:Relationship to treatment response and psychosocial functioning

Negative symptoms are associated with poor clinical and psychosocial outcome in schizophrenia. Their prevalence and identification in first-episode patients remains controversial. In a large cohort of patients in the early stage of schizophrenia, schizophreniform or schizoaffective disorder, we investigated, over the different phases of the OPTiMiSE trial (baseline, 4, 10 and 22 weeks of treatment), the prevalence of negative symptoms of moderate severity, unconfounded by depression and extrapyramidal symptoms at baseline. Moreover, we assessed symptomatic remission, attrition rate and psychosocial functioning in subjects with short-term (4 weeks) persistent unconfounded negative symptoms (PNS) and in those with negative symptoms that did not persist at follow-up and/or were confounded at baseline (N-PNS). Negative symptoms of moderate severity were observed in 59% of subjects at baseline. They were associated with worse psychosocial functioning and longer duration of psychosis at intake in the study. Eleven percent of subjects had PNS unconfounded at baseline and 7.9% had PNS unconfounded at both baseline and end of 4-week treatment. Psychosocial functioning was comparable in PNS and N-PNS subjects at baseline but it was significantly worse in the former group after 4-weeks. PNS subjects showed lower remission and higher attrition rates at the end of all treatment phases. Fifty-six percent of subjects completing phase 3 (clozapine treatment) had PNS, and 60% of them were non-remitters at the end of this phase. The presence of short-term PNS during the first phases of psychosis was associated with poor clinical outcome and resistance to antipsychotic treatment, including clozapine