Examining temporal trends in psychological distress and the co-occurrence of common substance use in a population-based sample of grade 7-12 students from 2013 to 2019

PURPOSE

Characterizing trends and correlates of adolescent psychological distress is important due to observed global increases over the last 20 years. Substance use is a commonly discussed correlate, though we lack an understanding about how co-occurrence of these concerns has been changing over time.

METHODS

Data came from repeated, representative, cross-sectional surveys of grade 7-12 students across Ontario, Canada conducted biennially from 2013 to 2019. Poisson regression with robust standard errors was used to examine changes in the joint association between psychological distress (operationalized as Kessler-6 [K6] scores ≥ 13) and substance use over time. Weighted prevalence ratios (PR) and their 99% confidence intervals were estimated, where p < 0.01 denotes statistical significance.

RESULTS

The prevalence of psychological distress doubled between 2013 and 2019, with adjusted increases of about 1.2 times each survey year. This biennial increase did not differ based on sex, perceived social standing, school level, or any substance use. Students using substances consistently reported a higher prevalence of psychological distress (between 1.2 times and 2.7 times higher). There were similarly no differential temporal trends based on substance use for very high distress (K6 ≥ 19) or K6 items explored individually.

CONCLUSION

Psychological distress steeply increased among adolescents and substance use remains important to assess and address alongside distress. However, the magnitude of temporal increases appears to be similar for adolescents reporting and not reporting substance use.

Assessing distress in the community: psychometric properties and crosswalk comparison of eight measures of psychological distress

BACKGROUND

Many measures are available for measuring psychological distress in the community. Limited research has compared these scales to identify the best performing tools. A common metric for distress measures would enable researchers and clinicians to equate scores across different measures. The current study evaluated eight psychological distress scales and developed crosswalks (tables/figures presenting multiple scales on a common metric) to enable scores on these scales to be equated.

METHODS

An Australian online adult sample (N = 3620, 80% female) was administered eight psychological distress measures: Patient Health Questionnaire-4, Kessler-10/Kessler-6, Distress Questionnaire-5 (DQ5), Mental Health Inventory-5, Hopkins Symptom Checklist-25 (HSCL-25), Self-Report Questionnaire-20 (SRQ-20) and Distress Thermometer. The performance of each measure in identifying DSM-5 criteria for a range of mental disorders was tested. Scale fit to a unidimensional latent construct was assessed using Confirmatory Factor Analysis (CFA). Finally, crosswalks were developed using Item Response Theory.

RESULTS

The DQ5 had optimal performance in identifying individuals meeting DSM-5 criteria, with adequate fit to a unidimensional construct. The HSCL-25 and SRQ-20 also had adequate fit but poorer specificity and/or sensitivity than the DQ5 in identifying caseness. The unidimensional CFA of the combined item bank for the eight scales showed acceptable fit, enabling the creation of crosswalk tables.

CONCLUSIONS

The DQ5 had optimal performance in identifying risk of mental health problems. The crosswalk tables developed in this study will enable rapid conversion between distress measures, providing more efficient means of data aggregation and a resource to facilitate interpretation of scores from multiple distress scales.

Combined universal and selective prevention for adolescent alcohol use: a cluster randomized controlled trial

BACKGROUND

No existing models of alcohol prevention concurrently adopt universal and selective approaches. This study aims to evaluate the first combined universal and selective approach to alcohol prevention.

METHOD

A total of 26 Australian schools with 2190 students (mean age: 13.3 years) were randomized to receive: universal prevention (Climate Schools); selective prevention (Preventure); combined prevention (Climate Schools and Preventure; CAP); or health education as usual (control). Primary outcomes were alcohol use, binge drinking and alcohol-related harms at 6, 12 and 24 months.

RESULTS

Climate, Preventure and CAP students demonstrated significantly lower growth in their likelihood to drink and binge drink, relative to controls over 24 months. Preventure students displayed significantly lower growth in their likelihood to experience alcohol harms, relative to controls. While adolescents in both the CAP and Climate groups demonstrated slower growth in drinking compared with adolescents in the control group over the 2-year study period, CAP adolescents demonstrated faster growth in drinking compared with Climate adolescents.

CONCLUSIONS

Findings support universal, selective and combined approaches to alcohol prevention. Particularly novel are the findings of no advantage of the combined approach over universal or selective prevention alone.

Parental supply of alcohol and alcohol consumption in adolescence: prospective cohort study

BACKGROUND

Parents are a major supplier of alcohol to adolescents, yet there is limited research examining the impact of this on adolescent alcohol use. This study investigates associations between parental supply of alcohol, supply from other sources, and adolescent drinking, adjusting for child, parent, family and peer variables.

METHOD

A cohort of 1927 adolescents was surveyed annually from 2010 to 2014. Measures include: consumption of whole drinks; binge drinking (>4 standard drinks on any occasion); parental supply of alcohol; supply from other sources; child, parent, family and peer covariates.

RESULTS

After adjustment, adolescents supplied alcohol by parents had higher odds of drinking whole beverages [odds ratio (OR) 1.80, 95% confidence interval (CI) 1.33-2.45] than those not supplied by parents. However, parental supply was not associated with bingeing, and those supplied alcohol by parents typically consumed fewer drinks per occasion (incidence rate ratio 0.86, 95% CI 0.77-0.96) than adolescents supplied only from other sources. Adolescents obtaining alcohol from non-parental sources had increased odds of drinking whole beverages (OR 2.53, 95% CI 1.86-3.45) and bingeing (OR 3.51, 95% CI 2.53-4.87).

CONCLUSIONS

Parental supply of alcohol to adolescents was associated with increased risk of drinking, but not bingeing. These parentally-supplied children also consumed fewer drinks on a typical drinking occasion. Adolescents supplied alcohol from non-parental sources had greater odds of drinking and bingeing. Further follow-up is necessary to determine whether these patterns continue, and to examine alcohol-related harm trajectories. Parents should be advised that supply of alcohol may increase children's drinking.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Classification of anxiety and depressive disorders: problems and solutions

The American Psychiatric Association and the World Health Organization have begun to revise their classifications of mental disorders. Four issues related to these revisions are discussed in this study: the structure of the classifications, the relationship between categories and dimensions, the sensitivity of categorical thresholds to definitions, and maximizing the utility and validity of the diagnostic process. There is now sufficient evidence to consider replacing the present groupings of disorders with an empirically based structure that reflects the actual similarities among disorders. For example, perhaps the present depression and anxiety disorders would be best grouped as internalizing disorders. Most mental disorders exist on a severity dimension. The reliability and validity of the classification might be improved if we accepted the dimensional nature of disorders while retaining the use of categorical diagnoses to enhance clinical utility. Definitions of the thresholds that define categories are very susceptible to detail. In International Classification of Diseases-11(ICD-11) and Diagnostic and Statistical Manual of Mental Disorders-V (DSM-V), disorders about which there is agreement should be identically defined, and disorders in which there is disagreement should be defined differently, so that research can identify which definition is more valid. The present diagnostic criteria are too complex to have acceptable clinical utility. We propose a reduced criterion set that can be remembered by clinicians and an enhanced criterion set for use with decision support tools.

The structure of adolescent psychopathology: a symptom-level analysis

BACKGROUND

Most empirical studies into the covariance structure of psychopathology have been confined to adults. This work is not developmentally informed as the meaning, age-of-onset, persistence and expression of disorders differ across the lifespan. This study investigates the underlying structure of adolescent psychopathology and associations between the psychopathological dimensions and sex and personality risk profiles for substance misuse and mental health problems.

METHOD

This study analyzed data from 2175 adolescents aged 13.3 years. Five dimensional models were tested using confirmatory factor analysis and the external validity was examined using a multiple-indicators multiple-causes model.

RESULTS

A modified bifactor model, with three correlated specific factors (internalizing, externalizing, thought disorder) and one general psychopathology factor, provided the best fit to the data. Females reported higher mean levels of internalizing, and males reported higher mean levels of externalizing. No significant sex differences emerged in liability to thought disorder or general psychopathology. Liability to internalizing, externalizing, thought disorder and general psychopathology was characterized by a number of differences in personality profiles.

CONCLUSIONS

This study is the first to identify a bifactor model including a specific thought disorder factor. The findings highlight the utility of transdiagnostic treatment approaches and the importance of restructuring psychopathology in an empirically based manner.

The epidemiology of traumatic event exposure worldwide: results from the World Mental Health Survey Consortium

BACKGROUND

Considerable research has documented that exposure to traumatic events has negative effects on physical and mental health. Much less research has examined the predictors of traumatic event exposure. Increased understanding of risk factors for exposure to traumatic events could be of considerable value in targeting preventive interventions and anticipating service needs.

METHOD

General population surveys in 24 countries with a combined sample of 68 894 adult respondents across six continents assessed exposure to 29 traumatic event types. Differences in prevalence were examined with cross-tabulations. Exploratory factor analysis was conducted to determine whether traumatic event types clustered into interpretable factors. Survival analysis was carried out to examine associations of sociodemographic characteristics and prior traumatic events with subsequent exposure.

RESULTS

Over 70% of respondents reported a traumatic event; 30.5% were exposed to four or more. Five types - witnessing death or serious injury, the unexpected death of a loved one, being mugged, being in a life-threatening automobile accident, and experiencing a life-threatening illness or injury - accounted for over half of all exposures. Exposure varied by country, sociodemographics and history of prior traumatic events. Being married was the most consistent protective factor. Exposure to interpersonal violence had the strongest associations with subsequent traumatic events.

CONCLUSIONS

Given the near ubiquity of exposure, limited resources may best be dedicated to those that are more likely to be further exposed such as victims of interpersonal violence. Identifying mechanisms that account for the associations of prior interpersonal violence with subsequent trauma is critical to develop interventions to prevent revictimization.

Examining the shared and unique relationships among substance use and mental disorders

BACKGROUND

Co-morbidity among use of different substances can be explained by a shared underlying dimensional factor. What remains unknown is whether the relationship between substance use and various co-morbid mental disorders can be explained solely by the general factor or whether there remain unique contributions of specific substances.

METHOD

Data were from the 2007 Australian National Survey of Mental Health and Wellbeing (NSMHWB). A unidimensional latent factor was constructed that represented general substance use. The shared and specific relationships between lifetime substance use indicators and internalizing disorders, suicidality and psychotic-like experiences (PLEs) were examined using Multiple Indicators Multiple Causes (MIMIC) models in the total sample. Additional analyses then examined the shared and specific relationships associated with substance dependence diagnoses as indicators of the latent trait focusing on a subsample of substance users.

RESULTS

General levels of latent substance use were significantly and positively related to internalizing disorders, suicidality and psychotic-like experiences. Similar results were found when examining general levels of latent substance dependence in a sample of substance users. There were several direct effects between specific substance use/dependence indicators and the mental health correlates that significantly improved the overall model fit but they were small in magnitude and had relatively little impact on the general relationship.

CONCLUSIONS

The majority of pairwise co-morbid relationships between substance use/dependence and mental health correlates can be explained through a general latent factor. Researchers should focus on investigating the commonalities across all substance use and dependence indicators when studying mental health co-morbidity.

Bipolar disorder in a national survey using the World Mental Health Version of the Composite International Diagnostic Interview: the impact of differing diagnostic algorithms

OBJECTIVE

The World Mental Health Version of the Composite International Diagnostic Interview (WMH-CIDI) DSM-IV bipolar disorder diagnostic algorithms were recalibrated in about 2006 following evidence of over-diagnosis of bipolar I disorder. There have been no reports of the impact of this recalibration on epidemiological findings.

METHOD

Data were taken from the 2007 Australian National Survey of Mental Health and Wellbeing. Findings for cases identified by the recalibrated bipolar disorder definition were contrasted against those identified by the un-recalibrated definition.

RESULTS

The 12-month prevalence of recalibrated bipolar disorder and un-recalibrated bipolar disorder were 0.9% and 1.7% respectively. The un-recalibrated bipolar disorder group was younger and more likely to have never married than the recalibrated bipolar disorder group. They were also more likely to have a comorbid alcohol use disorder, substance use disorder and asthma or arthritis. While they were more likely to have at least severe interference in at least one of the Sheehan Scale domains of functioning, they were less likely to have made a suicide attempt. Similarly, they were less likely to have consulted a psychiatrist.

CONCLUSION

It is not possible to be certain about the nature of these differences. Some may be artifactual (reflecting greater statistical power to detect differences with the larger un-recalibrated bipolar disorder defined sample), while others may be indicative of the inclusion of a clinically distinct subpopulation with the un-recalibrated bipolar disorder definition, thereby producing a more heterogeneous sample. These findings indicate the need for clarity in the diagnostic algorithm used in epidemiological reports on bipolar disorder using the World Mental Health Version of the Composite International Diagnostic Interview.

Remission from post-traumatic stress disorder in the general population

BACKGROUND

Few studies have focused on post-traumatic stress disorder (PTSD) remission in the population, none have modelled remission beyond age 54 years and none have explored in detail the correlates of remission from PTSD. This study examined trauma experience, symptom severity, co-morbidity, service use and time to PTSD remission in a large population sample.

METHOD

Data came from respondents (n=8841) of the 2007 Australian National Survey of Mental Health and Wellbeing (NSMHWB). A modified version of the World Health Organization's World Mental Health Composite International Diagnostic Interview (WMH-CIDI) was used to determine the presence and age of onset of DSM-IV PTSD and other mental and substance use disorders, type, age, and number of lifetime traumas, severity of re-experiencing, avoidance and hypervigilance symptoms and presence and timing of service use.

RESULTS

Projected lifetime remission rate was 92% and median time to remission was 14 years. Those who experienced childhood trauma, interpersonal violence, severe symptoms or a secondary anxiety or affective disorder were less likely to remit from PTSD and reported longer median times to remission compared to those with other trauma experiences, less severe symptoms or no co-morbidity.

CONCLUSIONS

Although most people in the population with PTSD eventually remit, a significant minority report symptoms decades after onset. Those who experience childhood trauma or interpersonal violence should be a high priority for intervention.

Investigating differential symptom profiles in major depressive episode with and without generalized anxiety disorder: true co-morbidity or symptom similarity?

BACKGROUND

Large community-based epidemiological surveys have consistently identified high co-morbidity between major depressive episode (MDE) and generalized anxiety disorder (GAD). Some have suggested that this co-morbidity may be artificial and the product of the current diagnostic system. Because of the added direct and indirect costs associated with co-morbidity, it is important to investigate whether methods of diagnostic classification are artificially increasing the level of observed co-morbidity.

METHOD

The item response theory (IRT) log-likelihood ratio procedure was used to test for differential item functioning (DIF) of MDE symptoms between respondents with and without a diagnosis of GAD in the 2001-2002 National Epidemiological Survey on Alcohol and Related Conditions (NESARC).

RESULTS

The presence of GAD significantly increased the chances of reporting any symptom of MDE, with odds ratios ranging from 2.54 to 5.36. However, there was no indication of significant DIF of MDE symptoms in respondents with and without GAD.

CONCLUSIONS

The lack of any significant DIF indicates that cases with GAD do not present with a distinct MDE symptom profile, one that is consistent with the endorsement of symptoms that are conceptually similar in nature between the two disorders, compared to cases without GAD. This does not support the hypothesis that co-morbidity between MDE and GAD is artificially inflated because of the similar symptom criteria required by the current diagnostic system. Instead, MDE and GAD may be thought of as two distinct diagnostic entities that frequently co-occur because of a shared underlying trait.

Biallelic mutation of MSH2 in primary human cells is associated with sensitivity to irradiation and altered RAD51 foci kinetics

BACKGROUND

Reports of differential mutagen sensitivity conferred by a defect in the mismatch repair (MMR) pathway are inconsistent in their conclusions. Previous studies have investigated cells established from immortalised human colorectal tumour lines or cells from animal models.

METHODS

We examined primary human MSH2-deficient neonatal cells, bearing a biallelic truncating mutation in MSH2, for viability and chromosomal damage after exposure to DNA-damaging agents.

RESULTS

MSH2-deficient cells exhibit no response to interstrand DNA cross-linking agents but do show reduced viability in response to irradiation. They also show increased chromosome damage and exhibit altered RAD51 foci kinetics after irradiation exposure, indicating defective homologous recombinational repair.

DISCUSSION

The cellular features and sensitivity of MSH2-deficient primary human cells are broadly in agreement with observations of primary murine cells lacking the same gene. The data therefore support the view that the murine model recapitulates early features of MMR deficiency in humans, and implies that the variable data reported for MMR-deficient immortalised human cells may be due to further genetic or epigenetic lesions. We suggest caution in the use of radiotherapy for treatment of malignancies in individuals with functional loss of MSH2.

Clinical, enzymatic and molecular characterization of nine new patients with malonyl-coenzyme A decarboxylase deficiency

We report nine new patients with malonic aciduria associated with enzyme-confirmed malonyl-CoA decarboxylase (MCD) deficiency in eight. Clinical details were available on eight, and molecular genetic characterization was obtained for nine. As for 15 previously described patients, cardinal clinical manifestations included developmental delay and cardiomyopathy; metabolic perturbations (e.g. acidosis) and seizures, however, were infrequent or not observed in our patients. For all, detection of elevated malonic acid in urine (+/- increased C3DC acylcarnitine by analysis employing tandem mass spectrometry) led to pursuit of enzyme studies. MCD activities (nmol/h PER mg protein) revealed: control (n = 22), 16.2 +/- 1.8 (SEM; range 5.7-46.2); patients (n = 8, assayed in duplicate), 1.7 +/- 0.3 (10% of parallel control; range 0.6-2.8). Molecular characterization by DNA sequence analysis and multiplex ligation-dependent probe amplification revealed nine novel mutations (c.796C>T; p.Gln266X, c.481delC; p.Leu161CysfsX18, c.1367A>C; p.Tyr456Ser, c.1319G>T; p.Ser440Ile, c.1430C>T; p.Ser477Phe, c.899G>T; p.Gly300Val, c.799-1683_949-1293del3128, and two other large genomic deletions comprising exons 1 or the complete gene) and two known mutations in the MLYCD gene. Our findings increase the number of enzyme-confirmed MCD-deficient patients by >50%, and expand our understanding of the phenotypic and molecular heterogeneity of this rare disorder.

Twelve-month prevalence and disability of DSM-IV bipolar disorder in an Australian general population survey

BACKGROUND

There have been few large-scale epidemiological studies which have examined the prevalence of bipolar disorder. The authors report 12-month prevalence data for DSM-IV bipolar disorder from the Australian National Survey of Mental Health and Well-Being.

METHOD

The broad methodology of the Australian National Survey has been described previously. Ten thousand, six hundred and forty-one people participated. The 12-month prevalence of euphoric bipolar disorder (I and II)--similar to the euphoric-grandiose syndrome of Kessler and co-workers--was determined. Those so identified were compared with subjects with major depressive disorder and the rest of the sample, on rates of co-morbidity with anxiety and substance use disorders as well as demographic features and measures of disability and service utilization. Polychotomous logistic regression was used to study the relationship between the three samples and these dependent variables.

RESULTS

There was a 12-month prevalence of 0-5 % for bipolar disorder. Compared with subjects with major depressive disorder, those with bipolar disorder were distinguished by a more equal gender ratio; a greater likelihood of being widowed, separated or divorced; higher rates of drug abuse or dependence; greater disability as measured by days out of role; increased rates of treatment with medicines; and higher lifetime rates of suicide attempts.

CONCLUSIONS

This large national survey highlights the marked functional impairment caused by bipolar disorder, even when compared with major depressive disorder.

Social phobia in the Australian National Survey of Mental Health and Well-Being (NSMHWB)

BACKGROUND

This article reports data on social phobia from the first large scale Australian epidemiological study. Prevalence rates, demographic correlates and co-morbidity in the sample that met criteria for social phobia are reported and gender differences examined.

METHOD

Data were obtained from a stratified sample of 10641 participants as part of the Australian National Survey of Mental Health and Well-Being (NSMHWB). A modified version of the Composite International Diagnostic Interview (CIDI) was used to determine the presence of social phobia, as well as other DSM-IV anxiety, affective and substance use disorders. The interview also screened for the presence of nine ICD-10 personality disorders, including anxious personality disorder, the equivalent of DSM-IV avoidant personality disorder (APD).

RESULTS

The estimated 12 month prevalence of social phobia was 2.3%, lower than rates reported in several recent nationally representative epidemiological surveys and closer to those reported in the Epidemiological Catchment Area study (ECA) and other DSM-III studies. Considerable co-morbidity was identified. Data indicated that the co-morbidity with depression and alcohol abuse and dependence were generally subsequent to onset of social phobia and that the additional diagnosis of APD was associated with a greater burden of affective disorder. Social phobia most often preceded major depression, alcohol abuse and generalized anxiety disorder.

CONCLUSIONS

Social phobia is a highly prevalent, highly co-morbid disorder in the Australian community. Individuals with social phobia who also screen positively for APD appear to be at greater risk of co-morbidity with all surveyed disorders except alcohol abuse or dependence.

The performance of the K6 and K10 screening scales for psychological distress in the Australian National Survey of Mental Health and Well-Being

BACKGROUND

Two new screening scales for psychological distress, the K6 and K10, have been developed but their relative efficiency has not been evaluated in comparison with existing scales.

METHOD

The Australian National Survey of Mental Health and Well-Being, a nationally representative household survey, administered the WHO Composite International Diagnostic Interview (CIDI) to assess 30-day DSM-IV disorders. The K6 and K10 were also administered along with the General Health Questionnaire (GHQ-12), the current de facto standard of mental health screening. Performance of the three screening scales in detecting CIDI/DSM-IV mood and anxiety disorders was assessed by calculating the areas under receiver operating characteristic curves (AUCs). Stratum-Specific Likelihood Ratios (SSLRs) were computed to help produce individual-level predicted probabilities of being a case from screening scale scores in other samples.

RESULTS

The K10 was marginally better than the K6 in screening for CIDI/DSM-IV mood and anxiety disorders (K10 AUC: 0.90, 95%CI: 0.89-0.91 versus K6 AUC: 0.89, 95%CI: 0.88-0.90), while both were significantly better than the GHQ-12 (AUC: 0.80, 95%CI: 0.78-0.82). The SSLRs of the K10 and K6 were more informative in ruling in or out the target disorders than those of the GHQ-12 at both ends of the population spectrum. The K6 was more robust than the K10 to subsample variation.

CONCLUSIONS

While the K10 might outperform the K6 in screening for severe disorders, the K6 is preferred in screening for any DSM-IV mood or anxiety disorder because of its brevity and consistency across subsamples. Precision of individual-level prediction is greatly improved by using polychotomous rather than dichotomous classification.

Clinical evaluation of the Life Support for Trauma and Transport (LSTAT) platform

INTRODUCTION

The Life Support for Trauma and Transport (LSTAT trade mark ) is a self-contained, stretcher-based miniature intensive care unit designed by the United States Army to provide care for critically injured patients during transport and in remote settings where resources are limited. The LSTAT contains conventional medical equipment that has been integrated into one platform and reduced in size to fit within the dimensional envelope of a North Atlantic Treaty Organization (NATO) stretcher. This study evaluated the clinical utility of the LSTAT in simulated and real clinical environments. Our hypothesis was that the LSTAT would be equivalent to conventional equipment in detecting and treating life-threatening problems.

METHODS

Thirty-one anesthesiologists and recovery room nurses compared the LSTAT with conventional monitors while managing four simulated critical events. The time required to reach a diagnosis and treatment was recorded for each simulation. Subsequently, 10 consenting adult patients were placed on the LSTAT after surgery for postoperative care in the recovery room. Questionnaires about aspects of LSTAT functionality were completed by nine nurses who cared for the patients placed on the LSTAT.

RESULTS

In all of the simulations, there was no clinically significant difference in the time to diagnosis or treatment between the LSTAT and conventional equipment. All clinicians reported that they were able to manage the simulated patients properly with the LSTAT. Nursing staff reported that the LSTAT provided adequate equipment to care for the patients monitored during recovery from surgery and were able to detect critical changes in vital signs in a timely manner.

DISCUSSION

Preliminary evaluation of the LSTAT in simulated and postoperative environments demonstrated that the LSTAT provided appropriate equipment to detect and manage critical events in patient care. Further work in assessing LSTAT functionality in a higher-acuity environment is warranted.

Interpreting scores on the Kessler Psychological Distress Scale (K10)

OBJECTIVE

To provide normative data on the Kessler Psychological Distress Scale (K10), a scale that is being increasingly used for clinical and epidemiological purposes.

METHOD

The National Survey of Mental Health And Well-Being was used to provide normative comparative data on symptoms, disability, service utilisation and diagnosis for the range of possible K10 scores.

RESULTS

The K10 is related in predictable ways to these other measures.

IMPLICATIONS

The K10 is suitable to assess morbidity in the population, and may be appropriate for use in clinical practice.

DSM-IV and ICD-10 generalized anxiety disorder: discrepant diagnoses and associated disability

BACKGROUND

It is commonly assumed that diagnoses according to DSM-IV and ICD-10 are equivalent. Recent discussions on generalized anxiety disorder (GAD) have suggested that ICD-10 criteria may be identifying a milder form of the disorder than DSM-IV. This report examines prevalence and associated disability of DSM-IV and ICD-10 GAD.

METHODS

The Composite International Diagnostic Interview was administered to a community sample of 10,641 people, and the diagnostic criteria that contributed to discrepancies between DSM-IV and ICD-10 GAD were identified. A multiple linear regression analysis was carried out to determine the strength of the relationship between disability, as measured by the SF-12, and discrepant diagnoses of GAD.

RESULTS

The concordance between DSM-IV and ICD-10 GAD was fair (kappa = 0.39). The two sources of discrepancy when DSM-IV was positive and ICD-10 was negative resulted from the requirement in ICD-10 that the respondent endorse symptoms of autonomic arousal (ICD-10 criterion B) and the requirement that ICD-10 GAD does not co-occur with panic/agoraphobia, social phobia or obsessive-compulsive disorder (ICD-10 criterion C). The two major sources of discrepancy when ICD-10 was positive and DSM-IV was negative resulted from the requirement in DSM-IV that the worry be excessive (DSM-IV criterion A) and that it causes clinically significant distress or impairment (DSM-IV criterion E). DSM-only GAD cases had significantly higher levels of disability than ICD-only cases of GAD after controlling for demographic variables and the presence of comorbid psychiatric disorders.

CONCLUSIONS

While the prevalence rates for DSM-IV and ICD-10 GAD are almost identical, these classification systems are diagnosing different groups of people.

Working memory dysfunction in major depression: an event-related potential study

OBJECTIVES

To study working memory function in untreated major depression using a digit probe identification and matching task.

METHODS

We compared behavioural performance and event-related potentials during processing of the Sternberg working memory task in 14 depressed patients and 14 healthy matched control subjects.

RESULTS

Patients made more mistakes than controls as the memory load was increased from one to 5 digits and had significantly slower reaction times at all levels of memory load. The patients' event-related potentials (ERPs) differed significantly from controls. Pathological changes were similar for auditory and visual presentation. Surface negative activity in the 157-210 ms section of the waveform was reduced for all levels of memory load, suggesting abnormal sensory/perceptual processing in the modality-specific association cortices, possibly due to a failure of selective attention mechanisms. In the 375-840 ms epoch, the patients' responses showed large amplitude sustained negative activity, maximal at Cz and a reduced late positive wave. The large prolonged negativity in the patients' ERPs suggests activation of additional neuronal assemblies than those normally participating in the task. This could reflect either compensatory mechanism or dysfunction of inhibitory systems. These changes were sensitive to memory load, suggesting that they reflect alterations of memory-related processes.

CONCLUSIONS

This study provides objective evidence that major depression significantly affects working memory. The ERP changes in depression could be accounted for by dysfunction of the central executive control of working memory.

Why does the burden of disease persist? Relating the burden of anxiety and depression to effectiveness of treatment

Why does the burden of mental disorders persist in established market economies? There are four possibilities: the burden estimates are wrong; there are no effective treatments; people do not receive treatment; or people do not receive effective treatments. Data from the Australian National Survey of Mental Health and Wellbeing about the two commonest mental disorders, generalized anxiety disorder and depression, have been used in examining these issues. The burden of mental disorders in Australia is third in importance after heart disease and cancer, and anxiety and depressive disorders account for more than half of that burden. The efficacy of treatments for both disorders has been established. However, of those surveyed, 40% with current disorders did not seek treatment in the previous year and only 45% were offered a treatment that could have been beneficial. Treatment was not predictive of disorders that remitted during the year. The burden therefore persists for two reasons: too many people do not seek treatment and, when they do, efficacious treatments are not always used effectively.

A comparison of ICD10 and DSM-IV criteria for posttraumatic stress disorder

The assumption that participants receiving an ICD10 diagnosis of posttraumatic stress disorder (PTSD) will also receive a DSM-IV diagnosis of PTSD was tested. Data were gathered for 1,364 participants using the Composite International Diagnostic Interview (CIDI). The 12-month prevalence of PTSD was 3% for DSM-IV and 7% for ICD10 Diagnostic Criteria for Research (ICD10-DCR). The agreement between the two systems was fair (kappa = .50). Forty eight percent of the discrepancies between the systems were accounted for by the additional criterion requiring clinically significant distress or impairment included in DSM-IV. The inclusion of symptoms of general numbing of responsiveness accounted for 18% of the discrepancies. It is concluded that ICD10-DCR PTSD cannot be assumed to be identical to DSM-IV PTSD.

Event-related potential (ERP) correlates of performance of intelligence tests

Any relationship between measures of cognitive function and brain electrical activity would be of considerable importance in the objective assessment of patients suspected of intellectual impairment. In healthy subjects, we have found a strong correlation between the event-related potentials evoked by a digit probe identification task and scores on intelligence tests (WAIS). Responses from subjects with higher performance on IQ tests are significantly 'more negative' than those from subjects with lower IQ. The characteristics of these IQ-dependent electrophysiological features suggest that they may be related to the subject's ability to focus on a task.

Wave form variations in auditory event-related potentials evoked by a memory-scanning task and their relationship with tests of intellectual function

The inter-subject wave form variability of auditory event-related potentials (ERPs) evoked by digit probe identification in a memory-scanning task (Sternberg paradigm) and the effects of reaction time (RT) and task difficulty were studied in 26 healthy subjects. The response wave forms were compared with the performance of psychological tests of intelligence and memory. ERPs to 1-digit sets consisted of a sequence of waves identified as P100, N170, P250, N290, P400, P560 and N640. The major inter-subject difference in the response wave form was either the presence or absence of the late parietal positive wave P560. This wave occurred significantly more often in responses associated with larger memory sets and slow RT, suggesting that its presence reflects subjective difficulty in performing a task. With increasing set size, the P400 showed variable effects in different subjects, ranging from relative preservation of amplitude, through attenuation, to replacement or overlap by a broad surface-negative wave. This predominantly 'negative-going' effect of increasing task difficulty on the P400 was significantly correlated with scores of psychological tests; the greater the amplitude difference between the responses to easy and more difficult tasks, the better the scores, suggesting that these wave form changes reflect a more effective cognitive processing mechanism.