Rumination and distraction in major depression: assessing response to pharmacological treatment

tDCS efficacy and utility of anhedonia and rumination as clinical predictors of response to tDCS in major depressive disorder (MDD)

BACKGROUND

Anhedonia and rumination are mental disorders' transdiagnostic features but remain difficult to treat. Transcranial direct current stimulation (tDCS) is a proven treatment for depression, but its effects on anhedonia and rumination and whether anhedonia and rumination can be used as a predictive biomarker of treatment response is not well known. This study aimed to investigate the tDCS efficacy and identify the predictive role of anhedonia and rumination in response to tDCS in patients with MDD.

METHODS

182 patients received 10 tDCS sessions delivered at 2 mA to left (anode) dorsolateral prefrontal cortex (DLPFC). Hamilton Rating Scale for Depression (HRSD-17), Snaith-Hamilton Pleasure Scale (SHAPS), and the 10-item Ruminative Response Scale (RRS-10) was administered to patients with MDD before treatment, following it, and after two weeks of tDCS.

RESULTS

There was an overall significant improvement in anhedonia from pre- to post-treatment. Regression analyses revealed that responders had higher baseline anhedonia and rumination (reflective pondering) scores. We found that the reduction in HRSD scores after tDCS was significantly associated with anhedonia's baseline values while no relation was found between baseline rumination and tDCS treatment response.

CONCLUSION

These results provide new evidence that pronounced anhedonia may be a significant clinical predictor of response to tDCS. Patients with severe or low baseline rumination had an equal chance of achieving clinical response. Prospective tDCS studies are necessary to validate the predictive value of the derived model.

Effect of Ketamine on Rumination in Treatment-Resistant Depressive Patients

BACKGROUND

A rapid antidepressant effect of ketamine has repeatedly been documented in the literature, and identifying clinical features associated with a better response to this treatment is currently an essential question. Considering the relationship between rumination and depression and the need to identify potential predictors of response to ketamine, we analyzed the effect of a single injection of ketamine 0.5 mg/kg on rumination in treatment-resistant depressive (TRD) patients and explored whether baseline ruminative style and early improvements of rumination would predict a greater antidepressant effect of ketamine.

METHODS

Ten TRD outpatients who participated in a 4-week open study on the antidepressant effect of ketamine also completed the Ruminative Response Scale the day before, the day after, and a week after ketamine administration.

RESULTS

We found that in our patients, a single rapid 1-minute intravenous injection of ketamine 0.5 mg/kg was efficacious in reducing rumination, but neither severity of rumination at baseline nor early improvements of rumination after ketamine injection predicted antidepressant response.

CONCLUSIONS

Our preliminary data suggest that a single injection of ketamine 0.5 mg/kg can be efficacious in reducing rumination in TRD patients but rumination does not seem to be a useful clinical predictor of response to ketamine. Larger studies are necessary to confirm these results.

Symptom continuum reported by affective disorder patients through a structure-validated questionnaire

BACKGROUND

Affective disorders, such as major depressive (MDD), bipolar I (BD I) and II (BD II) disorders, are overlapped at a continuum, but their exact loci are not clear. The self-reports from patients with affective disorders might help to clarify this issue.

METHODS

We invited 738 healthy volunteers, 207 individuals with BD I, 265 BD II, and 192 MDD to answer a 79 item-MATRIX about on-going affective states.

RESULTS

In study 1, all 1402 participants were divided random-evenly and gender-balanced into two subsamples; one subsample was used for exploratory factor analysis, and another for confirmatory factor analysis. A structure-validated inventory with six domains of Overactivation, Psychomotor Acceleration, Distraction/ Impulsivity, Hopelessness, Retardation, and Suicide Tendency, was developed. In study 2, among the four groups, MDD scored the highest on Retardation, Hopelessness and Suicide Tendency, whereas BD I on Distraction/ Impulsivity and Overactivation.

CONCLUSION

Our patients confirmed the affective continuum from Suicide Tendency to Overactivation, and described the different loci of MDD, BD I and BD II on this continuum.

Anxiety during ketamine infusions is associated with negative treatment responses in major depressive disorder

About 20 to 30 percent of patients with Major Depressive Disorder (MDD) do not respond to standard treatment and are considered treatment-resistant. The N-methyl-d-aspartate (NMDA) glutamate receptor antagonist ketamine has demonstrated rapid antidepressant effects in treatment-resistant MDD, but it is unknown whether its acute psychological effects are related to the later antidepressant effect. Therefore, we investigated the association between antidepressant responses to ketamine and the quality of ketamine-induced psychological experiences in MDD. A total of 31 patients (M = 49.5 ± 11.2 years, 16 women) were treated with three ketamine infusions per week (0.5 mg/ kg over 40 min) administered for two consecutive weeks. Depression severity was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) at baseline, after four and 24 h and at end of treatment. The 5-Dimensional Altered States of Consciousness Rating Scale (5D-ASC) was applied four hours after the first infusion to assess the subjective quality of acute psychological effects. Patients with a ≥ 50% MADRS reduction from baseline to end of treatment were considered as responders. After six infusions, 17 of 31 patients (55%) showed a response to ketamine treatment, while 14 patients (45%) had no response. Anxiety-related experiences induced by ketamine were significantly higher in non-responders. Percentage MADRS reduction after four hours and individual levels of ketamine-induced anxiety were predictive of a response at end of treatment. The study demonstrated the considerable impact of ketamine-induced anxiety on the antidepressant efficacy of ketamine. It underpins the importance of considering patients' subjective experiences and underlines the possibility of a phenotypic response predictor.

Socio-demographic and clinical predictors of non-response/non-remission in treatment resistant depressed patients: A systematic review

Up to one third of patients adequately treated for Major Depressive Disorder (MDD) do not respond to multiple interventions. Many studies investigated predictors in MDD outcome, but no study focused on predictors of non-response or non-remission to antidepressants in subjects with treatment resistant depression (TRD). The present study aimed to evaluate possible socio-demographic and clinical predictors of non-response and non-remission in MDD patients who failed to benefit from at least one antidepressant trial. A total of 51 papers were included. A number of severity indicators, such as longer duration of depressive episode, moderate-high suicidal risk, anxious comorbidity, higher number of hospitalizations and higher dosage of antidepressants, were associated with non-response as well as age. Interestingly, severity of illness, as well as comorbid personality disorders and anxiety symptoms, had also a predictive value in non-remission with the addition of marital status. Considering limitations, selected studies were observational or randomized non controlled/controlled trials and different TRD definitions and outcome measures were used. Overall, predictors of outcome were similar to MDD, but specific socio-demographic and clinical factors should be considered in clinical practice to formulate a more focused treatment in TRD patients.

Mindfulness-based yoga intervention for women with depression

OBJECTIVES

The purpose of this study was to examine the efficacy of a 12-week mindfulness-based yoga intervention on depressive symptoms and rumination among depressed women.

DESIGN

Prospective, randomized, controlled 12 week intervention pilot study. Depressive symptoms were assessed at baseline, post-intervention (12 weeks), and one-month follow-up.

SETTING

Women with a history of diagnosed depression and currently depressed were randomized to a mindfulness-based yoga condition or a walking control.

INTERVENTIONS

The mindfulness-based yoga intervention consisted of a home-based yoga asana, pranayama and meditation practice with mindfulness education sessions delivered over the telephone. The walking control condition consisted of home-based walking sessions and health education sessions delivered over the phone.

MAIN OUTCOME MEASURES

The Beck Depression Inventory (BDI) and Ruminative Responses Scale (RRS).

RESULTS

Both groups reported decreases in depressive symptoms from baseline to post-intervention, f(1,33)=34.83, p<0.001, and from baseline to one-month follow-up, f(1,33)=37.01, p<0.001. After controlling for baseline, there were no significant between group differences on depression scores at post-intervention and the one-month follow-up assessment. The mindfulness-based yoga condition reported significantly lower levels of rumination than the control condition at post-intervention, after controlling for baseline levels of rumination, f(1,31)=6.23, p<0.01.

CONCLUSIONS

These findings suggest that mindfulness-based yoga may provide tools to manage ruminative thoughts among women with elevated depressive symptoms. Future studies, with larger samples are needed to address the effect of yoga on depression and further explore the impact on rumination.

Response style and severity and chronicity of depressive disorders in primary health care

BACKGROUND

Response styles theory of depression postulates that rumination is a central factor in occurrence, severity and maintaining of depression. High neuroticism has been associated with tendency to ruminate. We investigated associations of response styles and neuroticism with severity and chronicity of depression in a primary care cohort study.

METHODS

In the Vantaa Primary Care Depression Study, a stratified random sample of 1119 adult patients was screened for depression using the Prime-MD. Depressive and comorbid psychiatric disorders were diagnosed using SCID-I/P and SCID-II interviews. Of the 137 patients with depressive disorders, 82% completed the prospective five-year follow-up with a graphic life chart enabling evaluation of the longitudinal course of episodes. Neuroticism was measured with the Eysenck Personality Inventory (EPI-Q). Response styles were investigated at five years using the Response Styles Questionnaire (RSQ-43).

RESULTS

At five years, rumination correlated significantly with scores of Hamilton Depression Rating Scale (r=0.54), Beck Depression Inventory (r=0.61), Beck Anxiety Inventory (r=0.50), Beck Hopelessness Scale (r=0.51) and Neuroticism (r=0.58). Rumination correlated also with proportion of follow-up time spent depressed (r=0.38). In multivariate regression, high rumination was significantly predicted by current depressive symptoms and neuroticism, but not by anxiety symptoms or preceding duration of depressive episodes.

CONCLUSIONS

Among primary care patients with depression, rumination correlated with current severity of depressive symptoms, but the association with preceding episode duration remained uncertain. The association between neuroticism and rumination was strong. The findings are consistent with rumination as a state-related phenomenon, which is also strongly intertwined with traits predisposing to depression.

Restoring mood balance in depression: ketamine reverses deficit in dopamine-dependent synaptic plasticity

BACKGROUND

One of the most novel and exciting findings in major depressive disorder research over the last decade is the discovery of the fast-acting and long-lasting antidepressant effects of ketamine. Indeed, the therapeutic effects of classic antidepressants, such as selective serotonin reuptake inhibitors, require a month or longer to be expressed, with about a third of major depressive disorder patients resistant to treatment. Clinical studies have shown that a low dose of ketamine exhibits fast-acting relatively sustained antidepressant action, even in treatment-resistant patients. However, the mechanisms of ketamine action at a systems level remain unclear.

METHODS

Wistar-Kyoto rats were exposed to inescapable, uncontrollable footshocks. To evaluate learned helplessness behavior, we used an active avoidance task in a shuttle box equipped with an electrical grid floor. After helplessness assessment, we performed in vivo electrophysiological recordings first from ventral tegmental area dopaminergic (DA) neurons and second from accumbens neurons responsive to fimbria stimulation. Ketamine was injected and tested on helpless behavior and electrophysiological recordings.

RESULTS

We show that ketamine is able to restore the integrity of a network by acting on the DA system and restoring synaptic dysfunction observed in stress-induced depression. We show that part of the antidepressant effect of ketamine is via the DA system. Indeed, injection of ketamine restores a decreased dopamine neuron population activity, as well as synaptic plasticity (long-term potentiation) in the hippocampus-accumbens pathway, via, in part, activation of D1 receptors.

CONCLUSIONS

This work provides a unique systems perspective on the mechanisms of ketamine on a disrupted limbic system.

Mindfulness and the attenuation of post-event processing in social phobia: an experimental investigation

The present experimental study examined the ability of metacognitive strategies to reduce the distress associated with post-event processing (PEP). Individuals with DSM-IV generalized social phobia (N = 57) were randomly allocated to receive brief training in mindfulness, distraction, or no training (control group). Next, they underwent an experimental PEP induction. Following the induction, they were instructed to apply the metacognitive strategy (mindfulness or distraction) they were taught or to continue thinking about the social event the way they typically would following such an event (control). Participants rated their distress on a visual analogue scale prior to the PEP induction, and then every minute for 5 min while applying the metacognitive strategy. They also rated their affect immediately after applying the metacognitive strategy. Results suggest that mindfulness reduces distress significantly over the post-event period and results in significantly more positive affect than when receiving no training. In contrast, distraction does not reduce distress over the post-event period performs comparable to receiving no training. The results of this experimental investigation suggest that mindfulness has the potential to reduce distress associated with PEP and provide further support for the clinical utility of mindfulness in the treatment of generalized social phobia.

Coping with depression and vulnerability to mania: A factor analytic study of the Nolen-Hoeksema (1991) Response Styles Questionnaire

OBJECTIVES

To assess the factor structure of the Nolen-Hoeksema (1991) Response Styles Questionnaire (RSQ), and to investigate the relationship between coping with depression and other measures of affective symptomatology in a student sample.

DESIGN

A factor analytic study of the RSQ followed by an investigation of the relationship between RSQ scale scores and measures of affective symptomatology.

METHOD

Five hundred twenty-eight undergraduate students completed a battery of questionnaires comprising the RSQ, Beck Depression Inventory, Hypomania Personality Questionnaire, Positive and Negative Affect Scale and the Dysfunctional Attitudes Scale. Factor analysis of the RSQ was performed and correlational and regression analyses were conducted on the data from the other four questionnaire measures.

RESULTS

Factor analysis revealed a meaningful 3-factor solution which measured coping styles characterized by (i) rumination; (ii) pleasant distraction and problemsolving; and (iii) risk-taking. Rumination and risk-taking were independently associated with both depression and hypomania scores, and hypomania was associated with both depression and dysfunctional attitudes. Additional relationships between coping and the other measures are also reported.

CONCLUSIONS

The results support the validity of the coping styles concept and suggest their natural separation into three distinct strategies. Abnormal coping is discussed as a potential contributing factor to affective symptoms, including symptoms of bipolar disorder.

Antidepressant mechanism of add-on repetitive transcranial magnetic stimulation in medication-resistant depression using cerebral glucose metabolism

BACKGROUND

Add-on repetitive transcranial magnetic stimulation (rTMS) is effective in treating medication-resistant depression (MRD), but little is known about the rTMS antidepressant mechanism and pathophysiology underlying MRD.

METHODS

Twenty MRD patients received 2 weeks of navigated add-on rTMS to the left dorsolateral prefrontal cortex (DLPFC). Treatment response was defined as a ≥50% decrease in HDRS after treatment. Cerebral glucose metabolism was measured from all MRD patients twice, before and 3 months after rTMS, and from 20 healthy controls once at baseline.

RESULTS

At baseline, MRD subjects presented significant hypometabolism at the bilateral DLPFC and anterior cingulum, as well as hypermetabolism at several limbic and subcortical regions compared to the controls. Higher metabolism at the medial PFC and rostral anterior cingulum, and lower metabolism at the limbic structures, including the left parahippocampus and fusiform gyrus, predicted a response to rTMS. After successful rTMS treatment, the abnormally elevated metabolism in the left middle temporal cortex and fusiform gyrus decreased significantly, suggesting a reversal of metabolic imbalances. However, the overall metabolic pattern was still abnormal, even after their depression was under control. In contrast, the non-responders showed a worsening pattern of increased metabolism in the bilateral temporal cortex and fusiform gyrus.

CONCLUSIONS

The antidepressant mechanism of add-on rTMS may be reflected as suppression of hyperactivity in the left temporal cortex and fusiform gyrus, perhaps through enhancing the function of the medial prefrontal cortex and anterior cingulum. The limbic-cortical dysregulation of glucose metabolism might be a trait of an underlying mechanism of MRD.

Poor performance on cognitive tasks in depression: Doing too much or not enough?

Depressed people perform poorly on cognitive tasks. It is unclear whether these deficits are due to decreased devotion of task-related resources or to increased attention to non-task-related information. In the present study, we examined the degree to which depressed and healthy adults displayed pupillary motility that varied at the frequency of presented stimuli on a cognitive task, which we interpreted as task-related processing, and at other frequencies, which we interpreted as reflecting intrinsic processing. Depressed participants made more consecutive errors than did controls. More pupillary motility at other frequencies was associated with poorer performance, whereas more pupillary motility at the frequency of presented stimuli was associated with better performance. Depressed participants had more pupillary motility at other frequencies, which partially mediated observed deficits in cognitive performance. These findings support the hypothesis that allocating cognitive resources to intrinsic processing contributes to observed cognitive deficits in depression.

Maladaptive mood repair responses distinguish young adults with early-onset depressive disorders and predict future depression outcomes

BACKGROUND

Clinical depression involves persistent dysphoria, implicating impaired affect regulation or mood repair failure. However, there is comparatively little information about the mood repair repertoires of individuals with histories of clinical depression, how their repertories differ from that of never-depressed people, and whether particular types of mood repair responses differentially contribute to depression risk.

METHOD

Adult probands who had childhood-onset depressive disorder (n=215) and controls with no history of major mental disorder (n=122) reported which specific (cognitive, behavioral, interpersonal and somatic-sensory) responses they typically deploy when experiencing sad affect, including responses known to appropriately attenuate dysphoria ('adaptive' responses) and those known to exacerbate dysphoria in the short or long run ('maladaptive' responses). Subjects were longitudinally followed and evaluated.

RESULTS

Remitted probands and probands in depressive episodes both reported a greater number of maladaptive responses and fewer adaptive responses to their own sadness than did controls, although probands did not have an absolute deficiency of adaptive responses. Maladaptive (but not adaptive) mood repair responses predicted future increases in depression symptoms and an increased probability of a recurrent depressive episode among probands (even after controlling for several clinical predictors of course). Post-hoc analyses revealed that maladaptive non-cognitive and maladaptive cognitive mood repair response sets each predicted depression outcomes.

CONCLUSIONS

Individuals with past and present episodes of depressive disorder report an array of cognitive and non-cognitive responses to their own sadness that are likely to exacerbate that affect, and this pattern predicts a worse course of the disorder.

Brooding and pondering: isolating the active ingredients of depressive rumination with exploratory factor analysis and structural equation modeling

Depressive rumination, as assessed by Nolen-Hoeksema's Response Styles Questionnaire (RSQ), predicts the onset, chronicity, and duration of depressed mood. However, some RSQ items contain depressive content and result in a heterogeneous factor structure. After the a priori elimination of items potentially confounded with depressed item content, Treynor, Gonzalez, and Nolen-Hoeksema identified two factors within the remaining RSQ rumination sub-scale that were differentially related to depression: brooding and pondering. However, Treynor et al. used a nonstandard form and administration of the RSQ. The present study sought to address these methodological idiosyncrasies and replicate the factor structure of Treynor et al. through exploratory factor analysis and structural equation modeling. Findings support the brooding and pondering solution and demonstrate that brooding relates more strongly to depression and anxiety than does pondering.

EFFECTS OF RUMINATION AND INITIAL SEVERITY ON REMISSION TO COGNITIVE THERAPY FOR DEPRESSION

Trait rumination, a tendency to focus on depressive symptoms and negative information, is associated with longer and more severe episodes of depression. This study examined whether trait rumination was also associated with initial remission from unipolar depression in Cognitive Therapy, which we hypothesized would target this coping style. Eighty one patients completed measures of depressive severity and rumination before and after 16-20 sessions of procedurally determined Cognitive Therapy. Pre-treatment rumination and severity were generally associated with later initial remission and lower odds of achieving remission. Limited evidence also suggested that for the most severe patients, rumination was associated with earlier initial remission and greater odds of achieving initial remission. Cognitive Therapy was associated with significant reductions in both rumination and severity. Results suggest that 1) pre-treatment assessment of rumination and severity could help to plan treatment course and 2) Cognitive Therapy is associated with changes in cognitive coping styles.

Downregulation of endocannabinoid signaling in the hippocampus following chronic unpredictable stress

Deficits in cognitive functioning and flexibility are seen following both chronic stress and modulation of endogenous cannabinoid (eCB) signaling. Here, we investigated whether alterations in eCB signaling might contribute to the cognitive impairments induced by chronic stress. Chronic stress impaired reversal learning and induced perseveratory behavior in the Morris water maze without significant effect on task acquisition. These cognitive impairments were reversed by exogenous cannabinoid administration, suggesting deficient eCB signaling underlies these phenomena. In line with this hypothesis, chronic stress downregulated CB1 receptor expression and significantly reduced the content of the endocannabinoid 2-arachidonylglycerol within the hippocampus. CB1 receptor density and 2-arachidonylglycerol content were unaffected in the limbic forebrain. These data suggest that stress-induced downregulation of hippocampal eCB signaling contributes to problems in behavioral flexibility and could play a role in the development of perseveratory and ruminatory behaviors in stress-related neuropsychiatric disorders.

Predictors of antidepressant response: A selective review

Modern antidepressant drugs have response rates in the 65% range. Considerable effort has been made to predict which patients would be more likely to respond to antidepressant treatment. Some progress has been made, more in finding psychological predictors than biological predictors of antidepressant response. In spite of slow progress, these findings have made a valuable contribution towards the understanding of antidepressant response. In future it may be possible for psychiatrists to use a more broad-based approach, tailoring therapies to the clinical profile of individuals.

Gender differences in unipolar depression: an update of epidemiological findings and possible explanations

OBJECTIVE

To give an update on epidemiological findings on sex differences in the prevalence of unipolar depression and putative risk factors.

MATERIAL AND METHODS

Systematic review of the literature.

RESULTS

Recent epidemiological research yields additional evidence for a female preponderance in unipolar depression, holding true across different cultural settings. Current explanations include artefacts, genetic, hormonal, psychological and psychosocial risk factors. Rather consistently, intrapsychic and psychosocial gender role related risk factors have been identified which may contribute to the higher depression risk in women. Gender role aspects are also reflected in endocrine stress reactions and possibly influence associated neuropsychological processes.

CONCLUSION

There is a need for more integrative models taking into account psychological, psychosocial, and macrosocial risk factors as well as their interactions, which also connect these factors with physiological and endocrine responses. Furthermore, it is conceivable that across the life span, as well as across cultural settings, individual risk factors will add with varying emphasis to the higher prevalence of depression in women.

A salutogenetic perspective on how men cope with major depression in daily life, with the help of professional and lay support

Worldwide, major depression is one of the main causes of premature death and lowered functional capacity, and its importance will increase in the coming years. At the same time, there is a gap in service provision, and the needs of depressed patients are often not met. Therefore, the aim of this study was to describe how men (N=12) with major depression (DSM-IV) cope with daily life with the help of professional and lay support. The men were selected by strategic sampling and analysed with an approach inspired by phenomenography. Four descriptive categories emerged: being unburdened, restoring one's health, feeling involved, and finding a meaning. A man receives help and support from health care in restoring his health but his own path to getting well is to resume his place in the public domain. To help him do so, lay support is vital, and an important task for the nurse is, therefore, to support him in maintaining his existing social network or in building a new one.

Self-Directed Thought and Response to Treatment for Depression: A Preliminary Investigation

The study this article is based on investigated the role of self-directed attention in the maintenance of depressive episodes. Measures of rumination and self-consciousness were used to predict response to treatment for depression. Further, the study investigated the potential interplay between self-directed attention and negative cognition. Thirty-two participants completed measures of rumination, private self-consciousness, and negative cognition prior to receiving group psychoeducational treatment for depression. Analyses revealed that although the main effects of measures of self-directed attention and negative cognition were not statistically significant, the interaction between self-directed thought (particularly rumination) and negative cognitive style predicted change in severity of depressive symptoms over the course of the treatment program. These findings suggest that the degree to which heightened self-directed attention contributes to poor treatment outcome for depression varies as a function of cognitive style.

Response styles among patients with minor depression and dysthymia in primary care

Ruminative responses to depression have predicted duration and severity of depressive symptoms. The authors examined how response styles change over the course of treatment for depression and as a function of type of treatment. They also examined the ability of response styles to predict treatment outcome and status at follow-up. Primary care patients (n = 96) with dysthymia or minor depression were randomly assigned to problem-solving therapy, paroxetine, or placebo. Patients' depressive symptoms and rumination, but not distraction, decreased over time. Pretreatment rumination and distraction were associated with more depressive symptoms at the conclusion of treatment; the latter finding was not consistent with the response style theory of depression. Results are discussed in terms of their implications for this theory.

Exposure to the stressor environment prevents the temporal dissipation of behavioral depression/learned helplessness

BACKGROUND

Exposure to uncontrollable stressors such as inescapable shock (IS) produces a set of behavioral changes such as poor escape learning that have been called behavioral depression and learned helplessness. This paradigm has been proposed to be a model of depression and of anxiety-related disorders such as posttraumatic stress disorder (PTSD). However, the behavioral changes persist for only a few days after the stressor, rendering the phenomenon questionable as a model. However, the original traumatic experience is re-experienced in PTSD and rumination occurs in depression. In a series of experiments we therefore sought to determine whether behavioral depression/learned helplessness could be made to endure by periodically "reminding" the subject of the original IS experience.

METHODS

Rats exposed to IS were tested for escape learning at various times thereafter. In different experiments the subjects were exposed to the environment in which IS had occurred at differing points in the interval between IS and escape testing.

RESULTS

Exposure to the environment in which IS had occurred prolonged the duration of behavioral depression/learned helplessness, and repeated exposures prolonged it indefinitely. This effect required exposure to the cues that had been present during IS (i.e., reminding) and was not duplicated by exposure to other stressors or stress environments.

CONCLUSIONS

Behavioral depression/learned helplessness can be maintained over time by processes that may be similar to those occurring in depression and PTSD, thereby strengthening the possibility that this paradigm is indeed a reasonable model of these disorders.