Diagnosing major depressive disorder IV: relationship between number of symptoms and the diagnosis of disorder

Problematic features of episode-based definitions of depression and a preliminary proposal for their replacement

Episodes of depression are constructed by imposing temporal and symptom-severity thresholds onto symptom levels that vary over time, resulting in a loss of information. Consequently, it is widely acknowledged that binary categorization of depressive episodes is problematic. Binary classification can make similar symptom levels appear different and different symptom levels appear similar. Furthermore, symptom severity is only one of several thresholds that are applied in the construction of depressive episodes in DSM-5 and ICD-11, others being: a minimum duration of symptoms, the application of a “no significant symptoms” threshold for remission, and time requirements (e.g., 2  months) for remission. Application of each of these thresholds leads to a loss of information. The joint occurrence of these four thresholds creates a complex set of circumstances in which similar patterns of symptoms may be categorized differently and different patterns may be categorized as similar. The ICD-11 definition can be expected to lead to better classification than the DSM-5 approach since it does not require two symptom-free months for remission, eliminating one of four problematic thresholds. A more radical change would be to adopt a truly dimensional perspective which would need to incorporate new elements to reflect time spent at various levels of depression. Such an approach, however, seems feasible both in clinical practice and research.

Clinical Significance of the Number of Depressive Symptoms in Major Depressive Disorder: Results from the CRESCEND Study

Our study aimed to establish the relationship between the number of depressive symptoms and the clinical characteristics of major depressive disorder (MDD). This would enable us to predict the clinical significance of the number of depressive symptoms in MDD patients. Using data from the Clinical Research Center for Depression (CRESCEND) study in Korea, 853 patients with DSM-IV MDD were recruited. The baseline and clinical characteristics of groups with different numbers of depressive symptoms were compared using the χ(2) test for discrete variables and covariance (ANCOVA) for continuous variables. In addition, the scores of these groups on the measurement tools were compared by ANCOVA after adjusting the potential effects of confounding variables. After adjusting the effects of monthly income and history of depression, a larger number of depressive symptoms indicated higher overall severity of depression (F [4, 756] = 21.458, P < 0.001) and higher levels of depressive symptoms (F [4, 767] = 19.145, P < 0.001), anxiety symptoms (F [4, 765] = 12.890, P < 0.001) and suicidal ideation (F [4, 653] = 6.970, P < 0.001). It also indicated lower levels of social function (F [4, 760] = 13.343, P < 0.001), and quality of life (F [4, 656] = 11.975, P < 0.001). However, there were no significant differences in alcohol consumption (F [4, 656] = 11.975, P < 0.001). The number of depressive symptoms can be used as an index of greater illness burden in clinical psychiatry.

The WAG/Rij strain: a genetic animal model of absence epilepsy with comorbidity of depression [corrected]

A great number of clinical observations show a relationship between epilepsy and depression. Idiopathic generalized epilepsy, including absence epilepsy, has a genetic basis. The review provides evidence that WAG/Rij rats can be regarded as a valid genetic animal model of absence epilepsy with comorbidity of depression. WAG/Rij rats, originally developed as an animal model of human absence epilepsy, share many EEG and behavioral characteristics resembling absence epilepsy in humans, including the similarity of action of various antiepileptic drugs. Behavioral studies indicate that WAG/Rij rats exhibit depression-like symptoms: decreased investigative activity in the open field test, increased immobility in the forced swimming test, and decreased sucrose consumption and preference (anhedonia). In addition, WAG/Rij rats adopt passive strategies in stressful situations, express some cognitive disturbances (reduced long-term memory), helplessness, and submissiveness, inability to make choice and overcome obstacles, which are typical for depressed patients. Elevated anxiety is not a characteristic (specific) feature of WAG/Rij rats; it is a characteristic for only a sub-strain of WAG/Rij rats susceptible to audiogenic seizures. Interestingly, WAG/Rij rats display a hyper-response to amphetamine similar to anhedonic depressed patients. WAG/Rij rats are sensitive only to chronic, but not acute, antidepressant treatments, suggesting that WAG/Rij rats fulfill a criterion of predictive validity for a putative animal model of depression. However, more and different antidepressant drugs still await evaluation. Depression-like behavioral symptoms in WAG/Rij rats are evident at baseline conditions, not exclusively after stress. Experiments with foot-shock stress do not point towards higher stress sensitivity at both behavioral and hormonal levels. However, freezing behavior (coping deficits) and blunted response of 5HT in the frontal cortex to uncontrollable sound stress, increased c-fos expression in the terminal regions of the meso-cortico-limbic brain systems and greater DA response of the mesolimbic system to forced swim stress suggest that WAG/Rij rats are vulnerable to some, but not to all types of stressors. We propose that genetic absence epileptic WAG/Rij rats have behavioral depression-like symptoms, are vulnerable to stress and might represent a model of chronic low-grade depression (dysthymia). Both 5HT and DAergic abnormalities detected in the brain of WAG/Rij rats are involved in modulation of vulnerability to stress and provocation of behavioral depression-like symptoms. The same neurotransmitter systems modulate SWDs as well. Recent studies suggest that the occurrence and repetition of absence seizures are a precipitant of depression-like behavior. Whether the neurochemical changes are primary to depression-like behavioral alterations remains to be determined. In conclusion, the WAG/Rij rats can be considered as a genetic animal model for absence epilepsy with comorbidity of dysthymia. This model can be used to investigate etiology, pathogenic mechanisms and treatment of a psychiatric comorbidity, such as depression in absence epilepsy, to reveal putative genes contributing to comorbid depressive disorder, and to screen novel psychotropic drugs with a selective and/or complex (dual) action on both pathologies.

An item response analysis of the DSM-IV criteria for major depression: findings from the Australian National Survey of Mental Health and Wellbeing

BACKGROUND

This study examines the psychometric properties and presence of gender bias in the major depression criteria using data from the Australian general population.

METHODS

Data came from a subsample of respondents from the 1997 National Survey of Mental Health and Wellbeing (NSMHWB; n=2061). A two-parameter logistic model was employed to yield severity and discrimination parameters, and the IRT log-likelihood-ratio test for differential item functioning (IRTLRDIF) procedure was utilized to evaluate gender bias.

RESULTS

DIF analyses indicated that the psychomotor difficulties criterion was endorsed at lower levels of severity by males than females. In general, the criteria were arrayed along a continuum of depression severity. Discrimination was greatest for concentration difficulties/indecision and lowest for death/suicidal thoughts and worthlessness/guilt. Worthlessness/guilt, psychomotor difficulties, and death/suicidal thoughts tapped the severe end of the depression continuum, whereas concentration difficulties/indecision and sleep disturbance tapped the mild range.

LIMITATIONS

The inclusion of stem questions precluded examination of two core symptoms of depression (depressed mood and loss of interest).

CONCLUSIONS

Collectively, the criteria performed well in defining a latent continuum of major depression. Few gender differences were observed, with the exception of the psychomotor difficulties criterion. Quantitative and qualitative analyses collectively hold promise of providing a scientifically rigorous basis for empirically-based modifications to the psychiatric classification system.

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.

Spike-wave discharges are necessary for the expression of behavioral depression-like symptoms

PURPOSE

The WAG/Rij strain of rats, a well-established model for absence epilepsy, has comorbidity for depression. These rats exhibit depression-like behavioral symptoms such as increased immobility in the forced swimming test and decreased sucrose intake and preference (anhedonia). These depression-like behavioral symptoms are evident in WAG/Rij rats, both at 3-4 and 5-6 months of age, with a tendency to aggravate in parallel with an increase in seizure duration. Here we investigated whether the behavioral symptoms of depression could be prevented by the suppression of absence seizures.

METHODS

Ethosuximide (ETX; 300 mg/kg/day, in the drinking water) was chronically applied to WAG/Rij rats from postnatal day 21 until 5 months. Behavioral tests were done before the cessation of the treatment. Electroencephalography (EEG) recordings were made before and after cessation of treatment to measure seizure severity at serial time-points.

RESULTS

ETX-treated WAG/Rij rats exhibited no symptoms of depression-like behavior in contrast to untreated WAG/Rij rats of the same age. Moreover, treated WAG/Rij rats did not differ from control age-matched Wistar rats. ETX treatment led to almost complete suppression of spike-wave discharges (SWDs) in 5-6 month old WAG/Rij rats. Discontinuation of chronic treatment was accompanied by a gradual emergence of SWDs; however, a persistent reduction in seizure activity was still present 47 days after discontinuation of the chronic treatment.

DISCUSSION

The results suggest that seizure activity is necessary for the expression of depression-like behavioral symptoms and confirm that epileptogenesis can be prevented by early and chronic treatment.

Accuracy of specific symptoms in the diagnosis of major depressive disorder in psychiatric out-patients: data from the MIDAS project

BACKGROUND

There is uncertainty about the diagnostic significance of specific symptoms of major depressive disorder (MDD). There is also interest in using one or two specific symptoms in the development of brief scales. Our aim was to elucidate the best possible specific symptoms that would assist in ruling in or ruling out a major depressive episode in a psychiatric out-patient setting.

METHOD

A total of 1523 psychiatric out-patients were evaluated in the Methods to Improve Diagnostic Assessment and Services (MIDAS) project. The accuracy and added value of specific symptoms from a comprehensive item bank were compared against the Structured Clinical Interview for DSM-IV (SCID).

RESULTS

The prevalence of depression in our sample was 54.4%. In this high prevalence setting the optimum specific symptoms for ruling in MDD were psychomotor retardation, diminished interest/pleasure and indecisiveness. The optimum specific symptoms for ruling out MDD were the absence of depressed mood, the absence of diminished drive and the absence of loss of energy. However, some discriminatory items were relatively uncommon. Correcting for frequency, the most clinically valuable rule-in items were depressed mood, diminished interest/pleasure and diminished drive. The most clinically valuable rule-out items were depressed mood, diminished interest/pleasure and poor concentration.

CONCLUSIONS

The study supports the use of the questions endorsed by the two-item Patient Health Questionnaire (PHQ-2) with the additional consideration of the item diminished drive as a rule-in test and poor concentration as a rule-out test. The accuracy of these questions may be different in primary care studies where prevalence differs and when they are combined into multi-question tests or algorithmic models.

Role of depression in heart failure--choosing the right antidepressive treatment

Major depression is a common feature of heart failure patients and possibly stems from their common biochemical background. Depression and heart failure co-morbidity has several clinical implications on the prognosis of these patients. Furthermore antidepressive drugs have known cardiovascular side effects, while their safety and efficacy in heart failure has not been fully elucidated yet. The right choice of antidepressive treatment in heart failure constitutes an issue of high importance as it can affect the clinical outcome of these patients. In this article we highlight the role of major depression in heart failure and demonstrate their common biochemical background. Moreover we review the acquired so far knowledge on the use of the various categories of antidepressants in heart failure by reference to the existing clinical studies on antidepressants efficacy and safety in heart failure. Even though certain conclusions cannot be drawn yet, evidence suggests that the use of selective serotonin reuptake inhibitors may have a beneficial effect on clinical outcome of heart failure patients.

Diagnosing major depressive disorder XII: can a self-report depression questionnaire be used to examine questions about the DSM-IV diagnostic criteria?

This paper is the final one in our series examining the DSM-IV diagnostic criteria for major depressive disorder. The data collected were part of the Rhode Island Methods to Improve Diagnostic Assessment and Services project, a unique integration of a research assessment protocol into a community-based clinical practice. We were able to examine a number of psychometric and conceptual issues in the diagnosis of depression because we modified the diagnostic interview to inquire about all diagnostic criteria, as well as additional associated features, of all patients. The results reported in the papers published earlier in the series suggested that some changes in the diagnostic criteria might be warranted. However, before changes are made to the diagnostic nomenclature, the results of any single study should be replicated. The cost of conducting this type of research is high, thereby reducing the likelihood of replication. As part of the Methods to Improve Diagnostic Assessment and Services project, we developed the Diagnostic Inventory for Depression (DID), a self-report scale that was specifically designed to assess the DSM-IV diagnostic criteria for major depressive disorder; thus, this scale could potentially be used to study many of the same questions examined in the present series, though at a fraction of the cost. In the present report, we used the DID to examine questions that were addressed in three of the prior reports in this series. The results of the present analysis based on the DID replicated the previously reported findings based on the SCID. This suggests that a self-report measure such as the DID could be used in other settings to examine the issues studied in the present series of papers, thereby facilitating the compilation of a more substantial literature upon which decisions regarding criteria modification could be based.