Impaired distractor inhibition on a selective attention task in unmedicated, depressed subjects

Subsyndromal depression leads to early under-activation and late over-activation during inhibitory control: an ERP study

Individuals with depressive disorders have deficits in inhibitory control and exhibit symptoms of impaired cognitive and emotional functioning. Individuals with subsyndromal depression are intermediate between the healthy group and clinically diagnosed patients with depressive disorders, and studying the characteristics of their inhibitory control functioning can help to investigate the mechanisms underlying the development of depressive disorders. Using two classical paradigms of inhibitory control, Flanker and Go/NoGo, the present study explored the differences in inhibitory control between individuals with subsyndromal depression and healthy individuals from the perspectives of both response inhibition and interference control. Behavioral results showed that both groups did not differ in response time and accuracy; in terms of event-related potentials, individuals with subsyndromal depression presented smaller N2 amplitudes as well as larger P3 amplitudes in the NoGo condition of the Go/NoGo paradigm; and smaller N2 amplitudes in the incongruent condition of the Flanker paradigm. Moreover, the depression-prone group showed lower theta power compared to the healthy group in the NoGo condition of the NoGo paradigm and the incongruent condition of the Flanker paradigm. The present study reveals that the depression-prone group may have a compensatory mechanism in the response inhibition, which is mainly manifested as early under-activation as well as late over-activation.

Less inhibited and more depressed? The puzzling association between mood, inhibitory control and depressive symptoms

BACKGROUND

Inhibitory control (IC) deficits have been proposed as a potential risk factor for depression. However, little is known about the intra-individual daily fluctuations in IC, and its relationship to mood and depressive symptoms. Here, we examined the everyday association between IC and mood, in typical adults with various levels of depressive symptoms.

METHODS

Participants (N = 106) reported their depressive symptoms and completed a Go-NoGo (GNG) task measuring IC at baseline. Then, they completed a 5-day ecological-momentary-assessment (EMA) protocol, in which they reported their current mood and performed a shortened GNG task twice/day using a mobile app. Depressive symptoms were measured again following the EMA. Hierarchical-linear-modeling (HLM) was applied to examine the association between momentary IC and mood, with post-EMA depressive symptoms as a moderator.

RESULTS

Individuals with elevated depressive symptoms demonstrated worse and more variable IC performance over the EMA. In addition, post-EMA depressive symptoms moderated the association between momentary IC and daily mood, such that reduced IC was associated with more negative mood only for those with lower, but not higher, symptoms.

LIMITATIONS

Future investigations should examine the validity of these outcomes in clinical samples, including patients with Major Depressive Disorder.

CONCLUSIONS

Variable, rather than mere reduced, IC, is related to depressive symptoms. Moreover, the role of IC in modulating mood may differ in non-depressed individuals and individuals with sub-clinical depression. These findings contribute to our understanding of IC and mood in real life and help account for some of the discrepant findings related to cognitive control models of depression.

The association between implicit and explicit affective inhibitory control, rumination and depressive symptoms

Inhibitory control underlies one's ability to maintain goal-directed behavior by inhibiting prepotent responses or ignoring irrelevant information. Recent models suggest that impaired inhibition of negative information may contribute to depressive symptoms, and that this association is mediated by rumination. However, the exact nature of this association, particularly in non-clinical samples, is unclear. The current study assessed the relationship between inhibitory control over emotional vs. non-emotional information, rumination and depressive symptoms. A non-clinical sample of 119 participants (mean age: 36.44 ± 11.74) with various levels of depressive symptoms completed three variations of a Go/No-Go task online; two of the task variations required either explicit or implicit processing of emotional expressions, and a third variation contained no emotional expressions (i.e., neutral condition). We found reductions in inhibitory control for participants reporting elevated symptoms of depression on all three task variations, relative to less depressed participants. However, for the task variation that required implicit emotion processing, depressive symptoms were associated with inhibitory deficits for sad and neutral, but not for happy expressions. An exploratory analysis showed that the relationship between inhibition and depressive symptoms occurs in part through trait rumination for all three tasks, regardless of emotional content. Collectively, these results indicate that elevated depressive symptoms are associated with both a general inhibitory control deficit, as well as affective interference from negative emotions, with implications for the assessment and treatment of mood disorders.

Attentional Control in Subclinical Anxiety and Depression: Depression Symptoms Are Associated With Deficits in Target Facilitation, Not Distractor Inhibition

Mood and anxiety disorders are associated with deficits in attentional control involving emotive and non-emotive stimuli. Current theories focus on impaired attentional inhibition of distracting stimuli in producing these deficits. However, standard attention tasks struggle to separate distractor inhibition from target facilitation. Here, we investigate whether distractor inhibition underlies these deficits using neutral stimuli in a behavioral task specifically designed to tease apart these two attentional processes. Healthy participants performed a four-location Posner cueing paradigm and completed self-report questionnaires measuring depressive symptoms and trait anxiety. Using regression analyses, we found no relationship between distractor inhibition and mood symptoms or trait anxiety. However, we find a relationship between target facilitation and depression. Specifically, higher depressive symptoms were associated with reduced target facilitation in a task-version in which the target location repeated over a block of trials. We suggest this may relate to findings previously linking depression with deficits in predictive coding in clinical populations.

Specific and non-specific match effects in negative priming

The negative priming effect occurs when withholding a response to a stimulus impairs generation of subsequent responding to a same or a related stimulus. Our goal was to use the negative priming procedure to obtain insights about the memory representations generated by ignoring vs. attending/responding to a prime stimulus. Across three experiments we observed that ignoring a prime stimulus tends to generate higher identity-independent, non-specific repetition effects, owing to an overlap in the coarse perceptual form of a prime distractor and a probe target. By contrast, attended repetition effects generate predominantly identity-specific sources of facilitation. We use these findings to advocate for using laboratory phenomena to illustrate general principles that can be of practical use to non-specialists. In the case of the negative priming procedure, we propose that the procedure provides a useful means for investigating attention/memory interactions, even if the specific cause (or causes) of negative priming effects remain unresolved.

Depressive Symptomatology and Priming Effects Among Younger and Older Adults

Background/Study Context: This study examined the potential impact of self-reported depressive symptoms on the age-related capacity for inhibition and suppression, utilizing a negative priming paradigm.

METHODS

One hundred eighty-five community-residing adults varying in age (98 younger adults, M_age = 22; 87 older adults, M_age = 69) completed a nonconscious priming task, the Geriatric Depression Scale (GDS), the White Bear Suppression Inventory (WBSI), the Depression Sensitivity Scale (DSS), a free thought suppression task, as well as several measures indexing overall cognitive ability and psychomotor speed. Hierarchical regressions investigated the interaction of depressive symptoms with age and its effect on both positive and negative priming performance, indexing both facilitation and inhibition effects, respectively.

RESULTS

Results support the hypothesis that noncognitive factors affect effortful performance among older adults, although this influence varied with the specific component of the GDS, i.e., Dysphoria, Social Withdrawal, and Cognitive Control, and with the measure of depressive symptoms, i.e., GDS versus DSS.

CONCLUSION

These data suggest that aging's impact on both facilitation and inhibition, e.g., positive and negative priming, are to an extent, a function of individual differences in depressive symptoms that interact with age in influencing the necessity to reallocate one's cognitive resources to deal with depressive thoughts and feelings.

Alterations in visual cortical activation and connectivity with prefrontal cortex during working memory updating in major depressive disorder

The present study examined the impacts of major depressive disorder (MDD) on visual and prefrontal cortical activity as well as their connectivity during visual working memory updating and related them to the core clinical features of the disorder. Impairment in working memory updating is typically associated with the retention of irrelevant negative information which can lead to persistent depressive mood and abnormal affect. However, performance deficits have been observed in MDD on tasks involving little or no demand on emotion processing, suggesting dysfunctions may also occur at the more basic level of information processing. Yet, it is unclear how various regions in the visual working memory circuit contribute to behavioral changes in MDD. We acquired functional magnetic resonance imaging data from 18 unmedicated participants with MDD and 21 age-matched healthy controls (CTL) while they performed a visual delayed recognition task with neutral faces and scenes as task stimuli. Selective working memory updating was manipulated by inserting a cue in the delay period to indicate which one or both of the two memorized stimuli (a face and a scene) would remain relevant for the recognition test. Our results revealed several key findings. Relative to the CTL group, the MDD group showed weaker postcue activations in visual association areas during selective maintenance of face and scene working memory. Across the MDD subjects, greater rumination and depressive symptoms were associated with more persistent activation and connectivity related to no-longer-relevant task information. Classification of postcue spatial activation patterns of the scene-related areas was also less consistent in the MDD subjects compared to the healthy controls. Such abnormalities appeared to result from a lack of updating effects in postcue functional connectivity between prefrontal and scene-related areas in the MDD group. In sum, disrupted working memory updating in MDD was revealed by alterations in activity patterns of the visual association areas, their connectivity with the prefrontal cortex, and their relationship with core clinical characteristics. These results highlight the role of information updating deficits in the cognitive control and symptomatology of depression.

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Unmedicated individuals with major depressive disorder showed several forms of deficits during visual working memory updating.

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Impaired visual working memory updating performance.

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Diminished category-specific response patterns in visual association areas, particularly those involved in scene processing.

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Loss of frontal functional connectivity with the scene-selective visual region during updating of scene information.

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Rumination is associated with heightened activity and functional connectivity for obsolete information in working memory.

A working memory training to decrease rumination in depressed and anxious individuals: a double-blind randomized controlled trial

BACKGROUND

Rumination is one of the hallmark characteristics of both anxiety disorders and depression, and has been linked to deficient executive functioning, particularly working memory (WM). Previous findings show that working memory capacity can be increased through training.

METHODS

The current study explored whether an adaptive stand-alone WM training could increase WMC and consequently reduce rumination, anxiety and depression by means of a double-blind randomized controlled trial in a sample of 98 patients with symptoms of anxiety and/or depression.

RESULTS

No positive effect of training on WMC was found. In addition, the results show that a WM training was not associated with a reduction of rumination, depression, nor anxiety.

LIMITATIONS

The high drop-out rate in both groups (20.11% from pre- to post-training) and the overrepresentation of men and use of anti-depressants in the placebo group might have influenced the results. Furthermore, expectations and perceptions about the training might have interacted with performance on WM tasks.

CONCLUSIONS

Overall, results show that a stand-alone WM training in patients with symptoms of anxiety and/or depression does not result in reduced rumination nor in reduced symptoms of depression and anxiety. We discuss potential explanations for these findings.

Neurocognitive functioning in bipolar depression: a component structure analysis

BACKGROUND

Previous studies of neurocognitive performance in bipolar disorder (BD) have focused predominantly on euthymia. In this study we aimed to compare the neurocognitive profile of BD patients when depressed with healthy controls and explore the component structure of neurocognitive processes in these populations.

METHOD

Cognitive tests of attention and executive function, immediate memory, verbal and visuospatial learning and memory and psychomotor speed were administered to 53 patients with a SCID-verified diagnosis of BD depression and 47 healthy controls. Test performance was assessed in terms of statistical significance, effect size and percentile standing. Principal component analysis (PCA) was used to explore underlying cognitive factor structure.

RESULTS

Multivariate analysis revealed an overall group effect, depressed BD patients performing significantly worse than controls. Patients performed significantly worse on 18/26 measures examined, with large effect sizes (d > 0.8) on tests of speed of processing, verbal learning and specific executive/working memory processes. Almost all tests produced at least one outcome measure on which ∼25-50% of the BD sample performed at more than 1 standard deviation (s.d.) below the control mean. Between 20% and 34% of patients performed at or below the fifth percentile of the control group in working memory, verbal learning and memory, and psychomotor/processing speed. PCA highlighted overall differences between groups, with fewer extracted components and less specificity in patients.

CONCLUSIONS

Overall, neurocognitive test performance is significantly reduced in BD patients when depressed. The use of different methods of analysing cognitive performance is highlighted, along with the relationship between processes, indicating important directions for future research.

Deficits in cue detection underlie event-based prospective memory impairment in major depression: an eye tracking study

This study examined the cue detection in the non-focal event-based prospective memory (PM) of individuals with and without a major depressive disorder using behavioural and eye tracking assessments. The participants were instructed to search on each trial for a different target stimulus that could be present or absent and to make prospective responses to the cue object. PM tasks included cue only and target plus cue, whereas ongoing tasks included target only and distracter only. The results showed that a) participants with depression performed more poorly than those without depression in PM; b) participants with depression showed more fixations and longer total and average fixation durations in both ongoing and PM conditions; c) participants with depression had lower scores on accuracy in target-plus-cue trials than in cue-only trials and had a higher gaze rate of targets on hits and misses in target-plus-cue trials than did those without depression. The results indicate that the state of depression may impair top-down cognitive control function, which in turn results in particular deficits in the engagement of monitoring for PM cues.

Don't be Too Strict with Yourself! Rigid Negative Self-Representation in Healthy Subjects Mimics the Neurocognitive Profile of Depression for Autobiographical Memory

Autobiographical memory (AM) comprises representation of both specific (episodic) and generic (semantic) personal information. Depression is characterized by a shift from episodic to semantic AM retrieval. According to theoretical models, this process ("overgeneralization"), would be linked to reduced executive resources. Moreover, "overgeneral" memories, accompanied by a negativity bias in depression, lead to a pervasive negative self-representation. As executive functions and AM specificity are also closely intricate among "non-clinical" populations, "overgeneral" memories could result in depressive emotional responses. Consequently, our hypothesis was that the neurocognitive profile of healthy subjects showing a rigid negative self-image would mimic that of patients. Executive functions and self-image were measured and brain activity was recorded, by means of fMRI, during episodic AMs retrieval in young healthy subjects. The results show an inverse correlation, that is, a more rigid and negative self-image produces lower performances in both executive and specific memories. Moreover, higher negative self-image is associated with decreased activity in the left ventro-lateral prefrontal and in the anterior cingulate cortex, repeatedly shown to exhibit altered functioning in depression. Activity in these regions, on the contrary, positively correlates with executive and memory performances, in line with their role in executive functions and AM retrieval. These findings suggest that rigid negative self-image could represent a marker or a vulnerability trait of depression by being linked to reduced executive function efficiency and episodic AM decline. These results are encouraging for psychotherapeutic approaches aimed at cognitive flexibility in depression and other psychiatric disorders.

Cognition and depression: current status and future directions

Cognitive theories of depression posit that people's thoughts, inferences, attitudes, and interpretations, and the way in which they attend to and recall information, can increase their risk for depression. Three mechanisms have been implicated in the relation between biased cognitive processing and the dysregulation of emotion in depression: inhibitory processes and deficits in working memory, ruminative responses to negative mood states and negative life events, and the inability to use positive and rewarding stimuli to regulate negative mood. In this review, we present a contemporary characterization of depressive cognition and discuss how different cognitive processes are related not only to each other, but also to emotion dysregulation, the hallmark feature of depression. We conclude that depression is characterized by increased elaboration of negative information, by difficulties disengaging from negative material, and by deficits in cognitive control when processing negative information. We discuss treatment implications of these conclusions and argue that the study of cognitive aspects of depression must be broadened by investigating neural and genetic factors that are related to cognitive dysfunction in this disorder. Such integrative investigations should help us gain a more comprehensive understanding of how cognitive and biological factors interact to affect the onset, maintenance, and course of depression.

Therapeutic horticulture in clinical depression: a prospective study of active components

AIM

This paper is a report of a study conducted to assess change in depression severity, perceived attentional capacity and rumination (brooding) in individuals with clinical depression during a therapeutic horticulture programme and to investigate if the changes were mediated by experiences of being away and fascination.

BACKGROUND

Individuals with clinical depression suffer from distortion of attention and rumination. Interventions can help to disrupt maladaptive rumination and promote restoration of depleted attentional capacity.

METHOD

A single-group study was conducted with a convenience sample of 28 people with clinical depression in 2009. Data were collected before, twice during, and immediately after a 12-week therapeutic horticulture programme, and at 3-month follow-up. Assessment instruments were the Beck Depression Inventory, Attentional Function Index, Brooding Scale, and Being Away and Fascination subscales from the Perceived Restorativeness Scale.

FINDINGS

Mean Beck Depression Inventory scores declined by 4.5 points during the intervention (F = 5.49, P = 0.002). The decline was clinically relevant for 50% of participants. Attentional Function Index scores increased (F = 4.14, P = 0.009), while Brooding scores decreased (F = 4.51, P = 0.015). The changes in Beck Depression Inventory and Attentional Function Index scores were mediated by increases in Being Away and Fascination, and decline in Beck Depression Inventory scores was also mediated by decline in Brooding. Participants maintained their improvements in Beck Depression Inventory scores at 3-month follow-up.

CONCLUSION

Being away and fascination appear to work as active components in a therapeutic horticulture intervention for clinical depression.

To the influence of general slowing and medication on identity- and location-based priming effects in patients with Parkinson's disease

Previous studies on inhibitory mechanisms assessed by negative priming (NP) paradigms in patients suffering from Parkinson's disease (PD) have yielded highly ambiguous results. The present study examined two possible reasons for this heterogeneity: general slowing and anti-Parkinsonian medication. Their effects on identity and location NP and positive priming (PP) were investigated. Twenty medicated PD patients and 20 PD patients after drug withdrawal were compared to 20 sex- and age-matched healthy controls. The influence of PD patients' general slowing on priming effects was statistically controlled. Location NP was found not to be affected by PD, whereas identity NP was reduced in medicated PD patients compared to non-medicated PD patients and healthy controls. At first, identity and location PP appeared to be enhanced in both PD groups. After controlling for general slowing, however, differences between PD patients and healthy controls disappeared. These findings endorse the notion that uncontrolled effects of both, PD-related general slowing and anti-Parkinsonian medication may have contributed to previously conflicting results on priming effects in PD patients.

Selective attention biases of people with depression: positive and negative priming of depression-related information

Selective attention biases are believed to be one of the cognitive vulnerabilities to depression. This study examined two types of attention biases, namely attention facilitation and attention disinhibition, towards mood-congruent words in 40 clinically depressed outpatients and 40 never-depressed healthy controls. Measures were differential reaction time towards neutral and depressive words in the positive and negative priming paradigms that were used to assess attention facilitation and attention disinhibition, respectively. Results showed that the depressed group exhibited enhanced attention facilitation to depressive words relative to neutral words, whereas the control group did not. The differential reduction of reaction time of the depressed group to the previously presented depressive words relative to the previously presented neutral words was greater than that in the control group. On the other hand, both groups showed similar attention disinhibition to depressive words relative to neutral words. The differential increase in reaction time to previously ignored depressive words relative to the previously ignored neutral words was similar in both groups. The above results suggest that major depressive disorder is characterized by attention facilitation by mood-congruent information, but inhibition difficulties in attention to depression-related information is not specific to depressive disorder.

Neurophysiological evidence of cognitive inhibition anomalies in persons with major depressive disorder

OBJECTIVE

The neural correlates of inhibitory deficits for emotional semantic material in persons with major depressive disorder (MDD) were investigated.

METHODS

Individuals (n=15) with a diagnosis of MDD or MDD in partial remission, and healthy controls (n=14) underwent recording of event-related brain potentials (ERPs) while performing a computerized emotional Stroop task.

RESULTS

There were no group performance differences on the emotional Stroop task. However, the analysis of ERP waveforms revealed a larger negative wave peaking at about 170ms over the left than the right hemisphere only in controls; a negative displacement (N450) at parietal sites for positive and negative words only for persons with MDD; in both groups, processing negative and positive words was associated with a positive displacement that peaked at about 450ms and was larger over the left lateral frontal region; and, the N450 modulation correlated with negative automatic thinking and depressive symptoms.

CONCLUSIONS

The electrophysiological data reveal early changes in neural activity associated with word processing as well as valence-related changes in the N450 component at parietal sites in MDD.

SIGNIFICANCE

This valence-related increase in N450 amplitude at parietal sites may reflect an automatic capture of attention by words with emotional valence.

Unimpaired negative but enhanced positive priming in Parkinson's disease: Evidence from an identity and a location priming task

Mechanisms of selective attention are frequently reported to be impaired in Parkinson's disease (PD). Fundamental to selective attention is attending to relevant information and, concurrently, ignoring irrelevant information. Both processes can be assessed by positive priming (PP) and negative priming (NP) tasks, respectively. Unlike previous studies, in the present experiment, two separate identity- and location-based priming tasks were applied to 48 PD patients and 48 sex- and age-matched healthy controls. Results indicated that identity and location PP were reliably enhanced in PD patients compared to controls. Both groups showed significant location NP of almost identical magnitude but no identity NP. However, there was evidence for a positive functional relationship between severity of bradykinesia and identity NP. Furthermore, with increasing depression scores, location NP was enhanced in PD patients but not in controls. These findings suggest that disturbed selective attention associated with PD is due to changed mechanisms mediating attention to relevant information rather than due to mechanisms involved in inhibition of irrelevant information.

The effect of emotional context on cognitive inhibition and attentional processing in dissociative identity disorder

In light of previous research, the current study tested the hypothesis that dissociative identity disorder (DID) would be characterised by effective cognitive inhibitory functioning when tested in a neutral context, but weakened inhibition when tested in an emotionally negative context. Using a negative priming task (i.e. the flanker task) to assess inhibitory ability 11 DID, 11 depressed, and 11 general population participants were tested in the two differing experimental contexts. The contexts were manipulated by instructions and word stimuli, and following the completion of this task participants completed the Dissociative Experiences Scale and the Schizotypal Personality Scale. DID participants displayed a greater degree of self-reported anxiety in the negative context and as expected displayed a reduction in inhibition in this context but not in the neutral context. The degree of negative priming for the depressed and general population samples remained stable across contexts as did their anxiety levels. The DID sample displayed slower response times to negative compared to neutral words but this attentional bias was not evident for the two comparison groups. The relationship between increased arousal, inhibitory functioning, dissociation and information processing in DID is discussed.

Memory and attention in Obsessive-Compulsive Disorder: a review

The present manuscript reviewed studies investigating biases and deficits in memory and attention related to Obsessive-Compulsive Disorder (OCD). Although the research has been mixed concerning memory for verbal information, there is more consistent evidence suggesting impairment for non-verbal information, particularly for complex visual stimuli and the individual's own actions. Further, a number of studies indicate that patients with OCD report less confidence in their judgments about recognition memory. Finally, OCD appears to be associated with an attentional bias favoring threatening information, as well as reduced levels of cognitive inhibition. The manuscript concludes with a number of recommendations for future research.

Executive functions and updating of the contents of working memory in unipolar depression

BACKGROUND

Depression is characterized by cognitive impairments, including executive dysfunctions. These executive deficits could reflect impairments of more basic executive processes, such as updating, set shifting and inhibition. While shifting and inhibition impairments are often reported, studies on depression have been somewhat obscure about specific deficits of the updating process. The main goal of that study was to assess the updating process in young in-patients with depression.

METHODS

We used a verbal n-back task to assess updating process. Load and mental manipulation within working memory (WM) were incremented by using three different levels of complexity (1,2,3-back). Neuropsychological tests and an attentional task (0-back) were also administered to subjects. Twenty-two individuals meeting DSM-IV criteria for Major Unipolar Depression and 22 healthy control subjects, matched on age, verbal IQ and education, were included in the study.

RESULTS

Subjects with depression showed significant deficits at the n-back task compared to control subjects. They were normal in tasks assessing the short-term maintenance in WM and attention. This suggests that depressed patients exhibit impairment in the updating process. Depressed patients also showed set shifting and inhibition deficits. Only the n-back task was correlated with the number of hospitalizations and the longitudinal course of the illness.

CONCLUSIONS

Our results suggest that young depressed in-patients have widespread executive dysfunctions, including updating, shifting and inhibition processes. We also found a correlation between a longitudinal measure of depression severity and an updating task performance. We suggest that using multiple executive tasks gives the opportunity to distinguish the specific influence of various executive processes on clinical dimensions in depression.

Motivation to serve in the military influences vulnerability to future posttraumatic stress disorder

High motivation and belief in a cause have been reported to be protective against posttraumatic stress disorder (PTSD), while below-average intellectual functioning and poor educational achievements have been reported to increase vulnerability to PTSD. The main goal of this study was to assess the effect of education, and intellectual and behavioral functioning on the risk for future PTSD. Data collected before exposure to trauma, on intellectual and behavioral functioning, and educational achievements of 901 male Israeli adolescents who had performed pre-induction screening tests by the Israeli Draft Board, and were later diagnosed with PTSD, were compared with a control group of adolescents who were not later diagnosed with PTSD. Future PTSD patients had significantly lower intelligence, fewer years of formal education and lower scores on a scale assessing motivation to serve in the military, in comparison with the control group, with effect sizes (ES) ranging from 0.14-0.34. In contrast, future PTSD patients scored significantly higher on a scale assessing social functioning, ES=0.13. However, when controlling for the differences in motivation to serve, all of these differences disappeared. In this cohort, although slightly below average intellectual functioning and formal education, and better social functioning, independently increased vulnerability to suffer from PTSD, these associations disappeared when the future PTSD patients' lower motivation to serve in the military was included in the analysis. This suggests that low motivation to serve in the military might increase vulnerability for PTSD.

What have we learned about cognition in myasthenia gravis?: a review of methods and results

Most individuals with myasthenia gravis (MG) complain of cognitive impairment, but empirical studies of cognition in MG have produced mixed results. In the present review, we critically examined the methodology and results of previous studies that investigated cognition in MG. Results from our review revealed that none of the studies met at least 50% of criteria under review. The most common shortcomings of previous studies included small sample size, no exclusion for visual difficulties in patients, inadequate assessment of mood, and poor control for prednisone use. Despite these methodological difficulties, mild impairments on measures of learning have been identified. These findings need to be replicated with adequate control of potential confounds before any conclusions can be made regarding cognition in this disease. Suggestions for design of future studies are provided.