Self-reported social functioning and prefrontal hemodynamic responses during a cognitive task in schizophrenia

Probing depression, schizophrenia, and other psychiatric disorders using fNIRS and the verbal fluency test: A systematic review and meta-analysis

Accessible neuroimaging tools that can identify specific frontal lobe dysfunction associated with psychiatric disorders could be useful for improving disease diagnosis and prognosis and treatment development. Functional near-infrared spectroscopy (fNIRS), in conjunction with the verbal fluency test (VFT), has emerged as an inexpensive and convenient method for understanding psychiatric disorders. However, questions remain regarding the specificity and uniqueness of fNIRS measurements for different disorders and the soundness of the methods applied previously. To address these knowledge gaps, we conducted a systematic review and meta-analysis of fNIRS studies using the VFT to probe psychiatric disorders. A literature search was conducted using PubMed and PsycINFO on October 27, 2020. Overall, 82% and 49% of the 121 included studies reported significantly reduced changes in oxyhemoglobin concentrations (HbO) and significantly fewer produced words during the VFT in psychiatric patients compared with healthy controls, respectively. For most psychiatric disorders, changes in HbO are more sensitive than changes in deoxyhemoglobin concentrations and VFT performance to detect psychopathologies. In addition, meta-analyses based on the proportion of channels that exhibited significant differences in HbO changes between patients and controls and on the effect sizes of group differences consistently showed that for major depression and schizophrenia, hypoactivation could be found across the frontotemporal regions, but its topographical distribution is disorder-specific. Thus, the fNIRS-VFT paradigm holds promise for understanding, detecting, and differentiating psychiatric disorders, and has the potential for developing accessible neuroimaging biomarkers for different psychiatric disorders. The findings are discussed with regard to the strengths and weaknesses of the applied methods, following by recommendations.

Structural and Functional Features of Developing Brain Capillaries, and Their Alteration in Schizophrenia

Schizophrenia affects more than 1% of the world's population and shows very high heterogeneity in the positive, negative, and cognitive symptoms experienced by patients. The pathogenic mechanisms underlying this neurodevelopmental disorder are largely unknown, although it is proposed to emerge from multiple genetic and environmental risk factors. In this work, we explore the potential alterations in the developing blood vessel network which could contribute to the development of schizophrenia. Specifically, we discuss how the vascular network evolves during early postnatal life and how genetic and environmental risk factors can lead to detrimental changes. Blood vessels, capillaries in particular, constitute a dynamic and complex infrastructure distributing oxygen and nutrients to the brain. During postnatal development, capillaries undergo many structural and anatomical changes in order to form a fully functional, mature vascular network. Advanced technologies like magnetic resonance imaging and near infrared spectroscopy are now enabling to study how the brain vasculature and its supporting features are established in humans from birth until adulthood. Furthermore, the contribution of the different neurovascular unit elements, including pericytes, endothelial cells, astrocytes and microglia, to proper brain function and behavior, can be dissected. This investigation conducted among different brain regions altered in schizophrenia, such as the prefrontal cortex, may provide further evidence that schizophrenia can be considered a neurovascular disorder.

Negative Symptoms and Cognitive Impairments in Schizophrenia: Two Key Symptoms Negatively Influencing Social Functioning

Schizophrenia is a chronic, disabling disorder, which commonly emerges in adolescence and young adulthood. While pharmacological treatment with currently available second-generation antipsychotics exerts beneficial effects on the positive symptoms of schizophrenia, they have little effect on negative symptoms or cognitive deficits. Because these two types of symptoms are enduring, and negatively impact social functioning throughout the course of the illness, there is an urgent requirement to develop new effective therapeutic approaches to manage them. Negative symptoms have proven difficult to assess accurately because of their complexity, even with commonly used clinical rating scales such as the Scales for Assessment of Negative Symptoms (SANS). In this context, new "next-generation" assessment tools have recently been developed, which include items representing the five domains encompassed by the two established clusters of negative symptoms (diminished expression and avolition), and enable the detection of changes in severity. Despite various therapeutic approaches to alleviating negative symptoms, there are currently no established methods available for clinical practice. Cognitive deficits are also a core feature in the majority of people with schizophrenia, with impaired performance observed across many cognitive domains, including verbal memory, working memory, attention, and executive functions. Such cognitive deficits are likely associated with either reduced or inefficient function of related distributed neural networks. Psychosocial treatments for cognitive impairments in schizophrenia seem promising given the beneficial effects of cognitive remediation therapy on such impairments, as well as on social functioning, as substantiated in several meta-analytic studies with modest effect sizes. Furthermore, using functional neuroimaging techniques, the size of these therapy-induced beneficial changes in neurocognitive performance has been demonstrated to be correlated with the degree of the changes in brain activation during performing some cognitive tasks in the prefrontal and temporal cortices. This suggests neurobiological effects are exerted by psychosocial cognitive remediation treatments.

Comparison of changes in oxygenated hemoglobin during the tree-drawing task between patients with schizophrenia and healthy controls

BACKGROUND

Tree-drawing test is used as a projective psychological test that expresses the abnormal internal experience in patients with schizophrenia (SZ). Despite the widely accepted view that the cognitive function is involved in characteristic tree-drawing in patients with SZ, no study has psychophysiologically examined it. The present study aimed to investigate the involvement of cognitive function during tree-drawing in patients with SZ. For that purpose, we evaluated the brain function in patients with SZ during a tree-drawing task by using near-infrared spectroscopy (NIRS) and compared them with those in healthy controls.

PATIENTS AND METHODS

The subjects were 28 healthy controls and 28 patients with SZ. Changes in the oxygenated hemoglobin ([oxy-Hb]) concentration in both the groups during the task of drawing a tree imagined freely (free-drawing task) and the task of copying an illustration of a tree (copying task) were measured by using NIRS.

RESULTS

Because of the difference between the task conditions, [oxy-Hb] levels in controls during the free-drawing task were higher than that during the copying task at the bilateral frontal pole regions and left inferior frontal region. Because of the difference between the groups, [oxy-Hb] levels at the left middle frontal region, bilateral inferior frontal regions, bilateral inferior parietal regions, and left superior temporal region during the free-drawing task in patients were lower than that in controls.

CONCLUSION

[oxy-Hb] during the tree-drawing task in patients with SZ was lower than that in healthy controls. Our results suggest that brain dysfunction in patients with SZ might be associated with their tree-drawing.

The relationship of categorical and phonological verbal fluency to negative schizotypy and social functioning in a non-clinical sample

INTRODUCTION

Research suggests that levels of schizotypy are related to cognitive and social functioning, with negative schizotypy being particularly related to deficits in verbal fluency (VF) and distinct social skills. Considering the possibility that different VF tasks may involve both shared and unique underlying processes, this study sought to examine the separate contributions of categorical and phonological forms of VF to social functioning in those with varying levels of negative schizotypy.

METHODS

Face-to-face interviews were conducted in which 228 college students completed VF tasks, the SPQ-BR, and a social functioning questionnaire.

RESULTS

Both phonological and categorical VF were inversely related to levels of negative schizotypy and inversely related to several social functioning domains. High and low levels of negative schizotypy groups were significantly different on elements of social engagement and interpersonal behaviour. In two instances, phonological VF appeared to moderate the relationships between negative schizotypy and specific elements of social functioning.

CONCLUSIONS

These findings support a general link between verbal processing and social functioning among those with greater negative schizotypy. Possible avenues of future research are discussed.

Association between social functioning and prefrontal cortex function during a verbal fluency task in schizophrenia: A near-infrared spectroscopic study

AIM

Impaired social functioning is a common characteristic of patients with schizophrenia. Social functioning requires the complex operation of various executive functions. Deficits in the prefrontal cortex (PFC) have been implicated in executive dysfunction. Here we aimed to clarify the relation between subjectively and objectively assessed social functioning, and their associations with PFC function in patients with schizophrenia.

METHODS

Twenty-three patients and 22 age- and sex-matched healthy controls (HC) were assessed. In the schizophrenia group, self- and caregiver-rated social functioning were measured using the Specific Level of Functioning Assessment (SLOF). The hemodynamic responses elicited by a verbal fluency task (VFT) in three regions of interest in the frontotemporal area were measured using multi-channel near-infrared spectroscopy (NIRS). We also investigated psychiatric symptoms, neurocognition, and cognitive insight to assess possible confounding factors.

RESULTS

Significant positive correlations were found between self- and caregiver-rated SLOF composite scores and three subdomain scores. Self- and caregiver-rated SLOF composite scores were significantly associated with dorsolateral PFC and frontopolar cortex (DLPFC/FPC) activation during the VFT. Psychiatric symptoms, global functioning, neurocognition, and cognitive insight were not associated with NIRS signals. General psychopathology was associated with NIRS signals in the ventrolateral PFC and the anterior temporal cortex. DLPFC and FPC activity may be associated with social functioning in patients with schizophrenia.

CONCLUSION

Our results suggest that the two distinct assessments of social functioning were significantly correlated. Moreover, DLPFC and FPC function was strongly associated with social functioning and the ability to carry out daily life in patients with schizophrenia.

Associations between depressive symptoms and fronto-temporal activities during a verbal fluency task in patients with schizophrenia

Though depressive symptoms are common in patients with schizophrenia, they are often left untreated and are associated with a high relapse rate, suicidal ideation, increased mortality, reduced social adjustment, and poor quality of life. The present study aims to elucidate the association between depressive symptoms and fronto-temporal activities during a cognitive task in patients with schizophrenia. The fronto-temporal activities of 41 Japanese patients with schizophrenia was evaluated during a verbal fluency task using 52-channel near-infrared spectroscopy (NIRS). Depressive symptoms were assessed using the depression/anxiety component of the Positive and Negative Syndrome Scale (PANSS) five-factor model. The depression/anxiety component of the PANSS five-factor model was negatively correlated with activities of the ventrolateral prefrontal cortex (PFC), right dorsolateral PFC, and left temporal regions. Our findings suggest that reduced fronto-temporal activities on NIRS during a verbal fluency task is related to depressive symptom severity in patients with schizophrenia.