Psychopathology research in the RDoC era: Unanswered questions and the importance of the psychophysiological unit of analysis

The NIMH Research Domain Criteria (RDoC) initiative seeks to re-conceptualize psychopathology by identifying transdiagnostic constructs that reflect core mechanisms of psychopathology. Although the RDoC framework has been discussed in many prior papers, there are several methodological and conceptual points that have yet to be fully specified. For example, little discussion exists on the importance of distinguishing each construct's nomological network and linking it to risk for psychopathology. It has also been unclear the extent to which RDoC constructs (within and across systems) should relate to one another and how these associations may differ as a function of developmental period. These are important questions as we enter the RDoC era and psychophysiological measures represent an exciting tool to address these issues. In this paper, we discuss the currently un- (or under-)specified aspects of the RDoC initiative and highlight the advantages of the psychophysiological 'unit of analysis.' We also briefly review existing psychophysiological studies, within the positive and negative valence systems, that exemplify the RDoC approach and make recommendations for how future studies can help the field progress in this mission.

Convergence of EEG and fMRI measures of reward anticipation

Deficits in reward anticipation are putative mechanisms for multiple psychopathologies. Research indicates that these deficits are characterized by reduced left (relative to right) frontal electroencephalogram (EEG) activity and blood oxygenation level-dependent (BOLD) signal abnormalities in mesolimbic and prefrontal neural regions during reward anticipation. Although it is often assumed that these two measures capture similar mechanisms, no study to our knowledge has directly examined the convergence between frontal EEG alpha asymmetry and functional magnetic resonance imaging (fMRI) during reward anticipation in the same sample. Therefore, the aim of the current study was to investigate if and where in the brain frontal EEG alpha asymmetry and fMRI measures were correlated in a sample of 40 adults. All participants completed two analogous reward anticipation tasks--once during EEG data collection and the other during fMRI data collection. Results indicated that the two measures do converge and that during reward anticipation, increased relative left frontal activity is associated with increased left anterior cingulate cortex (ACC)/medial prefrontal cortex (mPFC) and left orbitofrontal cortex (OFC) activation. This suggests that the two measures may similarly capture PFC functioning, which is noteworthy given the role of these regions in reward processing and the pathophysiology of disorders such as depression and schizophrenia.

Is risk-taking propensity a familial vulnerability factor for alcohol use? An examination in two independent samples

Research indicates that increased risk-taking propensity (RTP) is associated with higher alcohol use. There is also some evidence to suggest that it is not just a state factor or 'scar,' but instead a vulnerability factor. If this is the case, increased RTP should be evident in healthy individuals that are at risk for alcohol use. To date, few studies have examined whether RTP is a familial vulnerability factor and thus, the aim of the current study was to test whether RTP aggregates within families and if increased RTP is evident in biological family members at risk for alcohol use. Sample 1 included 87 biological, adult sibling pairs and Sample 2 included 111 biological mother and adolescent dyads (total N = 396). All participants completed a behavioral measure of RTP and were assessed for alcohol use. Results in both samples were strikingly consistent. In Sample 1, RTP was correlated among siblings and greater frequency of proband alcohol use predicted greater sibling RTP, over and above sibling alcohol use. In Sample 2, RTP was correlated among mothers and their offspring and greater maternal alcohol use problems predicted greater adolescent RTP over and above adolescent substance use. Together, these findings suggest that RTP may be a familial vulnerability factor for alcohol use as it aggregates within families and is increased in relatives of individuals with higher levels of alcohol use.

Blunted neural response to rewards as a vulnerability factor for depression: Results from a family study

Depressive disorders are associated with significant economic and public health burdens as well as increased morbidity. Yet, perhaps due to the heterogeneous nature of the disease, prevention and intervention efforts are only moderately efficacious. A better understanding of core mechanisms of depressive disorders might aid in the development of more targeted intervention, and perhaps help identify individuals at risk. One mechanism that may be particularly important to depressive phenotypes is reward insensitivity. Examination of neurobiological correlates of reward-processing, which should relate more directly to the neuropathology of depression, may be helpful in identifying liability for the disorder. To that end, we used a family study design to examine whether a neural response to rewards is a familial risk factor for depression in a sample of probands with a wide range of internalizing psychopathology, as well as their biological siblings. Event-related potentials were recorded during a simple forced-choice gambling paradigm, in which participants could either win or lose small amounts of money. Lower levels of positive affect in probands predicted a reduced neural response to rewards in siblings, even over and above the sibling's own level of positive and negative affect. Additionally, the neural response to rewards was familial (i.e., correlated among siblings). Combined, these analyses suggest that a blunted neural response to rewards may be useful in identifying individuals vulnerable to depressive illnesses.

Cognitive flexibility mediates the relation between intolerance of uncertainty and safety signal responding in those with panic disorder

There is a growing literature associating anxiety disorders with an inability to inhibit defensive responding during safety conditions of threatening tasks. However, investigations on the relation between panic disorder (PD) and defensive responding to safety have yielded mixed results. A recent study from our laboratory revealed that intolerance of uncertainty (IU) moderates this association, such that only individuals with PD and a high IU exhibit heightened startle potentiation during safety. The mechanism underlying this relationship is unknown. Given that safety conditions typically alternate with periods of threat, cognitive flexibility (i.e., the ability to adjust one's habitual responding to a situation, given the input of new information) may be involved in the ongoing reappraisal of danger and adjustment of defensive responding. Thus, the present study sought to investigate whether deficits in cognitive flexibility mediate the association between IU and defensive responding to safety among a sample of 71 adults diagnosed with PD. As hypothesised, cognitive flexibility mediated the relationship between IU and heightened startle potentiation during safety conditions. This finding suggests that within this subgroup, a failure to inhibit defensive responding during safety conditions may be due to deficits in cognitive flexibility.

Anxiety sensitivity and the anticipation of predictable and unpredictable threat: Evidence from the startle response and event-related potentials

There is growing evidence that heightened sensitivity to unpredictable threat is a core mechanism of dysfunction in anxiety disorders. However, it is unclear whether anxiety sensitivity is also associated with sensitivity to unpredictable threat. In the present study, 131 participants completed the Anxiety Sensitivity Index-3, which includes physical concerns (PC), social concerns (SC), and cognitive concerns (CC) subscales, and a predictable vs. unpredictable threat-of-shock task. Startle eyeblink and ERP responses (N100, P300) to the acoustic startle probes were measured during the task. PC and CC were associated with heightened and attenuated, respectively, startle for the unpredictable (but not predictable) condition. CC were also associated with attenuated probe N100 for the unpredictable condition only, and PC were associated with increased P300 suppression across the predictable and unpredictable conditions. This study provides novel evidence that the different anxiety sensitivity dimensions demonstrate unique relationships with the RDoC domains "acute" and "potential" threat.

Visuospatial and mathematical dysfunction in major depressive disorder and/or panic disorder: A study of parietal functioning

The parietal cortex is critical for several different cognitive functions, including visuospatial processing and mathematical abilities. There is strong evidence indicating parietal dysfunction in depression. However, it is less clear whether anxiety is associated with parietal dysfunction and whether comorbid depression and anxiety are associated with greater impairment. The present study compared participants with major depression (MDD), panic disorder (PD), comorbid MDD/PD and controls on neuropsychological measures of visuospatial processing, Judgement of Line Orientation (JLO), and mathematical abilities, Wide Range Achievement Test (WRAT) Arithmetic. Only comorbid MDD/PD was associated with decreased performance on JLO, whereas all psychopathological groups exhibited comparably decreased performance on WRAT Arithmetic. Furthermore, the results were not accounted for by other comorbid disorders, medication use or psychopathology severity. The present study suggests comorbid depression and anxious arousal are associated with impairment in visuospatial processing and provides novel evidence indicating mathematical deficits across depression and/or anxiety. Implications for understanding parietal dysfunction in internalising psychopathology are discussed.

Event-related potentials to acoustic startle probes during the anticipation of predictable and unpredictable threat

The startle reflex is a robust measure of defense system activation. Startle probes also elicit ERP P300 and N100 responses that capture attentional engagement. The startle probe-elicited P300 and N100 have been primarily examined during affective picture viewing paradigms, and no study has examined these measures in the context of a threat anticipation task or in relation to threat predictability. In the present study, 131 participants completed a no (N), predictable (P), and unpredictable (U) threat-of-shock task, and the startle eye blink reflex, P300, and N100 responses to the startle probe were measured. We also examined several psychometric properties of these psychophysiological measures. Results indicated probe P300 attenuation during the P and U relative to N condition. In contrast, probe N100 enhancement was present only for the U condition. The P300 and N100 decreased (i.e., habituated) at comparable rates across the different threat conditions. The startle reflex also decreased, but only startle during the U (and not P) condition continued to differ from the N condition by the end of the task. Internal consistency of the ERP measures was acceptable and comparable to the startle reflex. Finally, the startle reflex was correlated with the probe N100, but not P300, across threat conditions. This study is one of the first to use startle probe ERPs to demonstrate that a context of potential threat also elicits attentional engagement. Furthermore, this study provides novel evidence that the probe N100 may provide a measure that is uniquely sensitive to unpredictable threat.

Resting state amygdala-prefrontal connectivity predicts symptom change after cognitive behavioral therapy in generalized social anxiety disorder

BACKGROUND

Aberrant amygdala-prefrontal interactions at rest and during emotion processing are implicated in the pathophysiology of generalized social anxiety disorder (gSAD), a common disorder characterized by fears of potential scrutiny. Cognitive behavioral therapy (CBT) is first-line psychotherapy for gSAD and other anxiety disorders. While CBT is generally effective, there is a great deal of heterogeneity in treatment response. To date, predictors of success in CBT for gSAD include reduced amygdala reactivity and increased activity in prefrontal regulatory regions (e.g., anterior cingulate cortex, "ACC") during emotion processing. However, studies have not examined whether tonic (i.e., at rest) coupling of amygdala and these prefrontal regions also predict response to CBT.

RESULTS

Twenty-one patients with gSAD participated in resting-state functional magnetic resonance imaging (fMRI) before 12 weeks of CBT. Overall, symptom severity was significantly reduced after completing CBT; however, the patients varied considerably in degree of symptom change. Whole-brain voxel-wise findings showed symptom improvement after CBT was predicted by greater right amygdala-pregenual ACC ("pgACC") connectivity and greater left amygdala-pgACC coupling encompassing medial prefrontal cortex. In support of their predictive value, area under receiver operating characteristic curve was significant for the left and right amygdala-pgACC in relation to treatment responders.

CONCLUSIONS

Improvement after CBT was predicted by enhanced resting-state bilateral amygdala-prefrontal coupling in gSAD. Preliminary results suggest baseline individual differences in a fundamental circuitry that may underlie emotion regulation contributed to variation in symptom change after CBT. Findings offer a new approach towards using a biological measure to foretell who will most likely benefit from CBT. In particular, the departure from neural predictors based on illness-relevant stimuli (e.g., socio-emotional stimuli in gSAD) permits the development of biomarkers that reflect commonalities in the neurobiology of anxiety and mood disorders.

Prefrontal engagement by cognitive reappraisal of negative faces

Cognitive reappraisal has been associated with increased activation in prefrontal cortex (PFC) and cingulate regions implicated in cognitive control and affect regulation. To date, neuroimaging studies of reappraisal have primarily used emotionally evocative scenes, and it remains unclear whether the same cognitive strategy applied to emotional facial expressions would involve similar or different neural underpinnings. The present study used fMRI to examine brain activation during cognitive reappraisal of negatively valenced facial expressions relative to passive viewing of negative and neutral facial expressions. Twenty-two healthy adults completed a cognitive reappraisal task comprised of three different conditions (Look-Neutral, Maintain-Negative, Reappraise-Negative). Results indicated that reappraisal was associated with a decrease in negative affect and engagement of PFC brain regions implicated in cognitive control and affect regulation (DLPFC, mPFC, and VLPFC). Furthermore, individual differences in habitual reappraisal use were associated with greater DLPFC and mPFC activation, while suppression use was associated with greater amygdala activation. The present study provides preliminary evidence that facial expressions are effective alternative 'targets' of prefrontal engagement during cognitive reappraisal. These findings are particularly relevant for future research probing the neural bases of emotion regulation in populations for whom aversive scenes may be less appropriate (e.g., children) and illnesses in which aberrant responses to social signals of threat and negative feedback are cardinal phenotypes.

Insula response to unpredictable and predictable aversiveness in individuals with panic disorder and comorbid depression

Background

Prior studies suggest that hyperactive insula responding to unpredictable aversiveness is a core feature of anxiety disorders. However, no study to date has investigated the neural correlates of unpredictable aversiveness in those with panic disorder (PD) with comorbid major depressive disorder (MDD). The aim of the current study was to examine group differences in neural responses to unpredictable and predictable aversiveness in 41 adults with either 1) current PD with comorbid MDD (PD-MDD), 2) current MDD with no lifetime diagnosis of an anxiety disorder (MDD-only), or 3) no lifetime diagnosis of psychopathology. All participants completed a functional magnetic resonance imaging (fMRI) scan while viewing temporally predictable or unpredictable negative or neutral images.

Findings

The results indicated that individuals with PD-MDD exhibited greater bilateral insula activation to unpredictable aversiveness compared with controls and individuals with MDD-only (who did not differ). There were no group differences in insula activation to predictable aversiveness.

Conclusions

These findings add to a growing literature highlighting the role of the insula in the pathophysiology of anxiety disorders.

Aversive responding to safety signals in panic disorder: the moderating role of intolerance of uncertainty

An inability to inhibit aversive responding during conditions that signal safety may be a core dysfunction associated with anxiety disorders. However, there has been inconsistent evidence as to whether individuals with panic disorder (PD) exhibit aversive responding during safety signals. It is therefore possible that only certain subgroups of PD patients, particularly those with high levels of intolerance of uncertainty (IU), evidence this type of abnormal responding. The aim of the current study was to examine whether IU moderates the association between PD and startle potentiation during (a) safety and (b) threat periods during a threat-of-shock task. Participants included 172 adults, 74 of which had current diagnoses of PD. Results indicated that at high levels of IU, PD was associated with greater startle potentiation during safety. At low levels of IU, PD was not associated with startle potentiation during safety. IU did not moderate the effect of PD on threat responding. These results suggest that PD patients with high levels of IU fail to inhibit aversive responding during safety, possibly due to a tendency to interpret distal threat as distressing.

The mediating effect of prefrontal asymmetry on the relationship between the COMT Val(158)Met SNP and trait consummatory positive affect

The Val(158)Met rs4680 polymorphism in the COMT gene regulates dopamine catabolism in the prefrontal cortex (PFC). Dopamine's involvement in reward experience suggests those with the methionine (Met) variant may exhibit trait-level sensitivity to reward due to more post-synaptic dopamine in the PFC. A physiological mediator of this association may be greater relative left asymmetry in the PFC, a putative biomarker for trait positive emotionality. Electroencephalograms of 120 participants were measured during a task that assesses two aspects of reward processing: pre-reward anticipation and post-reward consummatory affect. Participants provided genetics samples and completed the Temporal Experience of Pleasure Scale (TEPS), which assesses trait-level anticipatory and consummatory positive affect. Met carriers had higher TEPS-Consummatory scores. This effect was mediated by greater relative left activation in the post-reward phase of the task. No effects were observed for the pre-reward phase. Results suggest that frontal asymmetry is an endophenotype between COMT genotype and trait reward responsivity.

Biomarkers of threat and reward sensitivity demonstrate unique associations with risk for psychopathology

Two emotional/motivational constructs that have been posited to underlie anxiety and depressive disorders are heightened sensitivity to threat and reduced sensitivity to reward, respectively. It is unclear, though, whether these constructs are only epiphenomena or also connote risk for these disorders (and relatedly, whether they connote risk for separate disorders). Using family history of psychopathology as an indicator of risk, the present study examined whether biomarkers of sensitivity to threat (startle potentiation) and reward (frontal EEG asymmetry) were associated with similar or different familial liabilities. In addition, the present study examined whether these biomarkers were associated with risk independent of proband DSM-IV diagnosis. One-hundred and seventy-three individuals diagnosed with panic disorder (PD), early onset major depressive disorder (MDD), both (comorbids), or controls completed two laboratory paradigms assessing sensitivity to predictable/unpredictable threat (measured via startle response) and reward (measured via frontal EEG asymmetry during a gambling task). Results indicated that across all participants: (a) startle potentiation to unpredictable threat was associated with family history of PD (but not MDD); and (b) frontal EEG asymmetry while anticipating reward was associated with family history of MDD (but not PD). Additionally, both measures continued to be associated with family history of psychopathology after controlling for proband DSM-IV diagnosis. Results suggest that the proposed biomarkers of sensitivity to unpredictable threat and reward exhibit discriminant validity and may add to the predictive validity of the DSM-IV defined constructs of PD and MDD, respectively.

Asians demonstrate reduced sensitivity to unpredictable threat: a preliminary startle investigation using genetic ancestry in a multiethnic sample

Research has indicated that individuals of Asian descent, relative to other racial groups, demonstrate reduced emotional responding and lower prevalence rates of several anxiety disorders. It is unclear though whether these group differences extend to biomarkers of anxiety disorders and whether genetic differences play a role. This study compared self-identified Caucasian, Latino, and Asian persons (total N = 174) on startle response during a baseline period and while anticipating unpredictable threat-a putative biomarker for certain anxiety disorders--as well as predictable threat. In addition, the association between genetic ancestry and startle response was examined within each racial group to determine potential genetic influences on responding. For the baseline period, Asian participants exhibited a smaller startle response relative to Caucasian and Latino participants, who did not differ. Within each racial group, genetic ancestry was associated with baseline startle. Furthermore, genetic ancestry mediated racial group differences in baseline startle. For the threat conditions, a Race × Condition interaction indicated that Asian participants exhibited reduced startle potentiation to unpredictable, but not predicable, threat relative to Caucasian and Latino participants, who did not differ. However, genetic ancestry was not associated with threat-potentiated startle in any racial group. This study adds to the growing literature on racial differences in emotional responding and provides preliminary evidence suggesting that genetic ancestry may play an important role. Moreover, reduced sensitivity to unpredictable threat may reflect a mechanism for why individuals of Asian descent are at less risk for particular anxiety disorders relative to other racial groups.

Intolerance of uncertainty mediates reduced reward anticipation in major depressive disorder

BACKGROUND

Reduced reward sensitivity has long been considered a fundamental deficit of major depressive disorder (MDD). One way this deficit has been measured is by an asymmetry in electroencephalogram (EEG) activity between left and right frontal brain regions. MDD has been associated with a reduced frontal EEG asymmetry (i.e., decreased left relative to right) while anticipating reward. However, the mechanism (or mediator) of this association is unclear. The present study examined whether intolerance of uncertainty (IU) mediated the association between depression and reduced reward anticipation.

METHODS

Data were obtained from a prior study reporting reduced frontal EEG asymmetry while anticipating reward in early-onset MDD. Participants included 156 individuals with early-onset MDD-only, panic disorder-only, both (comorbids), or controls. Frontal EEG asymmetry was recorded during an uncertain reward anticipation task. Participants completed a self-report measure of IU.

RESULTS

All three psychopathology groups reported greater IU relative to controls. Across all participants, greater IU was associated with a reduced frontal EEG asymmetry. Furthermore, IU mediated the relationship between MDD and frontal EEG asymmetry and results remained significant after controlling for neuroticism, suggesting effects were not due to broad negative affectivity.

LIMITATIONS

MDD participants were limited to those with early-onset depression. Measures were collected cross-sectionally, precluding causal relationships.

CONCLUSIONS

IU mediated the relationship between MDD and reduced reward anticipation, independent of neuroticism. Explanations are provided regarding how IU may contribute to reduced reward anticipation in depression. Overall, IU appears to be an important mechanism for the association between depression and reduced reward anticipation.

Are individual differences in appetitive and defensive motivation related? A psychophysiological examination in two samples

Appetitive and defensive motivation account for a good deal of variance in personality and mental health, but whether individual differences in these systems are correlated or orthogonal has not been conclusively established. Previous investigations have generally relied on self-report and have yielded conflicting results. We therefore assessed the relation between psychophysiological indices of appetitive and defensive motivation during elicitation of these motivational states: specifically, frontal electroencephalogram asymmetry during reward anticipation and startle response during anticipation of predictable or unpredictable threat of shock. Results in a sample of psychopathology-free community members (n=63), an independent sample of undergraduates with a range of internalising symptoms (n=64), and the combination of these samples (n=127) revealed that differences in responding to the two tasks were not significantly correlated. Average coefficients approached zero in all three samples (community: .04, undergraduate: -.01, combined: .06). Implications of these findings for research on normal and abnormal personality are discussed.

Startle response to unpredictable threat in comorbid panic disorder and alcohol dependence

BACKGROUND

Although the adverse consequences of comorbid panic disorder (PD) and alcohol dependence (AD) are well-established, relatively little is known about the mechanisms underlying their co-occurrence. Several researchers have postulated that alcohol's ability to dampen response to unpredictable threat may be an important motivational factor in comorbid PD and AD. To date, no research has examined these processes using a clinical sample and it is unclear whether individuals with PD and AD evidence different reactivity to unpredictable threat relative to individuals with PD-only.

METHODS

The aim of the current study was to examine differences in aversive responding during predictable and unpredictable threat-of-shock in three groups of individuals with: (1) current PD and remitted AD (PD and AD), (2) current PD but no lifetime diagnosis of AD (PD-only), and (3) no lifetime diagnoses of PD or AD (controls). Aversive responding was assessed using a well-established electromyography (EMG) startle paradigm.

RESULTS

Results indicated that PD and AD individuals evidenced greater startle potentiation during unpredictable (but not predictable) threat relative to controls and PD-only individuals (who did not differ).

CONCLUSIONS

These findings suggest that heightened reactivity to unpredictable threat may be an important process in PD and AD comorbidity and a possible key motivational factor underlying engagement in alcohol use.

An empirical evaluation of recovery transformation at a large community psychiatric rehabilitation organization

In recent decades, the concept of "recovery" from Severe Mental Illness (SMI) has gained increased prominence among organizations providing behavioral health services. Many states and organizations are currently developing plans to transform their mental health systems in accordance with recovery-oriented care. Even though efforts to bring the principles of recovery to mental health agencies have been well documented in the United States and abroad, there is little empirical evidence to suggest that recovery-oriented services are advantageous. The purpose of this longitudinal study was to evaluate the effectiveness of a recovery-oriented transformation carried out by a large, private, not-for-profit psychiatric rehabilitation organization serving individuals with SMI. This transformation targeted the philosophy and specific procedures involved in the provision of care to residents within the organization. The outcome variables selected to evaluate the impact of the transformation were grouped into the following categories: (a) objective indicators of recovery, (b) self-report indicators of recovery, (c) indicators of staff competency, and (d) processes that promote recovery. Six-hundred and 27 residents and 490 staff participated in the evaluation. The findings suggest that recovery-oriented services had a positive impact on rates of overnight hospitalization, residents' ability to function in the community, some professional skills of employees, and working alliance between direct care providers and residents. This indicates that comprehensive and well-structured recovery-oriented care may offer a cost-efficient and effective alternative to the deficit approach to mental health care.

Does anxiety sensitivity correlate with startle habituation? An examination in two independent samples

Individuals with anxiety disorders have previously demonstrated abnormal habituation to aversiveness over time. As anxiety sensitivity (AS), or an individuals' propensity to fear of anxiety-related sensations, has been shown to be a risk factor for anxiety disorders (particularly panic disorder), the present study examined whether AS was also associated with abnormal habituation. This association was examined in two independent samples of undergraduates (Ntotal=178). Habituation was operationalised as the reduction in startle response to multiple startle probes presented over 2.5 minutes and three definitions of this reduction were employed. Results indicated that individuals with higher levels of AS evidenced deficits in startle habituation, but the strength of this relationship was somewhat dependent on the definition of startle habituation, with the most robust definition being an analysis of participants' individual slopes across all nine blinks. The present findings suggest that startle habituation is a key mechanism underlying AS, and may help elucidate the role this risk factor plays in the pathogenesis of anxiety disorders.

Association between respiratory sinus arrhythmia and reductions in startle responding in three independent samples

Evidence suggests that respiratory sinus arrhythmia (RSA) may be an important indicator of physiological flexibility. However, few studies have examined the relation between RSA and defensive habituation, a process contingent on physiological flexibility. In three independent samples, habituation was defined as the time course of 9 startle responses. In Sample one and two, startle was recorded (1) while shock electrodes were attached to participants' and (2) before a threat-of-shock task. In Sample three, startle was recorded without these two components. In the first two samples, startle magnitude significantly decreased over time but in Sample three, startle only decreased at a trend level. Further, low RSA was associated with less of a reduction in startle magnitude over time within the first two samples, but was unrelated to startle reduction in the third. This suggests that low RSA is associated with less habituation to contextual anxiety, which may reflect difficulties regulating anxiety.

The moderating effect of parental illicit substance use disorders on the relation between adolescent depression and subsequent illicit substance use disorders

BACKGROUND

Previous research has demonstrated that depression and family history of illicit substance use disorders (ISUDs) are risk factors for the development of ISUDs. However, no study to date has examined whether these risk factors interact to predict onset. In addition, history of parental and sibling ISUDs have been identified as risk factors almost exclusively in healthy individuals and thus, it is unknown whether they confer unique risk among adolescents with a history of depression.

METHODS

The current study examined these questions using data from the Oregon Adolescent Depression Project (OADP). DSM diagnoses of probands were assessed during 4-waves, first in adolescence (ages 14-18) and subsequently up until age 30. Lifetime DSM diagnoses of ISUDs in biological mothers, fathers, and siblings were obtained.

RESULTS

Proportional hazards model analyses indicated that there was a significant depression by parental ISUDs interaction. Among probands with parental ISUDs (and not among those without parental ISUDs), depression in adolescence was significantly associated with a shorter time to develop an ISUD. Sibling ISUDs were not associated with onset and did not interact with adolescent depression.

CONCLUSION

Prevention and intervention efforts targeted at this particularly at-risk group may be effective.

Dysfunctional attitudes as a moderator of pharmacotherapy and psychotherapy for chronic depression

OBJECTIVE

Individuals with chronic depression exhibit heterogeneous responses to treatment. Important individual differences may therefore exist within this particularly difficult to treat population that act as moderators of treatment response.

METHOD

The present study examined whether pretreatment levels of dysfunctional attitudes (DA) moderated treatment response in a large sample of chronically depressed individuals. Data were taken from the Research Evaluating the Value of Augmenting Medication with Psychotherapy (REVAMP) treatment study--a multi-site treatment and augmentation study of 808 chronically depressed individuals. REVAMP comprised two phases: 1) a 12-week open-label antidepressant trial and 2), a subsequent phase, in which phase 1 non-remitters (N = 491) were randomized to either receive an ongoing medication algorithm alone, medication plus cognitive behavioral analysis system of psychotherapy, or medication plus brief supportive psychotherapy.

RESULT

In phase 1, compared to the pharmacotherapy response of patients with lower DA scores, the response for patients with higher DA scores was steeper, but leveled off toward the end of the phase. In phase 2, DA predicted a differential response in the medication only arm, but not in the two psychotherapy + medication conditions. Specifically, in the phase 2 medication only condition, patients with higher DA improved while those with lower DA scores did not.

CONCLUSION

These results indicate that the relation between DA and treatment response in chronic depression is complex, but suggest that greater DA may be associated with a steeper reduction and/or better response to pharmacotherapy.

Relation between Respiratory Sinus Arrythymia and Startle Response during Predictable and Unpredictable Threat

Research suggests that lower respiratory sinus arrhythmia (RSA) is associated with greater aversive responding. One physiological indicator of aversive responding is startle potentiation. While a few studies have demonstrated an inverse association between RSA and startle potentiation, no study to date has distinguished whether this relation is similar for predictable versus unpredictable aversive stimuli. This is an important distinction, given that degree of predictability has been shown to be an important determinant of aversive responding. The present study examined whether resting RSA was associated with startle eye blink responding during predictable and unpredictable threat of electric shock. Resting RSA was collected during a 6-minute seated baseline phase at the beginning of the experimental session. Participants then completed a computerized startle task in which predictable and unpredictable shocks were administered. Results indicated that lower resting RSA was associated with greater startle potentiation during unpredictable threat, but not during predictable threat. These findings are consistent with a growing body of literature suggesting that individual differences in RSA are associated with aversive responding, and extend previous work by suggesting that RSA may be more robustly associated with a heightened sensitivity to unpredictable threat. This pattern of results may have implications for the understanding of pathological anxiety given that individuals with anxiety disorders typically exhibit low RSA and heightened responding during unpredictable threat.

A psychophysiological investigation of threat and reward sensitivity in individuals with panic disorder and/or major depressive disorder

Heightened sensitivity to threat and reduced sensitivity to reward are potential mechanisms of dysfunction in anxiety and depressive disorders, respectively. However, few studies have simultaneously examined whether these mechanisms are unique or common to these disorders. In this study, sensitivity to predictable and unpredictable threat (measured by startle response during threat anticipation) and sensitivity to reward (measured by frontal electroencephalographic [EEG] asymmetry during reward anticipation) were assessed in 4 groups (N = 191): those with (1) panic disorder (PD) without a lifetime history of depression, (2) major depression (MDD) without a lifetime history of an anxiety disorder, (3) comorbid PD and MDD, and (4) controls. General distress/negative temperament (NT) was also assessed via self-report. Results indicated that PD (with or without comorbid MDD) was uniquely associated with heightened startle to predictable and unpredictable threat, and MDD (with or without comorbid PD) was uniquely associated with reduced frontal EEG asymmetry. Both psychophysiological measures of threat and reward sensitivity were stable on retest approximately 9 days later in a subsample of participants. Whereas the comorbid group did not respond differently on the tasks relative to the PD-only and MDD-only groups, they did report greater NT than these 2 groups (which did not differ from each other). Results suggest that heightened sensitivity to threat and reduced sensitivity to reward may be specific components of PD and MDD, respectively. In addition, relative to noncomorbid depression and PD, comorbid MDD and PD may be characterized by heightened NT, but not abnormal levels of these "specific" components.

Lifetime rates of psychopathology in single versus multiple diagnostic assessments: comparison in a community sample of probands and siblings

Lifetime prevalence rates of psychopathology vary a great deal depending on whether they are estimated from cross-sectional or prospective longitudinal studies, with the former yielding significantly lower rates. Such findings, however, come from comparisons of separate studies from different countries and cohorts. Here, we compare lifetime rates of psychopathology between a community sample of individuals assessed on multiple occasions to their siblings who completed only a single diagnostic evaluation. Data come from the Oregon Adolescent Depression Project. We included 442 original participants who completed four prospective diagnostic assessments over the course of fifteen years, and 657 of their siblings who completed a single lifetime assessment. Comparisons of rates of depressive, bipolar, anxiety, and substance use disorders were made using survival analysis. We found that rates of depressive disorders, specifically major depressive disorder, were elevated among individuals who completed multiple diagnostic assessments relative to individuals who completed a single lifetime assessment. We did not find significant differences in rates of aggregate anxiety, bipolar, or substance use disorders. Within a single cohort, cross-sectional surveys appear to underestimate the lifetime rates of major depression relative to prospective, longitudinal designs. This suggests that disorders with an episodic course may be under-reported in cross-sectional surveys. Rates of anxiety, bipolar, and substance use disorders did not differ across assessment methods. To further evaluate method effects on lifetime estimates of psychopathology, future work may benefit from comparing rates of retrospectively- and prospectively-derived diagnoses in individuals who are repeatedly assessed over a lengthy follow-up period.

Parsing trait and state effects of depression severity on neurocognition: Evidence from a 26-year longitudinal study

Cognitive dysfunction in mood disorders falls along a continuum, such that more severe current depression is associated with greater cognitive impairment. It is not clear whether this association reflects transient state effects of current symptoms on cognitive performance, or persistent, trait-like differences in cognition that are related to overall disorder severity. We addressed this question in 42 unipolar and 47 bipolar participants drawn from a 26-year longitudinal study of psychopathology, using measures of attention/psychomotor processing speed, cognitive flexibility, verbal fluency, and verbal memory. We assessed (a) the extent to which current symptom severity and past average disorder severity predicted unique variance in cognitive performance; (b) whether cognitive performance covaried with within-individual changes in symptom severity; and (c) the stability of neurocognitive measures over six years. We also tested for differences among unipolar and bipolar groups and published norms. Past average depression severity predicted performance on attention/psychomotor processing speed in both groups, and in cognitive flexibility among unipolar participants, even after controlling for current symptom severity, which did not independently predict cognition. Within-participant state changes in depressive symptoms did not predict change in any cognitive domain. All domains were stable over the course of six years. Both groups showed generalized impairment relative to published norms, and bipolar participants performed more poorly than unipolar participants on attention/psychomotor processing speed. The results suggest a stable relationship between mood disorder severity and cognitive deficits.

The predictive power of depression screening procedures for veterans with coronary artery disease

Depression leads to a worse outcome for patients with coronary artery disease (CAD). Thus, accurately identifying depression in CAD patients is imperative. In many veterans affairs (VA) hospitals, patients are screened for depression once a year using the patient health questionnaire (PHQ-9). Although the PHQ-9 is generally considered a specific and sensitive measure of depression, there is reason to believe that these screening procedures may miss a large number of cases of depression within CAD patients and cardiology patients more generally. The goal of this study was to provide data as to the predictive power of this depression screening procedure by (a) comparing the prevalence rate of depression identified by the PHQ-9 to known prevalence rates and (b) examining whether patients identified as “depressed” also had conditions that consistently co-occur with depression (eg, post-traumatic stress disorder [PTSD], other medical issues). Participants were 813 consecutive patients who received an angiogram in the cardiac catheterization laboratory at a large VA Medical Center. Prevalence of depression was 6.9% in the overall sample and less than 6% when the sample was restricted to CAD patients with significant stenosis. Depression was significantly associated with PTSD, smoking, and alcohol problems. However, depression was not associated with other medical problems such as diabetes, renal failure, peripheral vascular disease, or anemia. In conclusion, the low prevalence rate of depression and lack of associations with comorbid medical problems may suggest that the VA’s depression screening procedures have low sensitivity for identifying depression in CAD patients. It is recommended that clinicians treating CAD regularly screen for depression and do not rely on archival depression screens.

Frontal brain asymmetry in depression with comorbid anxiety: a neuropsychological investigation

The approach-withdrawal model posits that depression and anxiety are associated with a relative right asymmetry in frontal brain activity. Most studies have tested this model using measures of cortical brain activity such as electroencephalography. However, neuropsychological tasks that differentially use left versus right frontal cortical regions can also be used to test hypotheses from the model. In two independent samples (Study 1 and 2), the present study investigated the performance of currently depressed individuals with or without a comorbid anxiety disorder and healthy controls on neuropsychological tasks tapping primarily left (verbal fluency) or right (design fluency) frontal brain regions. Across both samples, results indicated that comorbid participants performed more poorly than depressed only and control participants on design fluency, while all groups showed equivalent performance on verbal fluency. Moreover, comorbid participants showed "asymmetrical" performance on these two tasks (i.e., poorer design [right frontal] relative to verbal [left frontal] fluency), whereas depressed only and control participants showed approximately symmetrical profiles of performance. Results from these two samples suggest an abnormal frontal asymmetry in neurocognitive performance driven primarily by right frontal dysfunction among anxious-depressed individuals and highlight the importance of considering comorbid anxiety when examining frontal brain functioning in depression.

Does intolerance of uncertainty predict anticipatory startle responses to uncertain threat?

Intolerance of uncertainty (IU) has been proposed to be an important maintaining factor in several anxiety disorders, including generalized anxiety disorder, obsessive-compulsive disorder, and social phobia. While IU has been shown to predict subjective ratings and decision-making during uncertain/ambiguous situations, few studies have examined whether IU also predicts emotional responding to uncertain threat. The present study examined whether IU predicted aversive responding (startle and subjective ratings) during the anticipation of temporally uncertain shocks. Sixty-nine participants completed three experimental conditions during which they received: no shocks, temporally certain/predictable shocks, and temporally uncertain shocks. Results indicated that IU was negatively associated with startle during the uncertain threat condition in that those with higher IU had a smaller startle response. IU was also only related to startle during the uncertain (and not the certain/predictable) threat condition, suggesting that it was not predictive of general aversive responding, but specific to responses to uncertain aversiveness. Perceived control over anxiety-related events mediated the relation between IU and startle to uncertain threat, such that high IU led to lowered perceived control, which in turn led to a smaller startle response. We discuss several potential explanations for these findings, including the inhibitory qualities of IU. Overall, our results suggest that IU is associated with attenuated aversive responding to uncertain threat.

Defining reactivity: how several methodological decisions can affect conclusions about emotional reactivity in psychopathology

There are many important methodological decisions that need to be made when examining emotional reactivity in psychopathology. In the present study, we examined the effects of two such decisions in an investigation of emotional reactivity in depression: (1) which (if any) comparison condition to employ; and (2) how to define change. Depressed (N = 69) and control (N = 37) participants viewed emotion-inducing film clips while subjective and facial responses were measured. Emotional reactivity was defined using no comparison condition (i.e., raw scores), baseline comparison condition (i.e., no stimulus presented), and neutral comparison condition (i.e., neutral stimulus presented). Change in emotional reactivity was assessed using four analytic approaches: difference scores, percentage change, residualised change, and ANCOVA. Results differed among the three comparison conditions and among several of the analytic approaches. Overall, our investigation suggests that choosing a comparison condition and the definition of change can significantly influence the presence of group differences in emotional reactivity. Recommendations for studies of emotional reactivity in psychopathology are discussed.

Do positive and negative temperament traits interact in predicting risk for depression? A resting EEG study of 329 preschoolers

Researchers have long been interested in whether particular temperamental traits in childhood connote risk for depressive disorders. For example, children characterized as having high negative emotionality (NE; sadness, fear, anger) and low positive emotionality (PE; anhedonia, listlessness, and lack of enthusiasm) are hypothesized to be at risk for depression. Few studies, however, have examined whether (and how) these two temperamental dimensions interact to confer risk. In a sample of 329 preschoolers, the present study addressed this question by examining the relation between PE and NE and asymmetry in resting EEG activity in frontal and posterior regions, which are putative biomarkers for depression. Using a laboratory battery to define temperament, we found an interaction of PE and NE on posterior asymmetry. Specifically, when PE was high, NE was associated with greater relative right activity. When PE was low, NE was not related to posterior asymmetry. These results were driven by differences in EEG activity in right posterior regions, an area associated with emotional processing and arousal, and were specific to girls. We found no relation between temperament and frontal asymmetry. These findings suggest that, at least for girls, PE and NE may have an interactive effect on risk for depression.

The effect of pre- vs. post-reward attainment on EEG asymmetry in melancholic depression

Clinical investigators have long theorized about the role of reward processing and positive affect in depression. One theory posits that compared to nonmelancholic depressives, melancholic depressives experience less consummatory (i.e., post-reward), but comparably low anticipatory (prior to reward), positive affect. We tested whether frontal EEG asymmetry, a putative marker of the anticipatory reward system, is present only before an individual receives a reward or also after receiving a reward (i.e., during consummatory reward processing). We also examined whether melancholic depression, a condition characterized by a deficit in consummatory reward processing, is associated with abnormal EEG asymmetries in alpha band power. Effects in other frequency bands (delta, theta, or beta) were also explored. EEG was recorded in 34 controls, 48 nonmelancholic depressives, and 17 melancholic depressives during a slot machine task designed to elicit anticipatory and consummatory reward processing. Results indicated that, for alpha, the frontal EEG asymmetry of greater relative left activity was specific to anticipatory reward processing. During the consummatory phase, individuals with melancholic depression exhibited different posterior EEG asymmetries than individuals with nonmelancholic depression (and controls at a trend level). This second finding was largely due to melancholics exhibiting relatively lower right posterior activity and nonmelancholics exhibiting relatively lower left activity. These results suggest that a posterior asymmetry may be a marker for melancholic depression and aberrant consummatory reward processing.

Effect of acute tryptophan depletion on emotions in individuals with personal and family history of depression following a mood induction

BACKGROUND

Acute tryptophan depletion (ATD) has shown depletion-specific increases in depressed mood and overall depressive symptoms, especially in those with a family history and in remitted patients. However, its effect on a broad range of emotions beyond depressed mood has been inconsistent, and studies have rarely employed a negative mood induction.

METHOD

The present double-blind study administered tryptophan-depleted and taste-matched placebo challenge drinks to individuals with a past diagnosis and family history of depression (i.e. depression-vulnerable subjects) and controls in order to investigate the effect of ATD on positive affect, anxiety, anger and depressed mood following a negative mood induction.

RESULTS

Certain aspects of positive affect decreased due to ATD in the depression vulnerables but not in the controls. No differential effects were found on depressed mood and anxiety.

CONCLUSIONS

A stress-induced blunted hedonic capacity may increase vulnerability to ATD and may be a core emotional abnormality in depression. Additionally, serotonin may have a stronger influence on positive affect than on other depression-related emotions during periods of stress.

Does physical anhedonia play a role in depression? A 20-year longitudinal study

BACKGROUND

Anhedonia towards physical or sensory experiences (i.e., physical anhedonia) has most often been examined as a differentia of schizophrenia and not depression, despite the fact that general anhedonia is a core feature of many models of Major Depressive Disorder (MDD).

METHODS

Forty-nine participants with non-psychotic MDD were recruited from inpatient settings and followed-up six times over 20 years. The three aims of the study was to assess a) the stability of physical anhedonia over time, b) whether physical anhedonia relates to the course of depressive symptoms over time, and c) whether physical anhedonia relates to three domains of functioning - work, social functioning, or re-hospitalizations.

RESULTS

We found that over time physical anhedonia was relatively stable and related to depressive symptoms (both between and within person). Physical anhedonia was also related to certain aspects of functioning, though less robustly than depressive symptoms.

LIMITATIONS

Because depressive symptoms, functioning, and physical anhedonia were measured concurrently at each follow-up, the direction of causality among these variables could not be assessed. Additionally, because our sample was recruited from inpatient settings, our findings may not generalize to individuals with less severe depression.

CONCLUSIONS

A trait tendency to experience decreased pleasure to positive physical stimuli is a clinically meaningful variable for those with MDD and may be a behavioral endophenotype for a more severe form of depression.

Subthreshold conditions as precursors for full syndrome disorders: a 15-year longitudinal study of multiple diagnostic classes

BACKGROUND

There has been increasing interest in the distinction between subthreshold and full syndrome disorders and specifically whether subthreshold conditions escalate or predict the onset of full syndrome disorders over time. Most of these studies, however, examined whether a single subthreshold condition escalates into the full syndrome form of that disorder. Equally important, though, is whether subthreshold conditions are likely to develop other full syndrome disorders and whether these associations are maintained after adjusting for comorbidity.

METHODS

A 15-year longitudinal study of subthreshold psychiatric conditions was conducted with 1,505 community-drawn young adults. We examined whether 1) subthreshold major depression, bipolar, anxiety disorders, alcohol use, substance use, conduct disorder and/or ADHD were precursors for the corresponding (homotypic) full syndrome disorder; 2) subthreshold conditions were precursors for other (heterotypic) full syndrome disorders; and 3) these homotypic and heterotypic precursors persisted after adjusting for comorbidity.

RESULTS

Subthreshold major depression, anxiety, alcohol use, substance use, and conduct all escalated into their corresponding full syndrome and nearly all homotypic developments were maintained after adjusting for comorbid subthreshold and full syndrome conditions. Many heterotypic associations were also observed and most remained after controlling for comorbidity, particularly among externalizing disorders (e.g., alcohol, substance, conduct/antisocial personality disorder).

CONCLUSIONS

Many subthreshold conditions have predictive validity as they may represent precursors for full syndrome disorders. Alternatively, dimensional conceptualizations of psychopathology which include these more minor conditions may yield greater validity. Subthreshold conditions may represent good targets for preventive interventions.

Independent associations between personality traits and clinical characteristics of depression

Few studies have examined age of onset and chronicity of depression in the same subject sample. The present study sought to determine whether personality traits related to early onset depression were different from those related to chronic depression. We tested the associations between personality self-reports and clinical characteristics of depression by conducting multiple and logistic regression analyses to determine whether personality uniquely predicted clinical characteristics and whether clinical characteristics uniquely predicted personality, after adjusting for depression severity. We also analyzed data at 6-month follow-up to determine whether age of onset and chronicity maintained their associations with personality. The study found that low levels of positive personality traits had unique associations with chronicity of depression, whereas elevated levels of negative personality traits had unique associations with an earlier onset of depression. Furthermore, associations were generally maintained over time, suggesting that associations between personality and these depression subtypes are stable.

Resting electroencephalogram asymmetry and posttraumatic stress disorder

The valence-arousal (W. Heller, 1993) and approach-withdrawal (R. J. Davidson, 1998a) models hypothesize that particular patterns of hemispheric brain activity are associated with specific motivational tendencies and psychopathologies. We tested several of these predictions in two groups-a posttraumatic stress disorder (PTSD) and a "supercontrol" group, selected to be maximally different from those with PTSD. Contrary to almost all hypotheses, individuals with PTSD did not differ from controls on resting electroencephalogram (EEG) asymmetry. Particular aspects of PTSD were also not related to EEG hemisphere differences. Our null findings are consistent with the few studies that have examined resting EEG asymmetries in PTSD and suggest that PTSD may be associated with different processes than psychopathologies previously examined in studies of hemispheric brain activity (e.g., major depressive disorder, panic disorder).

Dysthymic disorder and double depression: prediction of 10-year course trajectories and outcomes

We sought to identify baseline predictors of 10-year course trajectories and outcomes in patients with dysthymic disorder and double depression. Eighty-seven outpatients with early-onset (<21 years) dysthymic disorder, with or without superimposed major depression, were assessed five times at 30-month intervals for 10 years. Baseline evaluations included semi-structured diagnostic interviews for Axis I and II psychopathology and childhood adversity. Direct interview and family history data were collected on first-degree relatives. Follow-up assessments included the Longitudinal Follow-up Evaluation and Hamilton Depression Rating Scale. Using mixed effects growth curve models, univariate predictors of depression severity and functional impairment at 10-year outcome included older age, less education, concurrent anxiety disorder, greater familial loading for chronic depression, a history of a poorer maternal relationship in childhood, and a history of childhood sexual abuse. In addition, longer duration of dysthymic disorder also predicted greater impairment 10 years later. Predictors of a poorer trajectory of depressive symptoms over time included ethnicity and personality disorders; predictors of a poorer trajectory of social functioning included familial loading of chronic depression and quality of the childhood maternal relationship. Thus, demographic, clinical, family history, and early adversity variables all contribute to predicting the long-term trajectory and outcome of DD. These variables should be routinely assessed in clinical evaluations and can provide clinicians with valuable prognostic information.

Family study of subthreshold psychopathology in a community sample

BACKGROUND

There has been increasing interest in the validity and familial transmission of subthreshold psychiatric conditions and the relationship between subthreshold conditions and full syndrome (FS) disorders. However, most of these studies examined a single subthreshold condition and thus fail to take into account the high co-morbidity among subthreshold conditions and between subthreshold conditions and FS disorders.

METHOD

A family study of subthreshold psychiatric conditions was conducted with 739 community-drawn young adults and their 1744 relatives. We examined (1) whether relatives of probands with subthreshold major depression, bipolar disorder, anxiety disorders, alcohol use, substance use, and/or conduct disorder exhibited an increased rate of the corresponding (homotypic) FS disorder; (2) whether subthreshold disorders were associated with increased familial rates of other (heterotypic) FS disorders; (3) whether subthreshold and FS conditions are associated with similar familial liabilities; and (4) whether these homotypic and heterotypic associations persisted after controlling for co-morbidity.

RESULTS

Significant homotypic associations were observed for subthreshold anxiety, alcohol, conduct, and a trend was observed for major depression. Only the homotypic association for alcohol and conduct remained after controlling for co-morbid subthreshold and FS conditions. Many heterotypic associations were observed and most remained after controlling for co-morbidity.

CONCLUSIONS

It is important to broaden the study of subthreshold psychopathology to multiple disorders. In particular cases, controlling for co-morbidity with other subthreshold and FS conditions altered the patterns of familial aggregation. Etiological processes that are common to particular disorders and subthreshold conditions are discussed.

Hemispatial PCA dissociates temporal from parietal ERP generator patterns: CSD components in healthy adults and depressed patients during a dichotic oddball task

Event-related potentials (31-channel ERPs) were recorded from 38 depressed, unmedicated outpatients and 26 healthy adults (all right-handed) in tonal and phonetic oddball tasks developed to exploit the perceptual challenge of a dichotic stimulation. Tonal nontargets were pairs of complex tones (corresponding to musical notes G and B above middle C) presented simultaneously to each ear (L/R) in an alternating series (G/B or B/G; 2-s fixed SOA). A target tone (note A) replaced one of the pair on 20% of the trials (A/B, G/A, B/A, A/G). Phonetic nontargets were L/R pairs of syllables (/ba/, /da/) with a short voice onset time (VOT), and targets contained a syllable (/ta/) with a long VOT. Subjects responded with a left or right button press to targets (counterbalanced across blocks). Target detection was poorer in patients than controls and for tones than syllables. Reference-free current source densities (CSDs; spherical spline Laplacian) derived from ERP waveforms were simplified and measured using temporal, covariance-based PCA followed by unrestricted Varimax rotation. Target-related N2 sinks and mid-parietal P3 sources were represented by CSD factors peaking at 245 and 440 ms. The P3 source topography included a secondary, left-lateralized temporal lobe maximum for both targets and nontargets. However, a subsequent hemispheric spatiotemporal PCA disentangled temporal lobe N1 and P3 sources as distinct factors. P3 sources were reduced in patients compared with controls, even after using performance as a covariate. Results are consistent with prior reports of P3 reduction in depression and implicate distinct parietal and temporal generators of P3 when using a dichotic oddball paradigm.

Reward sensitivity in depression: A biobehavioral study

The approach-withdrawal model posits 2 neural systems of motivation and emotion and hypothesizes that these systems are responsible for individual differences in emotional reactivity, or affective styles. The model also proposes that depression is characterized by a deficit in reward-seeking behavior (i.e., approach motivation) and is associated with a relative decrease in left frontal brain activity. The authors tested aspects of this model by comparing the electroencephalogram alpha power of depressed and nondepressed individuals during a task that manipulated approach motivation. The study found that control participants and individuals with late-onset depression exhibited the hypothesized increase in left frontal activity during the approach task but individuals with early-onset depression did not. This suggests that early-onset depression may be associated with a deficit in the hypothesized approach motivation system.

Ten-year prospective follow-up study of the naturalistic course of dysthymic disorder and double depression

OBJECTIVE

The purpose of this study was to describe the 10-year course and outcome of dysthymic disorder.

METHOD

The authors conducted a naturalistic, prospective, longitudinal follow-up of 97 adults with early-onset dysthymic disorder and 45 adults with nonchronic major depressive disorder selected from consecutive admissions to several outpatient facilities. Follow-up data were obtained for 90% of the cohort. Assessments were conducted at baseline, 30, 60, 90, and 120 months. Measures included the Longitudinal Interval Follow-Up Evaluation and the Hamilton Depression Rating Scale.

RESULTS

The Kaplan-Meier estimated recovery rate from dysthymic disorder was 73.9%, with a median time to recovery of 52 months. Among patients who recovered, the estimated risk of relapse into another period of chronic depression was 71.4%. Chronic depressive relapses took a variety of forms and were not limited to dysthymia. Nonetheless, the distinction between chronic and nonchronic forms of depression was relatively stable over the follow-up period. Mixed-effects models indicated that patients with dysthymic disorder experienced a significantly slower rate of improvement in symptoms over time and exhibited significantly greater depression at the 10-year point, compared to patients with nonchronic major depression.

CONCLUSIONS

Dysthymic disorder has a protracted course and is associated with a high risk of relapse. The nature of chronic depressive episodes varies over time within individuals, indicating that the various manifestations of chronic depression in DSM-IV do not represent distinct disorders. However, the distinction between chronic and nonchronic forms of depression is relatively stable and may provide a useful basis for subtyping in genetic and neurobiological research.

Behavioral activation system deficits predict the six-month course of depression

BACKGROUND

Behavioral activation system (BAS) deficits are hypothesized to increase risk for depression. This study tested the hypothesis that BAS deficits, measured with both self-report and electrophysiological methods, would predict the six-month course of depression.

METHODS

67 participants with major depressive disorder (MDD) with or without pre-existing dysthymia were assessed at baseline with Carver and White's [Carver, C.S., White, T.L., 1994. Behavioral inhibition, behavioral activation, and affective responses to impending reward and punishment: the BIS/BAS scales. J. Pers. Soc. Psychol. 67, 319-333.] BIS/BAS scales and resting EEG. The week-by-week course of their depressive symptoms was assessed six months later with the Longitudinal Interval Follow-up Evaluation (LIFE).

RESULTS

Baseline self-reported BAS sensitivity predicted depression diagnosis (MDD or dysthymia) at follow-up, number of MDD symptoms at follow-up, average weekly level of depression, and time to recovery. These effects persisted after controlling for baseline clinical variables associated with a worse course. Baseline resting EEG alpha asymmetry did not significantly predict the course of depression.

LIMITATIONS

Although BAS sensitivity predicted the subsequent course of depression, we cannot determine whether it played a causal role in maintaining depression.

CONCLUSIONS

Lower self-reported BAS sensitivity predicts a worse course of depression but EEG asymmetries do not.

Low positive emotionality in young children: Association with EEG asymmetry

Low positive emotionality (PE; e.g., listlessness, anhedonia, and lack of enthusiasm) has been hypothesized to be a temperamental precursor or risk factor for depression. The present study sought to evaluate the validity of this hypothesis by testing whether low PE children have similar external correlates as individuals with depression. This paper focused on the external correlate of EEG asymmetry. Previous studies have reported that individuals at risk for depression exhibited a frontal EEG asymmetry (greater right than left activity). Others have reported an association with posterior asymmetries (greater left than right activity). In the present study, children classified as having low PE at age 3 exhibited an overall asymmetry at age 5-6 with less relative activity in the right hemisphere. This asymmetry appeared to be largely due to a difference in the posterior region because children with low PE exhibited decreased right posterior activity whereas high PE children exhibited no posterior asymmetry. These findings support the construct validity of the hypothesis that low PE may be a temperamental precursor or risk factor for depression.

The prevalence and co-morbidity of subthreshold psychiatric conditions

BACKGROUND

In previous studies of subthreshold conditions, co-morbidity has been largely ignored. The purpose was to examine rates of co-morbidity among subthreshold disorders and between subthreshold and full-syndrome disorders for the major non-psychotic classes of disorders from DSM-IV.

METHOD

Participants came from the Oregon Adolescent Depression Project (mean age=16.6 years; females=52.1%). On the basis of a diagnostic interview (K-SADS), participants were assigned to eight subthreshold disorders (MDD, bipolar, eating, anxiety, alcohol use, substance use, conduct, ADHD).

RESULTS

Of the 1704 adolescents in the analyses, 52.5% had at least one subthreshood disorder. Of those, 40.0% had also experienced a co-morbid subthreshold condition, and 29.9% of those had a second co-morbid subthreshold condition. Of those with a subthreshold, 36.4% also had a full syndrome. The subthreshold forms of externalizing disorders were co-morbid with each other. As expected, subthreshold anxiety was co-morbid with subthreshold MDD but subthreshold anxiety was also co-morbid with subthreshold alcohol, conduct, and ADHD. The pattern of co-morbidities was nearly identical for males and females.

CONCLUSIONS

The hypotheses that externalizing disorders would be co-morbid with other externalizing disorders and that internalizing disorders would be co-morbid with other internalizing disorders was partially supported. Co-morbidities between subthreshold disorders and between subthreshold disorders and full syndrome should impact future research and clinical practice. The assessment of subthreshold disorders needs to include the assessment of other subthreshold and full-syndrome conditions.

Family study of chronic depression in a community sample of young adults

OBJECTIVE

The validity of the distinctions between dysthymic disorder, chronic major depressive disorder, and episodic major depressive disorder was examined in a family study of a large community sample of young adults.

METHOD

First-degree relatives (N=2,615) of 30 probands with dysthymic disorder, 65 probands with chronic major depressive disorder, 313 probands with episodic major depressive disorder, and 392 probands with no history of mood disorder were assessed by using direct interviews and informant reports.

RESULTS

The rates of major depressive disorder were significantly greater among the relatives of probands with dysthymic disorder and chronic major depressive disorder than among the relatives of probands with episodic major depressive disorder, who in turn exhibited a higher rate of major depressive disorder than the relatives of probands with no history of mood disorder. The relatives of probands with dysthymic disorder had a significantly higher rate of dysthymic disorder than the relatives of probands with no history of mood disorder, and the relatives of probands with chronic major depressive disorder had a significantly higher rate of chronic major depressive disorder than the relatives of probands with no history of mood disorder. However, the relatives of the three groups of probands with depression did not differ on rates of dysthymic disorder and chronic major depressive disorder.

CONCLUSIONS

Chronic depression is distinguished from episodic depression by a more severe familial liability. This familial liability may contribute to the more pernicious course of chronic depression.