Stroop-test interference in bipolar disorder

"The captain wanted to stay with the sinking … (can't say boat)": How hypomanic personality traits interfere with inhibitory control?

Inhibitory control, the ability to suppress or countermand an action or thought, is notably impaired in patients with bipolar disorder. However, the specific characteristics of this impairment and whether deficits can manifest prior to a formal bipolar disorder diagnosis or among individuals with subsyndromal symptoms are relatively unknown. Here we test whether healthy individuals exhibiting a higher level of hypomanic personality traits respond more rapidly, albeit with weaker inhibitory control. We evaluated 83 native French speakers using the Hypomanic Personality Scale (HPS) and administered the Hayling Sentence Completion Test for response inhibition and the Stroop Test for interference control. We found negative correlations between the HPS score and both the response initiation and response inhibition times on the Hayling Sentence Completion Test, but the scores did not affect accuracy. Regarding the Stroop Test, we observed a significant positive correlation between the scores for hypomanic personality traits and the number of errors on the color-word condition. Our findings demonstrate that a high level of hypomanic personality traits correlates with faster reaction times on response inhibition tasks and higher error rates on interference tasks. This underlines the importance of distinguishing between inhibitory control concepts when examining the risks of bipolar disorder.

Dissociable effects of music and white noise on conflict-induced behavioral adjustments

Auditory stimuli, encompassing a continually expanding collection of musical genres and sonic hues, present a safe and easily administrable therapeutic option for alleviating cognitive deficits associated with neuropsychological disorders, but their effects on executive control are yet to be completely understood. To better understand how the processing of certain acoustic properties can influence conflict processing, we had a large of cohort of undergraduate students complete the Stroop colour and word test in three different background conditions: classical music, white noise, and silence. Because of pandemic guidelines and the necessity to run the experiment remotely, participants also completed the Wisconsin card sorting test (WCST), so that the reliability and consistency of acquired data could be assessed. We found that white noise, but not classical music increased the response time difference between congruent (low conflict) and incongruent (high conflict) trials (conflict cost), hence impairing performance. Results from the WCST indicated that home-based data collection was reliable, replicating a performance bias reported in our previous laboratory-based experiments. Both the auditory stimuli were played at a similar intensity, thus their dissociable effects may have resulted from differing emotional responses within participants, where white noise, but not music elicited a negative response. Integrated with previous literature, our findings indicate that outside of changes in tempo and valence, classical music does not affect cognitive functions associated with conflict processing, whilst white noise impairs these functions in a manner similar to other stressors, and hence requires further research before its implementation into neuropsychiatric care.

Talk2Me: Automated linguistic data collection for personal assessment

Language is one the earliest capacities affected by cognitive change. To monitor that change longitudinally, we have developed a web portal for remote linguistic data acquisition, called Talk2Me, consisting of a variety of tasks. In order to facilitate research in different aspects of language, we provide baselines including the relations between different scoring functions within and across tasks. These data can be used to augment studies that require a normative model; for example, we provide baseline classification results in identifying dementia. These data are released publicly along with a comprehensive open-source package for extracting approximately two thousand lexico-syntactic, acoustic, and semantic features. This package can be applied arbitrarily to studies that include linguistic data. To our knowledge, this is the most comprehensive publicly available software for extracting linguistic features. The software includes scoring functions for different tasks.

Semantic Ambiguity Resolution in Patients With Bipolar Disorder-An Event-Related Potential Study

Deficits in inhibitory function are assumed to underlie psychopathology in bipolar disorder (BD), especially in states of mania. A subdomain of inhibition, semantic inhibition (SI), referring to the suppression of irrelevant word meanings, may underlie formal thought disorder, such as flights of ideas. In the present study, we investigated SI in patients with BD during semantic ambiguity resolution using behavioral and event-related potential (ERP) measures. We presented 14 patients with BD with current manic, hypomanic, or mixed clinical states and 28 healthy controls sequentially with word triplets containing either a homonym (e.g., “organ”) or a comparable unambiguous word (e.g., “piano”). Participants were instructed to make a decision whether or not the target word was related to the meaning field of the first two words. The inappropriate homonym meaning had to be inhibited to correctly perform the target decision. In addition to reaction times (RT) and error rates (ER), the N400 ERP component to the target, an electrophysiological index of semantic processing, was analyzed as measure of the amount of SI that had taken place. Analyses of the behavioral data revealed that BD patients exhibited an overall worse performance in terms of RT and ER. In the ERP data, we found differences in N400 amplitude to ambiguous and unambiguous conditions over the right hemisphere in patients with BD depending on target congruence: In incongruent trials, N400 amplitude was smaller in ambiguous than in unambiguous words. In congruent trials, in contrast, N400 amplitude was larger in ambiguous than in unambiguous words. Such ERP differences between ambiguous and unambiguous words were absent in controls. We conclude that N400 amplitude differences in the ambiguous and unambiguous conditions of the BD group may reflect insufficient suppression of irrelevant homonym meanings in the right hemisphere. Disturbed SI processes might contribute to formal thought disorder in BD.

Developing Dimensional, Pandiagnostic Inhibitory Control Constructs With Self-Report and Neuropsychological Data

Trait markers, or intermediate phenotypes linking different units of analysis (self-report, performance) from the Research Domain Criteria (RDoC) matrix across populations is a necessary step in identifying at-risk individuals. In the current study, 150 healthy controls (HC) and 456 individuals with bipolar disorder (BD) Type I or II, NOS (not otherwise specified) or Schizoaffective BD completed self-report neuropsychological tests of inhibitory control (IC) and executive functioning. Bifactor analyses were used to examine the factor structure of these measures and to evaluate for invariance across groups. Bifactor analyses found modest convergence of items from neuropsychological tests and self-report measures of IC among HC and BD. The factor scores showed evidence of a general IC construct (i.e., subdomain) across measures. Importantly, invariance testing indicated that the same construct was measured equally well across groups. Groups differed on the general factor for three of the four scales. Convergence on a general IC factor and invariance across diagnosis supports the use of combined dimensional measures to identify clinical risk and highlights how prospective RDoC studies might integrate units of analysis.

Cognitive Remediation and Bias Modification Strategies in Mood and Anxiety Disorders

PURPOSE OF REVIEW

Cognitive impairments and biases, which are prevalent in patients with mood and anxiety disorders, can affect quality of life and functioning. Traditional treatments are only insufficiently addressing these impairments and biases. We review the cognitive impairments and biases present in these disorders as well as treatments targeting these domains.

RECENT FINDINGS

Interventions aimed at improving cognitive impairments and biases may help improve cognitive deficits and overall functioning in patients with mood and anxiety disorders. Direct comparisons of treatments for cognitive impairments or biases versus more traditional psychosocial interventions have produced diverse results.

SUMMARY

Overall, treatments for cognitive impairments and cognitive biases warrant additional study in clinical trials. Future research should explore cognitive remediation and cognitive bias modification adjunctive to psychosocial treatments to optimize patient outcomes in mood and anxiety disorders.

Neurobiology of Risk for Bipolar Disorder

Bipolar disorder (BD) is a chronic mental illness which follows a relapsing and remitting course and requires lifetime treatment. The lack of biological markers for BD is a major difficulty in clinical practice. Exploring multiple endophenotypes to fit in multivariate genetic models for BD is an important element in the process of finding tools to facilitate early diagnosis, early intervention, prevention of new episodes, and follow-up of treatment response in BD. Reviewing of studies on neuroimaging, neurocognition, and biochemical parameters in populations with high genetic risk for the illness can yield an integrative perspective on the neurobiology of risk for BD. The most up-to-date data reveals consistent deficits in executive function, response inhibition, verbal memory/learning, verbal fluency, and processing speed in risk groups for BD. Functional magnetic resonance imaging (fMRI) studies report alterations in the activity of the inferior frontal gyrus, medial prefrontal cortex, and limbic areas, particularly in the amygdala in unaffected first-degree relatives (FDR) of BD compared to healthy controls. Risk groups for BD also present altered immune and neurochemical modulation. Despite inconsistencies, accumulating data reveals cognitive and imaging markers for risk and to a less extent resilience of BD. Findings on neural modulation markers are preliminary and require further studies. Although the knowledge on the neurobiology of risk for BD has been inadequate to provide benefits for clinical practice, further studies on structural and functional changes in the brain, neurocognitive functioning, and neurochemical modulation have a potential to reveal biomarkers for risk and resilience for BD. Multimodal, multicenter, population-based studies with large sample size allowing for homogeneous subgroup analyses will immensely contribute to the elucidation of biological markers for risk for BD in an integrative model.

Neurocognitive functioning in euthymic patients with bipolar disorder and unaffected relatives: A review of the literature

BACKGROUND

Neurocognitive deficits are present in bipolar disorder (BD) patients and their unaffected (nonbipolar) relatives, but it is not clear which domains are most often impaired and the extent of the impairment resulting from shared genetic factors. In this literature review, we address these issues and identify specific neurocognitive tasks most sensitive to cognitive deficits in patients and unaffected relatives.

METHOD

We conducted a systematic review in Web of Science, PubMed/Medline and PsycINFO databases.

RESULTS

Fifty-one articles assessing cognitive functioning in BD patients (23 studies) and unaffected relatives (28 studies) were examined. Patients and, less so, relatives show impairments in attention, processing speed, verbal learning/memory, and verbal fluency.

CONCLUSION

Studies were more likely to find impairment in patients than relatives, suggesting that some neurocognitive deficits may be a result of the illness itself and/or its treatment. However, small sample sizes, differences among relatives studied (e.g., relatedness, diagnostic status, age), and differences in assessment instruments may contribute to inconsistencies in reported neurocognitive performance among relatives. Additional studies addressing these issues are needed.

New insights into the endophenotypic status of cognition in bipolar disorder: genetic modelling study of twins and siblings

BACKGROUND

Twin studies have lacked statistical power to apply advanced genetic modelling techniques to the search for cognitive endophenotypes for bipolar disorder.

AIMS

To quantify the shared genetic variability between bipolar disorder and cognitive measures.

METHOD

Structural equation modelling was performed on cognitive data collected from 331 twins/siblings of varying genetic relatedness, disease status and concordance for bipolar disorder.

RESULTS

Using a parsimonious AE model, verbal episodic and spatial working memory showed statistically significant genetic correlations with bipolar disorder (rg = |0.23|-|0.27|), which lost statistical significance after covarying for affective symptoms. Using an ACE model, IQ and visual-spatial learning showed statistically significant genetic correlations with bipolar disorder (rg = |0.51|-|1.00|), which remained significant after covarying for affective symptoms.

CONCLUSIONS

Verbal episodic and spatial working memory capture a modest fraction of the bipolar diathesis. IQ and visual-spatial learning may tap into genetic substrates of non-affective symptomatology in bipolar disorder.

Impaired conflict resolution and vigilance in euthymic bipolar disorder

Difficulty attending is a common deficit of euthymic bipolar patients. However, it is not known whether this is a global attentional deficit or relates to a specific attentional network. According to the attention network approach, attention is best understood in terms of three functionally and neuroanatomically distinct networks-alerting, orienting, and executive control. In this study, we explored whether and which of the three attentional networks are altered in euthymic Bipolar Disorder (BD). A sample of euthymic BD patients and age-matched healthy controls completed the Attention Network Test for Interactions and Vigilance (ANTI-V) that provided not only a measure of orienting, executive, and alerting networks, but also an independent measure of vigilance (tonic alerting). Compared to healthy controls, BD patients have impaired executive control (greater interference), reduced vigilance (as indexed by a decrease in the d' sensitivity) as well as slower overall reaction times and poorer accuracy. Our results show that deficits in executive attention and sustained attention often persist in BD patients even after complete remission of affective symptoms, thus suggesting that cognitive enhancing treatments programmed to improve these deficits could contribute to improve their functional recovery.

Executive function in parents of patients with familial versus sporadic bipolar disorder

OBJECTIVE

Studies investigating the cognitive function of healthy relatives of patients with bipolar disorder are conflicting, and the neurocognitive profile of relatives of bipolar disorder probands is still unclear. We aimed to evaluate executive function in unaffected parents of familial and sporadic patients with bipolar disorder.

METHODS

The study included 24 unaffected familial parents (FP) of patients with bipolar disorder, 26 unaffected sporadic parents (SP) of patients with bipolar disorder and 26 controls matched with the parents for gender, age and duration of education (76 subjects in total). All of the subjects were interviewed with the Structured Clinical Interview for DSM-IV-Axis I. Executive function was assessed using the California Verbal Learning Test (CVLT), the Trail Making Test (TMT), the Wisconsin Card Sorting Test (WCST) and the Stroop test.

RESULTS

In comparison to their respective matched controls, FP performed significantly worse on the CVLT, TMT, WCST and Stroop test, whereas SP performed significantly worse only on WCST perseverative errors and Stroop color test. FP performed significantly worse than SP on the CVLT, TMT, and WCST.

CONCLUSION

The present study investigated relatives with and without a family history of bipolar disorder separately and found that executive function was impaired in parents with a positive family history of bipolar disorder. These findings bring more evidence suggesting that deficits in prefrontal executive function and verbal memory are associated with familial vulnerability to bipolar disorder and that executive function and verbal memory impairments may represent a potential endophenotype of bipolar disorder.

How Does Mindfulness Meditation Work? Proposing Mechanisms of Action From a Conceptual and Neural Perspective

Cultivation of mindfulness, the nonjudgmental awareness of experiences in the present moment, produces beneficial effects on well-being and ameliorates psychiatric and stress-related symptoms. Mindfulness meditation has therefore increasingly been incorporated into psychotherapeutic interventions. Although the number of publications in the field has sharply increased over the last two decades, there is a paucity of theoretical reviews that integrate the existing literature into a comprehensive theoretical framework. In this article, we explore several components through which mindfulness meditation exerts its effects: (a) attention regulation, (b) body awareness, (c) emotion regulation (including reappraisal and exposure, extinction, and reconsolidation), and (d) change in perspective on the self. Recent empirical research, including practitioners' self-reports and experimental data, provides evidence supporting these mechanisms. Functional and structural neuroimaging studies have begun to explore the neuroscientific processes underlying these components. Evidence suggests that mindfulness practice is associated with neuroplastic changes in the anterior cingulate cortex, insula, temporo-parietal junction, fronto-limbic network, and default mode network structures. The authors suggest that the mechanisms described here work synergistically, establishing a process of enhanced self-regulation. Differentiating between these components seems useful to guide future basic research and to specifically target areas of development in the treatment of psychological disorders.

The neurocognitive functioning in bipolar disorder: a systematic review of data

BACKGROUND

During the last decades, there have been many different opinions concerning the neurocognitive function in Bipolar disorder (BD). The aim of the current study was to perform a systematic review of the literature and to synthesize the data in a comprehensive picture of the neurocognitive dysfunction in BD.

METHODS

Papers were located with searches in PubMed/MEDLINE, through June 1st 2015. The review followed a modified version of the recommendations of the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses statement.

RESULTS

The initial search returned 110,403 papers. After the deletion of duplicates, 11,771 papers remained for further evaluation. Eventually, 250 were included in the analysis.

CONCLUSION

The current review supports the presence of a neurocognitive deficit in BD, in almost all neurocognitive domains. This deficit is qualitative similar to that observed in schizophrenia but it is less severe. There are no differences between BD subtypes. Its origin is unclear. It seems it is an enduring component and represents a core primary characteristic of the illness, rather than being secondary to the mood state or medication. This core deficit is confounded (either increased or attenuated) by the disease phase, specific personal characteristics of the patients (age, gender, education, etc.), current symptomatology and its treatment (especially psychotic features) and long-term course and long-term exposure to medication, psychiatric and somatic comorbidity and alcohol and/or substance abuse.

Behavioral response inhibition in psychotic disorders: diagnostic specificity, familiality and relation to generalized cognitive deficit

Difficulty inhibiting context-inappropriate behavior is a common deficit in psychotic disorders. The diagnostic specificity of this impairment, its familiality, and its degree of independence from the generalized cognitive deficit associated with psychotic disorders remain to be clarified. Schizophrenia, schizoaffective and bipolar patients with history of psychosis (n=523), their available first-degree biological relatives (n=656), and healthy participants (n=223) from the multi-site B-SNIP study completed a manual Stop Signal task. A nonlinear mixed model was used to fit logistic curves to success rates on Stop trials as a function of parametrically varied Stop Signal Delay. While schizophrenia patients had greater generalized cognitive deficit than bipolar patients, their deficits were similar on the Stop Signal task. Further, only bipolar patients showed impaired inhibitory control relative to healthy individuals after controlling for generalized cognitive deficit. Deficits accounted for by the generalized deficit were seen in relatives of schizophrenia and schizoaffective patients, but not in relatives of bipolar patients. In clinically stable patients with psychotic bipolar disorder, impaired inhibitory behavioral control was a specific cognitive impairment, distinct from the generalized neuropsychological impairment associated with psychotic disorders. Thus, in bipolar disorder with psychosis, a deficit in inhibitory control may contribute to risk for impulsive behavior. Because the deficit was not familial in bipolar families and showed a lack of independence from the generalized cognitive deficit in schizophrenia spectrum disorders, it appears to be a trait related to illness processes rather than one tracking familial risk factors.

A comparison of euthymic bipolar patients with unaffected first-degree relatives and healthy controls in terms of neuropsychological functions

OBJECTIVE

Cognitive dysfunction in bipolar disorder (BD) is well established in the literature. The neurocognitive deficits have been considered to be endophenotypic markers of BD, and studies have examined whether neurocognitive deficits exist in first-degree relatives of individuals with BD I. We hypothesized that performance in tests of neurocognitive function would be impaired in euthymic BD I patients and their unaffected first-degree relatives compared to that of healthy controls.

METHODS

We compared the performance of bipolar patients, their first-degree relatives, and healthy controls in a battery of neurocognitive tests to reveal possible endophenotypes of BD. A diagnostic interview and neuropsychological test battery were administered to 30 BD I patients, 55 of their unaffected first-degree relatives and 32 healthy controls.

RESULTS

The patients and their first-degree relatives were significantly impaired in executive function assessed using the Wisconsin Card Sorting Test (WCST) and Trail Making Test-B (TMT-B) relative to the controls (WCST; perseverative errors: p < 0.0005, categories completed: p = 0.002, TMT-B; p = 0.002). There were no significant differences between the groups in terms of attention, psychomotor speed, verbal memory, or learning.

CONCLUSION

Our study suggests that the deficits in executive function may be endophenotypic markers of genetic vulnerability to BD I.

Ventral prefrontal executive function impairment as a potential endophenotypic marker for bipolar disorder

BACKGROUND

Patients with remitted bipolar disorder have cognitive impairments, particularly in executive functions. However, the findings of studies that investigated cognitive functions in unaffected relatives of patients with bipolar disorder are conflicting.

AIMS

The aim of this study is to investigate executive functions in healthy parents of patients with bipolar I disorder, along with bipolar I disorder patients and matched controls. It has been hypothesized that both patients with bipolar I disorder and their parents would have executive function impairments compared with controls.

METHODS

25 patients with bipolar I disorder, in full remission, 25 healthy controls that matched the patients with respect to age, gender and education, 50 healthy parents of those patients and 50 healthy controls that matched the parents for age, gender and education were included in the study. All the participants were interviewed with Structured Clinical Interview for DSM-IV-Axis I (SCID-I). Executive functions were assessed using the Verbal Fluency Test (VFT), Trail Making Test (TMT), Wisconsin Card Sorting Test (WCST) and Stroop Test.

RESULTS

Patients performed significantly worse than their matched controls on the VFT, TMT and Stroop tests, but not on the WCST. Parents performed significantly worse than their matched controls on the TMT and Stroop tests, but not on the VFT and WCST.

CONCLUSIONS

Our results bring more evidence that deficits in ventral, but not dorsal prefrontal executive functions are associated with familial vulnerability to bipolar disorder and ventral prefrontal executive function impairments may represent a potential endophenotype for bipolar disorder.

Normative data for healthy older adults and an abbreviated version of the Stroop test

Normative data for the Kaplan version of the Stroop Test are presented for 153 healthy, cognitively intact older adults aged 50-89 years. Increasing age was associated with decreased performance on all three subtests (Stroop A, Stroop B, and Stroop C), while years of education was only associated with Stroop B performance. Hence the normative data were stratified by age into three groups (50-64, 65-74, 75-89). Completion times for the first half of each trial (half-time scores) were found to have good split-half reliability and correlated highly with the original full administration scores. Means and standard deviations for the half-time administration are also presented for this sample. The current study provides more comprehensive normative data for older adults than previously available, as well as normative information for half-time scores that may have future clinical utility as an alternative, abbreviated version of the Kaplan Stroop Test.

Sustained attention in bipolar I disorder patients with familial psychosis and their first-degree relatives

Sustained attention (SA) was examined in patients with familial, psychotic Bipolar Disorder (BD) (n=43), their non-bipolar, non-psychotic relatives (n=44) and controls (n=47). Patients were impaired compared to relatives, but the latter did not differ from controls. Having a relative with familial, psychotic BD does not confer risk for SA deficits.

Cognitive functioning in severe psychiatric disorders: a general population study

In clinical samples, patients with severe psychiatric disorders are found to have cognitive impairments. Less is known whether this applies to samples derived from the general population. We aimed to study cognitive functioning in a population-based sample comprising individuals with schizophrenia, other non-affective psychoses, bipolar disorders, major depressive disorder, and controls derived from the same population. The current analysis was based on 148 persons with severe mental disorders and 66 control subjects, derived from the Psychoses in Finland study. All subjects were interviewed with SCID, and a neuropsychological test battery was administered. Subjects with schizophrenia had a generalized cognitive impairment (d = 0.43-1.07), while those with other non-affective psychoses were impaired in verbal memory and processing speed (d = 0.43-0.59). Subjects with bipolar disorders were not impaired. Unipolar major depressive disorder associated with slowed processing speed (d = 0.64). Our findings on cognitive impairments in subjects with schizophrenia and other non-affective psychoses derived from the general population support previous findings of a generalized cognitive dysfunction in these subjects. However, our results suggest that subjects with bipolar disorders from non-clinical populations may not have significant cognitive impairments. Our results emphasize the importance of using control samples derived from the same population and studied similarly as those with disorders in evaluating cognitive functioning of subjects with severe mental disorders.

Executive functioning in familial bipolar I disorder patients and their unaffected relatives

OBJECTIVE

To compare the executive function of patients with familial bipolar I disorder (BP-I) with a history of psychotic symptoms to their first-degree relatives and normal controls.

METHODS

Three domains of executive function: response inhibition, working memory, and cognitive set shifting were assessed in 44 familial patients with a lifetime diagnosis of BP-I who had experienced psychotic symptoms, 42 of their unaffected first-degree relatives, and 47 controls.

RESULTS

Bipolar disorder patients and their unaffected relatives had significantly worse scores for response inhibition compared to healthy controls. The groups did not differ in working memory or cognitive set shifting.

CONCLUSIONS

Impairments in response inhibition are associated with both psychotic bipolar disorder and genetic liability for this illness. Our results indicate that deficits in this specific domain of executive functioning are a promising candidate endophenotype for psychotic bipolar disorder.

A 2-year naturalistic study on cognitive functioning in bipolar disorder

OBJECTIVE

Cognitive alterations in bipolar disorder may reflect genetic influence. However, to what degree mood, medication, thyroid function and other factors impact on longitudinal cognitive functioning remains unclear.

METHOD

A group of patients with bipolar (spectrum) disorder (n = 76) underwent two monthly cognitive assessments over a 2-year period in a prospective, repeated measures design. Regression models were used to investigate associations with predictors, corrected for multiple testing.

RESULTS

Patients with bipolar disorder performed worse than healthy controls (n = 61) on all cognitive domains tested. Effect sizes were small, with a maximum of -0.36 for sustained attention. However, cognitive performance varied substantially over the 2-year follow-up, co-varying with subjective cognitive complaints and impacting on functioning. Alterations in sustained attention and motor speed were the only impairments that were invariant over time. Predictors had very limited explanatory power on temporal variation in cognition. Use of second-generation antipsychotics was associated with the largest negative effects on cognition, which were evident in the areas of motor speed and basic information processing (-0.35 < β < -0.5).

CONCLUSION

Cognitive function in bipolar disorder varies significantly over time, largely independent of clinical factors. The temporal stability of sustained attention is the exception, suggesting it may represent a possible candidate intermediary phenotype.

Intact neurovascular coupling during executive function in migraine without aura: Interictal near-infrared spectroscopy study

An altered neurovascular coupling has been proposed in migraine. We aimed to investigate neurovascular coupling during a mental task interictally in patients with migraine without aura (MO) by near-infrared spectroscopy (NIRS). Twelve migraineurs and 12 healthy controls were included. Using NIRS, we recorded the magnitude and latency of cortical changes in oxyhaemoglobin (HbO2) and deoxyhaemoglobin (Hb) during the colour-word matching Stroop test via 16 channels covering the forehead. We found no differences in the magnitude of responses between migraineurs and healthy subjects in the incongruent Stroop task subtracted by the neutral Stroop task on either side of the frontal cortex for HbO2 (left, P = 0.984; right, P = 0.406) or Hb (left, P = 0.689; right, P = 0.406) values. No differences in error rate ( P = 0.611) or reaction time ( P = 0.936) were found between healthy subjects and MO patients for incongruent tasks. The present study suggests that vascular reactivity and oxygen supply during a mental task in patients with MO are intact interictally.