Predicting antidepressant treatment outcome based on socioeconomic status and citalopram dose

Therapeutic and Structural Dimensions in Psychiatric Prescribing: Bridging Psychedelics and Antidepressants

ABSTRACT

As practitioners seek more personalized approaches, exploring how patients' environments, relationship templates, and mindsets factor into symptom burden can help broaden understanding of how psychotropic medications facilitate recovery. Despite increasing focus on medications to provide relief, there is an important and undeniable influence the therapeutic environment has on shaping outcomes, particularly for the patient-clinician alliance. While environmental dimensions are relevant for informing possible placebo or nocebo responses, they also build upon the pharmacodynamic and neurobiological effects of medications. By heightening neuroplasticity, some antidepressants may amplify the effects of nonmedication factors in patients' lives, including the patient-prescriber therapeutic relationship. There are important parallels between antidepressants and psychedelics in emerging literature. For instance, the preparatory and integrative work with a provider can be crucial in determining outcomes. This paper will draw from the extant literature to discuss the therapeutic relationship in psychiatric practice, including in acute care settings and instances in which psychotropic prescribing is a key aspect of treatment.

Concurrent stress modulates the acute and post-acute effects of psilocybin in a sex-dependent manner

There is renewed interest in psychedelics, such as psilocybin, as therapies for multiple difficult-to-treat psychiatric disorders. Even though psychedelics can induce highly pleasant or aversive experiences, depending on multiple personal and environmental factors, there is little research into how such experiences impact post-acute mood-altering actions. Here we aimed at offsetting this gap. First, we tested whether acute psilocybin effects differed between sexes. Adult male and female C57BL/6J mice received saline or psilocybin (5 mg/kg; i.p.), and head-twitch response (HTR) frequency was quantified. Notably, while psilocybin increased HTR frequency in both sexes, the effect was greater in females. We then tested if stress exposure during acute drug effects impacted post-acute psilocybin actions. Following drug treatment, mice were returned to their homecage or restrained for 1 h. Anxiety- and depression-like behaviors were assessed starting 24 h following drug administration, using the marble burying, novelty-suppressed feeding, and splash tests. Psilocybin induced anxiolytic-, but not antidepressant-like, which were fully blocked by stress in males, but only partially so in females. Lastly, we assessed the acute stress-psilocybin interaction on plasma corticosterone levels in a separate cohort of mice, treated as above. Both stress and psilocybin independently increased corticosterone levels, without additive or interactive effects being observed for either sex. Our data reveals the role of sex and peri-acute negative experiences in the acute and post-acute actions of psilocybin. These findings underline the importance of non-pharmacological factors, such as the quality of the psychedelic experience, in the mood-altering effects of psychedelics, holding significant for both their therapeutic and recreational use.

More and Less Fear in Serotonin Transporter Knockout Mice

Recent theories suggest that reduced serotonin transporter (5-HTT) function, which increases serotonin (5-HT) levels at the synapse, enhances neural plasticity and affects sensitivity to environmental cues. This may promote learning about emotionally relevant events. However, the boundaries that define such emotional learning remain to be established. This was investigated using 5-HTT knockout (5-HTTKO) mice which provide a model of long-term elevated 5-HT transmission and are associated with increased anxiety. Compared to wild-type controls, 5-HTTKO mice were faster to discriminate between an auditory cue that predicted footshock (CS+) and a cue predicting no footshock (CS-). Notably, this enhanced discrimination performance was driven not by faster learning that the CS+ predicted footshock, but rather by faster learning that the CS- cue signals the absence of footshock and thus provides temporary relief from fear/anxiety. Similarly, 5-HTTKO mice were also faster to reduce their fear of the CS+ cue during subsequent extinction. These findings are consistent with facilitated inhibitory learning that predicts the absence of potential threats in 5-HTTKO mice. However, 5-HTTKO mice also exhibited increased generalisation of fear learning about ambiguous aversive cues in a novel context, different from the training context. Thus, 5-HTTKO mice can exhibit both more and less fear compared to wild-type controls. Taken together, our results support the idea that loss of 5-HTT function, and corresponding increases in synaptic 5-HT availability, may facilitate learning by priming of aversive memories. This both facilitates inhibitory learning for fear memories but also enhances generalisation of fear.

A network-based analysis anticipates time to recovery from major depression revealing a plasticity by context interplay

Predicting disease trajectories in patients with major depressive disorder (MDD) can allow designing personalized therapeutic strategies. In this study, we aimed to show that measuring patients' plasticity - that is the susceptibility to modify the mental state - identifies at baseline who will recover, anticipating the time to transition to wellbeing. We conducted a secondary analysis in two randomized clinical trials, STAR*D and CO-MED. Symptom severity was assessed using the Quick Inventory of Depressive Symptomatology while the context was measured at enrollment with the Quality-of-Life Enjoyment and Satisfaction Questionnaire. Patients were retrospectively grouped based on both their time to response or remission and their plasticity levels at baseline assessed through a network-based mathematical approach that operationalizes plasticity as the inverse of the symptom network connectivity strength. The results show that plasticity levels at baseline anticipate time to response and time to remission. Connectivity strength among symptoms is significantly lower - and thus plasticity higher - in patients experiencing a fast recovery. When the interplay between plasticity and context is considered, plasticity levels are predictive of disease trajectories only in subjects experiencing a favorable context, confirming that plasticity magnifies the influence of the context on mood. In conclusion, the assessment of plasticity levels at baseline holds promise for predicting MDD trajectories, potentially informing the design of personalized treatments and interventions. The combination of high plasticity and the experience of a favorable context emerges as critical to achieve recovery.

Beyond psychedelics: set and setting in general psychiatric practice

Psychedelic compounds continue gaining scientific and regulatory traction as potential new treatments for psychiatric disorders. While most psychiatrists will likely not work directly with these compounds, psychedelic research practices provide insights that may improve conventional psychiatric care. Through its emphasis on 'set and setting' (mindset and environment, respectively), psychedelic research highlights the importance of non-pharmacologic factors maximizing therapeutic outcomes. While psychedelics and serotonergic antidepressants are distinctly different in their subjective experience, new findings suggest mechanistic overlap between them. Both have been found to modulate neurotrophins, enhance neuroplasticity, and reopen critical periods of learning, molded by the environmental context in which they are administered.

This paper will argue that by integrating insights from psychedelic research (particularly set and setting), depression treatment outcomes in traditional psychiatric settings can improve by optimizing non-pharmacological factors in treatment, including the provision of high-quality psychotherapy.

Uncovering the determinants of brain functioning, behavior and their interplay in the light of context

Notwithstanding the huge progress in molecular and cellular neuroscience, our ability to understand the brain and develop effective treatments promoting mental health is still limited. This can be partially ascribed to the reductionist, deterministic and mechanistic approaches in neuroscience that struggle with the complexity of the central nervous system. Here, I introduce the Context theory of constrained systems proposing a novel role of contextual factors and genetic, molecular and neural substrates in determining brain functioning and behavior. This theory entails key conceptual implications. First, context is the main driver of behavior and mental states. Second, substrates, from genes to brain areas, have no direct causal link to complex behavioral responses as they can be combined in multiple ways to produce the same response and different responses can impinge on the same substrates. Third, context and biological substrates play distinct roles in determining behavior: context drives behavior, substrates constrain the behavioral repertoire that can be implemented. Fourth, since behavior is the interface between the central nervous system and the environment, it is a privileged level of control and orchestration of brain functioning. Such implications are illustrated through the Kitchen metaphor of the brain. This theoretical framework calls for the revision of key concepts in neuroscience and psychiatry, including causality, specificity and individuality. Moreover, at the clinical level, it proposes treatments inducing behavioral changes through contextual interventions as having the highest impact to reorganize the complexity of the human mind and to achieve a long-lasting improvement in mental health.

Drug development in psychopharmacology: Insights from evolutionary psychiatry

In the last decade, no other branch of clinical pharmacology has been subject to as much criticism of failed innovation and unsatisfactory effectiveness as psychopharmacology. Evolutionary psychiatry can offer original insights on the problems that complicate pharmacological research. Considering that invalid phenotyping is a major obstacle to drug development, an evolutionary perspective suggests targeting clinical phenotypes related to evolved behavior systems because they are more likely to map onto the underlying biology than constructs based on predetermined diagnostic criteria. Because of their emphasis on symptom remission, pharmacological studies of psychiatric populations rarely include functional capacities as the primary outcome measure and neglect the impact of social context on the effects of psychiatric drugs. Evolutionary psychiatry explains why it is appropriate to replace symptoms with functional capacities as the primary target of psychiatric therapies and why social context should be a major focus of studies assessing the effectiveness of drugs currently used and new drugs under development. When the focus of research shifts to those questions that go beyond the "disease-based" concept of drug action, evolutionary psychiatry clearly emerges as a reference framework to assess drug effectiveness and to optimize clinicians' decisions about prescribing, deprescribing, and non-prescribing.

Ecocebo: How the interaction between environment and drug effects may improve pharmacotherapy outcomes

This narrative review describes the research on the effects of the association between environmental context and medications, suggesting the benefit of specific design interventions in adjunction to pharmacotherapy. The literature on Evidence-Based Design (EBD) studies and Neuro-Architecture show how contact with light, nature, and specific physical features of urban and interior architecture may enhance the effects of analgesic, anxiolytics, and antidepressant drugs. This interaction mirrors those already known between psychedelics, drugs of abuse, and setting. Considering that the physical feature of space is a component of the complex placebo configuration, the aim is to highlight those elements of built or natural space that may help to improve drug response in terms of efficacy, tolerability, safety, and compliance. Ecocebo, the integration of design approaches such as EBD and Neuro-Architecture may thus contribute to a more efficient, cost-sensitive, and sustainable pharmacotherapy.

Subjective experience of the environment determines serotoninergic antidepressant treatment outcome in male mice

BACKGROUND

The effects of the selective serotonin reuptake inhibitors (SSRIs), the first-line antidepressant treatment, have been proposed to be affected, at least in part, by the living environment. Since the quality of the environment depends not only on its objective features, but also on the subjective experience, we hypothesized that the latter plays a key role in determining SSRI treatment outcome.

METHODS

We chronically administered the SSRI fluoxetine to two groups of adult CD-1 male mice that reportedly show distinct subjective experiences of the environment measured as consistent and significantly different responses to the same emotional and social stimuli. These distinct socioemotional profiles were generated by rearing mice either in standard laboratory conditions (SN) or in a communal nest (CN) where three dams breed together their offspring, sharing caregiving behavior.

RESULTS

At adulthood, CN mice displayed higher levels of agonistic and anxiety-like behaviors than SN mice, indicating that they experience the environment as more socially challenging and potentially dangerous. We then administered fluoxetine, which increased offensive and anxious response in SN, while producing opposite effects in CN mice. BDNF regulation was modified by the treatment accordingly.

LIMITATIONS

Subjective experience in mice was assessed as behavioral response to the environment.

CONCLUSIONS

These results show that the subjective experience of the environment determines fluoxetine outcome. In a translational perspective, our findings suggest considering not only the objective quality, but also the subjective appraisal, of the patient's living environment for developing effective personalized therapeutic approaches in psychiatry.

A mathematical formula of plasticity: Measuring susceptibility to change in mental health and data science

Plasticity is increasingly recognized as a critical concept in psychiatry and mental health because it allows the reorganization of neural circuits and behavior during the transition from psychopathology to wellbeing. Differences in individual plasticity may explain why therapies, such as psychotherapeutic and environmental interventions, are highly effective in some but not in all patients. Here I propose a mathematical formula to assess plasticity - i.e., the susceptibility to change - to identify, at baseline, which individuals or populations are more likely to modify their behavioral outcome according to therapies or contextual factors. The formula is grounded in the network theory of plasticity so that, when representing a system (e.g., a patient's psychopathology) as a weighed network where the nodes are the system features (e.g., symptoms) and the edges are the connections (i.e., correlations) among them, the network connectivity strength is an inverse measure of the plasticity of the system: the weaker the connectivity, the higher the plasticity and the greater the susceptibility to change. The formula is predicted to be generalizable, measuring plasticity at multiple scales, from the single cell to the whole brain, and can be applied to a wide range of research fields, including neuroscience, psychiatry, ecology, sociology, physics, market and finance.

Heterogeneity of depression across the socioeconomic spectrum

Why is lower socioeconomic status associated with higher rates of depression? And, is the surplus of depression at lower SES just more of the same type as depression found at higher levels, or is it distinctive? We addressed these questions by examining the relations among SES, amygdala volume, and symptoms of depression in healthy young adults. Amygdala volume, a risk factor for depression, does not synergize with SES in a diathesis-stress relation, nor does it mediate the relation of SES to depression. Rather, SES and amygdala volume are independent, additive risk factors. They are also associated with different depression symptoms and, whereas perceived stress fully mediates the relation of SES to depression, it has no relation to amygdala volume. These findings suggest heterogeneity of depression across the socioeconomic spectrum, with implications for treatment selection as well as for future genetic and brain studies.

Using Machine Learning to Predict Antidepressant Treatment Outcome From Electronic Health Records

Objective

To evaluate if a machine learning approach can accurately predict antidepressant treatment outcome using electronic health records (EHRs) from patients with depression.

Method

This study examined 808 patients with depression at a New York City-based outpatient mental health clinic between June 13, 2016 and June 22, 2020. Antidepressant treatment outcome was defined based on trend in depression symptom severity over time and was categorized as either "Recovering" or "Worsening" (i.e., non-Recovering), measured by the slope of individual-level Patient Health Questionnaire-9 (PHQ-9) score trajectory spanning 6 months following treatment initiation. A patient was designated as "Recovering" if the slope is less than 0 and as "Worsening" if the slope was no less than 0. Multiple machine learning (ML) models including L2 norm regularized Logistic Regression, Naive Bayes, Random Forest, and Gradient Boosting Decision Tree (GBDT) were used to predict treatment outcome based on additional data from EHRs, including demographics and diagnoses. Shapley Additive Explanations were applied to identify the most important predictors.

Results

The GBDT achieved the best results of predicting "Recovering" (AUC: 0.7654 ± 0.0227; precision: 0.6002 ± 0.0215; recall: 0.5131 ± 0.0336). When excluding patients with low PHQ-9 scores (<10) at baseline, the results of predicting "Recovering" (AUC: 0.7254 ± 0.0218; precision: 0.5392 ± 0.0437; recall: 0.4431 ± 0.0513) were obtained. Prior diagnosis of anxiety, psychotherapy, recurrent depression, and baseline depression symptom severity were strong predictors.

Conclusions

The results demonstrate the potential utility of using ML in longitudinal EHRs to predict antidepressant treatment outcome. Our predictive tool holds the promise to accelerate personalized medical management in patients with psychiatric illnesses.

A paradigm shift in translational psychiatry through rodent neuroethology

Mental disorders are a significant cause of disability worldwide. They profoundly affect individuals' well-being and impose a substantial financial burden on societies and governments. However, despite decades of extensive research, the effectiveness of current therapeutics for mental disorders is often not satisfactory or well tolerated by the patient. Moreover, most novel therapeutic candidates fail in clinical testing during the most expensive phases (II and III), which results in the withdrawal of pharma companies from investing in the field. It also brings into question the effectiveness of using animal models in preclinical studies to discover new therapeutic agents and predict their potential for treating mental illnesses in humans. Here, we focus on rodents as animal models and propose that they are essential for preclinical investigations of candidate therapeutic agents' mechanisms of action and for testing their safety and efficiency. Nevertheless, we argue that there is a need for a paradigm shift in the methodologies used to measure animal behavior in laboratory settings. Specifically, behavioral readouts obtained from short, highly controlled tests in impoverished environments and social contexts as proxies for complex human behavioral disorders might be of limited face validity. Conversely, animal models that are monitored in more naturalistic environments over long periods display complex and ethologically relevant behaviors that reflect evolutionarily conserved endophenotypes of translational value. We present how semi-natural setups in which groups of mice are individually tagged, and video recorded continuously can be attainable and affordable. Moreover, novel open-source machine-learning techniques for pose estimation enable continuous and automatic tracking of individual body parts in groups of rodents over long periods. The trajectories of each individual animal can further be subjected to supervised machine learning algorithms for automatic detection of specific behaviors (e.g., chasing, biting, or fleeing) or unsupervised automatic detection of behavioral motifs (e.g., stereotypical movements that might be harder to name or label manually). Compared to studies of animals in the wild, semi-natural environments are more compatible with neural and genetic manipulation techniques. As such, they can be used to study the neurobiological mechanisms underlying naturalistic behavior. Hence, we suggest that such a paradigm possesses the best out of classical ethology and the reductive behaviorist approach and may provide a breakthrough in discovering new efficient therapies for mental illnesses.

Combinatorial approaches for treating neuropsychiatric social impairment

Social behaviour is an essential component of human life and deficits in social function are seen across multiple psychiatric conditions with high morbidity. However, there are currently no FDA-approved treatments for social dysfunction. Since social cognition and behaviour rely on multiple signalling processes acting in concert across various neural networks, treatments aimed at social function may inherently require a combinatorial approach. Here, we describe the social neurobiology of the oxytocin and endocannabinoid signalling systems as well as translational evidence for their use in treating symptoms in the social domain. We leverage this systems neurobiology to propose a network-based framework that involves pharmacology, psychotherapy, non-invasive brain stimulation and social skills training to combinatorially target trans-diagnostic social impairment. Lastly, we discuss the combined use of oxytocin and endocannabinoids within our proposed framework as an illustrative strategy to treat specific aspects of social function. Using this framework provides a roadmap for actionable treatment strategies for neuropsychiatric social impairment. This article is part of the theme issue 'Interplays between oxytocin and other neuromodulators in shaping complex social behaviours'.

What Can Reinforcement Learning Models of Dopamine and Serotonin Tell Us about the Action of Antidepressants?

Although evidence suggests that antidepressants are effective at treating depression, the mechanisms behind antidepressant action remain unclear, especially at the cognitive/computational level. In recent years, reinforcement learning (RL) models have increasingly been used to characterise the roles of neurotransmitters and to probe the computations that might be altered in psychiatric disorders like depression. Hence, RL models might present an opportunity for us to better understand the computational mechanisms underlying antidepressant effects. Moreover, RL models may also help us shed light on how these computations may be implemented in the brain (e.g., in midbrain, striatal, and prefrontal regions) and how these neural mechanisms may be altered in depression and remediated by antidepressant treatments. In this paper, we evaluate the ability of RL models to help us understand the processes underlying antidepressant action. To do this, we review the preclinical literature on the roles of dopamine and serotonin in RL, draw links between these findings and clinical work investigating computations altered in depression, and appraise the evidence linking modification of RL processes to antidepressant function. Overall, while there is no shortage of promising ideas about the computational mechanisms underlying antidepressant effects, there is insufficient evidence directly implicating these mechanisms in the response of depressed patients to antidepressant treatment. Consequently, future studies should investigate these mechanisms in samples of depressed patients and assess whether modifications in RL processes mediate the clinical effect of antidepressant treatments.

Time moderates the interplay between 5-HTTLPR and stress on depression risk: gene x environment interaction as a dynamic process

The serotonin-transporter-linked promoter region (5-HTTLPR) has been widely investigated as contributing to depression vulnerability. Nevertheless, empirical research provides wide contrasting findings regarding its involvement in the etiopathogenesis of the disorder. Our hypothesis was that such discrepancy can be explained considering time as moderating factor. We explored this hypothesis, exploiting a meta analytic approach. We searched PubMed, PsychoINFO, Scopus and EMBASE databases and 1096 studies were identified and screened, resulting in 22 studies to be included in the meta-analyses. The effect of the 5-HTTLPR x stress interaction on depression risk was found to be moderated by the following temporal factors: the duration of stress (i.e. chronic vs. acute) and the time interval between end of stress and assessment of depression (i.e. within 1 year vs. more than 1 year). When stratifying for the duration of stress, the effect of the 5-HTTLPR x stress interaction emerged only in the case of chronic stress, with a significant subgroup difference (p = 0.004). The stratification according to time interval revealed a significant interaction only for intervals within 1 year, though no difference between subgroups was found. The critical role of time interval clearly emerged when considering only chronic stress: a significant effect of the 5-HTTLPR and stress interaction was confirmed exclusively within 1 year and a significant subgroup difference was found (p = 0.01). These results show that the 5-HTTLPR x stress interaction is a dynamic process, producing different effects at different time points, and indirectly confirm that s-allele carriers are both at higher risk and more capable to recover from depression. Overall, these findings expand the current view of the interplay between 5-HTTLPR and stress adding the temporal dimension, that results in a three-way interaction: gene x environment x time.

Recentering neuroscience on behavior: The interface between brain and environment is a privileged level of control of neural activity

Despite the huge and constant progress in the molecular and cellular neuroscience fields, our capability to understand brain alterations and treat mental illness is still limited. Therefore, a paradigm shift able to overcome such limitation is warranted. Behavior and the associated mental states are the interface between the central nervous system and the living environment. Since, in any system, the interface is a key regulator of system organization, behavior is proposed here as a unique and privileged level of control and orchestration of brain structure and activity. This view has relevant scientific and clinical implications. First, the study of behavior represents a singular starting point for the investigation of neural activity in an integrated and comprehensive fashion. Second, behavioral changes, accomplished through psychotherapy or environmental interventions, are expected to have the highest impact to specifically reorganize the complexity of the human mind and thus achieve a solid and long-lasting improvement in mental health.

Antidepressant-Like Effect of a Selenoindolizine in Mice: In Vivo and In Silico Evidence for the Involvement of the Serotonergic 5-HT2A/C Receptors

The monoaminergic dysfunction plays a central role in major depressive disorder (MDD), a mental disturbance associated with constant feeling of sadness and lack of interest. The available treatments do not present a desirable efficacy and some of them provoke several adverse effects. In this context, organoselenium compounds and molecules containing the indolizine nucleus have demonstrated interesting pharmacological properties, including antidepressant-like effects. In this study, the antidepressant-like effect of 2-phenyl-1-(phenylselanyl)indolizine (SeI), a selenium-containing indolizine derivative, was investigated on the forced swimming test (FST) and on the tail suspension test (TST) in male Swiss mice. The involvement of the serotonergic system in this effect was also accessed. The selenium compound SeI (10-100 mg/kg, intragastrical (i.g.)) was administered 0.5 h before the behavioral tests, and it diminished the immobility on both FST and TST experiments, which is an indication of antidepressant-like effect. No changing in the locomotor motion was observed in the open-field test (OFT). The anti-immobility effect of SeI was not altered by the preadministration of the selective serotonergic receptor antagonists ondansetron (1 mg/kg, intraperitoneally (i.p.), antagonist of 5-HT₃ receptor) and WAY100635 (0.1 mg/kg, subcutaneous route (s.c.), antagonist of 5-HT_1A receptor). In contrast, the preadministration of ketanserin (1 mg/kg, i.p., antagonist of 5-HT_2A/C receptor) blocked this effect, demonstrating that the antidepressant-like effect of SeI involves 5-HT_2A/C. In addition, molecular docking studies showed a strong interaction between SeI and the receptors of 5-HT_2A and 5-HT_2C. The toxicological results demonstrated that SeI has low potential to cause adverse effects in mice. It was found that the antidepressant-like effect of SeI is related to modulation of the serotonergic system, and this selenium compound could be included in new treatment approaches for MDD.

The interaction between Environmental Enrichment and fluoxetine in inhibiting sucrose-seeking renewal in mice depend on social living condition

RATIONALE

Several single or combined therapeutic approaches have been developed to treat addiction, however with partial efficacy in preventing relapse. Recently, the living environment has been suggested as a critical intervening factor determining the treatment outcomes. Despite accumulating evidence confirming a role of living conditions in the vulnerability to addictive behaviours, their impact on single or integrative therapeutic strategies preventing relapse is yet to be identified.

OBJECTIVES

Here, we explore the possible interaction between brief Environmental Enrichment (EE) exposure and acute fluoxetine administration in inhibiting sucrose-seeking behaviours, and whether this effect could be affected by living environment.

METHODS

Social and isolated adult male C57BL/6 mice were trained to sucrose self-administration associated to a specific conditioning context (CxA), followed by a 7-day extinction in a different context (CxB). Afterwards, mice were exposed for 22 h to EE and then injected with fluoxetine (10 mg/kg, i.p.) 1 h before a CxA-induced sucrose-seeking test.

RESULTS

Brief EE exposure and acute fluoxetine administration alone inhibited context-induced sucrose-seeking in both housing conditions; however, they exhibited additive properties only in social condition.

CONCLUSIONS

Our data show that social environment may influence the EE/fluoxetine interaction in inhibiting relapse to sucrose. These findings suggest that setting up proper living conditions to boost the efficacy of therapeutic approaches may represent a fundamental strategy to treat addiction disorders.

Adiponectin predicts poor response to antidepressant drugs in major depressive disorder

OBJECTIVE

Produced by adipocytes, adiponectin crosses the blood-brain barrier to bind with specific receptors in the hypothalamus, brainstem, hippocampus, and cortex. In patients with major depressive disorder (MDD), circulating levels of adiponectin inversely related with antidepressant response to ketamine, and predicted a better response to multi-target drug combinations than to escitalopram. We investigated the effect of adiponectin on response to antidepressants in a naturalistic setting.

METHODS

We assessed baseline plasma levels of adiponectin in 121 MDD inpatients, treated with antidepressant drug monotherapy based on clinical need (selective serotonin reuptake inhibitors, venlafaxine, duloxetine) in a specialized hospital setting. Severity of depression was weekly assessed with Hamilton scale ratings.

RESULTS

Adiponectin plasma levels were higher in patients with MDD compared with healthy controls, and negatively influenced the pattern of antidepressant response (higher baseline levels, worse response) independent of the drug class and of the baseline severity of depression, and of age, sex, and body mass index.

CONCLUSIONS

The identification of adiponectin as a predictor of antidepressant response to drugs of different mechanism of action, such as ketamine, SSRIs, and SNRIs, and both in experimental and in clinical settings, warrants interest for further study of its pathways to search for novel biomarkers and therapeutic targets.

Brain-immune crosstalk in the treatment of major depressive disorder

A growing number of studies are pointing out the need for a conceptual shift from a brain-centered to a body-inclusive approach in mental health research. In this perspective, the link between the immune and the nervous system, which are deeply interconnected and continuously interacting, is one of the most important novel theoretical framework to investigate the biological bases of major depressive disorder and, more in general, mental illness. Indeed, depressed patients show high levels of inflammatory markers, administration of pro-inflammatory drugs triggers a depressive symptomatology and antidepressant efficacy is reduced by excessive immune system activation. A number of molecular and cellular mechanisms have been hypothesized to act as a link between the immune and brain function, thus representing potential pharmacologically targetable processes for the development of novel and effective therapeutic strategies. These include the modulation of the kynurenine pathway, the crosstalk between metabolic and inflammatory processes, the imbalance in acquired immune responses, in particular T cell responses, and the interplay between neural plasticity and immune system activation. In the personalized medicine approach, the assessment and regulation of these processes have the potential to lead, respectively, to novel diagnostic approaches for the prediction of treatment outcome according to the patient's immunological profile, and to improved efficacy of antidepressant compounds through immune modulation.

Selecting antidepressants according to a drug-by-environment interaction: A comparison of fluoxetine and minocycline effects in mice living either in enriched or stressful conditions

Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for major depressive disorder. It has been recently proposed that these drugs, by enhancing neural plasticity, amplify the influences of the living conditions on mood. Consequently, SSRI outcome depends on the quality of the environment, improving symptomatology mainly in individuals living in favorable conditions. In adverse conditions, drugs with a different mechanism of action might have higher efficacy. The antibiotic minocycline, with neuroprotective and anti-inflammatory properties, has been recently proposed as a novel potential antidepressant treatment. To explore the drug-by-environment interaction, we compared the effects on depressive-like behavior and neural plasticity of the SSRI fluoxetine and minocycline in enriched and stressful conditions. We first exposed C57BL/6 adult female mice to 14 days of chronic unpredictable mild stress to induce a depressive-like profile. Afterward, mice received vehicle, fluoxetine, or minocycline for 21 days, while exposed to either enriched or stressful conditions. During the first five days, fluoxetine led to an improvement in enrichment but not in stress. By contrast, minocycline led to an improvement in both conditions. After 21 days, all groups showed a significant improvement in enrichment while fluoxetine worsened the depressive like behavior in stress. The effects of the drugs on neural plasticity, measured as long-term potentiation, were also environment-dependent. Overall, we show that the environment affects fluoxetine but not minocycline outcome, indicating that the latter represents a potential alternative to SSRIs to treat depressed patients living in adverse conditions. From a translation perspective, our finding call for considering the drug-by-environment interaction to select the most effective pharmacological treatment.

Shaping therapeutic trajectories in mental health: Instructive vs. permissive causality

We are currently facing the challenge of improving treatments for psychiatric disorders such as major depression. Notably, antidepressants have an incomplete efficacy, mostly due to our limited knowledge of their action. Here we present a theoretical framework that considers the distinction between instructive and permissive causality, which allows formalizing and disentangling the effects exerted by different therapeutic strategies commonly used in psychiatry. Instructive causality implies that an action determines a specific effect while permissive causality allows an action to take effect or not. We posit that therapeutic strategies able to improve the quality of the living environment or the ability to face it, including changes in lifestyle and psychotherapeutic interventions, rely mainly on instructive causality and thus shape the individual's ability to face the psychopathology and build resilience. By contrast, pharmacological treatments, such as selective serotonin reuptake inhibitors, act primarily through a permissive causality: they boost neural plasticity, i.e. the ability of the brain to change itself, and therefore allow for instructive interventions to produce beneficial effects or not. The combination of an instructive and a permissive action represents the most promising approach since the quality of the living environment can shape the path leading to mental health while drug treatment can increase the likelihood of achieving such a goal.

Antidepressant-like effect of a selenopropargylic benzamide in mice: involvement of the serotonergic system

RATIONALE

Major depressive disorder is a psychiatric disorder that requires considerable attention, since it dramatically impairs the quality of life of the sufferers. The available treatments do not have the efficacy needed, often presenting several side effects. Organoselenium compounds and benzamides have presented some pharmacological properties, among them an antidepressant-like effect.

OBJECTIVES AND METHODS

This study evaluated the antidepressant-like effect of N-(3-(phenylselanyl)prop-2-yn-1-yl)benzamide (SePB), an organoselenium compound containing a benzamide moiety, on the forced swimming test (FST) and the tail suspension test (TST) in mice, as well as the involvement of the serotonergic system in its effect.

RESULTS

SePB, tested after different times (15-120 min) and doses (1-50 mg/kg, intragastrically (i.g.)), reduced immobility of male mice during FST and TST, without changing locomotor activity in the open-field test (OFT), demonstrating its antidepressant-like effect. SePB (10 mg/kg) also produced an antidepressant-like effect in female mice in the TST. The preadministration of the serotonin (5-HT) depletor p-chlorophenylalanine (pCPA; 100 mg/kg, intraperitoneal route (i.p.) once daily for 4 days) prevented the anti-immobility effect of SePB, indicating that the serotonergic system is involved in the SePB antidepressant-like effect. The preadministration of the selective serotonergic receptor antagonists WAY100635 (0.1 mg/kg, subcutaneous route (s.c.), a selective 5-HT_1A receptor antagonist), ketanserin (1 mg/kg, i.p., a 5-HT_2A/2C receptor antagonist), and ondansetron (1 mg/kg, i.p., a selective 5-HT₃ receptor antagonist) also prevented the anti-immobility effect of SePB, demonstrating that these receptors are involved in the antidepressant-like effect of SePB.

CONCLUSION

The search for new antidepressants drugs is a noteworthy goal. This study has described a new compound with an antidepressant-like effect, whose mechanism of action is related to modulation of the serotonergic system.

Do people living in disadvantaged circumstances receive different mental health treatments than those from less disadvantaged backgrounds?

BACKGROUND

Socio-economic status (SES) has been linked to treatment outcomes for mental health problems, whilst little to no literature has explored the effects of SES on access to both medication and psychological therapy. The aim of this study was to explore whether access to mental health treatments differed by SES.

METHODS

The North West Coast Household Health Survey (HHS) collected data from residents aged 18+ from across 20 disadvantaged and 8 less disadvantaged neighbourhoods in 2015, and from 20 disadvantaged neighbourhoods in 2018. Logistic regression was used to explore the effects of SES on access to treatment (medication, psychological therapy) for people who had experienced mental health problems in the past 12 months.

RESULTS

Of 6860 participants, 2932 reported experiencing mental health problems in the past 12 months. People from more disadvantaged backgrounds experienced greater rates of anxiety and depression. Anti-depressant and anti-psychotic medication treatment was significantly more common in residents with lower SES, as well as counselling. Regression analysis showed that residents from more disadvantaged neighbourhoods who reported mental distress were more likely to receive medication.

CONCLUSIONS

This appears to be the first study showing higher levels of treatment with medication and psychological therapy in people from disadvantaged backgrounds. Future research needs to address the underlying factors associated with increased mental health treatment uptake in people from lower socio-economic backgrounds.

Do people living in disadvantaged circumstances receive different mental health treatments than those from less disadvantaged backgrounds?

BACKGROUND

Socio-economic status (SES) has been linked to treatment outcomes for mental health problems, whilst little to no literature has explored the effects of SES on access to both medication and psychological therapy. The aim of this study was to explore whether access to mental health treatments differed by SES.

METHODS

The North West Coast Household Health Survey (HHS) collected data from residents aged 18+ from across 20 disadvantaged and 8 less disadvantaged neighbourhoods in 2015, and from 20 disadvantaged neighbourhoods in 2018. Logistic regression was used to explore the effects of SES on access to treatment (medication, psychological therapy) for people who had experienced mental health problems in the past 12 months.

RESULTS

Of 6860 participants, 2932 reported experiencing mental health problems in the past 12 months. People from more disadvantaged backgrounds experienced greater rates of anxiety and depression. Anti-depressant and anti-psychotic medication treatment was significantly more common in residents with lower SES, as well as counselling. Regression analysis showed that residents from more disadvantaged neighbourhoods who reported mental distress were more likely to receive medication.

CONCLUSIONS

This appears to be the first study showing higher levels of treatment with medication and psychological therapy in people from disadvantaged backgrounds. Future research needs to address the underlying factors associated with increased mental health treatment uptake in people from lower socio-economic backgrounds.

Predictors of remission after repetitive transcranial magnetic stimulation for the treatment of major depressive disorder: An analysis from the randomised non-inferiority THREE-D trial

BACKGROUND

Although repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for major depressive disorder (MDD), treatment selection is still mainly a process of trial-and-error. The present study aimed to identify clinical predictors of remission after a course of rTMS delivered to the left DLPFC to improve patient selection.

METHODS

Data from a large randomised non-inferiority trial comparing standard 10 Hz and intermittent theta burst stimulation (iTBS) for the treatment of MDD were used for the exploratory analyses. Individual variables were assessed for their association with remission and then included in a logistic regression model to determine odds ratios (OR) and corresponding 95% confidence intervals. Model discrimination (internal validation) was carried out to assess model optimism using the c-index. ClinicalTrials.gov identifier: NCT01887782.

FINDINGS

388 subjects were included in the analysis (199-iTBS and 189-10 Hz, respectively). Higher baseline severity of both depressive and anxiety symptoms were associated with a lower chance of achieving remission (OR=0.64, 95% CI 0.46-0.88; and 0.78, 95% CI 0·60-0.98, respectively). Current employment was a positive predictor for remission (OR=1.69, 95% CI 1.06-2.7), while greater number of treatment failures was associated with lower odds of achieving remission (OR=0.51, 95% CI 0.27-0.98). A non-linear effect of age and remission was observed. An analysis to allow an estimate of the probability of remission using all variables was assessed. The c-index for the fitted model was 0.687.

INTERPRETATION

Our results suggest that measuring depression symptom severity, employment status, and refractoriness are important in prognosticating outcome to a course of rTMS in MDD.

FUNDING

Canadian Institutes of Health Research MOP-136801.