In memory of Professor Iain Wilkinson: cognitive and neuroimaging endophenotypes in a consanguineous schizophrenia multiplex family.

BACKGROUND: Schizophrenia endophenotypes may help elucidate functional effects of genetic risk variants in multiply affected consanguineous families that segregate recessive risk alleles of large effect size. We studied the association between a schizophrenia risk locus involving a 6.1Mb homozygous region on chromosome 13q22-31 in a consanguineous multiplex family and cognitive functioning, haemodynamic response and white matter integrity using neuroimaging. METHODS: We performed CANTAB neuropsychological testing on four affected family members (all homozygous for the risk locus), ten unaffected family members (seven homozygous and three heterozygous) and ten healthy volunteers, and tested neuronal responses on fMRI during an n-back working memory task, and white matter integrity on diffusion tensor imaging (DTI) on four affected and six unaffected family members (four homozygous and two heterozygous) and three healthy volunteers. For cognitive comparisons we used a linear mixed model (Kruskal-Wallis) test, followed by posthoc Dunn's pairwise tests with a Bonferroni adjustment. For fMRI analysis, we counted voxels exceeding the p < 0.05 corrected threshold. DTI analysis was observational. RESULTS: Family members with schizophrenia and unaffected family members homozygous for the risk haplotype showed attention (p < 0.01) and working memory deficits (p < 0.01) compared with healthy controls; a neural activation laterality bias towards the right prefrontal cortex (voxels reaching p < 0.05, corrected) and observed lower fractional anisotropy in the anterior cingulate cortex and left dorsolateral prefrontal cortex. CONCLUSIONS: In this family, homozygosity at the 13q risk locus was associated with impaired cognition, white matter integrity, and altered laterality of neural activation.

The Arabic Questionnaire for Psychotic Experiences in patients with psychotic disorders: a clinical validation.

BACKGROUND: Psychotic experiences are reported in the general population. The Questionnaire for Psychotic Experiences (QPE) was created to test the phenomenological features of these experiences and compare them with those reported in patients with psychiatric and other medical conditions. The aim of this study was to test the psychometric properties of the Arabic version of the QPE. METHODS: We recruited 50 patients with psychotic disorders from the Hamad Medical Hospital in Doha, Qatar. Patients underwent assessment over three sessions with trained interviewees using the Arabic versions of QPE, Positive and Negative Syndrome Scale (PANSS), Beck Depression Inventory (BDI), and the Global Assessment of Functioning Scale (GAF). Patients were also reassessed using the QPE and GAF after 14-days from the initial assessment in order to test for the stability of the scale. In this respect, this is the first study that assesses the test-retest reliability of the QPE. The psychometric properties including convergent validity, stability, and internal consistency met the benchmarked criteria. RESULTS: Results confirmed that the Arabic version of QPE accurately measured the experiences of patients that were also reported using the PANSS, an internationally accepted, well-established scale for measuring psychotic symptom severity. CONCLUSION: We propose the use of the QPE to describe the phenomenology of PEs across modalities in Arabic speaking communities.

Prevalence and associated factors of DSM-5 insomnia disorder in the general population of Qatar.

BACKGROUND: Epidemiological studies of insomnia in the Middle East remain scarce. The present study aimed to estimate the prevalence of insomnia and explore its associations in the general population of Qatar. With almost 100 nationalities, Qatar is one of the most culturally diverse, richest, and fastest developing countries in the Arabian Peninsula. METHODS: A probability sample of community-dwelling adults were surveyed in February of 2019. A total of 1611 respondents completed face-to-face interviews in Arabic or English. Logistic regression modeled associations with insomnia, our dependent variable, as defined by a score of ≤16 on the eight-item Sleep Condition Indicator or according to criteria for insomnia in the Diagnostic & Statistical Manual of Mental Disorders, fifth edition or DSM-5. RESULTS: Approximately, 5.5% of the sample screened positive for insomnia and the 30-day prevalence of those who met all the DSM-5 criteria for insomnia disorder was 3.0%. In addition, 2.0% of the sample screened positive for depression and 3.4% for anxiety in the past 2 weeks. Multivariable analysis showed the following were significantly associated with insomnia: Arab ethnicity, young age, unemployment, being married, having less than high school education, fair or poor health, anxiety, and depression. CONCLUSIONS: Insomnia prevalence was in the lower range of previously reported DSM-defined estimates from developed Western countries. Our findings highlight the need for raising awareness and improving sleep hygiene in potential risk groups such as younger adults and those of Arab ethnicity, in addition to incorporating insomnia screening in the provision of mental health services.

Quality of diabetes care in patients with schizophrenia: a case-control study in Qatar.

BACKGROUND: Patients with schizophrenia are at least twice as likely to develop diabetes mellitus compared to the general population. This is of significance in Qatar given the high prevalence of obesity and diabetes. Furthermore, the lifespan of people with schizophrenia is shortened by approximately 15 years, partly due to long-term microvascular and macrovascular complications. High quality diabetes care can significantly reduce morbidity and mortality. We assessed the level of diabetes care delivered to patients in Qatar with schizophrenia and diabetes compared to those with diabetes alone. METHODS: We performed a retrospective chart review of patients with diabetes mellitus with (n = 73) and without (n = 73) schizophrenia. Demographic information and electronic medical records were reviewed to determine adherence to American Diabetes Association standards of diabetes care in the last 6 and 12 months. Optimal diabetes care was defined as having completed glycated hemoglobin (HbA1c), lipid profile and retinal examination within 12 months. RESULTS: Optimal diabetes care was significantly lower in patients with schizophrenia and diabetes compared to diabetes alone [26.0% (n = 19/73) vs 52.1% (n = 38/73), p = 0.002]. Patients with diabetes and schizophrenia were also significantly less likely to have had body mass index recorded within 6 months (p = 0.008) and HbA1c (p = 0.006), lipid profile (p = 0.015), estimated glomerular filtration rate (eGFR) (p = 0.001) and order for retinal examination (p = 0.004) over 12 months. After adjusting for multiple comparisons, only assessment of eGFR (p = 0.01) and order for retinal examination (p = 0.04) remained significant. CONCLUSION: Patients in Qatar with schizophrenia and diabetes, receive sub-optimal diabetes care compared to those with diabetes alone.

Lifetime prevalence and potential determinants of psychotic experiences in the general population of Qatar.

BACKGROUND: To estimate the lifetime prevalence and potential determinants of psychotic experience(s) (PEs) in the general population of Qatar - a small non-war afflicted, conservative, high-income, middle-eastern country with recent rapid urbanization including an influx of migrants. METHODS: A probability-based sample (n = 1353) of non-migrants and migrants were interviewed face-to-face and administered a 7-item psychosis screener adapted from the Composite International Diagnostic Interview, the Kessler 6-item psychological distress scale, and the 5 items assessing odd (paranormal) beliefs and magical thinking (OBMT) from the Schizotypal Personality Questionnaire. Using bivariate and logistic regression analyses, lifetime prevalence rates of PEs were estimated then compared before and after adjustment for socio-demographics, Arab ethnicity, psychological distress, and OBMT. RESULTS: Prevalence of PEs was 27.9%. Visual hallucinations were most common (12.8%), followed by persecutory delusions (6.7%) and auditory hallucinations (6.9%). Ideas of reference (3.6%) were least prevalent. PEs were significantly higher in Arabs (34.7%) compared with non-Arabs (16.4%, p < 0.001) with the exception of ideas of reference and paranoid delusions. Female gender was associated with a higher prevalence of PEs in the Arab group only (p < 0.001). Prevalence of PEs was significantly higher among Arabs (48.8% v. 15.8%, p < 0.001) and non-Arabs (35.2% v. 7.3%, p < 0.001) with OBMT. Arab ethnicity (OR = 2.10, p = 0.015), psychological distress (OR = 2.29 p = 0.003), and OBMT (OR = 6.25, p < 0.001) were independently associated with PEs after adjustment for all variables. CONCLUSIONS: Ethnicity, but not migration was independently associated with PEs. Evidence linking Arab ethnicity, female gender, and psychological distress to PEs through associations with OBMT was identified for future prospective investigations.

Chemoenzymatic Synthesis of Trehalosamine, an Aminoglycoside Antibiotic and Precursor to Mycobacterial Imaging Probes.

Trehalosamine (2-amino-2-deoxy-α,α-d-trehalose) is an aminoglycoside with antimicrobial activity against Mycobacterium tuberculosis, and it is also a versatile synthetic intermediate used to access imaging probes for mycobacteria. To overcome inefficient chemical synthesis approaches, we report a two-step chemoenzymatic synthesis of trehalosamine that features trehalose synthase (TreT)-catalyzed glycosylation as the key transformation. Soluble and recyclable immobilized forms of TreT were successfully employed. We demonstrate that chemoenzymatically synthesized trehalosamine can be elaborated to two complementary imaging probes, which label mycobacteria via distinct pathways.

Tailoring Trehalose for Biomedical and Biotechnological Applications.

Trehalose is a non-reducing sugar whose ability to stabilize biomolecules has brought about its widespread use in biological preservation applications. Trehalose is also an essential metabolite in a number of pathogens, most significantly the global pathogen Mycobacterium tuberculosis, though it is absent in humans and other mammals. Recently, there has been a surge of interest in modifying the structure of trehalose to generate analogues that have applications in biomedical research and biotechnology. Non-degradable trehalose analogues could have a number of advantages as bioprotectants and food additives. Trehalose-based imaging probes and inhibitors are already useful as research tools and may have future value in the diagnosis and treatment of tuberculosis, among other uses. Underlying the advancements made in these areas are novel synthetic methods that facilitate access to and evaluation of trehalose analogues. In this review, we focus on both aspects of the development of this class of molecules. First, we consider the chemical and chemoenzymatic methods that have been used to prepare trehalose analogues and discuss their prospects for synthesis on commercially relevant scales. Second, we describe ongoing efforts to develop and deploy detectable trehalose analogues, trehalose-based inhibitors, and non-digestible trehalose analogues. The current and potential future uses of these compounds are discussed, with an emphasis on their roles in understanding and combatting mycobacterial infection.

Deoxyfluoro-d-trehalose (FDTre) analogues as potential PET probes for imaging mycobacterial infection.

Mycobacterium tuberculosis, the etiological agent of human tuberculosis, requires the non-mammalian disaccharide trehalose for growth and virulence. Recently, detectable trehalose analogues have gained attention as probes for studying trehalose metabolism and as potential diagnostic imaging agents for mycobacterial infections. Of particular interest are deoxy-[(18)F]fluoro-d-trehalose ((18)F-FDTre) analogues, which have been suggested as possible positron emission tomography (PET) probes for in vivo imaging of M. tuberculosis infection. Here, we report progress toward this objective, including the synthesis and conformational analysis of four non-radioactive deoxy-[(19)F]fluoro-d-trehalose ((19)F-FDTre) analogues, as well as evaluation of their uptake by M. smegmatis. The rapid synthesis and purification of several (19)F-FDTre analogues was accomplished in high yield using a one-step chemoenzymatic method. Conformational analysis of the (19)F-FDTre analogues using NMR and molecular modeling methods showed that fluorine substitution had a negligible effect on the conformation of the native disaccharide, suggesting that fluorinated analogues may be successfully recognized and processed by trehalose metabolic machinery in mycobacteria. To test this hypothesis and to evaluate a possible route for delivery of FDTre probes specifically to mycobacteria, we showed that (19)F-FDTre analogues are actively imported into M. smegmatis via the trehalose-specific transporter SugABC-LpqY. Finally, to demonstrate the applicability of these results to the efficient preparation and use of short-lived (18)F-FDTre PET radiotracers, we carried out (19)F-FDTre synthesis, purification, and administration to M. smegmatis in 1 hour.

Discrimination of voice gender in the human auditory cortex.

Discerning a speaker's gender from their voice is a basic and crucial aspect of human communication. Voice pitch height, the perceptual correlate of fundamental frequency, is higher in females and provides a cue for gender discrimination. However, male and female voices are also differentiated by multiple other spectral and temporal characteristics, including mean formant frequency and spectral flux. The robust perceptual segregation of male and female voices is thought to result from processing the combination of discriminating features, which in neural terms may correspond to early sound object analysis occurring in non-primary auditory cortex. However, the specific mechanism for gender perception has been unclear. Here, using functional magnetic resonance imaging, we show that discrete sites in non-primary auditory cortex are differentially activated by male and female voices, with female voices consistently evoking greater activation in the upper bank of the superior temporal sulcus and posterior superior temporal plane. This finding was observed at the individual subject-level in all 24 subjects. The neural response was highly specific: no auditory regions were more activated by male than female voices. Further, the activation associated with female voices was 1) larger than can be accounted for by a sole effect of fundamental frequency, 2) not due to psychological attribution of female gender and 3) unaffected by listener gender. These results demonstrate that male and female voices are represented as distinct auditory objects in the human brain, with the mechanism for gender discrimination being a gender-dependent activation-level cue in non-primary auditory cortex.

Reduced attention-driven auditory sensitivity in hallucination-prone individuals.

BACKGROUND: Evidence suggests that auditory hallucinations may result from abnormally enhanced auditory sensitivity. AIMS: To investigate whether there is an auditory processing bias in healthy individuals who are prone to experiencing auditory hallucinations. METHOD: Two hundred healthy volunteers performed a temporal order judgement task in which they determined whether an auditory or a visual stimulus came first under conditions of directed attention ('attend-auditory' and 'attend-visual' conditions). The Launay-Slade Hallucination Scale was used to divide the sample into high and low hallucination-proneness groups. RESULTS: The high hallucination-proneness group exhibited a reduced sensitivity to auditory stimuli under the attend-auditory condition. By contrast, attention-directed visual sensitivity did not differ significantly between groups. CONCLUSIONS: Healthy individuals prone to hallucinatory experiences may possess a bias in attention towards internal auditory stimuli at the expense of external sounds. Interventions involving the redistribution of attentional resources would have therapeutic benefit in patients experiencing auditory hallucinations.

Chemoenzymatic synthesis of trehalose analogues: rapid access to chemical probes for investigating mycobacteria.

Trehalose analogues are emerging as valuable tools for investigating Mycobacterium tuberculosis, but progress in this area is slow due to the difficulty in synthesizing these compounds. Here, we report a chemoenzymatic synthesis of trehalose analogues that employs the heat-stable enzyme trehalose synthase (TreT) from the hyperthermophile Thermoproteus tenax. By using TreT, various trehalose analogues were prepared quickly (1 h) in high yield (up to >99 % by HPLC) in a single step from readily available glucose analogues. To demonstrate the utility of this method in mycobacteria research, we performed a simple "one-pot metabolic labeling" experiment that accomplished probe synthesis, metabolic labeling, and imaging of M. smegmatis in a single day with only TreT and commercially available materials.

Qatar's National Mental Health Study-The World Mental Health Qatar.

BACKGROUND: We provide an overview of Qatar's first epidemiological study on prevalence, predictors, and treatment contact for mood and anxiety disorders. AIMS: We highlight the importance of the three-pronged study, its aims, and its key components. MATERIALS & METHODS: The first component comprised a probability-based representative survey of Qatari and non-Qatari (Arab) adult males and females recruited from the general population and interviewed using the International Diagnostic Interview (CIDI version 3.3). The second component, a clinical reappraisal study, assessed concordance between diagnoses based on the CIDI and independent clinical assessments conducted by trained clinical interviewers. The third component comprised a resting-state functional magnetic resonance imaging study of healthy survey respondents who were matched to patients with psychosis. RESULTS: 5000 survey interviews provided data on prevalence and treatment of common mental disorders. Clinical re-interviews (N = 485) provided important diagnostic validity data. Finally, state-of-the art structural and functional brain markers for psychosis were also collected (N = 100). DISCUSSION: Descriptive epidemiological data were collected to inform future mental health priorities in Qatar and situates these within a global context. CONCLUSION: The study fills important gaps in regional and global estimates and establish necessary baseline to develop comprehensive risk estimates for mental health in Qatar's young population.

Twelve-month prevalence, persistence, severity, and treatment of mood and anxiety disorders in Qatar's national mental health study.

OBJECTIVES: To estimate 12-month prevalence, persistence, severity, and treatment of mental disorders and socio-demographic correlates in Qatar. METHODS: We conducted the first national population-based telephone survey of Arab adults between 2019 and 2022 using the Composite International Diagnostic Interview and estimated 12-month DSM-5 mood and anxiety disorders and their persistence (the proportion of lifetime cases who continue to meet 12-month criteria). RESULTS: The 12-month prevalence of any disorder was 21.1% (10.4% mild, 38.7% moderate, and 50.9% severe) and was associated with: younger age, female, previously married, and with persistence of any disorder. Persistence was 74.7% (64.0% mood and 75.6% anxiety) and was significantly associated with secondary education or lower. Minimally adequate treatment received among those with any 12-month mental disorder was 10.6% (74.6% in healthcare and 64.6% non-healthcare sectors). Severity and the number of disorders significantly associated with each other and with treatment received (χ2 = 7.24, p = 0.027) including adequate treatment within the mental health specialty sector (χ2 = 21.42, p < 0.001). CONCLUSIONS: Multimorbidity and sociodemographics were associated with 12-month mental disorder. Treatment adequacy in Qatar are comparable to high-income countries. Low treatment contact indicate need for population-wide mental health literacy programes in addition to more accessible and effective mental health services.

Lifetime prevalence, risk, and treatment of mood and anxiety disorders in Qatar's national mental health study.

OBJECTIVES: To estimate lifetime prevalence, risk, and treatment for mental disorders and their correlates in Qatar's general population for the first time. METHODS: We conducted a national phone survey of 5,195 Qatari and Arab residents in Qatar (2019-2022) using the Composite International Diagnostic Interview Version 3.3 and estimated lifetime mood and anxiety defined diagnoses. Survival-based discrete time models, lifetime morbid risk, and treatment projections were estimated. RESULTS: Lifetime prevalence of any disorder was 28.0% and was associated with younger cohorts, females, and migrants, but lower formal education. Treatment contact in the year of disorder onset were 13.5%. The median delay in receiving treatment was 5 years (IQR = 2-13). Lifetime treatment among those with a lifetime disorder were 59.9% for non-healthcare and 63.5% for healthcare; it was 68.1% for any anxiety and 80.1% for any mood disorder after 50 years of onset. Younger cohorts and later age of onset were significantly predictors of treatment. CONCLUSIONS: Lifetime prevalence of mental disorders in Qatar is comparable to other countries. Treatment is significantly delayed and delivered largely in non-healthcare sectors thus the need for increased literacy of mental illness to reduce stigma and improve earlier help-seeking in healthcare settings.

Targeting Mycobacterium tuberculosis Persistence through Inhibition of the Trehalose Catalytic Shift.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is the leading cause of death worldwide by infectious disease. Treatment of Mtb infection requires a six-month course of multiple antibiotics, an extremely challenging regimen necessitated by Mtb's ability to form drug-tolerant persister cells. Mtb persister formation is dependent on the trehalose catalytic shift, a stress-responsive metabolic remodeling mechanism in which the disaccharide trehalose is liberated from cell surface glycolipids and repurposed as an internal carbon source to meet energy and redox demands. Here, using a biofilm-persister model, metabolomics, and cryo-electron microscopy (EM), we found that azidodeoxy- and aminodeoxy-d-trehalose analogues block the Mtb trehalose catalytic shift through inhibition of trehalose synthase TreS (Rv0126), which catalyzes the isomerization of trehalose to maltose. Out of a focused eight-member compound panel constructed by chemoenzymatic synthesis, the natural product 2-trehalosamine exhibited the highest potency and significantly potentiated first- and second-line TB drugs in broth culture and macrophage infection assays. We also report the first structure of TreS bound to a substrate analogue inhibitor, obtained via cryo-EM, which revealed conformational changes likely essential for catalysis and inhibitor binding that can potentially be exploited for future therapeutic development. Our results demonstrate that inhibition of the trehalose catalytic shift is a viable strategy to target Mtb persisters and advance trehalose analogues as tools and potential adjunctive therapeutics for investigating and targeting mycobacterial persistence.

Clinical reappraisal of the composite international diagnostic interview version 3.3 in Qatar's National Mental Health Study.

OBJECTIVES: Lifetime DSM-5 diagnoses generated by the lay-administered Composite International Diagnostic Interview for DSM-5 (CIDI) in the World Mental Health Qatar (WMHQ) study were compared to diagnoses based on blinded clinician-administered reappraisal interviews. METHODS: Telephone follow-up interviews used the non-patient edition of the Structured Clinician Interview for DSM-5 (SCID) oversampling respondents who screened positive for five diagnoses in the CIDI: major depressive episode, mania/hypomania, panic disorder, generalized anxiety disorder, and obsessive-compulsive disorder. Concordance was also examined for a diagnoses of post-traumatic stress disorder based on a short-form versus full version of the PTSD Checklist for DSM-5 (PCL-5). RESULTS: Initial CIDI prevalence estimates differed significantly from the SCID for most diagnoses ( χ 1 2 ${\chi }_{1}^{2}$  = 6.6-31.4, p = 0.010 < 0.001), but recalibration reduced most of these differences and led to consistent increases in individual-level concordance (AU-ROC) from 0.53-0.76 to 0.67-0.81. Recalibration of the short-form PCL-5 removed an initially significant difference in PTSD prevalence with the full PCL-5 (from χ 1 2 ${\chi }_{1}^{2}$  = 610.5, p < 0.001 to χ 1 2 ${\chi }_{1}^{2}$  = 2.5, p = 0.110) while also increasing AU-ROC from 0.76 to 0.81. CONCLUSIONS: Recalibration resulted in valid diagnoses of common mental disorders in the Qatar National Mental Health Survey, but with inflated prevalence estimates for some disorders that need to be considered when interpreting results.

Chromate reduction is expedited by bacteria engineered to produce the compatible solute trehalose.

The toxicity and solubility of chromium(VI) can be decreased by certain microbes that reduce chromium(VI) to chromium(III). However, these bacteria do not escape unscathed from this process. Chromium(VI) reduction damages the essential macromolecules of living systems. Trehalose protects organisms from chemical stress but has not been tested in the context of bioremediation. We engineered bacteria to produce trehalose and found that they then reduced 1 mM chromium(VI) to chromium(III), whereas wild-type cells were only able to reduce half that amount. Thus, by providing bacteria with a biochemical defense against the side-effects of chromate reduction may be a new approach to cleaning up sites that are contaminated with high levels of chromate.

Cross-cultural Differences in Hallucinations: A Comparison Between Middle Eastern and European Community-Based Samples.

BACKGROUND AND HYPOTHESIS: While literature indicates that culture modulates phenomenological characteristics of hallucinations in schizophrenia-spectrum disorders, little is known about the extent culture modulates these characteristics in nonclinical samples. STUDY DESIGN: We compared lifetime prevalence, age of onset, and phenomenology of hallucinations as assessed with the Questionnaire for Psychotic Experiences between samples of nonclinical participants used from the Netherlands (N = 2999) and Qatar (N = 2999). While participant recruitment differed between the 2 countries, the samples were relatively equal in terms of demographic factors. STUDY RESULTS: Our findings indicate that the lifetime prevalence of tactile and olfactory hallucinations are the same across countries. However, the prevalence of auditory hallucinations (AH) and visual hallucinations (VH) were twice as high in the Dutch sample. The reported age of onset for auditory and tactile hallucinations was younger for the Dutch sample. Findings from the measurement invariance supported cross-cultural comparisons with exception for duration, distress, and insight. Qatar's and Dutch participants reported similar valence and extent of interaction with AH and VH. However, compared to those in the Netherlands, participants from Qatar reported significantly more impact on daily functioning and a higher prevalence of receiving commands from hallucinations in the past week. CONCLUSIONS: While AH and VH were more often reported in the Dutch sample, participants in Qatar generally had higher mean factor scores for past week AH and VH than in the Netherlands. The phenomenology of hallucinations in the Qatar sample was of greater clinical relevance, with potentially important implications for early screening and prevention.

Design and field procedures for the clinical reappraisal of the Composite International Diagnostic Interview version 3.3 in Qatar's national mental health study.

BACKGROUND: The Composite International Diagnostic Interview (CIDI) has been clinically reappraised in several studies conducted mainly in the US and Europe. This report describes the methodology used to conduct one of the Middle East's largest clinical reappraisal studies. The study was carried out in conjunction with the World Mental Health Qatar-the first national psychiatric epidemiological study of common mental disorders in the country. This study aimed to evaluate the diagnostic consistency of core modules of the newly translated and adapted Arabic version of the CIDI 5.0 against the independent clinical diagnoses based on the Structured Clinical Interview for DSM-5 (SCID-5). METHODS: Telephone follow-up interviews were administered by trained clinicians using the latest research edition of the SCID for DSM-5. Telephone administered interviews were key in the data collection, as the study took place during the COVID-19 pandemic. RESULTS: Overall, within 12 months, 485 interviews were completed. The response rate was 52%. Quality control monitoring documented excellent adherence of clinical interviews to the rating protocol. CONCLUSIONS: The overall methods used in this study proved to be efficient and effective. For future research, instrument cultural adaptation within the cultural context is highly recommended.

Age of onset and cumulative risk of mental disorders: a cross-national analysis of population surveys from 29 countries.

BACKGROUND: Information on the frequency and timing of mental disorder onsets across the lifespan is of fundamental importance for public health planning. Broad, cross-national estimates of this information from coordinated general population surveys were last updated in 2007. We aimed to provide updated and improved estimates of age-of-onset distributions, lifetime prevalence, and morbid risk. METHODS: In this cross-national analysis, we analysed data from respondents aged 18 years or older to the World Mental Health surveys, a coordinated series of cross-sectional, face-to-face community epidemiological surveys administered between 2001 and 2022. In the surveys, the WHO Composite International Diagnostic Interview, a fully structured psychiatric diagnostic interview, was used to assess age of onset, lifetime prevalence, and morbid risk of 13 DSM-IV mental disorders until age 75 years across surveys by sex. We did not assess ethnicity. The surveys were geographically clustered and weighted to adjust for selection probability, and standard errors of incidence rates and cumulative incidence curves were calculated using the jackknife repeated replications simulation method, taking weighting and geographical clustering of data into account. FINDINGS: We included 156 331 respondents from 32 surveys in 29 countries, including 12 low-income and middle-income countries and 17 high-income countries, and including 85 308 (54·5%) female respondents and 71 023 (45·4%) male respondents. The lifetime prevalence of any mental disorder was 28·6% (95% CI 27·9-29·2) for male respondents and 29·8% (29·2-30·3) for female respondents. Morbid risk of any mental disorder by age 75 years was 46·4% (44·9-47·8) for male respondents and 53·1% (51·9-54·3) for female respondents. Conditional probabilities of first onset peaked at approximately age 15 years, with a median age of onset of 19 years (IQR 14-32) for male respondents and 20 years (12-36) for female respondents. The two most prevalent disorders were alcohol use disorder and major depressive disorder for male respondents and major depressive disorder and specific phobia for female respondents. INTERPRETATION: By age 75 years, approximately half the population can expect to develop one or more of the 13 mental disorders considered in this Article. These disorders typically first emerge in childhood, adolescence, or young adulthood. Services should have the capacity to detect and treat common mental disorders promptly and to optimise care that suits people at these crucial parts of the life course. FUNDING: None.