Major depression, minor depression, and double depression: are they distinct clinical entities?

Normal Versus Pathological Mood: Implications for Diagnosis

Is there a clear line between normal and abnormal mood? Studies of manifest and latent structure provide strong support for a continuum that extends from asymptomatic to subsyndromal to syndromal cases of increasing severity. Subsyndromal symptoms are impairing, predict syndrome onset and relapse, and account for more doctor's visits and suicide attempts than the full syndromes, yet they are not recognized in the current classification. For most research and some clinical activities, dimensional diagnoses are recommended, and examples are offered for how such diagnoses could be made. For clinical activities requiring decisions, a multithreshold model is proposed in which both lower (e.g., mild depression, capturing subsyndromal cases) and upper (e.g., major depression, capturing clinically significant cases) diagnostic categories are used to inform clinical care. Beyond its implications for diagnosis, the dimensionality of depression and anxiety has implications for etiology and for research aimed at understanding how emotions become disrupted in psychopathology.

Diagnosis of depression in elderly patients

Depression in old age is a pathological process, not a normal reaction to growing older. The majority of people cope with ageing, and many feel happy and fulfilled. However, there is a bias among health professionals and the community in general to accept lower functioning and more symptoms in older people (Alexopoulos, 1992). Depression tends to be denied by the current generation of elderly people, many of whom were raised in an atmosphere where showing feelings was discouraged, and this adds to diagnostic difficulties. Comorbid medical conditions, the tendency of patients to somatise, cognitive deterioration, and multiple life events, often of loss (e.g. bereavement, retirement, moving to smaller housing), all further complicate the diagnostic process.

An Analysis of Two Genome-wide Association Meta-analyses Identifies a New Locus for Broad Depression Phenotype

BACKGROUND

The genetics of depression has been explored in genome-wide association studies that focused on either major depressive disorder or depressive symptoms with mostly negative findings. A broad depression phenotype including both phenotypes has not been tested previously using a genome-wide association approach. We aimed to identify genetic polymorphisms significantly associated with a broad phenotype from depressive symptoms to major depressive disorder.

METHODS

We analyzed two prior studies of 70,017 participants of European ancestry from general and clinical populations in the discovery stage. We performed a replication meta-analysis of 28,328 participants. Single nucleotide polymorphism (SNP)-based heritability and genetic correlations were calculated using linkage disequilibrium score regression. Discovery and replication analyses were performed using a p-value-based meta-analysis. Lifetime major depressive disorder and depressive symptom scores were used as the outcome measures.

RESULTS

The SNP-based heritability of major depressive disorder was 0.21 (SE = 0.02), the SNP-based heritability of depressive symptoms was 0.04 (SE = 0.01), and their genetic correlation was 1.001 (SE = 0.2). We found one genome-wide significant locus related to the broad depression phenotype (rs9825823, chromosome 3: 61,082,153, p = 8.2 × 10^-9) located in an intron of the FHIT gene. We replicated this SNP in independent samples (p = .02) and the overall meta-analysis of the discovery and replication cohorts (1.0 × 10^-9).

CONCLUSIONS

This large study identified a new locus for depression. Our results support a continuum between depressive symptoms and major depressive disorder. A phenotypically more inclusive approach may help to achieve the large sample sizes needed to detect susceptibility loci for depression.

Antidepressants normalize the default mode network in patients with dysthymia

IMPORTANCE

The default mode network (DMN) is a collection of brain regions that reliably deactivate during goal-directed behaviors and is more active during a baseline, or so-called resting, condition. Coherence of neural activity, or functional connectivity, within the brain's DMN is increased in major depressive disorder relative to healthy control (HC) subjects; however, whether similar abnormalities are present in persons with dysthymic disorder (DD) is unknown. Moreover, the effect of antidepressant medications on DMN connectivity in patients with DD is also unknown.

OBJECTIVE

To use resting-state functional-connectivity magnetic resonance imaging (MRI) to study (1) the functional connectivity of the DMN in subjects with DD vs HC participants and (2) the effects of antidepressant therapy on DMN connectivity.

DESIGN

After collecting baseline MRI scans from subjects with DD and HC participants, we enrolled the participants with DD into a 10-week prospective, double-blind, placebo-controlled trial of duloxetine and collected MRI scans again at the conclusion of the study. Enrollment occurred between 2007 and 2011.

SETTING

University research institute.

PARTICIPANTS

Volunteer sample of 41 subjects with DD and 25 HC participants aged 18 to 53 years. Control subjects were group matched to patients with DD by age and sex.

MAIN OUTCOME MEASURES

We used resting-state functional-connectivity MRI to measure the functional connectivity of the brain's DMN in persons with DD compared with HC subjects, and we examined the effects of treatment with duloxetine vs placebo on DMN connectivity.

RESULTS

Of the 41 subjects with DD, 32 completed the clinical trial and MRI scans, along with the 25 HC participants. At baseline, we found that the coherence of neural activity within the brain's DMN was greater in persons with DD compared with HC subjects. Following a 10-week clinical trial, we found that treatment with duloxetine, but not placebo, normalized DMN connectivity.

CONCLUSIONS AND RELEVANCE

The baseline imaging findings are consistent with those found in patients with major depressive disorder and suggest that increased connectivity within the DMN may be important in the pathophysiology of both acute and chronic manifestations of depressive illness. The normalization of DMN connectivity following antidepressant treatment suggests an important causal pathway through which antidepressants may reduce depression.

Correlates associated with unipolar depressive disorders in a Latino population

BACKGROUND

This study reports the comparison and associations of demographic, clinical and psychosocial correlates with three unipolar depressive disorders: dysthymia (DYS), major depression (MD) and double depression (DD), and examines to which extent these variables predict the disorders.

SAMPLING AND METHOD

Previously collected data from 563 adults from a community in Puerto Rico were analyzed. One hundred and thirty individuals with DYS, 260 with MD and 173 with DD were compared by demographic variables, psychiatric and physical comorbidity, familial psychopathology, psychosocial stressors, functional impairment, self-reliance, problem recognition and formal use of mental health services. Multinomial regression was used to assess the association of the predictor variables with each of the three disorders.

RESULTS

Similarities outweighed the discrepancies between the disorders. The main differences observed were between MD and DD, while DYS shared common characteristics with both MD and DD. After other variables were controlled, anxiety, functional impairment and problem recognition most strongly predicted a DD diagnosis, while age predicted a DYS diagnosis.

CONCLUSION

MD, DYS and DD are not completely different disorders, but they do differ in key aspects that might be relevant for nosology, research and practice. A dimensional system that incorporates specific categories of disorders would better reflect the different manifestations of unipolar depressive disorders.

Subthreshold symptoms of depression in preadolescent girls are stable and predictive of depressive disorders

OBJECTIVE

Given the risk for adolescent depression in girls to lead to a chronic course of mental illness, prevention of initial onset could have a large impact on reducing chronicity. If symptoms of depression that emerge during childhood were stable and predictive of later depressive disorders and impairment, then secondary prevention of initial onset of depressive disorders would be possible.

METHOD

Drawing from the Pittsburgh Girls Study, an existing longitudinal study, 232 nine-year-old girls were recruited for the present study, half of whom screened high on a measure of depression at age 8 years. Girls were interviewed about depressive symptoms using a diagnostic interview at ages 9, 10, and 11 years. Caregivers and interviewers rated impairment in each year.

RESULTS

The stability coefficients for DSM-IV symptom counts for a 1- to 2-year interval were in the moderate range (i.e., intraclass coefficients of 0.40-0.59 for continuous symptom counts and Kendall tau-b coefficients of 0.34-0.39 for symptom level stability). Depressive disorders were also relatively stable at this age. Poverty moderated the stability, but race and pubertal stage did not. Among the girls who did not meet criteria for a depressive disorder at age 9 years, the odds of meeting criteria for depressive disorders and for demonstrating impairment at age 10 or 11 years increased by 1.9 and 1.7, respectively, for every increase in the number of depression symptoms.

CONCLUSIONS

Early-emerging symptoms of depression in girls are stable and predictive of depressive disorders and impairment. The results suggest that secondary prevention of depression in girls may be accomplished by targeting subthreshold symptoms manifest during childhood.

Clinically significant non-major depression in a community-dwelling elderly population: epidemiological findings

OBJECTIVE

The aim of this study was to investigate the 1-month prevalence, symptom profiles and demographic correlates in late-life clinically significant non-major depression (CSNMD) among a community-dwelling elderly population.

METHODS

One thousand five hundred subjects aged 65 years and older, who were randomly selected from three communities in Taiwan, received comprehensive psychiatric assessment by trained psychiatrists. Two categorical diagnoses of depressive disorder, including major depression and CSNMD, were made. The 1-month prevalence was calculated. Frequencies of depressive symptoms across CSNMD and major depression were compared. The risks of CSNMD based on demographic characteristics were estimated using multinominal logistic regression.

RESULTS

The 1-month prevalence of CSNMD among the community-dwelling elderly was 8.8%. Symptoms of diminished interest, appetite changes, sleep disturbance, worthlessness or inappropriate guilt, trouble in concentrating or indecisiveness, and suicidal thoughts or acts were less frequent in CSNMD than in major depression, but symptoms of depressed mood, psychomotor changes, and fatigue or loss of energy were as frequent in both categories of illness. CSNMD shares similar demographic risks, such as living in an urban area, female gender and low educational status, with major depression.

CONCLUSIONS

CSNMD is common among community-dwelling elders in Taiwan, and with its identical demographic characteristics, but qualitatively different presentation, we suggest CSNMD may be considered part of a spectrum of severe late life depressions with a distinct manifestation. Major depression and CSNMD may share common demographic characteristics with different manifestation. We conclude that late-life depression is a dimensional disease.

Examining minor and major depression in adolescents

BACKGROUND

Research has shown that a large proportion of adolescents with symptoms of depression and substantial distress or impairment fail to meet the diagnostic criteria for a major depressive disorder (MDD). However, many of these undiagnosed adolescents may meet criteria for a residual category of the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition-Text Revised (DSM-IV-TR), Depressive Disorder Not Otherwise Specified. Minor Depression (mDEP), an example of one of these categories, allows the inclusion of sub-threshold cases that fall below the diagnostic criteria of the five symptoms required for MDD. Minor depression in adolescence is important because it is significantly related to MDD in adulthood. The present study examines a number of risk factors, functional impairment, comorbidity and service utilization patterns associated with depression in community adolescents who met the DSM-IV criteria for mDEP and compares their profile to adolescents who met the criteria for MDD.

METHOD

Puerto Rican adolescents 11 to 17 years old were selected from an island-wide probability household sample of children ranging in age from 4 to 17. The Diagnostic Interview Schedule in Spanish (DISC IV), together with a structured protocol of risks and protective factors, and service utilization questionnaires were administered to primary caretakers and their children.

RESULTS

Our findings indicate that youngsters with mDEP had significant impairment and used more mental health services than those with major depression. In addition, adolescents with mDEP had similar outcomes when compared to those meeting full criteria for MDD in terms of psychosocial correlates and comorbidity.

CONCLUSIONS

The results, although not definitive, suggest a need for further research in order to determine the validity of the present DSM IV diagnostic criteria for mDEP in adolescents.

Family study of subthreshold depressive symptoms: risk factor for MDD?

BACKGROUND

Family study data from a large community sample of young adults and their first-degree relatives were used to examine three questions regarding the relation between subthreshold depression (SubD) and major depressive disorder (MDD): (a) is there an elevated rate of MDD in the relatives of probands with SubD? (b) does SubD aggregate in the families of probands with MDD and SubD? (c) is the relationship between SubD and familial psychopathology specific to MDD?

METHODS

A total of 941 probands were assessed twice during adolescence and then at age 24. Direct and informant information was obtained on 2750 first-degree relatives of 840 probands.

RESULTS

The rate of MDD in the relatives of probands with SubD (24.3%) was significantly lower than the relatives of probands with MDD (31.9%) but was significantly higher than the relatives of probands with no history of mood disorder (NMD; 20.2%). Relatives of MDD, SubD and NMD probands did not differ on rates of SubD (9.0, 9.4 and 9.0%, respectively). Familial aggregation of psychopathology in SubD probands was specific to MDD.

LIMITATIONS

The primary limitation may be the absence of a standardized definition and assessment procedure for the SubD category. In addition, the sample size, although large, may have been inadequate to detect smaller associations or the moderating effects of sex.

CONCLUSION

The results data support the view that SubD occupies a milder position on a continuum with MDD.

Incidence of major depression: prediction from subthreshold categories in the Stirling County Study

BACKGROUND

Validity of the newly-proposed categories of Minor Depression (MinD) and Subsyndromal Depression (SSD) would be strengthened if they were found to be related to the incidence of Major Depressive Episode (MDE). In this report, the subsequent incidence of MDE was assessed in terms of baseline evidence about the two subthreshold categories and Dysthymic Disorder (DysD).

METHODS

The Diagnostic Interview Schedule was used to interview 489 subjects twice between 1991 and 1995 as part of the Stirling County Study. Life table methods were used to calculate incidence rates and log linear analysis was employed for statistical assessment.

RESULTS

The average annual incidence of MDE was 10 per 1000. The rates associated with the baseline categories were 210 per 1000 for DysD, 21 for MinD; 13 for SSD; and four for the remainder of subjects who constituted the reference group. Only the incidence related to DysD was significantly higher than that for the reference group. Comparing Time 1 and Time 2, one-third of the subjects gained or lost symptoms and the comorbidity of MDE and DysD increased.

LIMITATIONS

The study population was, on average, 63 years of age. Older age and the small size of the cohort may have influenced the findings. Another limitation may relate to the use of lifetime rather than current symptomatology.

CONCLUSIONS

DysD is strongly associated with MDE suggesting that the chronic and episodic forms of unipolar depression constitute one disorder. The other subthreshold categories should be further investigated in terms of prodromal qualities. The persistence of dysphoria, as in DysD, may be a more important feature of the depression prodrome than the number of symptoms.

Correlates of remission in primary care patients treated for minor depression

As minor depression is perhaps the most common form of mood disorder seen in primary care, we sought to explore the effects of both pharmacologic and psychosocial interventions for primary care patients with this condition. Three hundred and eighteen primary care patients meeting criteria for minor depression (defined as endorsing 3 or 4 of the nine DSM-IV symptoms of major depression, at least one of which was either depressed mood or anhedonia, for a period of at least four weeks, and scoring > or = 10 on the Hamilton Rating Scale for Depression) from 4 diverse geographic sites were enrolled in a randomized controlled 11 week trial of paroxetine, problem-solving therapy or placebo. Patients who attended at least 4 treatment sessions and who received a Hamilton score by an independent rater at either 6 or 11 weeks were used in the analysis (77% of enrolled patients). A score of < or = 6 on the Hamilton was defined as a positive response to treatment. Fifty four percent of patients met our criteria for remission (HRS-D < or = 6) by week 11, with no difference among treatments. Patients who were women, younger, of European descent, homemakers or retired persons (as opposed to unemployed) and who had lower baseline severity of depression were more likely to remit across all treatment conditions. Although explicitly addressed in the data analysis, differences in outcomes across the four sites of the investigations limit our confidence in the generalizabilty of our findings. In addition, patients with lower levels of educational attainment had a higher dropout rate, suggesting further caution about the generalizability of the findings. Defining remission in this categorical way, we found no differences among the interventions studied, but did find that outcome was related to demographic and clinical characteristics of the patients. While it is difficult to know why female patients were more likely to remit, this may be a function of the association in our subject populations between male gender and the likelihood (approximately .46) of being a patient in the VA system. The remaining variables associated with higher probability of remission appear to reflect social advantage and lower severity or complexity of illness.

Profile of discrete emotions in affective disorders in older primary care patients

PURPOSE

This research examined whether the frequencies of specific emotions are associated with major and minor depression in older primary care patients.

DESIGN AND METHODS

Older primary care patients (N = 146), prescreened with a depression questionnaire, completed a diagnostic interview and an emotions questionnaire.

RESULTS

Controlling for age, sex, and other psychiatric and medical illnesses, major depressives differed from nondepressed controls in nine emotions; minor depressives differed from controls in four emotions. Major depressives differed from the controls more in sadness, joy, and interest--but not anger, fear, or guilt--than in comparison sets of emotions. Minor depressives differed from the controls more in sadness and inner-directed hostility--but not guilt, anger, fear, joy, or interest--than in comparison sets of emotions.

IMPLICATIONS

The frequencies of discrete emotions are differentially associated with major and minor depression; future research is needed to determine their specific diagnostic and treatment implications.

Dysthymia and cyclothymia in psychiatric practice a century after Kraepelin

Kraepelin had a modern vision of affective illness. He hypothesized that affective recurrences arose from enduring dispositions of depressive, cyclothymic, irritable, or 'manic' types. These dispositions appeared as 'temperaments' in English translations of his work. In the extreme, such temperamental gloominess or moodiness is today officially diagnosed as 'dysthymic' or 'cyclothymic'; irritable and hyperthymic (or manic) dispositions have not received official sanction in the contemporary psychiatric nomenclature. This paper reviews recent research which supports Kraepelin's theoretical framework regarding dysthymic and cyclothymic dispositions both as clinically relevant extreme forms of temperament and as precursors of major affective episodes. Compelling lines of evidence along epidemiologic, clinical-descriptive, familial-genetic, therapeutic, and follow-up perspectives are summarized for each disposition. Much of what in contemporary psychiatry is considered to be in the realm of subthreshold affective conditions, overlaps considerably with Kraepelin's concepts of the trait affective dispositions described herein. Most importantly, although Kraepelin's observations were based primarily on hospitalized, severely ill affective patients, his broad vision still guides us today for understanding etiology and instituting public health and preventive measures in major affective episodes.

Correlates of symptomatic, minor and major depression in the elderly

BACKGROUND

Associations between different types of depression with clinical characteristics and putative vulnerability factors from several domains (health, disability, personality, familial psychopathology) were studied in a sample of elderly subjects, in order to find arguments that support or discard the notion of discontinuity in correlates of depression.

METHODS

Subjects were 183 depressed elderly persons from the general population, general practitioners and mental health care outpatient clinics, and a random elderly control group (n=74). Depression was subdivided into symptomatic (n=45), DSM-IV minor (n=73), and DSM-IV major (n=65) depression. The groups were compared with respect to a variety of variables from different domains.

RESULTS

Most variables showed a marked difference between the control group and the depressive groups, and smaller or no differences between depressive subtypes.

LIMITATIONS

The data were collected cross-sectionally.

CONCLUSIONS

With a few notable exceptions, all subtypes of depression were significantly different from the control group, while differences between depressive subtypes were generally smaller. Depressive subtypes showed no discontinuum with respect to the associated variables. Similar associations in different subtypes of depression may indicate common vulnerability factors.

Depressive illness

WHO estimate that by the beginning of the next century major unipolar depression will be one of the most important causes of ill health overall. Whereas the cause of depression is still obscure, it is becoming clear that a number of diverse factors are likely to be implicated, both genetic and environmental. Effective treatment of depression similarly involves a variety of methods, from electro-convulsive therapy to inter-personal psychotherapy. The pathophysiology of depression is gradually becoming accessible through research strategies, such as functional neuroimaging paired with mood altering interventions.

Late-onset minor and major depression: early evidence for common neuroanatomical substrates detected by using MRI

The purpose of our study was to examine the neuroanatomical correlates of late-onset minor and major depression and to compare them with similar measures obtained from nondepressed controls. Our study groups were comprised of 18 patients with late-onset minor depression, 35 patients diagnosed with late-onset major depression, and 30 nondepressed controls. All subjects were scanned by using a 1. 5-tesla MRI scanner. Absolute whole brain volume and normalized measures of prefrontal and temporal lobe volumes were obtained and used for comparison among groups. Our findings indicate that patients with minor depression present with specific neuroanatomical abnormalities that are comparable with the major depression group but significantly different from the controls. Normalized prefrontal lobe volumes show a significant linear trend with severity of depression, with volumes decreasing with illness severity. Whole brain volumes did not differ significantly among groups. These findings have broad implications for the biology of late-life depression and suggest that there may be common neurobiological substrates that underlie all clinically significant forms of late-onset mood disturbances.

Boundaries of major depression: an evaluation of DSM-IV criteria

OBJECTIVE

Little is known about the boundaries between major depression and milder subsyndromal depressive states. With respect to depressive symptoms, does DSM-IV "carve nature at its joints"?

METHOD

In personally interviewed female twins from a population-based registry, the authors examined whether a range of values along three dimensions of the depressive syndrome assessed in the last year (number of symptoms listed in DSM-III-R under diagnostic criterion A for major depressive episode, level of severity or impairment required to score symptoms as present, and duration of episode) predicted future depressive episodes in the index twin and risk of major depression in the co-twin.

RESULTS

An increasing number of criterion A symptoms predicted, in a monotonic fashion, a greater risk for future depressive episodes in the index twin as well as a greater risk for major depression in the co-twin. No such consistent relationship was seen with duration of episode. For severity, a single monotonic function predicted risk in the co-twin, while index twins with severe impairment had a substantially higher risk for future episodes than did those with less severe impairment. Four or fewer criterion A symptoms, syndromes composed of symptoms involving no or minimal impairment, and episodes of less than 14 days' duration all significantly predicted both future depressive episodes in the index twin and risk of major depression in the co-twin.

CONCLUSIONS

The authors found little empirical support for the DSM-IV requirements for 2 weeks' duration, five symptoms, or clinically significant impairment. Most functions appeared continuous. These results suggest that major depression--as articulated by DSM-IV--may be a diagnostic convention imposed on a continuum of depressive symptoms of varying severity and duration.