Reduced frontopolar activation during verbal fluency task associated with poor social functioning in late‐onset major depression: Multi‐channel near‐infrared spectroscopy study

Aim: Functional neuroimaging studies to date have indicated prefrontal dysfunction in late‐onset major depression (LOD). The relationships between prefrontal dysfunction and clinical characteristics including social functioning, however, have been unclear. The objective of the present study was to evaluate prefrontal hemodynamic response related to an executive task in LOD and to assess the relationship between activation in the prefrontal regions and clinical characteristics including social functioning. Methods: Twenty‐four subjects with LOD and 30 age‐ and gender‐matched healthy subjects were recruited for the present study. Hemoglobin concentration changes in the prefrontal and superior temporal cortical surface area were measured during verbal fluency task (VFT) using 52‐channel near‐infrared spectroscopy (NIRS), which enables real‐time monitoring of cerebral blood volume (CBV) in the cortical surface area. Results: The two groups had a distinct spatiotemporal pattern of oxy‐hemoglobin concentration change; LOD patients had less activation in a broad area covering both prefrontal and superior temporal cortices than healthy controls. In addition, reduced activation of the frontopolar region had a significant positive correlation with lower self‐assessment of social functioning scores in the patient group. Conclusion: Reduced frontopolar cortical activation was associated with social functioning impairment in patients with LOD, and NIRS may be an efficient clinical tool for monitoring these characteristics.     

Reduced frontopolar activation during verbal fluency task in schizophrenia: a multi-channel near-infrared spectroscopy study

Functional neuroimaging studies to date have shown prefrontal dysfunction during executive tasks in schizophrenia. However, relationships between hemodynamic response in prefrontal sub-regions and clinical characteristics have been unclear. The objective of this study is to evaluate prefrontal hemodynamic response related to an executive task in schizophrenia and to assess the relationship between activation in the prefrontal sub-regions and clinical status. Fifty-five subjects with schizophrenia and age- and gender-matched 70 healthy subjects were recruited for this case-control study in a medical school affiliated hospital in the Tokyo metropolitan area, Japan. We measured hemoglobin concentration changes in the prefrontal (dorsolateral, ventrolateral, and frontopolar regions) and superior temporal cortical surface area during verbal fluency test using 52-channel near-infrared spectroscopy, which enables real-time monitoring of cerebral blood volumes in the cortical surface area under a more restraint-free environment than positron emission tomography or functional magnetic resonance imaging. The two groups showed distinct spatiotemporal pattern of oxy-hemoglobin concentration change during verbal fluency test. Schizophrenia patients were associated with slower and reduced increase in prefrontal activation than healthy controls. In particular, reduced activations of the frontopolar region, rather than lateral prefrontal or superior temporal regions, showed significant positive correlations with lower global assessment of functioning scores in the patient group, although task performance was not significantly associated with the scores. These results suggest that reduced frontopolar cortical activation is associated with functional impairment in patients with schizophrenia and that near-infrared spectroscopy may be an efficient clinical tool for monitoring these characteristics.     

Contribution of divergent thinking to community functioning in schizophrenia

Fluency deficits have been associated with poor community functioning in patients with schizophrenia. In our previous study we demonstrated that the ability to generate higher-quality responses on tasks of divergent thinking as measured by several fluency tests was impaired in patients with schizophrenia. The purpose of the present study was to investigate the contribution of the deficits in divergent thinking to community dysfunction in schizophrenia. Forty Japanese outpatients with schizophrenia and 32 healthy control subjects were recruited for this study and assessed over a broad spectrum of the neurocognitive domain. Their capacity for divergent thinking was assessed by idea, design, and word fluency tests. Community functioning was assessed by using the Global Assessment of Functioning (GAF), the Life Assessment Scale for the Mentally Ill (LASMI), and the Social Functioning Scale (SFS). The results confirmed the qualitative deficits of divergent thinking in schizophrenia. Stepwise multiple regressions using neurocognitive and demographic/clinical variables as predictors revealed that the higher-quality response scores on the tasks of divergent thinking significantly contributed to community functioning. Moreover, the deficit on the verbal task of divergent thinking significantly contributed to impairment in the area of daily living, and the deficit on the nonverbal task of divergent thinking significantly contributed to impairment in the area of interpersonal relations. The results of this study reveal the importance and the possibility of cognitive remediation and cognitive training with strategies that target capacity for divergent thinking to improve community functioning in patients with schizophrenia.     

Working memory and prefrontal/temporal hemodynamic responses during post-task period in patients with schizophrenia: A multi-channel near-infrared spectroscopy study

The relationship between cognitive impairments and social dysfunction in schizophrenia is widely accepted. Neuroimaging studies in patients with schizophrenia have demonstrated abnormal function in the prefrontal region during various neurocognitive tasks. However, studies exploring the neural basis of these cognitive impairments are still limited. Multi-channel near-infrared spectroscopy (NIRS) is a non-invasive functional neuroimaging technique used to detect the spatiotemporal characteristics of brain activity. Previous NIRS studies indicated oxy-hemoglobin (oxy-Hb) increase in patients with schizophrenia during the verbal fluency task (VFT), but to a lesser extent than in healthy participants. Furthermore, aberrant re-increase in the prefrontal region was observed during the post-task period. We hypothesized that prefrontal/temporal oxy-Hb aberrant re-increase during the post-task period was associated with cognitive impairment because oxy-Hb aberrant re-increase represent inadequate suppression of neural activity in the post-task period.We recruited 30 patients with schizophrenia and 30 healthy participants in this study. All participants underwent 52-channel NIRS measurement using the VFT. The patients with schizophrenia showed oxy-Hb aberrant re-increase in prefrontal and temporal regions during the post-task period. Although there was no significant relationship between changes in the oxy-Hb during the task and the scores of the Brief Assessment of Cognition in Schizophrenia (BACS), a significant negative correlation was observed between the oxy-Hb during the post-task period and BACS working memory z-scores (in DLPFC and temporal regions). These results suggest that oxy-Hb re-increase during the post-task period in prefrontal and temporal regions is associated with WM deficits in patients with schizophrenia and NIRS may be a potential biomarker of working memory in chronic schizophrenia.     

Improvements in spontaneity and social functioning in patients with schizophrenia after cognitive training

Cognitive rehabilitation approaches are in the spotlight as a novel strategy for promoting social participation in patients with schizophrenia, as the connection between cognitive deficits and functional outcomes in schizophrenia has been consistently demonstrated over the last decade. Divergent thinking is typically applied when someone is confronted with questions that do not have a single fixed answer. We identified divergent thinking deficits in patients with schizophrenia using qualitative measures involving idea and design fluency tests, and found that the impairment in generating high-quality responses on divergent thinking tasks was an important determinant of poor community functioning among patients. Based on our findings, we suggested that divergent thinking was an important neurocognitive skill that deserves consideration as a potential target for intervention, and developed a training program specifically for divergent thinking deficits in patients with schizophrenia. We evaluated the effects of this program on measures of divergent thinking (e.g., fluency measures), negative symptoms, and social functioning. After the training program, participants in the divergent thinking program had significantly greater improvements on measures of idea fluency, negative symptoms, and interpersonal relations than the participants in the control program. These results suggest that interventions for divergent thinking in patients with schizophrenia may lead to improvements in patients' social functioning. In recent years, intrinsic motivation has become a focus of attention as a critical mechanism for explaining the relationship between neurocognition and psychosocial functioning in patients with schizophrenia. Divergent thinking is thought to be relevant to spontaneity and intrinsic motivation. The training program for divergent thinking deficits may have achieved its effects on negative symptoms and social functioning through an improvement in spontaneity and intrinsic motivation. The potential of the cognitive training program to enhance patients' quality of life is discussed.     

Prefrontal activation predicts social functioning improvement after initial treatment in late-onset depression

The activation of oxygenated hemoglobin (oxy-Hb) has been shown to be lacking in the prefrontal cortex (PFC) of patients with late-onset depression (LOD), in verbal fluency task (VFT)-related near-infrared spectroscopy (NIRS). In our previous studies, we have emphasized the connection between the lack of activation in the frontopolar cortex and social functioning disorder in patients with LOD. In this study, we investigated whether the responsiveness to medical treatment of untreated patients with LOD, particularly social functioning improvements, could be predicted by NIRS findings at the initial examination. The subjects were 29 patients with LOD who were diagnosed with major depression at 65 years or older at the initial examination (mean age ± standard deviation, 72.4 ± 5.71 years). We measured the changes in hemoglobin concentration in the prefrontal and temporal cortex regions during a VFT by using 52-channel NIRS. In addition, depression status and social functioning were evaluated with the Hamilton Depression Rating Scale and the Social Adaptation Self-evaluation Scale, respectively, at the initial examination and 8 weeks after the treatment. A negative correlation was found between the NIRS activation in the right ventrolateral PFC region before treatment and the improvement in social functioning. These results suggested that the social functioning improvements were greater in LOD with initially lower NIRS activation in the right ventrolateral PFC region. NIRS is a simple technique that can be used before treatment to evaluate the social functioning levels of patients with LOD, and predict social functioning improvement after treatment.     

A randomized controlled trial of cognitive behavioral therapy for individuals at clinical high risk of psychosis

Background

Symptomatic and functional outcomes in schizophrenia are associated with the duration of untreated psychosis. However, no candidate biomarkers have been adopted in clinical settings. Multichannel near-infrared spectroscopy (NIRS), which can easily and noninvasively measure hemodynamics over the prefrontal cortex, is a candidate instrument for clinical use.

Aims

We intended to explore prefrontal dysfunction among individuals at different clinical stages, including ultra-high-risk (UHR), first-episode psychosis (FEP), and chronic schizophrenia (ChSZ), compared to healthy subjects.

Method

Twenty-two UHR subjects, 27 patients with FEP, 38 patients with ChSZ, and 30 healthy subjects participated. We measured hemodynamic changes during a block-designed letter fluency task using multichannel NIRS instruments.

Results

We found that the activations of the bilateral ventrolateral prefrontal cortex, and the fronto-polar and anterior parts of the temporal cortical regions in the UHR group were lower than those of the controls, but similar to those of the FEP and ChSZ groups. However, the activations in the bilateral dorsolateral prefrontal cortex regions decrease with advancing clinical stage.

Conclusions

To the best of our knowledge, this is the first study directly comparing differences in hemodynamic changes with respect to the 3 clinical stages of psychosis. Furthermore, this study also demonstrates different patterns of impairment according to the progression of clinical stages using NIRS instruments. NIRS measurements for UHR and FEP individuals may be candidate biomarkers for the early detection of the clinical stages of psychosis.     

Poor premorbid social functioning and theory of mind deficit in schizophrenia: evidence of reduced context processing?

Investigations have demonstrated deficits in theory of mind (ToM) ability in schizophrenia. Yet, the development of, and mechanisms associated with these deficits are not well understood. The present investigation examined the hypothesis that, among chronic schizophrenia patients, impaired ToM is associated with failures in context processing, greater disorganized symptoms, and poor premorbid functioning. Forty-two inpatients with schizophrenia spectrum disorders were assessed on tests of ToM, visual and linguistic context processing, executive functioning, and verbal IQ. Symptomatology and premorbid functioning were also assessed. Results revealed that more impaired ToM was associated with poorer performance on both visual and linguistic context processing measures and higher ratings of disorganization on the BRRS. ToM was also associated with poorer childhood social functioning and an earlier age of illness onset. ToM was not associated with verbal processing speed, verbal fluency, response inhibition, sequence learning, or estimated verbal IQ. A significant regression model including measures of childhood peer problems and visual and language context processing significantly predicted ToM performance and accounted for 43% of the variance. These findings suggest that, among chronic schizophrenia patients, deficits in ToM ability may be the result of context processing impairments. These impairments may be a factor in both poor social functioning during childhood and greater disorganized symptoms after illness onset.     

Relationship between regional cerebral blood flow and verbal fluency in Alzheimer's disease

Category and letter verbal fluency tests are widely used for dementia detection and severity measure. Performances of these tasks have been regarded to be mainly associated with the left frontal lobe function. However, some recent studies suggest that there are different neuropsychological bases between these two tasks, and the brain region which contributes to these performances still remains unclear in Alzheimer's disease (AD). To clarify the neural basis of verbal fluency in AD, we examined the relationship between performances of these tasks and regional cerebral blood flow (rCBF). Twenty-five AD patients were administered verbal fluency tasks and single photon emission computed tomography (SPECT) scans. Thirteen cortical regions of interest were symmetrically defined in each hemisphere. Letter fluency scores were correlated significantly only with the left prefrontal (Brodmann's area (BA) 10-46) regional cerebral blood flow (rCBF). In contrast, category fluency scores were correlated most strongly with the left temporal rCBF and also with the left prefrontal (BA 10-46) rCBF. In conclusion, the present study suggests that left prefrontal (BA 10-46) dysfunction contributes to decline in both letter and category fluency scores in AD, while typical posterior dysfunction of AD has a closer relationship with decline in category fluency scores.     

Phonological fluency is uniquely impaired in Japanese-speaking schizophrenia patients: confirmation study

In alphabet-based language-speaking patients with schizophrenia, category fluency is disproportionately disturbed as compared with phonological fluency. Deficits in category and phonological fluency observed in Japanese patients, however, were similar. The aim of the present study was to replicate these findings by modifying the task to minimize the influence of lack of motivation and concentration in the patients. Similar deficits were found in both types of fluency in Japanese patients. Patients who speak Japanese have deficits in phonological fluency, compared with patients who speak alphabet-based languages, suggesting that the pattern of impairment in verbal fluency in schizophrenia is dependent on the specific language system.     

Does cognition predict community function only in schizophrenia?: a study of schizophrenia patients, bipolar affective disorder patients, and community control subjects

Cognitive deficits predict functioning in schizophrenia; however, little is known as to whether the association is present in other mental disorders. If specific cognitive deficits uniquely predict functional impairment in schizophrenia the association of select aspects of brain dysfunction with daily living would suggest an intervention target and perhaps a means by which to improve the functioning of schizophrenia patients. The relationship of cognition and functioning was investigated in schizophrenia (n=39), bipolar affective disorder (n=27), and nonpsychiatric control (n=38) participants to determine whether the associations varied across groups. We examined verbal memory, verbal learning, verbal fluency, vigilance, executive functioning, symptomatology, and generalized cognitive functioning for associations with social function. Correlational analyses revealed particular cognitive domains (e.g., verbal memory) to be associated with social functioning in schizophrenia, bipolar, and control subjects; however generalized cognitive function and symptomatology were also associated with social functioning in patients. Multiple regression analyses revealed that in schizophrenia poor verbal memory predicted worse social functioning even after the effects of generalized cognitive dysfunction were considered. Verbal memory indices failed to account for variance in social function in bipolar patients and control subjects after consideration of generalized cognitive function. Bipolar patients with worse planning and problem solving tended to have worse social functioning. Therefore, unlike schizophrenia patients who may fail to process verbally mediated material, bipolar patients' difficulty with logical approaches to problems in daily living may have the greatest impact on their community function.     

Prefrontal activation during verbal fluency tests in schizophrenia--a near-infrared spectroscopy (NIRS) study

Letter- or semantically-cued verbal fluency tests (VFT) induce different, but overlapping activities in the prefrontal cortex (PFC) in healthy subjects. Functional differences between letter and semantic VFT may be important in elucidating the nature of language-related problems in schizophrenia since more profound impairment in semantically-cued retrieval may be suggestive of semantic system dysfunction specific to this disorder. However, the functional differences between the letter vs. semantic VFT on prefrontal metabolism in the subjects with schizophrenia have not been described. In the present study, we used near-infrared spectroscopy (NIRS) to assess hemoglobin concentration changes in the bilateral PFCs in subjects and controls. Sixteen subjects with schizophrenia and 19 healthy controls performed letter and semantic VFTs. Prefrontal hemodynamic changes were simultaneously monitored by NIRS. While healthy subjects performed both tasks equivalently, the subjects with schizophrenia showed more compromised performance in the semantic VFTs compared to the letter VFTs. NIRS measurement revealed that the pattern of PFC activation was greater during the letter VFT when compared to the semantic VFT in the healthy subjects, suggesting more prominent PFC involvement in letter-cued retrieval. In contrast, the subjects with schizophrenia showed the opposite pattern of activation, implying that the semantic mode of lexical access might impose greater cognitive demands on the PFC. The present study is the first to detect abnormal patterns of PFC activation in adults with schizophrenia in response to the distinct cognitive demands associated with letter and semantic VFT.     

Decreased prefrontal activation during letter fluency task in adults with pervasive developmental disorders: a near-infrared spectroscopy study

Functional neuroimaging studies have suggested that dysfunction of prefrontal cortex (PFC) is present in persons with pervasive developmental disorders (PDD). Recently, the development of near-infrared spectroscopy (NIRS) has enabled noninvasive bedside measurement of regional cerebral blood volume. Although NIRS enables the noninvasive clarification of brain functions in many psychiatric disorders, it has not yet been used to examine subjects with PDD. The aim of our study was to conduct an NIRS cognitive activation study to verify PFC dysfunction in PDD. The subjects were 10 adults with PDD and 10 age- and gender-matched healthy subjects. Hemoglobin concentration changes were measured with a 24-channel NIRS machine during the letter fluency task. While the number of words generated during the letter fluency task did not differ significantly between groups, the analysis of covariance including IQ as a confounding covariate showed that the PDD group was associated with bilateral reduction in oxy-hemoglobin concentration change as compared with the control group. The statistical results did not change when only IQ-matched high-functioning subjects (N=7) were included. Moreover, reduced oxy-hemoglobin concentration change for the right PFC was significantly correlated with verbal communication deficits within the PDD group. The present findings are consistent with proposed prefrontal dysfunction in PDD subjects identified by other neuroimaging modalities. The present results may be also potentially useful for applying NIRS to clinical settings of child psychiatry.     

Mapping hypofrontality during letter fluency task in schizophrenia: a multi-channel near-infrared spectroscopy study

Cognitive impairment and associated frontal lobe dysfunction characterize schizophrenia. The letter fluency test (LFT) has been used as one of the most sensitive measures of the cognitive dysfunction, but the nature and topography of the hypofrontality have yet to be fully elucidated. In this study we used multi-channel near-infrared spectroscopy (NIRS), a recently developed noninvasive functional imaging technique, to measure changes in the concentration of oxygenated hemoglobin in the prefrontal cortices of 31 schizophrenia patients and 26 age- and sex-matched healthy controls during performance of the LFT. The results demonstrated reduced prefrontal cortex activation during the LFT among the schizophrenia patients in comparison with the healthy controls, even after controlling for medication. The hypofrontality was most salient in the prefrontal ventrolateral subregion bilaterally. The reduced activity appeared to be due not only to the lesser magnitude but also to the lesser fluctuation of the changes in oxygenated hemoglobin concentration. The hypofrontality appeared to be independent of the patients' symptomatological manifestations. We concluded that measuring NIRS during performance of the LFT can detect prefrontal lobe dysfunction of schizophrenia patients and may provide a new tool to monitor their treatment and course.     

Fonctions cognitives sous-jacentes aux déficits de fluence verbale dans la schizophrénie : revue de la littérature

Individuals with schizophrenia usually show impairment on various cognitive functions, including long-term memory, executive functions and language. Compared to healthy controls, their performance is impaired in verbal fluency tests. These tests require participants to generate in a given time as many words as they can, belonging to a given category (semantic fluency), or beginning with a specific letter (orthographic fluency). Various cognitive functions are involved in verbal fluency tests: psychomotor speed, executive functions, language, long-term verbal memory and semantic memory. The purpose of the present study was to clarify the functional origin of verbal fluency deficits in schizophrenia through a literature review. Nineteen articles were selected in Pubmed and PsycINFO after initial screening and detailed review. They were formally analyzed with regard to general performance, cognitive strategies used in semantic and orthographic fluency tests and, underlying cognitive origin of deficits. Results show that individuals with schizophrenia produce fewer words than healthy controls in both types of fluency tests. Their impairment is more apparent in semantic than in orthographic fluency tests. Results of studies reviewed also show that individuals with schizophrenia adopt the same clustering (i.e. production of related words within a subcategory) and switching (i.e. ability to shift between clusters when a subcategory is exhausted) strategies than healthy controls, but less efficiently. Several hypotheses, such as the impairment of executive functions, semantic memory or speed of information processing, were put forward to account for this finding. Interestingly, the few studies in which researchers performed an analysis of the semantic relationships between words produced in fluency tests showed a less semantic coherence among people with schizophrenia than in healthy controls. Such a difference could be explained by disorganization of semantic memory or impairment in the activation of conceptual representations in semantic memory. Studies in which correlations and regression analyzes were performed allow for clarifying the cognitive origin underlying verbal fluency deficits in schizophrenia. The links between these deficits and information processing speed as well as working memory are well established. These two cognitive domains also appear to be strong predictors of performance in semantic and orthographic fluency tasks in schizophrenia. Individuals with schizophrenia usually present with a significant slowdown in the speed of information processing. Such a slowdown is likely to account for their poor performance in verbal fluency tests, which require the independent and rapid production of words. Working memory disorders are also core cognitive symptoms of schizophrenia. Working memory is involved in verbal fluency tests since they involve “strategic” activation of verbal information in long-term memory, inhibition of inappropriate words, switching between clusters, etc. However, the concept of working memory also partially encompasses the notion of executive functions so that the results reported in the present literature review, according to which impairment of verbal fluency in schizophrenia results from working memory deficits but not from executive functions deficits, are difficult to interpret. Results are also less clear-cut in regard to verbal long-term memory and to language abilities. Finally, numerous studies had shown that individuals with schizophrenia present specific deficits in the organization of semantic memory. However, the impact of this deficit on verbal fluency was explored in one study only. To conclude, verbal fluency tests are sensitive to various neurocognitive conditions and are helpful for differential diagnosis. Further studies are still needed to clarify the functional origin of verbal fluency deficits in schizophrenia, in particular the differential role of executive functions and working memory as well as the impact of semantic memory impairment.     

Fronto-temporal function may distinguish bipolar disorder from schizophrenia

OBJECTIVES: There is evidence for differential neural alterations within the prefrontal cortex (PFC) in bipolar disorder I (BDI) and schizophrenia that may translate into different cognitive deficits. Our objective was to compare the cognitive profile of stable BDI and schizophrenic patients using neuropsychological tasks which utilize frontal systems but differ in terms of the exact neural circuits and cognitive processes involved. METHODS: We studied 43 patients with BDI, 54 with schizophrenia and 46 matched healthy participants. All participants completed (i) the Wisconsin Card Sorting Test (WCST) which is known to recruit the dorsal and ventral PFC, (ii) the verbal fluency task (VFT), which engages frontal-temporal regions, and (iii) the Stroop Colour Word Test (SWCT) which depends on the integrity of the cingulo-frontal network. A series of multivariate analyses examined differences between the cognitive profiles of BD and schizophrenic patients relative to that of healthy participants controlling for general intellectual ability and gender. RESULTS: Bipolar disorder I patients showed minimal verbal fluency impairment while schizophrenic patients demonstrated marked deficits on this task relative to the control and BDI groups. The two patient groups had comparable performance on the WCST. In the SWCT, schizophrenic patients showed impairment in both congruent and incongruent conditions while BD patients had deficits only in the latter. CONCLUSIONS: Absence of significant verbal fluency abnormalities and by inference dysfunction in the associated fronto-temporal circuitry may distinguish BDI from schizophrenia. Both disorders may show impairment in tasks involving cingulo-frontal networks with evidence of greater cingulate dysfunction in schizophrenia.     

Task dependent prefrontal dysfunction in persons with Asperger's disorder investigated with multi-channel near-infrared spectroscopy

Dysfunction of the prefrontal cortex has been previously reported in individuals with Asperger's disorder. In the present study, we used multi-channel near-infrared spectroscopy (NIRS) to detect changes in the oxygenated hemoglobin concentration ([oxy-Hb]) during two verbal fluency tasks. The subjects were 20 individuals with Asperger's disorder and 18 age- and IQ-matched healthy controls. The relative [oxy-Hb] in the prefrontal cortex was measured during the category and letter fluency tasks. The mean total [oxy-Hb] during the category fluency task did not differ significantly between the groups; however, during the letter fluency task, the mean [oxy-Hb] in persons with Asperger's disorder was significantly lower than that in controls. These results suggested task-relevant or task-specific prefrontal dysfunction in persons with Asperger's disorder.     

Verbal fluency in adults with high functioning autism or Asperger syndrome

The semantic and phonemic fluency performance of adults with high functioning autism (HFA), Asperger syndrome and a neurotypical control group were compared. All participants were matched for age and verbal ability. Results showed that the participants with HFA were significantly impaired in their performance of both semantic fluency tasks and the phonemic fluency task using the letter M. The Asperger group was only impaired in their performance of the semantic fluency task ‘professions’. The social components of the ‘professions’ task may have influenced the performance of the two disorder groups for this subtest negatively. The fluency deficits could not be attributed to a lack of the use of strategies or to difficulties in switching between strategies. The impairment in two of the three verbal fluency subtests in the HFA group can be attributed to the relatively low processing speed found in this group.     

Increased cerebellar vermis white-matter volume in men with schizophrenia

We aimed to investigate cerebellar structural abnormalities and their functional significance in patients with schizophrenia. Forty right-handed men with schizophrenia and 40 sex, age and handedness matched controls underwent a volumetric magnetic resonance scan with 1 mm3 isotropic spatial resolution. Cerebellar grey- and white-matter volumes were analysed using voxel-based morphometry. Patients with schizophrenia completed a battery of neuropsychological tests assessing sustained attention (continuous performance test), memory (Hopkins memory test) and executive function (verbal fluency and Wisconsin card sorting tests). Patients with schizophrenia exhibited significantly increased cerebellar vermis white-matter volume compared with controls. By contrast, total cerebellar volume, and grey- and white-matter volumes of cerebellar hemispheres were not significantly different between groups. Increased vermis white-matter volume in patients was associated with poor verbal fluency performance. We concluded that increased white-matter in the cerebellar vermis, possibly suggesting anomalous connectivity, may be associated with verbal executive dysfunction in men with chronic schizophrenia.