Phenomenology of racing and crowded thoughts in mood disorders: a theoretical reappraisal

Dynamics of spontaneous thoughts: Exploration, attentional profile and the segmentation of the stream of thoughts

For a long time, clinical knowledge and first-person reports have pointed to individual differences in the dynamics of spontaneous thoughts, in particular in the extreme case of psychiatric conditions (e.g. racing thoughts in Attention Deficit / Hyperactivity Disorder, ADHD; rumination in depression). We used a novel procedure to investigate this individual variability by combining verbal fluency tasks and introspective reports of thought content. Our goal was twofold. First, we tested the hypothesis that a greater segmentation of the stream of thoughts would be associated with trait inattention, in line with subjective reports of ADHD patients. Second, we tested whether the segmentation of the stream of thoughts increased with an increased tendency for exploratory behavior, following recent theoretical claims on the mechanisms underpinning the generation of spontaneous thoughts. Our results support both hypotheses, shedding light on the factors contributing to the individual variability in the dynamics of the stream of thought.

Spanish validation of the short version of the racing and crowded thoughts questionnaire (RCTQ-13)

BACKGROUND

The Racing and Crowded Thoughts Questionnaire (RCTQ-13) is the most widely used specific scale for the measurement of racing thoughts, but there is currently no Spanish version that allow the evaluation in Spanish-speaking patients. The objective of this study is to translate, adapt, and validate the RCTQ-13 in a Colombian population with affective disorders.

METHODS

The questionnaire was translated and back-translated, and corrections were implemented following a pilot test to improve comprehensibility. We included patients with Bipolar I Disorder and with Major depressive disorder seen in three centers in the city of Medellín, Colombia. We evaluate structural validity with confirmatory factor analysis, internal consistency, and test-retest reliability. Construct validity was also assessed with the comparison between euthymic, maniac, and depressive episodes and the correlation with worry, rumination, and mania scales. Responsiveness was measured 1 month after the first evaluation. Based on item response theory (IRT), we also estimated item difficulty, discrimination, and fit using a generalized partial credit model.

RESULTS

Two hundred fifty subjects were included. Confirmatory factor analysis revealed that the three-factor structure of the scale was appropriate. Internal consistency was adequate for the entire scale (Cronbach's alpha = 0.95, 95% CI: 0.94-0.96) and for each factor. Test-retest reliability was good (intraclass correlation coefficient = 0.82, 95%IC: 0.70-0.88). For construct validity, we observed differences between patients with different types of affective episodes, a moderate positive correlation with the Penn State Worry Scale (r = 0.55) and the Ruminative Response Scale (r = 0.42), and a low negative correlation with the Young Mania Rating Scale (r = - 0.10). Responsiveness was proved to be adequate. Under IRT, the response thresholds for the response options are organized for all items. The infit was adequate for all items and the outfit was acceptable.

CONCLUSIONS

The Spanish version of the RCTQ-13 is a reliable, valid, and responsive scale and can be used for the clinical assessment of the construct of racing and crowded thoughts in patients with the spectrum of affective disorders in whom this experience can be expressed with different nuances. Further research is needed to expand the relationship with rumination and worry.

Disentangling racing thoughts from mind wandering in adult attention deficit hyperactivity disorder

Introduction

Mental restlessness reported by adult with Attention Deficit Hyperactivity Disorder (ADHD) has been mainly explained by excessive mind wandering. However, the description of a mind constantly on the go is also akin to racing thoughts, predominantly described in bipolar disorder. This paper aimed at disentangling mind wandering from racing thoughts in adult with ADHD. Associations between those mental phenomena and the ADHD symptomatology were also investigated.

Methods

To this aim, 84 adults with ADHD completed self-reported questionnaires, including the Mind Wandering-Deliberate and Mind Wandering-Spontaneous questionnaires, the Racing and Crowded Thoughts Questionnaire and the Daydreaming Frequency Scale. Factorial analysis and multiple linear regressions were performed.

Results

The factor analysis yielded a two-factor solution. The first factor encompassed the three facets of racing thoughts and was predicted by emotional lability. The second comprised deliberated-MW, spontaneous-MW and daydreaming, but was neither related to the ADHD symptoms, nor functional impairment.

Discussion

These findings suggest that MW and racing thoughts are two distinguishable mental phenomena. Racing thoughts appear to be a relevant hypothesis to explain the mental restlessness in adult ADHD.

Psychopathological Dissection of Bipolar Disorder and ADHD: Focussing on Racing Thoughts and Verbal Fluency

In the present study, we propose a review and a synthesis of the work of our group about the phenomenology and the cognitive mechanisms of racing thoughts in bipolar disorder (BD) and ADHD. Contrary to the mainstream idea according to which racing thoughts are pathognomonic of BD, our work suggests that racing thoughts are enhanced in ADHD compared to hypomanic episodes of BD, whereas in euthymic episodes of BD self-reported racing thoughts are similar to the rates reported by healthy controls. Using verbal fluency tasks, we found many similarities between bipolar and ADHD subjects with one clear difference: lexical search strategy in hypomania is based on phonemic similarities rather than semantic-relatedness. However, this distinction observed in this cognitive task is certainly difficult to grasp during a clinical interview aiming to differentiate mild hypomania from combined ADHD presentation. The main landmark to distinguish them remains the episodic nature of bipolar disorders as opposed to the lifelong presentation of ADHD symptoms, a dichotomous view that is not so clear-cut in clinical practice.

Investigating racing thoughts via ocular temporal windows: deficits in the control of automatic perceptual processes

BACKGROUND

Racing thoughts have been found in several states of bipolar disorder (BD), but also in healthy populations with subclinical mood alterations. The evaluation of racing thoughts relies on subjective reports, and objective measures are sparse. The current study aims at finding an objective neuropsychological equivalent of racing thoughts in a mixed group of BD patients and healthy controls by using a bistable perception paradigm.

METHOD

Eighty-three included participants formed three groups based on participants' levels of racing thoughts reported via the Racing and Crowded Thoughts Questionnaire. Participants reported reversals in their perception during viewing of the bistable Necker cube either spontaneously, while asked to focus on one interpretation of the cube, or while asked to accelerate perceptual reversals. The dynamics of perceptual alternations were studied both at a conscious level (with manual temporal windows reflecting perceptual reversals) and at a more automatic level (with ocular temporal windows derived from ocular fixations).

RESULTS

The rate of windows was less modulated by attentional conditions in participants with racing thoughts, and most clearly so for ocular windows. The rate of ocular windows was especially high when participants with racing thoughts were asked to focus on one interpretation of the Necker cube and when they received these instructions for the first time.

CONCLUSIONS

Our results indicate that in subjects with racing thoughts automatic perceptual processes escape cognitive control mechanisms. Racing thoughts may involve not only conscious thought mechanisms but also more automatic processes.

An overactive mind: Investigating racing thoughts in ADHD, hypomania and comorbid ADHD and bipolar disorder via verbal fluency tasks

BACKGROUND

Adults with Attention Deficit Hyperactivity Disorder (ADHD) often report mental restlessness akin to racing thoughts found in hypomanic and mixed episodes of bipolar disorder (BD). Past research has suggested that racing thoughts in BD can be tackled via process-oriented verbal fluency measures. In ADHD, it is still unknown whether racing thoughts is due to comorbid BD, and its neuropsychological underpinnings remain to be investigated. To this aim, this study investigates process-oriented verbal fluency measures in adults with ADHD compared to adults with BD in a hypomanic episode, adults with ADHD + BD and healthy controls.

METHODS

Three verbal fluency tasks, i.e., the free, the letter and the semantic conditions, were administered to 37 adults with ADHD, 25 adults with BD in a hypomanic episode, 22 adults with comorbid ADHD + BD (euthymia) and 31 healthy subjects. Word production, clustering, and switching were analysed in verbal fluency tasks.

RESULTS

Adults with ADHD, ADHD + BD and hypomania showed increased switches in the free verbal fluency task, compared to healthy controls, despite equivalent number of words produced. Unlike the ADHD and ADHD + BD groups, phonological clustering measures in the semantic task were increased in the hypomanic group compared to healthy controls.

LIMITATIONS

BD groups were under medication.

CONCLUSIONS

Semantic overactivation, reflected by increased switches in the unconstrained verbal fluency task, appear to be a common mechanism involved in racing thoughts in both ADHD and BD. By contrast, unusual sounds-based associations are specific of hypomanic speech and might contribute to the distinction trait and state racing thoughts.

Vocalization and physiological hyperarousal in infant-caregiver dyads where the caregiver has elevated anxiety

Co-regulation of physiological arousal within the caregiver-child dyad precedes later self-regulation within the individual. Despite the importance of unimpaired self-regulatory development for later adjustment outcomes, little is understood about how early co-regulatory processes can become dysregulated during early life. Aspects of caregiver behavior, such as patterns of anxious speech, may be one factor influencing infant arousal dysregulation. To address this, we made day-long, naturalistic biobehavioral recordings in home settings in caregiver-infant dyads using wearable autonomic devices and miniature microphones. We examined the association between arousal, vocalization intensity, and caregiver anxiety. We found that moments of high physiological arousal in infants were more likely to be accompanied by high caregiver arousal when caregivers had high self-reported trait anxiety. Anxious caregivers were also more likely to vocalize intensely at states of high arousal and produce intense vocalizations that occurred in clusters. High-intensity vocalizations were associated with more sustained increases in autonomic arousal for both anxious caregivers and their infants. Findings indicate that caregiver vocal behavior differs in anxious parents, cooccurs with dyadic arousal dysregulation, and could contribute to physiological arousal transmission. Implications for caregiver vocalization as an intervention target are discussed.

Investigating racing thoughts in insomnia: A neglected piece of the mood-sleep puzzle?

BACKGROUND

Cognitive arousal is thought to play a key role in insomnia disorder. However, although patients frequently complain about racing thoughts appearing at bedtime, studies have considered 'cognitive arousal' as a synonym of rumination and worry, but not as racing thoughts per se. The latter have been mainly linked to hypomanic/manic episodes of bipolar disorder (BD). Here we aimed at investigating self-reported racing thoughts in insomnia disorder, and their specific contribution to insomnia severity, as compared to worry and rumination.

METHODS

72 adults with insomnia disorder, 49 patients with BD in a hypomanic episode and 99 healthy individuals completed the Racing and Crowded Thoughts Questionnaire (RCTQ). Mood symptoms were assessed in patients with insomnia disorder.

RESULTS

RCTQ scores were overall higher in insomnia disorder, especially in sleep-onset insomnia, compared to the hypomanic and healthy groups. Moreover, racing thoughts showed an increase in the evening and at bedtime in sleep-onset insomnia. Importantly, racing thoughts at bedtime, but not rumination and worry, were associated with insomnia severity.

DISCUSSION

Our results are the first to show that racing thoughts is a transdiagnostic symptom in mood and sleep disorders. Racing thoughts, not only rumination and worry, might contribute to the maintenance of sleep difficulties in insomnia. Clinical trials' registration number: NCT04752254.

Beyond motor hyperactivity: Racing thoughts are an integral symptom of adult attention deficit hyperactivity disorder

Adults with ADHD experience mental restlessness, akin to racing thoughts, but data on this symptom in ADHD remain scarce. Our study aims at investigating self-reported racing thoughts in adults with ADHD, and its relationship with affective dysregulation and insomnia. We were also interested in whether racing thoughts may aid differential diagnosis with bipolar disorder (BD). 182 adults with ADHD, 30 ADHD+BD, 31 hypomanic BD, and 20 euthymic BD patients completed the Racing and Crowded Thoughts Questionnaire (RCTQ). ADHD, anxiety, insomnia and depression symptoms, as well as affective temperament were also assessed in ADHD and ADHD+BD subjects. Results show that RCTQ scores were higher in ADHD compared to hypomania and euthymia and were associated with cyclothymic traits and anxiety. Moreover, in ADHD and ADHD+BD, racing thoughts increased in the evening and at bedtime and were associated with insomnia severity. In conclusion, self-reported racing thoughts are a neglected but an intrinsic feature of adult ADHD that is particularly related to cyclothymia and anxiety, but cannot differentiate ADHD and BD.

Pattern of occurrence of obsessive-compulsive symptoms in bipolar disorder

Apparent comorbidity between Bipolar Disorder (BD) and Obsessive-Compulsive Disorder (OCD) is a common condition, but its meaning has not been clarified yet. The present study aimed to evaluate the pattern of occurrence of obsessive-compulsive symptoms (OCS) in the different phases of BD. One hundred and sixty-five BD patients, 62 (37.5%) euthymic, 34 (20.6%) in hypomanic/manic phase, 43 (26%) in depressive phase and 26 (15.7%) in mixed state, were assessed with the Yale-Brown Obsessive-Compulsive Scale (YBOCS), the Hamilton Depression Rating Scale (HAM-D), the Young Mania Rating Scale (YMRS) and the Ruminative Response Scale (RRS). In the whole sample, the severity of OCS was associated to the severity of depressive symptoms. The highest severity of OCS (YBOCS total score) was observed in the mixed group and the lowest scores in the hypomanic/manic group. Our findings suggest that OCS in BD patients appear as a state-dependent phenomenon cycling with the mood phases, particularly exacerbating in the context of depressive and mixed states.

Structure in the stream of consciousness: Evidence from a verbalized thought protocol and automated text analytic methods

A key question about the spontaneous stream of thought (SST), often called the stream of consciousness, concerns its serial structure: How are thoughts in an extended sequence related to each other? In this study, we used a verbalized thought protocol to investigate "clump-and-jump" structure in SST-clusters of related thoughts about a topic followed by a jump to a new topic, in a repeating pattern. Several lines of evidence convergently supported the presence of clump-and-jump structure: high interrater agreement in identifying jumps, corroboration of rater-assigned jumps by automated text analytic methods, identification of clumps and jumps by a data-driven algorithm, and the inferred presence of clumps and jumps in unverbalized SST. We also found evidence that jumps involve a discontinuous shift in which a new clump is only modestly related to the previous one. These results illuminate serial structure in SST and invite research into the processes that generate the clump-and-jump pattern.

La dépression mixte

La dépression mixte correspond à un syndrome dépressif avec des éléments d’activation psychomotrice de la lignée hypomaniaque. Cette situation pathologique reste mal connue des cliniciens alors qu’elle est présente chez 10 à 20 % des patients dépressifs. Sa faible reconnaissance a été probablement liée à l’absence de ce concept dans les classifications internationales. Le DSM-5 a proposé une refonte de la définition des états mixtes, dépassant une conception particulièrement restrictive dans le DSM-IV. Des « caractéristiques mixtes » peuvent servir de spécificateur pour un épisode de trouble de l’humeur, dépressif ou maniaque. La dépression avec caractéristique mixte est définie par la présence de trois symptômes de la lignée maniaque associée à la dépression, hors agitation, distractibilité ou irritabilité. L’approche proposée par le DSM-5 manque de cohérence clinique et est finalement assez difficile à appliquer. Surtout elle ne permet pas d’identifier la majorité des dépressions mixtes. En effet les formes les plus fréquentes bien décrites dans les travaux de Koukopoulos ou Bennazzi se caractérisent par des symptômes hypomanes peu spécifiques comme l’irritabilité et l’agitation psychomotrice (ou parfois surtout l’absence de ralentissement psychomoteur) et des symptômes hypomanes limités à l’activation psychique qui s’exprime notamment à travers la tachypsychie subjective (avec des caractéristiques phénoménologiques différentes de celle de l’hypomanie) et la pression du discours. Les patients avec une dépression mixte sont particulièrement à risque de conduites suicidaires, d’abus de substances mais surtout de résistance thérapeutique car, même si on manque d’essais cliniques à leur sujet, ces patients non seulement nécessitent la prescription de thymorégulateurs mais aussi le plus souvent un arrêt des antidépresseurs qui ont souvent induit le caractère mixte de la dépression.

Resting-state functional connectivity of emotion regulation networks in euthymic and non-euthymic bipolar disorder patients

Background

Previous functional magnetic resonance imaging studies in bipolar disorder (BD) have evidenced changes in functional connectivity (FC) in brain areas associated with emotion processing, but how these changes vary with mood state and specific clinical symptoms is not fully understood.

Methods

We investigated resting-state FC between a priori regions of interest (ROIs) from the default-mode network and key structures for emotion processing and regulation in 27 BD patients and 27 matched healthy controls. We further compared connectivity patterns in subgroups of 15 euthymic and 12 non-euthymic patients and tested for correlations of the connectivity strength with measures of mood, anxiety, and rumination tendency. No correction for multiple comparisons was applied given the small population sample and pre-defined target ROIs.

Results

Overall, regardless of mood state, BD patients exhibited increased FC of the left amygdala with left sgACC and PCC, relative to controls. In addition, non-euthymic BD patients showed distinctive decrease in FC between right amygdala and sgACC, whereas euthymic patients showed lower FC between PCC and sgACC. Euthymic patients also displayed increased FC between sgACC and right VLPFC. The sgACC–PCC and sgACC–left amygdala connections were modulated by rumination tendency in non-euthymic patients, whereas the sgACC-VLPFC connection was modulated by both the current mood and tendency to ruminate.

Conclusions

Our results suggest that sgACC-amygdala coupling is critically affected during mood episodes, and that FC of sgACC play a pivotal role in mood normalization through its interactions with the VLPFC and PCC. However, these preliminary findings require replication with larger samples of patients.

Thought and language disturbance in bipolar disorder quantified via process-oriented verbal fluency measures

Bipolar disorder (BD) is characterized by speech abnormalities, reflected by symptoms such as pressure of speech in mania and poverty of speech in depression. Here we aimed at investigating speech abnormalities in different episodes of BD, including mixed episodes, via process-oriented measures of verbal fluency performance - i.e., word and error count, semantic and phonological clustering measures, and number of switches-, and their relation to neurocognitive mechanisms and clinical symptoms. 93 patients with BD - i.e., 25 manic, 12 mixed manic, 19 mixed depression, 17 depressed, and 20 euthymic-and 31 healthy controls were administered three verbal fluency tasks - free, letter, semantic-and a clinical and neuropsychological assessment. Compared to depression and euthymia, switching and clustering abnormalities were found in manic and mixed states, mimicking symptoms like flight of ideas. Moreover, the neuropsychological results, as well as the fact that error count did not increase whereas phonological associations did, showed that impaired inhibition abilities and distractibility could not account for the results in patients with manic symptoms. Rather, semantic overactivation in patients with manic symptoms, including mixed depression, may compensate for trait-like deficient semantic retrieval/access found in euthymia. "For those who are manic, or those who have a history of mania, words move about in all directions possible, in a three-dimensional 'soup', making retrieval more fluid, less predictable." Kay Redfield Jamison (2017, p. 279).

Racing thoughts revisited: A key dimension of activation in bipolar disorder

BACKGROUND

Racing and crowded thoughts are frequently reported respectively in manic and mixed episodes of bipolar disorder (BD). However, questionnaires assessing this symptom are lacking. Here we aimed to investigate racing thoughts across different mood episodes of BD through a self-report questionnaire that we developed, the 34-item Racing and Crowded Thoughts Questionnaire (RCTQ). In addition to assessing its factor structure and validity, we were interested in the RCTQ's ability to discriminate mixed and non-mixed depression.

METHODS

221 BD patients and 120 controls were clinically assessed via the YMRS (mania) and the QIDS-C16 (depression), then fulfilled the RCTQ, rumination, worry, and anxiety measures. Three depression groups were operationalized according to YMRS scores: YMRS scores 2 > 6 and YMRS scores = 1 or 2, for respectively mixed and non-pure depression, and YMRS = 0 for pure-depression.

RESULTS

Confirmatory factor analysis showed that the three-factor model of the RCTQ yielded the best fit indices, which improved after the removal of redundant items, resulting in a 13-item questionnaire. Hypomanic and anxiety symptoms were the main predictors of scores; rumination was not a significant predictor. RCTQ results were similar between mixed groups and non-pure depression, and both were higher than in pure-depression.

LIMITATIONS

Patients' pharmacological treatment might have influenced the results.

CONCLUSIONS

The 13-item RCTQ captures different facets of racing thoughts heightened in hypomanic and mixed states, but also in depression with subclinical hypomanic/activation symptoms (e.g. non-pure depression characterized by enhanced subjective irritability), suggesting that it is particularly sensitive to activation symptoms in BD, and could become a valuable tool in the follow-up of patients.

Measuring racing thoughts in healthy individuals: The Racing and Crowded Thoughts Questionnaire (RCTQ)

Racing thoughts refer to an acceleration and overproduction of thoughts, which have been associated with manic and mixed episodes. Phenomenology distinguishes 'crowded' from 'racing' thoughts, associated with mixed depression and mania, respectively. Recent data suggest racing thoughts might also be present in healthy individuals with sub-affective traits and symptoms. We investigated this assumption, with a 34-item self-rating scale, the Racing and Crowded Thoughts Questionnaire (RCTQ), and evaluated its reliability, factor structure, and concurrent validity. 197 healthy individuals completed the RCTQ, the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego - autoquestionnaire (TEMPS-A), the Beck Depression Inventory (BDI), the Altman Self-Rating Mania scale (ASRM), and the Ruminative Response Scale (RRS). Exploratory factor analysis yielded a three-factor solution, labeled 'thought overactivation', 'burden of thought overactivation', and 'thought overexcitability'. Internal consistency of each of the three subscales of the RCTQ was excellent. The TEMPS-A cyclothymia score was associated with the three factors, suggesting good concurrent validity. The 'thought activation' subscale was selectively associated with current elated mood and included items conveying both the notion of increased amount and velocity of thoughts, whereas the 'burden of thought overactivation' subscale was associated with current low mood. The 'thought overexcitability' subscale included items conveying the notion of distractibility, and was associated with both elated and low mood. Rumination was not a significant predictor of RCTQ subscores. These results suggest that the RCTQ has good psychometric properties. Racing and crowded thoughts, as measured by the RCTQ, are a multi-faceted phenomenon, distinct from rumination, and particularly associated with mood instability even in its milder forms.

Alterations in neural systems mediating cognitive flexibility and inhibition in mood disorders

Impairment in mental flexibility may be a key component contributing to cardinal cognitive symptoms among mood disorders patients, particularly thought control disorders. Impaired ability to switch from one thought to another might reflect difficulties in either generating new mental states, inhibiting previous states, or both. However, the neural underpinnings of impaired cognitive flexibility in mood disorders remain largely unresolved. We compared a group of mood disorders patients (n = 29) and a group of matched healthy subjects (n = 32) on a novel task-switching paradigm involving happy and sad faces, that allowed us to separate generation of a new mental set (Switch Cost) and inhibition of the previous set during switching (Inhibition Cost), using fMRI. Behavioral data showed a larger Switch Cost in patients relative to controls, but the average Inhibition Cost did not differ between groups. At the neural level, a main effect of group was found with stronger activation of the subgenual cingulate cortex in patients. The larger Switch Cost in patients was reflected by a stronger recruitment of brain regions involved in attention and executive control, including the left intraparietal sulcus, precuneus, left inferior fontal gyrus, and right anterior cingulate. Critically, activity in the subgenual cingulate cortex was not downregulated by inhibition in patients relative to controls. In conclusion, mood disorder patients have exaggerated Switch Cost relative to controls, and this deficit in cognitive flexibility is associated with increased activation of the fronto-parietal attention networks, combined with impaired modulation of the subgenual cingulate cortex when inhibition of previous mental states is needed.

[Mixed depression and DSM-5: A critical review]

BACKGROUND

Mixed depression is a depressive syndrome characterized by the presence, along with the typical depressive symptoms of depression, of those of over activation and excitation. If sometimes this activation is expressed by classical hypomanic symptoms, it is often observed by means of more subtle expression: inner tension, crowded thoughts, dramatic expression suffering, and unproductive agitation. It is important to identify mixed depression because such patients are particularly at risk of suicidal behaviors, substance abuse and therapeutic resistance. Even if therapeutic strategies continue to be discussed, treatments should rely on mood stabilizers and antipsychotics instead of antidepressants as in pure depression. Even though the concept of mixed depression has been described for more than twenty years, first by Koukopoulos and then by other authors, it had been little studied, especially because it did not appear in international psychiatric classifications. The DSM-IV supported a very narrow conception of the mixed states because the criteria required simultaneous full manic and full depressive syndromes, corresponding only to some dysphoric manias. The recently published DSM-5 proposes modifications in mood and bipolar disorder classifications, and especially introduces the possibility to specify depressive and manic episodes with "mixed features". To diagnose depression with mixed features, a full depressive syndrome has to be present together most of time with three hypomanic symptoms, except symptoms that are considered as overlapping (that can be observed either in mania or in depression), i.e. agitation, irritability and distractibility.

METHODS

Critical analysis of DSM criteria and review of literature.

RESULTS

We first analyzed the clinical relevance of the definition of depression with mixed features which could correspond to mixed depression. The problem is that the hypomanic symptoms allowed by the manual lead to symptom associations that are rather illogical (as euphoria with depression) or improbable (as increased or excessive involvement in activities that have a high potential for painful consequences). Also, some more specific symptoms that can be observed in mixed depression are not mentioned (such as hypersensitivity to light or noise, absence of motor retardation, dramatic expressivity of suffering). The DSM-5, as did DSM-IV, refers to an understanding of mixed depression as a simple addition of depressive and manic symptoms. The classification does not take into account that the symptoms could be rather different from hypomania, as the expression of an overactive thought in a depressed mind. Secondly, we reviewed cohort studies using the DSM-5 criteria (or similar criteria with the exclusion of overlapping symptoms), and as a consequence of the poorly defined symptoms, we found that the diagnosis of mixed depression according to DSM-5 is almost impossible, either in unipolar or in bipolar depression.

CONCLUSIONS

We think, with others, that the definition of the mixed depression by the DSM-5 is not clinically relevant and misses important information about the concept. Clinicians can be attentive to the identification of mixed character in depression, even if DSM-5 criteria are not fully met. Unfortunately, the DSM-5 definition could undermine research efforts for a better understanding of epidemiology, phenomenology and therapeutics of mixed depression. We propose and discuss alternative solutions for defining mixed depression, such as the absence of exclusion of "overlapping" symptoms, a more insighted phenomenology, or a dimensional approach.

Neural correlates of generation and inhibition of verbal association patterns in mood disorders

OBJECTIVES

Thought disorders such as rumination or flight of ideas are frequent in patients with mood disorders, and not systematically linked to mood state. These symptoms point to anomalies in cognitive processes mediating the generation and control of thoughts; for example, associative thinking and inhibition. However, their neural substrates are not known.

METHOD

To obtain an ecological measure of neural processes underlying the generation and suppression of spontaneous thoughts, we designed a free word association task during fMRI allowing us to explore verbal associative patterns in patients with mood disorders and matched controls. Participants were presented with emotionally negative, positive or neutral words, and asked to produce two words either related or unrelated to these stimuli.

RESULTS

Relative to controls, patients produced a reverse pattern of answer typicality for the related vs unrelated conditions. Controls activated larger semantic and executive control networks, as well as basal ganglia, precuneus and middle frontal gyrus. Unlike controls, patients activated fusiform gyrus, parahippocampal gyrus and medial prefrontal cortex for emotional stimuli.

CONCLUSIONS

Mood disorder patients are impaired in automated associative processes, but prone to produce more unique/personal associations through activation of memory and self-related areas.

Natural speech comprehension in bipolar disorders: an event-related brain potential study among manic patients

BACKGROUND

Thought and language disturbances are crucial clinical features in Bipolar Disorders (BD), and constitute a fundamental basis for social cognition. In BD, clinical manifestations such as disorganization and formal thought disorders may play a role in communication disturbances. However, only few studies have explored language disturbances in BD at a neurophysiological level. Two main Event-Related brain Potentials (ERPs) have been used in language comprehension research: the N400 component, elicited by incongruous word with the preceding semantic context, and the Late Positive Component (LPC), associated with non-specifically semantic and more general cognitive processes. Previous studies provided contradictory results regarding N400 in mood disorders, showing either preserved N400 in depression or dysthymia, or altered N400 in BD during semantic priming paradigm. The aim of our study was to explore N400 and LPC among patients with BD in natural speech conditions.

METHODS

ERPs from 19 bipolar type I patients with manic or hypomanic symptomatology and 19 healthy controls were recorded. Participants were asked to listen to congruous and incongruous complete sentences and to judge the match between the final word and the sentence context. Behavioral results and ERPs data were analyzed.

RESULTS

At the behavioral level, patients with BD show worst performances than healthy participants. At the electrophysiological level, our results show preserved N400 component in BD. LPC elicited under natural speech conditions shows preserved amplitude but delayed latency in difference waves.

LIMITATIONS

Small size of samples, absence of schizophrenic group and medication status.

CONCLUSIONS

In contrast with the only previous N400 study in BD that uses written semantic priming, our results show a preserved N400 component in ecological and natural speech conditions among patients with BD. Possible implications in terms of clinical specificity are discussed.

Subjective experience of thought overactivation in mood disorders: beyond racing and crowded thoughts

BACKGROUND

Racing thoughts, crowded thoughts and flight of ideas are frequent symptoms in mood disorders, but the underlying subjective experience of overactivation of thought processes remains poorly documented.

METHODS

Qualitative analysis of audiotaped interviews explored subjective experience of thought overactivation in patients with mood disorders (sample 1, n = 45). Quantitative analysis considered the properties of a newly developed rating scale in sample 1, in an additional sample of patients with mood disorders (sample 2, n = 37) and in healthy subjects (sample 3, n = 38).

RESULTS

Qualitative analysis of individual interviews revealed that 5 conceptual categories characterized thought overactivation: sequential thought flow, overstimulation, competition for resource allocation, unexpected/unexplained onset, and association with mood and emotions. A principal component analysis of the initial 16-item rating scale indicated that a single component explained 55.9% of the variance, with major and exclusive contributions from 9 items, which were retained in the final 9-item Subjective Thought Overactivation Questionnaire (STOQ; Cronbach's α = 0.95). Total score correlated significantly with activation, depression and perceived conflict subscales of the Internal State Scale (ISS; rs = 0.57-0.66, p < 0.001). It was associated with decreased well-being (ISS; rs = -0.48, p = 0.001) and increased state anxiety (State-Trait Anxiety Inventory; rs = 0.60, p < 0.001). The STOQ score was significantly higher in patients than in healthy subjects. It allowed distinguishing between ISS mood states, with the highest median score in mixed states.

LIMITATIONS

Sample size, representativeness, possible bias in qualitative analysis, and quality of expert consensus.

CONCLUSIONS

Qualitative analysis of clinical interviews, together with a new short rating scale, contributed to a documentation of subjective thought overactivation, an important but often undetected feature in mood disorders.