Examining the Incremental Validity of the Perth Alexithymia Questionnaire (PAQ) Relative to the 20-Item Toronto Alexithymia Scale (TAS-20).

The 20-item Toronto Alexithymia Scale (TAS-20) is the most widely used instrument for assessing alexithymia, with more than 25 years of research supporting its reliability and validity. The items that compose this scale were written to operationalize the components of the construct that are based on clinical observations of patients and thought to reflect deficits in the cognitive processing of emotions. The Perth Alexithymia Questionnaire (PAQ) is a recently introduced measure and is based on a theoretical attention-appraisal model of alexithymia. An important step with any newly developed measure is to evaluate whether it demonstrates incremental validity over existing measures. In this study using a community sample (N = 759), a series of hierarchical regression analyses were conducted that included an array of measures assessing constructs closely associated with alexithymia. Overall, the TAS-20 showed strong associations with these various constructs to which the PAQ was unable to add any meaningful increase in prediction relative to the TAS-20. We conclude that until future studies with clinical samples using several different criterion variables demonstrate incremental validity of the PAQ, the TAS-20 should remain the self-report measure of choice for clinicians and researchers assessing alexithymia, albeit as part of a multi-method approach.

An examination of the cross-cultural equivalence of the personality inventory for DSM-5 across Chinese and U.S. samples.

The Personality Inventory for DSM-5 (PID-5) was designed to measure the personality traits of the alternative model of personality disorders (AMPD). It is comprised of 25 lower order facet scales. Factor analytic investigation of these scales has consistently recovered five factors corresponding to the trait domains of the AMPD. Most of these factor analytic studies, however, have been conducted in the United States and Western European countries and languages. Fewer studies have examined the factor structure of the PID-5 in East Asian countries; and no studies have examined whether the five-factor structure found in Western countries/cultures/languages is congruent with those from East Asia. In this study, we examine the PID-5 factor structure in adult community samples from the People's Republic of China (PRC; N = 233 [116 females], Mage = 35.88, range = 22-60) and the United States (N = 237 [118 females], Mage = 35.44, range = 22-60) using exploratory structural equation modelling and assess whether the factor structures across these samples are congruent using Tucker's congruence coefficient. A five-factor solution was an adequate-to-good fit in both samples. The factor structure obtained from the U.S. sample was congruent with the PID-5 normative sample factor structure. The compositional configuration of the factors in the five-factor structure in the PRC sample, however, showed poor congruence with the U.S. sample. A six-factor model proved to be a better fitting model in the PRC sample. We conclude that the PID-5 does not have factor structure equivalence across U.S. and Chinese cultures/languages. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Revisiting the Concept of Pensée Opératoire: Some Conceptual, Empirical, and Clinical Considerations.

The concept of pensée opératoire (operational thinking) was introduced by French psychoanalysts in 1963 and a decade later was included as an essential component of the alexithymia construct as formulated by the U.S. analysts John Nemiah and Peter Sifneos. Despite a large body of research on alexithymia, the pensée opératoire component is not well understood, especially among clinicians and researchers who are not familiar with French psychoanalytic literature. In this article we clarify the definition and metapsychological conceptualization of the concept, review findings from some relevant empirical studies, and critique a recent proposal for redefining the alexithymia construct that departs from the original understanding of pensée opératoire. We also discuss some clinical implications of the concept and some strategies that psychotherapists can employ in the treatment of patients with this mode of thinking.

Measurement invariance of the Personality Inventory for the DSM-5 (PID-5) for Nigerian and White American university students.

In a previous study, it was reported that the typically replicable factor structure of the Personality Inventory for Diagnostic and Statistical Manual of Mental Disorders, fifth edition (PID-5) was noninvariant across samples of Black American and White American university students. The investigators of that study attributed this noninvariance across these two racial groups to Black American racialization, defined as Black individuals living in a predominantly non-Black society. In the current investigation, we examined further the effects of Black racialization by examining PID-5 factor structure invariance using a sample of nonracialized Black (Nigerian) university students (i.e., Black people living in a primarily Black society) and a sample of White American students. The factor structure of the PID-5 across the samples indicated overall configural invariance, suggesting that the same PID-5 facet traits, for the most part, load on the same factors for the nonracialized Black people and White Americans. This result is consistent with the view that Black racialization likely contributes to PID-5 factor structure noninvariance across White and Black Americans. There were some differences, however, between the Nigerian and White American students with respect to metric invariance and scalar invariance, suggesting the facet-to-factor loadings have different magnitudes of association across groups and that domain scale score elevations in Nigerian and White American students are not comparable; this was particularly prominent for the disinhibition domain. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Five-Factor Model and DSM-5 Alternative Model of Personality Disorder Profile Construction: Associations with Cognitive Ability and Clinical Symptoms.

Although numerous studies have explored latent profiles using the Five-Factor Model (FFM) of normative personality, no studies have investigated how broad personality traits (i.e., FFM) and pathological personality traits using the alternative model of personality disorder (AMPD) may combine for latent personality profiles. The present study recruited outpatients (N = 201) who completed the Big Five Aspects Scales (BFAS), Personality Inventory for DSM-5 (PID-5), Structured Clinical Interview for DSM-IV (SCID-I/P), gambling and alcohol use measures, and the Weschler Intelligence subtests. When FFM and AMPD measures were combined, latent profile analyses revealed four profiles, Internalizing-Thought disorder, Externalizing, Average-Detached, and Adaptive. Detachment and openness to experience were the most and least essential traits for profile distinction, respectively. No associations between group membership and cognitive ability measures were found. Internalizing-Thought disorder membership was linked with a current mood and anxiety disorder diagnosis. Externalizing profile membership was associated with younger age, problematic gambling, alcohol use, and a current substance use disorder diagnosis. The four FFM-AMPD profiles overlapped with the four FFM-only and three AMPD-only profiles. Overall, the FFM-AMPD profiles appeared to have better convergent and discriminant validity with DSM-relevant psychopathology.

Assessment of response bias in personality disorder research.

Most research on personality disorders (PDs) relies upon self-reported information, commonly collected via standardized self-report inventories or structured interviews. Such data might, for instance, be culled from archival records from applied evaluative contexts or collected as part of dedicated anonymized research studies. Many factors-such as disengagement, distractibility, or motivation to appear in a certain manner-may influence whether self-reported information accurately reflects an examinee's genuine personality characteristics. Despite resultant risks to the validity of collected data, very few measures used in PD research include embedded indicators of response validity. In this article, we review the need for validity measures and strategies that exist to identify invalid self-report data, and we offer several suggestions for PD researchers to consider in order to detect invalid self-reported information and improve the quality of their data. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Replicating patient-level moderators of CBT and IPT's comparative efficacy for depression.

Although evidence-based psychotherapies, such as cognitive behavioral therapy (CBT) and interpersonal psychotherapy (IPT), produce comparable average outcomes, it is plausible that some patients who possess one or more specific characteristics may respond better to one over the other. Addressing this what works best for whom question, researchers have tested the moderating influence of patient characteristics on comparative treatment effects (viz. aptitude-treatment interactions [ATIs]). However, few ATIs have emerged or replicated, thereby providing little treatment-selection guidance. Informed by a systematic review of patient ATIs in trials that compared CBT versus IPT for depression (Bernecker et al., 2017), this study aimed to replicate (a) significant ATIs previously established in a single study; and (b) significant ATIs previously examined twice, with only one study demonstrating a moderating effect. Data derived from a trial in which adult outpatients with major depression were randomly assigned to 16 weeks of CBT (n = 41) or IPT (n = 39). Patient characteristics were measured at baseline, and patients rated their depression throughout treatment. Multilevel models revealed one ATI replication; for patients with more self-sacrificing interpersonal problems, CBT outperformed IPT; the reverse was true for patients with fewer such problems. Other moderators either failed to replicate or directionally contradicted prior research. Results help inform optimal treatment matching for some patients, which reflects a type of psychotherapy personalization. However, they also highlight limitations of traditional ATI research and suggest that different methods are needed to inform responsive personalization efforts more expansively and reliably. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Revising the trait model of the alternative model of personality disorders: Comment on Clark and Watson's structural review.

In their review of examination of the self-report Personality Inventory for Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition (DSM-5; PID-5) factor structure and joint factor analysis of this instrument with other self-report measures of personality and psychopathology, Clark and Watson (2022) make argument for a set of modifications to the DSM-5 alternative model of personality disorders (AMPD)-the AMPD-5.1. In this commentary we offer opinion that their proposed modifications to the AMPD are problematic. In particular, we express concern that their modifications are based solely on research that uses a single instrument to measure the model and that this instrument employs a self-report measure methodology. We argue further that this method of assessment is vulnerable to response bias which could potentially alter the substantive structure of the model. We suggest that any proposed revised model should also be informed by other forms of measurement (e.g., informant report and structured interviews). In addition, we also argue that the best approach to delineating the universe of pathological personality traits should also include clinician input. Such input would maximize the clinical utility of any revised model. We believe that to propose a modified model that is based on self-report only and does not include other sources of information is presumptive and premature. At best, we think that Clark and Watson (2022) have only provided suggestions for a revision and expansion of the Personality Inventory for DSM-5 (i.e., the PID-5.1). (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Higher trait neuroticism is associated with greater fatty acid amide hydrolase binding in borderline and antisocial personality disorders.

Borderline personality disorder (BPD) and antisocial personality disorder (ASPD) are the two most frequently diagnosed and researched DSM-5 personality disorders, and both are characterized by high levels of trait neuroticism. Fatty acid amide hydrolase (FAAH), an enzyme of the endocannabinoid system (ECS), has been linked to regulation of mood through modulation of anandamide, an endocannabinoid. We hypothesized that prefrontal cortex (PFC) FAAH binding would relate to trait neuroticism in personality disorders. Thirty-one individuals with personality disorders (20 with BPD and 11 with ASPD) completed the investigation. All participants completed the revised NEO Personality Inventory, which yields standardized scores (e.g., T scores) for the traits of neuroticism, openness, conscientiousness, agreeableness, and extraversion. All participants were medication free and were not utilizing illicit substances as determined by drug urinalysis. Additionally, none of the participants had a comorbid major depressive episode, bipolar disorder, psychotic disorder, or substance use disorder. Each participant underwent one [11C]CURB PET scan. Consistent with our hypothesis, neuroticism was positively correlated with PFC FAAH binding (r = 0.42, p = 0.021), controlling for genotype. Neuroticism was also positively correlated with dorsal putamen FAAH binding (r = 0.53, p = 0.0024), controlling for genotype. Elevated brain FAAH is an endophenotype for high neuroticism in BPD and ASPD. Novel pharmacological therapeutics that inhibit FAAH could emerge as potential new treatments for BPD and ASPD with high neuroticism.

N400 event-related brain potential and functional outcome in persons at clinical high risk for psychosis: A longitudinal study.

BACKGROUND: The N400 event-related brain potential (ERP) semantic priming effect is thought to reflect activation by meaningful stimuli of related concepts in semantic memory and has been found to be deficient in schizophrenia. We tested the hypothesis that, among individuals at clinical high risk (CHR) for psychosis, N400 semantic priming deficits predict worse symptomatic and functional outcomes after one year. METHODS: We measured N400 semantic priming at baseline in CHR patients (n = 47) and healthy control participants (n = 25) who viewed prime words each followed by a related or unrelated target word, at stimulus-onset asynchronies (SOAs) of 300 or 750 ms. We measured patients' psychosis-like symptoms with the Scale of Prodromal Symptoms (SOPS) Positive subscale, and academic/occupational and social functioning with the Global Functioning (GF):Role and Social scales, respectively, at baseline and one-year follow-up (n = 29). RESULTS: CHR patients exhibited less N400 semantic priming than controls across SOAs; planned contrasts indicated this difference was significant at the 750-ms but not the 300-ms SOA. In patients, reduced N400 semantic priming at the 750-ms SOA was associated with lower GF:Social scores at follow-up, and greater GF:Social decrements from baseline to follow-up. Patients' N400 semantic priming was not associated with SOPS Positive or GF:Role scores at follow-up, or change in these from baseline to follow-up. CONCLUSIONS: In CHR patients, reduced N400 semantic priming at baseline predicted worse social functioning after one year, and greater decline in social functioning over this period. Thus, the N400 may be a useful prognostic biomarker of real-world functional outcome in CHR patients.

Normative data for PID-5 domains, facets, and personality disorder composites from a representative sample and comparison to community and clinical samples.

The introduction of the alternative model of personality disorders in the fifth edition of the Diagnostic and Statistical Model of Mental Disorders (American Psychiatric Association, 2013) represented a substantive change in how personality disorders (PDs) are diagnosed. One barrier to its adoption (among several) in clinical practice, however, is a lack of information as to what constitutes an elevated score on the 25 domains and facets that comprise Criterion B. Unique sets of facets can be configured to assess any 1 of 6 PDs retained in the alternative model of personality disorders; each of these facets can in turn be added to create a PD sum score. In the current study, using the Personality Inventory for Diagnostic and Statistical Model of Mental Disorders, Fifth Edition (Krueger et al., 2012), we report mean scores using this instrument that align with 1.0, 1.5, and 2.0 SD elevations for the 25 facets, five domains, and six PD composites on the basis of Krueger and colleagues' (2012) representative sample and compare these with those obtained from a community and a clinical sample. These normative data may be useful to clinicians in determining whether a client has elevated scores on pathological personality domains, facets, or PDs. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Evaluating the measurement invariance of the Personality Inventory for DSM-5 (PID-5) in Black Americans and White Americans.

The Personality Inventory for the DSM-5 (PID-5) assesses the five pathological personality trait domains that comprise the descriptive core of the DSM-5 Alternative Model of Personality Disorders (AMPD). The PID-5 five-domain factor structure is aligned with the AMPD and is reported as replicable across samples in the U.S., in other countries, and in different languages. In this study, the PID-5 factor structure is examined in two distinct racial groups within the U.S.-White Americans (WA) and Black Americans (BA). Student participants from four universities in the U.S. (N = 1,834)-composed of groups of WA (n = 1,274) and BA (n = 560)-were proportionally parsed into derivation and replication subsamples. The "traditional" PID-5 five-factor structure emerged for the WA group in the derivation subsample and was subsequently confirmed in the WA replication subsample. In the BA group derivation subsample, a single-factor solution emerged, which was also confirmed in the BA replication sample. This single-factor solution in the BA group reflects large shared covariation across all pathological personality domains, suggesting an undifferentiated, broadly based level of demoralization represented by the item pool of the PID-5. We argue that this structure can be construed as mirroring a racialized and prejudice-based living experience for many BAs in a predominantly non-Black society. Based on the results with the samples employed in the present study, we conclude that the PID-5 is not an equivalent measure of pathological personality traits across Black Americans and White Americans. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The Development of Preliminary HiTOP Internalizing Spectrum Scales.

As part of a broader project to create a comprehensive self-report measure for the Hierarchical Taxonomy of Psychopathology consortium, we developed preliminary scales to assess internalizing symptoms. The item pool was created in four steps: (a) clarifying the range of content to be assessed, (b) identifying target constructs to guide item writing, (c) developing formal definitions for each construct, and (d) writing multiple items for each construct. This yielded 430 items assessing 57 target constructs. Responses from a heterogeneous scale development sample (N = 1,870) were subjected to item-level factor analyses based on polychoric correlations. This resulted in 39 scales representing a total of 213 items. The psychometric properties of these scales replicated well across the development sample and an independent validation sample (N = 496 adults). Internal consistency analyses established that most scales assess relatively narrow forms of psychopathology. Structural analyses demonstrated the presence of a strong general factor. Additional analyses of the 35 nonsexual dysfunction scales revealed a replicable four-factor structure with dimensions we labeled Distress, Fear, Body Dysmorphia, and Mania. A final set of analyses established that the internalizing scales varied widely-and consistently-in the strength of their associations with neuroticism and extraversion.

Specific early maladaptive schemas differentially mediate the relations of emotional and sexual maltreatment to recent life events in youth with depression.

The current study provided a novel investigation of relations among particular types of childhood maltreatment (emotional vs. physical vs. sexual maltreatment), specific cognitive schema themes and the generation of dependent versus independent life events. Participants included 227 adolescents and emerging adults (74% female; aged 12-29) in a current episode of a unipolar depressive disorder drawn from three archival cross-sectional studies. Childhood maltreatment and life events from the past 6 months were assessed using detailed contextual interviews with independent, standardized ratings. Emotional maltreatment was uniquely associated with schema themes of emotional deprivation and subjugation, and sexual maltreatment was uniquely associated with schema themes of abandonment, vulnerability and dependence/incompetence. Further, subjugation and abandonment cross-sectionally mediated the relations of emotional and sexual maltreatment, respectively, to greater dependent, but not independent, life events. Physical maltreatment was not associated with cognitive schemas or recent life events after accounting for its overlap with emotional and sexual maltreatment. Results suggest targets for cognitive intervention that may improve outcomes for youth with specific histories of emotional and sexual maltreatment.

Reliability and construct validity of the general factor of personality disorder.

Criterion B of the alternative model of personality disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), outlines maladaptive trait dimensions that characterize personality disorders. Emerging evidence from bifactor confirmatory factor analyses suggest these traits are related at a higher order level by a general factor of personality disorder (g-PD). Further, emerging evidence points to traits most closely related to borderline personality disorder as underpinnings of g-PD. Further investigation is required to better understand the shared basis of personality disorder, with attention to the reliability and validity of g-PD. The g-PD theory was examined in a clinical (n = 242), and community sample (n = 252) of adults, using a brief form of the Personality Inventory for DSM-5 (PID-5). Structural analyses supported a correlated 6-factor model and a bifactor solution, validating the g-PD structure. Reliability indices supported the unidimensionality, reliability, and replicability of the g-PD factor. The strongest loading and most unidimensional items on the g-PD factors were from the Negative Affectivity and Disinhibition trait domains, partially replicating the trait profile of borderline personality disorder traits. In validity analyses, the nomological network of the general and specific factors were examined. g-PD was more strongly correlated with internalizing measures and impairment than specific factors, but specific factors were more strongly correlated with thought disorder and externalizing measures than g-PD. Our results support the nature and reliability of a general factor characterized by Negative Affectivity and Disinhibition unifying personality disorder traits in a brief form of the PID-5. Implications for the alternative model of personality disorder, PID-5, and g-PD theory are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Les progrès dans la réalisation de la classification quantitative de la psychopathologie.

Shortcomings of approaches to classifying psychopathology based on expert consensus have given rise to contemporary efforts to classify psychopathology quantitatively. In this paper, we review progress in achieving a quantitative and empirical classification of psychopathology. A substantial empirical literature indicates that psychopathology is generally more dimensional than categorical. When the discreteness versus continuity of psychopathology is treated as a research question, as opposed to being decided as a matter of tradition, the evidence clearly supports the hypothesis of continuity. In addition, a related body of literature shows how psychopathology dimensions can be arranged in a hierarchy, ranging from very broad "spectrum level" dimensions, to specific and narrow clusters of symptoms. In this way, a quantitative approach solves the "problem of comorbidity" by explicitly modeling patterns of co-occurrence among signs and symptoms within a detailed and variegated hierarchy of dimensional concepts with direct clinical utility. Indeed, extensive evidence pertaining to the dimensional and hierarchical structure of psychopathology has led to the formation of the Hierarchical Taxonomy of Psychopathology (HiTOP) Consortium. This is a group of 70 investigators working together to study empirical classification of psychopathology. In this paper, we describe the aims and current foci of the HiTOP Consortium. These aims pertain to continued research on the empirical organization of psychopathology; the connection between personality and psychopathology; the utility of empirically based psychopathology constructs in both research and the clinic; and the development of novel and comprehensive models and corresponding assessment instruments for psychopathology constructs derived from an empirical approach.

Cross-Cutting Symptom Domains Predict Functioning in Psychotic Disorders.

OBJECTIVE: Previous research shows elevated disability in psychotic disorders. However, co-occurring symptomatology has been increasingly highlighted as predictive of clinical outcomes in the psychotic spectrum. The current study investigates how both psychotic and nonpsychotic symptom domains predict functioning across psychotic disorders. METHODS: Outpatients (N = 128) with psychotic spectrum diagnoses participated in the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition (DSM-5) Field Trials at the Centre for Addiction and Mental Health in Toronto, Canada, in 2011, including the repeated administration of "cross-cutting" brief screening measures that assessed internalizing (eg, anxiety, depression), substance use (eg, alcohol, psychoactive drug use), and psychotic symptoms. Level of functioning was also assessed by self-report and clinician-rated World Health Organization Disability Assessment Schedule 2.0 (WHO-DAS-II). The relation between symptom domains and disability was examined concurrently and prospectively via hierarchical regression. RESULTS: Psychosis was strongly linked to self-reported disability when considered in isolation (ß = 0.22, P < .001; R2 = 0.11). However, when all 3 symptom domains were included in analyses, internalizing symptoms were the strongest concurrent (ß = 0.31, P < .001; R2 = 0.17) and prospective (ß = 0.29, P < .001; R2 = 0.15) predictor of disability. In the concurrent model, an interaction between internalizing and substance use emerged, wherein high internalizing symptoms were particularly detrimental in persons with high levels of substance use (ß = 0.08, P < .05; R2 = 0.014). Results were similar for clinician-rated WHO-DAS-II. CONCLUSIONS: This research supports the potential clinical utility of rapid screening tools available in the newest psychiatric diagnostic manual. The internalizing symptom domain was the strongest predictor of functional outcome for outpatients with psychotic disorders. The results highlight the relevance of a broad range of symptoms, including those that fall outside the primary psychiatric concern, in recovery-oriented clinical work in psychosis.

A bifactor analysis of the 20-item Toronto Alexithymia Scale: Further support for a general alexithymia factor.

The 20-Item Toronto Alexithymia Scale (TAS-20) is the most widely used measure to assess the personality construct of alexithymia and is composed of three-factor analytically derived subscales. These subscales measure and represent three critical, theoretically based facets of alexithymia. The subscales are distinct, yet highly interrelated and only as a collective body do they reflect adequately the alexithymia construct. Although different studies using both university student and community samples suggest that TAS-20 total scores are largely reflective of variation on a single construct, and that subscale scores do not provide unique and reliable information beyond total scores, many users of the scale frequently continue to employ and even rely more heavily on subscale scores rather than total scale scores when interpreting research study outcomes. Our goal in this study is to provide clinicians and researchers with replicable psychometric information for the TAS-20 estimated from bifactor modeling in an attempt to provide further support for using total rather than subscale scores. In general, our findings were consistent with previous studies indicating that TAS-20 total scores can be considered indicative of a single construct. The replication of these earlier results from previous investigations provides additional support for the use of a total TAS-20 score and questions the utility of using TAS-20 subscale scores. Based on these results, we recommend that researchers and clinicians use a single total TAS-20 score and not subscale scores. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

An evaluation of alexithymia subtypes using latent profile analysis.

Four subtypes of the alexithymia construct have been proposed based on different response patterns to the Cognitive and Affective dimensions of the Bermond-Vorst Alexithymia Questionnaire (BVAQ). Previous studies investigating whether alexithymia subtypes can be statistically estimated have not found complete support for these specific subtypes. These previous studies, however, contained several methodological limitations such as relatively small sample sizes, and considerations of only a limited number of proposed subtypes. In the current investigation, we examined whether the four proposed subtypes could be statistically detected in a large sample of undergraduate students (N = 612) who completed the BVAQ, using latent profile analysis (LPA). Based on observed responses to the five BVAQ subscales, consistent with previous studies, our results did not find support for the four proposed alexithymia subtypes. Rather, our results suggested LPA solutions that correspond to individuals with various degrees of alexithymia 'severity'. Although further studies are needed, especially with clinical samples, these results question the idea of four alexithymia subtypes and suggest that the implementation of these subtypes into various research studies may be a premature endeavour.

The efficacy of antidepressant medication and interpersonal psychotherapy for adult acute-phase depression: study protocol of a systematic review and meta-analysis of individual participant data.

BACKGROUND: Antidepressant medication and interpersonal psychotherapy (IPT) are both recommended interventions in depression treatment guidelines based on literature reviews and meta-analyses. However, 'conventional' meta-analyses comparing their efficacy are limited by their reliance on reported study-level information and a narrow focus on depression outcome measures assessed at treatment completion. Individual participant data (IPD) meta-analysis, considered the gold standard in evidence synthesis, can improve the quality of the analyses when compared with conventional meta-analysis. AIMS: We describe the protocol for a systematic review and IPD meta-analysis comparing the efficacy of antidepressants and IPT for adult acute-phase depression across a range of outcome measures, including depressive symptom severity as well as functioning and well-being, at both post-treatment and follow-up (PROSPERO: CRD42020219891). METHOD: We will conduct a systematic literature search in PubMed, PsycINFO, Embase and the Cochrane Library to identify randomised clinical trials comparing antidepressants and IPT in the acute-phase treatment of adults with depression. We will invite the authors of these studies to share the participant-level data of their trials. One-stage IPD meta-analyses will be conducted using mixed-effects models to assess treatment effects at post-treatment and follow-up for all outcome measures that are assessed in at least two studies. CONCLUSIONS: This will be the first IPD meta-analysis examining antidepressants versus IPT efficacy. This study has the potential to enhance our knowledge of depression treatment by comparing the short- and long-term effects of two widely used interventions across a range of outcome measures using state-of-the-art statistical techniques.