Assessment of suicidality in trials of psychological interventions for depression: a meta-analysis.

BACKGROUND: Psychological interventions that are efficacious as treatments for depression could indirectly affect suicide-related outcomes. We examined suicidal thoughts and behaviours as eligibility criteria, outcomes, and adverse events across trials of psychotherapy for depression. METHODS: We used a publicly available meta-analytic database developed through systematic searches (updated as of May 1, 2023) to identify randomised controlled trials in which a psychological intervention for depression was compared with an inactive or non-specific control condition in adults with depression and in which any suicide-related outcomes were reported. We also identified studies in which suicide risk was an exclusion criterion. We excluded inpatient studies and trials of unguided digital interventions or collaborative care that included a psychological component. Pairs of reviewers worked independently to select studies and extract data. In a random-effects meta-analysis with robust variance estimation, we assessed the effect of the psychological intervention on suicide outcomes in trials in which suicide was explicitly assessed as an outcome with clinical scales with established psychometric properties. Risk of bias was assessed with the Cochrane risk-of-bias tool (version 2). FINDINGS: Of the 469 randomised trials we identified in which a psychological intervention was compared with an inactive control in people with depression, 251 excluded people judged at risk of suicide. Any assessment of suicide was included in only 45 trials, 12 of which assessed suicidal ideation or risk as an outcome. These 12 trials included 3930 participants, 2795 (71%) of whom were female and 1135 (29%) of whom were male; data for age and ethnicity were not consistently reported. Psychological interventions for depression were associated with a small reduction in suicidal ideation and risk in 11 trials (one trial reported only follow-up data) after the intervention (standardised mean difference -0·31 [95% CI -0·60 to -0·03]) but not at follow-up (-0·49 [-1·31 to 0·32]). Suicide-related adverse events were reported in 25 trials, and suicide-related serious adverse events (eg, suicide attempts, deaths by suicide) were reported in 13 trials. Heterogeneity was substantial across all analyses, and prediction intervals crossed zero. INTERPRETATION: Trials of psychological interventions for depression rarely report assessments of suicide. Psychological interventions might reduce suicidal ideation in patients with depression, but more randomised controlled trials are required to clarify this effect. Monitoring and reporting of suicide-related adverse events should be improved in trials of psychological interventions for depression, and future trials should incorporate outcomes related to suicidal thoughts or behaviours. FUNDING: None. TRANSLATION: For the Spanish translation of the abstract see Supplementary Materials section.

The moderating role of depressive symptoms in the association between heart rate variability and cognitive performance in cardiac patients.

INTRODUCTION: Coronary heart disease (CHD) is strongly associated with cognitive impairment, which is a core feature of depression, highly prevalent in patients with CHD. Interestingly, patients with CHD and individuals with depression display reduced heart rate variability (HRV), which proxies a complex network integrating autonomic and attentional systems. This study investigated the moderating role of depressive symptoms in the relation between reduced HRV and cognitive performance in patients with CHD. METHOD: The sample included 274 patients with CHD (mean [standard deviation] age = 62 [9.5] years; 13 % women) admitted to cardiac rehabilitation units. Visual attention and task switching were assessed through the Trail Making Test (TMT). Depressive symptoms were assessed with the Beck Depression Inventory-II (BDI-II). Resting electrocardiographic recordings were collected to compute HRV indices. RESULTS: Patients with more severe depressive symptoms displayed an inverse association between HRV and cognitive performance (TMT-A: b = -0.08, p = .022; TMTB: b = -0.07, p = .042), whereas patients with milder depressive symptoms showed no significant association (TMT-A: b = -0.00, p = .90; TMTB: b = -0.02, p = .44). CONCLUSIONS: Depressive symptoms may strengthen the relation between reduced HRV and poorer cognitive performance in cardiac patients. The presence of depressive symptoms may signal the dysfunction of a network subserving autonomic and cognitive function.

Low odor awareness predicts reduced olfactory abilities in women with depressive symptoms, but not with anxiety symptoms.

BACKGROUND: Olfactory disorders and affective symptoms are tightly related. However, the factors underlying this association are not yet understood. One candidate factor is "odor awareness": the degree of attention individuals pays to the odors. However, the association between odor awareness and olfactory abilities in individuals with affective symptoms has not been clarified yet. METHOD: The present study examined whether odor awareness may moderate (a) the relation between olfactory dysfunctions and depressive and anxiety symptoms; (b) the relation between the perceptual ratings of the odors and depressive and anxiety symptoms in a sample of healthy women (n = 214). Self-report measures of depression and anxiety were collected, whereas the Sniffin' Stick test was employed to measure olfactory abilities. RESULTS: Linear regression analysis revealed that individuals with higher depressive symptoms presented lower olfactory abilities and that odor awareness was a significant moderator of the association between depressive symptoms and olfactory abilities. Anxiety symptoms were not related to any of the olfactory abilities considered, and this relationship did not change according to odor awareness. The familiarity rating of the odor was significantly predicted by odor awareness. These results were confirmed by Bayesian statistics. LIMITATIONS: The sample was composed only of women. CONCLUSIONS: In a healthy population of women, only the presence of depressive symptoms is related to reduced olfactory performance. Odor awareness may be implicated in the development and maintenance of olfactory dysfunction; hence it could be used as a useful target for specific treatments in clinical settings.

Alexithymia modulates the attitudes towards odors but not the olfactory abilities or the affective reactions to odors.

Although emotion and olfaction are closely linked, only a few studies have investigated olfactory processing in alexithymia, a condition characterized by altered emotional processing. These results do not allow comprehensive conclusions on whether individuals with alexithymia present lower olfactory abilities or only altered affective reactions and awareness of odors. Three pre-registered experiments were conducted to clarify this relation. We assessed olfactory functions, the affective qualities of odors, the awareness of odors, the attitudes towards them, and the ability to form olfactory images in the mind. Bayesian statistics were used to assess differences between low, medium and high alexithymia groups, and Linear Mixed Models (LMMs) were applied to investigate the modulation of the affective and cognitive components of alexithymia. We observed that individuals with a high level of alexithymia presented the same olfactory abilities, and did not show differences in their rating of odors compared to individuals with low alexithymia levels, while they reported lower levels of social and common odor awareness and a more indifferent attitude towards odors. Olfactory imagery was not affected by alexithymia level, and the affective and cognitive components of alexithymia, when considered separately, modulated olfactory perception differently. Learning more about olfactory perception in individuals with alexithymia leads to a better understanding of how alexithymia impacts the perception of hedonic stimuli coming from different sensory modalities. Our results imply that treatment goals for alexithymia should be the enhancement of the conscious perception of odors, supporting the use of mindfulness-based protocols in the alexithymia treatment.

A New Validation of Montreal Cognitive Assessment on a Large Sample of Elderly Patients Undergoing Elective Orthopedic Surgery.

Objective: The hip and knee arthroplasties are reliable and suitable surgical procedures aimed at restoring the patients' functioning. The most representative age range for these replacement surgeries is between 65 and 84 years for females. With aging, the likelihood of developing cognitive deficits increases, and there is evidence that elderly patients undergoing surgery orthopedic are at higher risk of developing cognitive problems in the postoperative phase. The Montreal Cognitive Assessment (MoCA) is often used for cognitive evaluation, but different cut-offs and validations are available in the literature. Given the importance of the problem, in this work we studied a hospitalized population candidate for orthopedic surgery to determine a new specific validation of the MoCA to assess the risk of MCI. Method: We applied MoCA and Mini-Mental State Examination (MMSE) to a sample of 492 (333 women) hospitalized patients for knee (74%) or hip surgery. A non-parametric receiver operating characteristic (ROC) curve analysis was conducted to investigate the predictive accuracy of the MoCA to assess cognitive impairment, using MMSE as the gold standard. Results: A score of 22.52 gives a sensitivity of 70% and a specificity of 78%. This value is providing a more coherent diagnosis with the MMSE as compared to the other cut-offs presented in the other available validations. No differences were found between patients in terms of age and gender, suggesting a general uniformity of the selected sample. Conclusions: Deepening the coherence in MCI diagnosis between MMSE and the other MoCA's scoring considered, our new cut-off seems reasonably better than previous Italian validation on an elderly population in matching MMSE classification.

Emotion regulation difficulties in the relation between stress-related insomnia symptoms and brain response to emotional faces: An fMRI study.

The aim of the current study was to investigate whether the experience of insomnia symptoms per se and symptoms of insomnia due to stress are associated with an increased brain response to the presentation of emotional faces. In addition, we also examined whether the effect of these sleep difficulties on emotional reactivity at the brain level depends on the experience of emotion regulation (ER) difficulties. The current sample consisted of 37 individuals (20 females, 17 males) selected from a larger group of 120 respondents who completed a survey about sleep problems and ER difficulties. Our results indicate that the tendency to experience stress-related insomnia symptoms but not insomnia symptoms per se modulates brain responses to emotional facial expressions, especially in areas of the parietal cortex, insula, and surrounding opercular voxels. Furthermore, difficulties in ER might play an important role, as the effect of stress-related insomnia symptoms on most of these brain regions disappears when controlling for difficulties in ER. However, an effect in the insula was maintained during the presentation of angry faces, suggesting that stress-related insomnia symptoms may increase the brain response to anger in the insula relatively independent from difficulties in ER. These findings suggest that individuals affected by stress-related insomnia symptoms show an enhanced brain response when presented with emotional stimuli (either positive or negative) in brain areas associated with hyperarousal, which could represent a possible ER deficit in these individuals. Thus, interventions that focus on targeting ER difficulties might be effective in reducing the hyperarousal state in individuals affected by stress-related insomnia symptoms.

Physiologically-Informed Gaussian Processes for Interpretable Modelling of Psycho-Physiological States.

The widespread popularity of Machine Learning (ML) models in healthcare solutions has increased the demand for their interpretability and accountability. In this paper, we propose the Physiologically-Informed Gaussian Process (PhGP) classification model, an interpretable machine learning model founded on the Bayesian nature of Gaussian Processes (GPs). Specifically, we inject problem-specific domain knowledge of inherent physiological mechanisms underlying the psycho-physiological states as a prior distribution over the GP latent space. Thus, to estimate the hyper-parameters in PhGP, we rely on the information from raw physiological signals as well as the designed prior function encoding the physiologically-inspired modelling assumptions. Alongside this new model, we present novel interpretability metrics that highlight the most informative input regions that contribute to the GP prediction. We evaluate the ability of PhGP to provide an accurate and interpretable classification on three different datasets, including electrodermal activity (EDA) signals collected during emotional, painful, and stressful tasks. Our results demonstrate that, for all three tasks, recognition performance is improved by using the PhGP model compared to competitive methods. Moreover, PhGP is able to provide physiological sound interpretations over its predictions.

Psychometric validation of the Italian version of the Emotional Style Questionnaire.

Emotional styles concern the ways in which individuals adapt and respond to the world and can be defined using six dimensions: outlook, resilience, social intuition, self-awareness, sensitivity to context and attention. The Emotional Style Questionnaire (ESQ) assesses how people vary across the dimensions and gauges an individual's overall level of emotional health. An Italian version of the ESQ (ESQ-ITA) could favour the understanding of cultural characteristics concerning emotions and personality within the Italian population, with both clinical and social implications. The aim of the present study is to validate the ESQ in the Italian language and to assess its psychometric properties. Two studies were conducted. Study 1 examined construct validity, internal consistency, and test-retest reliability, through Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA), Cronbach's alpha estimates, and by estimating the Spearman's rank correlation Study 2 examined construct validity and internal consistency through the CFA and Cronbach's alpha estimates and investigated criterion validity by correlating the ESQ-ITA dimensions with the corresponding scales or subscales used for the validation estimating, again, the Spearman's rank correlation coefficient Study 2 also examined the criterion validity of the validated scales and the ESQ-ITA overall score to assess its suitability as an indicator of emotional health. ESQ-ITA was confirmed to be reliable and stable. The correlation between the ESQ-ITA overall score and the other scales and questionnaires supports the use of ESQ-ITA to measure emotional health. The Italian version of the ESQ opens up the possibility to enrich the research landscape with new knowledge that will be useful for advancing the pathogenetic and therapeutic aspects of psychological distress and emotional dysregulation.

Human body odors of happiness and fear modulate the late positive potential component during neutral face processing: a preliminary ERP study on healthy subjects.

Human body odors (HBOs) are powerful stimuli that can affect emotional, cognitive and behavioral processes. However, the characterization of the physiological response to HBOs is still to be fully investigated. Here, we analyzed the self-assessed emotion perception and the EEG event-related potentials (ERP) on 17 healthy young women during a simultaneous visual-olfactory stimulation. Particularly, we evaluated the effect of happiness and fear HBO on the amplitude of ERP waveforms elicited by neutral face processing. In addition, we evaluated the subjective valence and arousal perception of the presented neutral faces by means of the self-assessment-manikin test. We observed a significant increase in the amplitude of the late positive potential (LPP) for central left sites (i.e., C3) during the administration of HBOs with respect to clean air. On the other hand, we did not observe any significant change in the subjective valence and arousal scores as well as for the early components of the ERP (i.e., P100, N170, Vertex-Positive-Potential). Our preliminary results suggest that fear and happiness HBO can induce a protracted increase in the LPP, and possibly reflect an automatic and sustained engagement with emotionally significant content.

Complexity Modulation in functional Brain-Heart Interplay series driven by Emotional Stimuli: an early study using Fuzzy Entropy.

Increasing attention has recently been devoted to the multidisciplinary investigation of functional brain-heart interplay (BHI), which has provided meaningful insights in neuroscience and clinical domains including cardiology, neurology, clinical psychology, and psychiatry. While neural (brain) and heartbeat series show high nonlinear and complex dynamics, a complexity analysis on BHI series has not been performed yet. To this end, in this preliminary study, we investigate BHI complexity modulation in 17 healthy subjects undergoing a 3-minute resting state and emotional elicitation through standardized image slideshow. Electroencephalographic and heart rate variability series were the inputs of an adhoc BHI model, which provides directional (from-heart-to-brain and from-brain-to-heart) estimates at different frequency bands. A Fuzzy entropy analysis was performed channel-wise on the model output for the two experimental conditions. Results suggest that BHI complexity increases in the emotional elicitation phase with respect to a resting state, especially in the functional direction from the heart to the brain. We conclude that BHI complexity may be a viable computational tool to characterize neurophysiological and pathological states under different experimental conditions.

The NEVERMIND e-health system in the treatment of depressive symptoms among patients with severe somatic conditions: A multicentre, pragmatic randomised controlled trial.

Background: This study assessed the effectiveness of the NEVERMIND e-health system, consisting of a smart shirt and a mobile application with lifestyle behavioural advice, mindfulness-based therapy, and cognitive behavioural therapy, in reducing depressive symptoms among patients diagnosed with severe somatic conditions. Our hypothesis was that the system would significantly decrease the level of depressive symptoms in the intervention group compared to the control group. Methods: This pragmatic, randomised controlled trial included 425 patients diagnosed with myocardial infarction, breast cancer, prostate cancer, kidney failure, or lower limb amputation. Participants were recruited from hospitals in Turin and Pisa (Italy), and Lisbon (Portugal), and were randomly assigned to either the NEVERMIND intervention or to the control group. Clinical interviews and structured questionnaires were administered at baseline, 12 weeks, and 24 weeks. The primary outcome was depressive symptoms at 12 weeks measured by the Beck Depression Inventory II (BDI-II). Intention-to-treat analyses included 425 participants, while the per-protocol analyses included 333 participants. This trial is registered in the German Clinical Trials Register, DRKS00013391. Findings: Patients were recruited between Dec 4, 2017, and Dec 31, 2019, with 213 assigned to the intervention and 212 to the control group. The sample had a mean age of 59·41 years (SD=10·70), with 44·24% women. Those who used the NEVERMIND system had statistically significant lower depressive symptoms at the 12-week follow-up (mean difference=-3·03, p<0·001; 95% CI -4·45 to -1·62) compared with controls, with a clinically relevant effect size (Cohen's d=0·39). Interpretation: The results of this study show that the NEVERMIND system is superior to standard care in reducing and preventing depressive symptoms among patients with the studied somatic conditions. Funding: The NEVERMIND project received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 689691.

The impact of COVID-19-related quarantine on psychological outcomes in patients after cardiac intervention: a multicenter longitudinal study.

Mandatory quarantine during the COVID-19 pandemic had substantial negative consequences on psychological health in the general population. Depression, anxiety, and insomnia were reported to increase the morbidity and mortality risk in cardiac patients after cardiac interventions. Nonetheless, a gap in the evidence appeared regarding the effects of COVID-19-related quarantine on psychological outcomes in patients after cardiac interventions. The present study aimed to longitudinally investigate the effects of quarantine on depressive, anxiety, and insomnia symptoms in a group of patients who underwent cardiac intervention. Seventy-three patients admitted for cardiac rehabilitation completed a psychological assessment before and a reassessment after the quarantine and were included in the quarantine group. The control group included 76 patients who completed both evaluations before the quarantine. Depressive (Beck Depression Inventory-II; BDI-II), anxiety (Beck Anxiety Inventory-II; BAI), and insomnia (Sleep Condition Indicator; SCI) symptoms were evaluated in both groups at one (assessment) and eight (reassessment) months after cardiac intervention. The statistical analyses revealed that at reassessment, the quarantine group showed higher global depressive, anxiety, and insomnia symptoms than the control group and increased cognitive symptoms of depression. A higher presence of clinically relevant depressed patients was seen in the quarantine group. The present results showed that the COVID-19-related mandatory quarantine negatively affected psychological outcomes in patients after cardiac intervention, increasing the probability for these patients to be depressed. This, in turn, could influence patients' health in a critical period for morbidity and mortality risk. This underlines the priority of integrating and improving targeted mental health support as the pandemic continues, especially for cardiac patients.

Cardiac sympathetic-vagal activity initiates a functional brain-body response to emotional arousal.

A century-long debate on bodily states and emotions persists. While the involvement of bodily activity in emotion physiology is widely recognized, the specificity and causal role of such activity related to brain dynamics has not yet been demonstrated. We hypothesize that the peripheral neural control on cardiovascular activity prompts and sustains brain dynamics during an emotional experience, so these afferent inputs are processed by the brain by triggering a concurrent efferent information transfer to the body. To this end, we investigated the functional brain­heart interplay under emotion elicitation in publicly available data from 62 healthy subjects using a computational model based on synthetic data generation of electroencephalography and electrocardiography signals. Our findings show that sympathovagal activity plays a leading and causal role in initiating the emotional response, in which ascending modulations from vagal activity precede neural dynamics and correlate to the reported level of arousal. The subsequent dynamic interplay observed between the central and autonomic nervous systems sustains the processing of emotional arousal. These findings should be particularly revealing for the psychophysiology and neuroscience of emotions.

The Influence of Emotion Regulation on the Association Between Depression and Heart Rate Variability in Cardiac Patients.

OBJECTIVE: Poor vagally mediated heart rate variability (vmHRV) is a mechanism linking depression to coronary heart disease (CHD). Reduced vmHRV is also considered an index of emotion dysregulation-the frequent use of maladaptive emotion regulation strategies, one of the most important being expressive suppression-which is a key component of depression. Therefore, this study aimed to investigate the moderating role of expressive suppression in the relation between depression and vmHRV in patients with CHD. METHODS: The sample included 235 patients with CHD (mean [standard deviation] age = 61.6 [9.8] years; 12% women) admitted to cardiac rehabilitation after a cardiac intervention. The Beck Depression Inventory-II was administered to assess depressive symptoms. Emotion regulation strategies based on either expressive suppression or cognitive reappraisal were assessed through the Emotion Regulation Questionnaire. Resting electrocardiographic recordings were collected for 5 minutes to compute HRV indices. RESULTS: Expressive suppression moderated the relation between depressive symptoms and vmHRV ( b = -0.03, p = .012). Patients with lower expressive suppression scores showed no association between depressive symptoms and vmHRV ( b = -0.00, p = .94), whereas those with higher expressive suppression scores showed a significant negative association between depressive symptoms and vmHRV ( b = -0.05, p = .015). CONCLUSIONS: The use of expressive suppression is likely to potentiate the relation between depressive symptoms and poor vmHRV, which could increase the cardiac risk in these patients. Targeting emotion regulation skills in cardiac rehabilitation programs may be useful for reducing the impact of depression in cardiac patients.

Olfactory meta-cognition in individuals with depressive and anxiety symptoms: The differential role of common and social odors.

BACKGROUND: Diminished olfactory functioning has been reported in depression, whereas evidence in anxiety disorders is still controversial. Olfactory meta-cognitive abilities (i.e., olfactory awareness, imagery and reactivity, and the importance of odors) are essential in shaping olfaction. Few studies examined these meta-cognitive abilities in relation to depressive, anxiety, and social anxiety symptoms, and none of them considered the awareness of social odors (i.e., body odors). METHODS: This pre-registered study examined the relationship between olfactory meta-cognitive abilities and symptoms of depression, general anxiety, and social anxiety in 429 individuals. Self-report measures of symptoms of depression, general anxiety, and social anxiety, along with self-report olfactory meta-cognitive scales, were collected using an online survey. RESULTS: Linear regression analyses revealed that olfactory awareness and importance of common odors were significantly directly predicted by symptoms of general anxiety, while affective importance to odors was negatively predicted by symptoms of depression. Regarding social odors, higher symptoms of depression and lower symptoms of social anxiety predicted increased awareness. LIMITATIONS: Higher prevalence of women and narrow age range of the participants. Depressive and anxiety symptoms were assessed only with self-report questionnaires. CONCLUSIONS: Symptoms of anxiety seem to be associated with higher levels of common odor awareness, corroborating the importance of olfactory functions in anxiety. In addition, results on social odors seem to reflect dysfunctional social behaviour that characterized symptoms of depression and social anxiety. Hence, the assessment of meta-cognitive abilities may represent a useful tool in the prevention and assessment of depressive, anxiety, and social anxiety symptoms.

The Einstein effect provides global evidence for scientific source credibility effects and the influence of religiosity.

People tend to evaluate information from reliable sources more favourably, but it is unclear exactly how perceivers' worldviews interact with this source credibility effect. In a large and diverse cross-cultural sample (N = 10,195 from 24 countries), we presented participants with obscure, meaningless statements attributed to either a spiritual guru or a scientist. We found a robust global source credibility effect for scientific authorities, which we dub 'the Einstein effect': across all 24 countries and all levels of religiosity, scientists held greater authority than spiritual gurus. In addition, individual religiosity predicted a weaker relative preference for the statement from the scientist compared with the spiritual guru, and was more strongly associated with credibility judgements for the guru than the scientist. Independent data on explicit trust ratings across 143 countries mirrored our experimental findings. These findings suggest that irrespective of one's religious worldview, across cultures science is a powerful and universal heuristic that signals the reliability of information.

Anxiety predicts impulsive-compulsive behaviours in Parkinson's disease: Clinical relevance and theoretical implications.

Patients with Parkinson's disease (PD) often present symptoms of anxiety, depression and apathy. These negative affect manifestations have been recently associated with the presence of impulsive compulsive behaviours (ICBs). However, their relation with the use of dopamine replacement therapy (DRT), a renewed risk factor for ICBs, is still not fully understood. Elucidating the role of these different ICBs predictors in PD could inform both prevention/intervention recommendations as well as theoretical models. In the present study, we have analysed data collected in 417 PD patients, 50 patients with Parkinsonian symptoms but with scan without evidence of dopaminergic deficit (SWEDD), and 185 healthy controls (HC). We examined each patient's clinical profile over a two-year time window, investigating the role of both negative affect and DRT on ICBs. Results confirmed the presence of higher levels of anxiety in both the clinical groups, and of higher level of ICBs in SWEDD patients, respect to both PD and HC. Mixed model analyses revealed a statistically significant association between anxiety and ICBs in the SWEDD patients who did not take any DRT. Findings suggest the independence between anxiety and DRT in ICBs development, and provide new evidence for the motivational opponency theoretical framework.

Resting state predicts neural activity during reward-guided decision making: An fMRI study on Balloon Analogue Risk Task.

In our previous work [8], we have shown that resting state (RS) functional connectivity metrics are significantly related with behavioural performance at Balloon Analogue Risk Task (BART). In the present study we investigated the hypothesis of an association between RS metrics and neural activity evoked by BART execution. A group-level whole-brain regression was run to assess whether RS metrics predict brain activation during the BART, in a sample of 35 young healthy adults (mean age 23 ± 2 years, 25 F). Results complete the previous findings showing that RS is also significantly associated with the neural activity during BART execution. Specifically, ALFF is positively associated with the activity of both the right inferior parietal lobule and the left caudate. These new results are coherent with previous evidence indicating RS abnormalities in clinical conditions characterised by symptoms of impulse control disorders, and further suggest that RS might be a stable predictor of both behavioural indices and neural correlates of impulsivity and of reward-guided decision-making.

The social odor scale: Development and initial validation of a new scale for the assessment of social odor awareness.

The degree of attention individuals pay to olfactory cues (called odor awareness) influences the role of odors in everyday life. Particularly, odors produced by the human body (i.e., social odors) are able to carry a wide variety of information and to elicit a broad spectrum of emotional reactions, making them essential in interpersonal relationships. Hence, despite the assessment of awareness toward social odors is crucial, a proper tool is still lacking. Here, we designed and initially validated the Social Odor Scale (SOS), a 12-item scale designed to measure the individual differences in awareness towards different social odors. In Study 1, an exploratory factor analysis (EFA; KMO test: MSA = 0.78; Bartlett's test: χ2(78) = 631.34, p < 0.001; Chi-squared test: χ2(42) = 71.84, p = 0.003) suggests that the three factors structure was the model that best fit with the Italian version of the scale. The confirmatory factor analysis (CFA) supports a second-order model with one higher-order factor representing social odor awareness in general and three lower-order factors representing familiar, romantic partner, and stranger social odors. The final version of the scale presented a good fit (RMSEA = 0.012, SRMR = 0.069, CFI = 0.998, TLI = 0.997). In Study 2, CFA was performed in the German version of the scale confirming the validity of scale structure. Study 3 and 4 revealed that SOS total score and its subscales were positively correlated with other validated olfactory scales, but not with olfactory abilities. Moreover, SOS was found to be related to the gender of the participants: women reported to be more aware to social odors and, specifically, to familiar social odors than men. Overall, the results indicated that SOS is a valid and reliable instrument to assess awareness toward social odors in everyday life.