Reduced prefrontal cortex activation using the Trail Making Test in schizophrenia

The histamine system and cognitive function: An in vivo H3 receptor PET imaging study in healthy volunteers and patients with schizophrenia

BACKGROUND

The histamine-3 receptor (H3R) is an auto- and heteroreceptor that inhibits the release of histamine and other neurotransmitters. Post-mortem evidence has found altered H3R expression in patients with psychotic disorders, which may underlie cognitive impairment associated with schizophrenia (CIAS).

AIMS

We used positron emission tomography (PET) imaging to compare brain uptake of an H3R selective tracer between patients with schizophrenia and matched controls (healthy individuals). Regions of interest included the dorsolateral prefrontal cortex (DLPFC) and striatum. We explored correlations between tracer uptake and symptoms, including cognitive domains.

METHODS

A total of 12 patients and 12 matched controls were recruited to the study and were assessed with psychiatric and cognitive rating scales. They received a PET scan using the H3R-specific radioligand [11C]MK-8278 to determine H3R availability.

RESULTS

There was no statistically significant difference in tracer uptake between patients and controls in the DLPFC (t19 = 0.79, p = 0.44) or striatum (t21 = 1.18, p = 0.25). An exploratory analysis found evidence for lower volume of distribution in the left cuneus (pFWE-corrected = 0.01). DLPFC tracer uptake was strongly correlated with cognition in controls (trail making test (TMT) A: r = 0.77, p = 0.006; TMT B: rho = 0.74, p = 0.01), but not in patients (TMT A: r = -0.18, p = 0.62; TMT B: rho = -0.06, p = 0.81).

CONCLUSIONS

These findings indicate H3R in the DLPFC might play a role in executive function and this is disrupted in schizophrenia in the absence of major alterations in H3R availability as assessed using a selective radiotracer for H3R. This provides further evidence for the role of H3R in CIAS.

From Neurodevelopmental to Neurodegenerative Disorders: The Vascular Continuum

Structural and functional integrity of the cerebral vasculature ensures proper brain development and function, as well as healthy aging. The inability of the brain to store energy makes it exceptionally dependent on an adequate supply of oxygen and nutrients from the blood stream for matching colossal demands of neural and glial cells. Key vascular features including a dense vasculature, a tightly controlled environment, and the regulation of cerebral blood flow (CBF) all take part in brain health throughout life. As such, healthy brain development and aging are both ensured by the anatomical and functional interaction between the vascular and nervous systems that are established during brain development and maintained throughout the lifespan. During critical periods of brain development, vascular networks remodel until they can actively respond to increases in neural activity through neurovascular coupling, which makes the brain particularly vulnerable to neurovascular alterations. The brain vasculature has been strongly associated with the onset and/or progression of conditions associated with aging, and more recently with neurodevelopmental disorders. Our understanding of cerebrovascular contributions to neurological disorders is rapidly evolving, and increasing evidence shows that deficits in angiogenesis, CBF and the blood-brain barrier (BBB) are causally linked to cognitive impairment. Moreover, it is of utmost curiosity that although neurodevelopmental and neurodegenerative disorders express different clinical features at different stages of life, they share similar vascular abnormalities. In this review, we present an overview of vascular dysfunctions associated with neurodevelopmental (autism spectrum disorders, schizophrenia, Down Syndrome) and neurodegenerative (multiple sclerosis, Huntington's, Parkinson's, and Alzheimer's diseases) disorders, with a focus on impairments in angiogenesis, CBF and the BBB. Finally, we discuss the impact of early vascular impairments on the expression of neurodegenerative diseases.

Application of Near-Infrared Spectroscopy for Evidence-Based Psychotherapy

This perspective article discusses the importance of evidence-based psychotherapy and highlights the usefulness of near-infrared spectroscopy (NIRS) in assessing the effects of psychotherapeutic interventions as a future direction of clinical psychology. NIRS is a safe and non-invasive neuroimaging technique that can be implemented in a clinical setting to measure brain activity via a simple procedure. This article discusses the possible benefits and challenges of applying NIRS for this purpose, and the available methodology based on previous studies that used NIRS to evaluate psychotherapeutic effects. Furthermore, this perspective article suggests alternative methodologies that may be useful, namely, the single- and multi-session evaluations using immediate pre- and post-intervention measurements. These methods can be used to evaluate state changes in brain activity, which can be derived from a single session of psychotherapeutic interventions. This article provides a conceptual schema important in actualizing NIRS application for evidence-base psychotherapy.

Divided Attention in Schizophrenia: A Dual Task Paradigm

Schizophrenia is known to be associated with attentional deficits. Few studies have examined whether the disorder is also associated with a deficit in the ability to divide attention, and they have given contradictory results. Some have reported that patients show greater loss of performance than healthy controls when moving from single tasks to dual tasks, and others have reported that performance loss is similar in both groups or even that patients perform the dual task better than either task on its own. To help resolve this controversy, we performed a first study in which we designed a dual task paradigm with a group of 36 healthy participants. This dual task involves 2 tasks of equivalent difficulty that make use of different sensory modalities. In the second study, we gave this dual task to 23 patients with schizophrenia and 25 healthy participants. Both groups decreased similarly their performance in dual tasks, but the patients showed lower baseline performance in the single task. Our findings suggest that patients with schizophrenia and healthy participants use similar strategies to divide their attention, but in a high-degrading stimuli condition patients perform below the controls in a single task.

Psychopathological Symptom Load and Distinguishable Cerebral Blood Flow Velocity Patterns in Patients With Schizophrenia and Healthy Controls: A Functional Transcranial Doppler Study

Introduction: Schizophrenia is a severe psychiatric disorder, with executive dysfunction and impaired processing speed playing a pivotal role in the course of the disease. In patients with schizophrenia, neurocognitive deficits appear to be related to alterations in cerebral hemodynamics. It is not fully understood if psychopathological symptom load (i.e., presence and severity of symptoms) is also related to alterations in cerebral hemodynamics. We aim to study the relationship between psychopathological symptom load and cerebral hemodynamics in the Middle Cerebral Artery (MCA) during a cognitive task in patients with schizophrenia and healthy controls. Methodology: Cerebral hemodynamics in the MCA were examined in 30 patients with schizophrenia and 15 healthy controls using functional Transcranial Doppler (fTCD) during the Trail Making Test (TMT). Psychopathological symptoms were measured using the Brief Psychiatric Rating Scale (BPRS). Patients were dichotomized according to BPRS scores: mild-moderate (BPRS < 41, n = 15) or marked-severe (BPRS ≧ 41, n = 15). Mean blood flow velocity (MFV) in the MCA and processing speed of the TMT were analyzed. Cerebral hemodynamics were analyzed using the general additional model (GAM) with a covariate analysis of variance (ANCOVA) for group comparisons. Results: Patients and healthy controls were comparable regarding demographics. Patients had a slower processing speed for the TMT-A (patients-severe: 52s, patients-moderate: 40s, healthy-controls: 32s, p = 0.019) and TMT-B [patients-severe: 111s, patients-moderate: 76s, healthy-controls: 66s, p < 0.001)]. Patients demonstrated differing hemodynamic profiles in both TMTs: TMT- A [F _{(6, 1,792)} = 17, p < 0.000); TMT-B [F _{(6, 2,692)} = 61.93, p < 0.000], with a delay in increase in MFV and a failure to return to baseline values. Conclusions: Patients with schizophrenia demonstrated slower speeds of processing during both the TMT-A and TMT-B. The speed of processing deteriorated with increasing psychopathological symptom load, additionally a distinct cerebral hemodynamic pattern in the MCA was observed. Our results further support the view that severity of schizophrenia, particularly psychopathological symptom load, influences performance in neurocognitive tasks and is related to distinct patterns of brain hemodynamics.

Cognition and interpersonal coordination of patients with schizophrenia who have sports habits

Team sports activities are effective for improving the negative symptoms and cognitive functions in patients with schizophrenia. However, the interpersonal coordination during the sports and visual cognition of patients with schizophrenia who have team sports habits are unknown. The main objectives of this study were to test two hypotheses: first, patients with schizophrenia perform the skill requiring ball passing and receiving worse than healthy controls; and second, the patients will be impaired in these functionings in accordance with the previous studies regarding schizophrenia in general. Twelve patients with schizophrenia and 15 healthy controls, who had habits in football, participated in this study. The participants performed three conventional cognitive tests and a 3-vs-1 ball possession task to evaluate their interpersonal coordination. The results showed that in the 3-vs-1 possession task, the displacement in the pass angle for the patients was significantly smaller than that for the control. The recall in the complex figure test, the performance in the trail making test, and that in the five-choice reaction task for the patients were worse than those for the control. Moreover, we found the significant partial correlations in the patients between the extradimensional shift error and the pass angle as well as between the time in the trail making test and the displacement in the pass angle, whereas there was no significant correlation in the control group. This study clarified the impaired interpersonal coordination during team sports and the visual cognition of patients with schizophrenia who have team sports habits.

Visuospatial task-related prefrontal activity is correlated with negative symptoms in schizophrenia

Control of attention is thought to be specifically impaired in schizophrenia due to abnormal function in the prefrontal cortex (PFC). The PFC plays a critical role in the identification of relevant stimuli and the development of appropriate biases for the identified signals, including selection of an appropriate attentional 'zoom'. We examined how demands associated with changes in attentional requirements in a Sustained Attention Task (SAT) may contribute to differences in functional involvement of the PFC and relation to clinical status. A group of 24 individuals with schizophrenia and 16 healthy controls (N = 40) performed the SAT and a visuospatial condition (vSAT) while activity in the bilateral anterior PFC was monitored using functional Near Infrared Spectroscopy (fNIRS). The results confirm that the right frontopolar region plays a role in control of attention for both patients and healthy controls. However, patients with schizophrenia exhibited a general attentional deficit and inefficient right-medial PFC activation. Additionally, we observed a strong regional association between left Middle Frontal Gyrus (MFG) activity during the vSAT task and the PANSS score driven by the negative symptom subscale. The presence of aberrant activation differences within the left-MFG region may describe a dysregulation of attentional networks linked to the clinical expression of negative and general symptoms.

Comparison of changes in the oxygenated hemoglobin level during a 'modified rock-paper-scissors task' between healthy subjects and patients with schizophrenia

AIM

The purpose of this study, using single-event-related near-infrared spectroscopy (NIRS), was to examine the psychophysiological and social function assessment of 30 schizophrenic patients during a modified rock-paper-scissors task.

METHODS

We set up a screen in front of the subjects, on which pictures of hand-gestures for rock, paper, and scissors were randomly presented. Subjects were asked to give verbal answers under the conditions of win, lose, and draw, respectively. Using the 44-channel NIRS system, we evaluated the maximum amplitude of oxygenated hemoglobin, latency, and the area based on the arithmetic mean of resulting values after the task between 30 outpatients with schizophrenia and 30 healthy subjects, and analyzed the frontal pole area, dorsolateral prefrontal region, and parietal association area as regions of interest (ROI).

RESULTS

In schizophrenic patients, oxygenated hemoglobin changes (Δoxy-Hb) when losing the task showed a significantly lower level of Δoxy-Hb in ROI than controls. In addition, a significant positive correlation was observed between the Global Assessment of Functioning Scale and Δoxy-Hb in ROI, and a significant negative correlation was observed between the Negative Syndrome scale of the Positive and Negative Syndrome Scale and Δoxy-Hb in ROI.

CONCLUSION

From these results, we conclude that Δoxy-Hb levels when performing the modified rock-paper-scissors task assessed using NIRS may be a useful psychophysiological marker to evaluate the cognitive and social functions of schizophrenic patients.

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.

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.

Functional near infra-red spectroscopy (fNIRS) in schizophrenia: A review

The research on the alterations in functional connectivity in schizophrenia has been facilitated by development of an array of functional neuroimaging techniques. Functional Near Infra Red Spectroscopy (fNIRS) is a novel diffuse optical neuromonitring method with its own advantages and limitations. The advantages of fNIRS have made it to be frequently used as a research tool by medical community in different settings. In fNIRS the property of haemoglobin to absorb near infrared light is used to measure brain activity. It provides the indirect measurement of the neuronal activity in the areas of interest. The advantage of fNIRS being less restrictive has made it to be used more commonly in the research of psychiatric disorders in general, schizophrenia in particular. The fNIRS studies on patients with schizophrenia have shown haemodynamic hypo activation primarily in the prefrontal cortex during various cognitive tasks. In this review, initially we have briefly explained the basic principles of fNIRS followed by detailed review of fNIRS findings in patients with schizophrenia.

P300 and neuropsychological measurements in patients with schizophrenia and their healthy biological siblings

BACKGROUND

Patients with schizophrenia and their first-degree relatives' exhibit abnormalities in neuropsychological and electrophysiological measures especially P300. The aim was to study the P300 and neuropsychological measures together in patients with schizophrenia, their unaffected siblings, and normal controls.

MATERIALS AND METHODS

Thirty patients diagnosed as schizophrenia, their unaffected biological siblings, and normal controls were included in the study. Inpatient group, the severity of symptoms was assessed by Positive and Negative Syndrome Scale. All subjects were administered P300 event-related potential, which was measured using oddball paradigm and specific neuropsychological tests from NIMHANS neuropsychiatry battery.

RESULTS

Both patients with schizophrenia and their unaffected biological siblings showed lower P300 amplitude and longer P300 latency when compared with the normal controls. The three groups showed statistically significant differences in digit symbol substitution test, digit vigilance test, Trail making test B and Stroop test (P < 0.001).

CONCLUSION

Patients with schizophrenia and their unaffected biological siblings show deficits in both cognitive function tests and P300 event-related potential. Our results suggest a continuum in the electrophysiological and neuropsychological measures among the three groups.

Determinants of cerebral hemodynamics during the Trail Making Test in schizophrenia

Patients with schizophrenia show deficits in cognitive functioning, and studies on cerebral hemodynamics have revealed aberrant patterns of mean cerebral blood flow velocity (MFV), an equivalent of cerebral blood flow (CBF). Therefore, we carried out a controlled study that assessed MFV in schizophrenia during a well-known neuropsychological task, the Trail Making Test (TMT). We measured MFV in the middle cerebral arteries using functional transcranial Doppler sonography in 15 schizophrenia patients and 15 healthy subjects. In comparison to healthy subjects, patients performed poorer on the TMT-A and the TMT-B, and there was increased cerebral blood flow velocity during the TMT-B. A comparison of subgroups of patients and controls matched in performance on the TMT-B revealed that these patients still showed significantly increased cerebral blood flow velocity. Increased MFV in schizophrenia suggests specific alterations of cerebral hemodynamics during the Trail Making Test, Part B, which are not detectable during visuomotor activity, and which are independent of performance. These findings emphasize the pathophysiological importance of cognitive functioning in schizophrenia, but cast doubts whether performance in this particular test plays a relevant role for CBF abnormalities in schizophrenia.

Does a combined intervention program of repetitive transcranial magnetic stimulation and intensive occupational therapy affect cognitive function in patients with post-stroke upper limb hemiparesis?

Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) to the contralesional hemisphere and intensive occupational therapy (iOT) have been shown to contribute to a significant improvement in upper limb hemiparesis in patients with chronic stroke. However, the effect of the combined intervention program of LF-rTMS and iOT on cognitive function is unknown. We retrospectively investigated whether the combined treatment influence patient's Trail-Making Test part B (TMT-B) performance, which is a group of easy and inexpensive neuropsychological tests that evaluate several cognitive functions. Twenty-five patients received 11 sessions of LF-rTMS to the contralesional hemisphere and 2 sessions of iOT per day over 15 successive days. Patients with right- and left-sided hemiparesis demonstrated significant improvements in upper limb motor function following the combined intervention program. Only patients with right-sided hemiparesis exhibited improved TMT-B performance following the combined intervention program, and there was a significant negative correlation between Fugl-Meyer Assessment scale total score change and TMT-B performance. The results indicate the possibility that LF-rTMS to the contralesional hemisphere combined with iOT improves the upper limb motor function and cognitive function of patients with right-sided hemiparesis. However, further studies are necessary to elucidate the mechanism of improved cognitive function.

Transcriptional regulation of GAD1 GABA synthesis gene in the prefrontal cortex of subjects with schizophrenia

Expression of GAD1 GABA synthesis enzyme is highly regulated by neuronal activity and reaches mature levels in the prefrontal cortex not before adolescence. A significant portion of cases diagnosed with schizophrenia show deficits in GAD1 RNA and protein levels in multiple areas of adult cerebral cortex, possibly reflecting molecular or cellular defects in subtypes of GABAergic interneurons essential for network synchronization and cognition. Here, we review 20years of progress towards a better understanding of disease-related regulation of GAD1 gene expression. For example, deficits in cortical GAD1 RNA in some cases of schizophrenia are associated with changes in the epigenetic architecture of the promoter, affecting DNA methylation patterns and nucleosomal histone modifications. These localized chromatin defects at the 5' end of GAD1 are superimposed by disordered locus-specific chromosomal conformations, including weakening of long-range promoter-enhancer loopings and physical disconnection of GAD1 core promoter sequences from cis-regulatory elements positioned 50 kilobases further upstream. Studies on the 3-dimensional architecture of the GAD1 locus in neurons, including developmentally regulated higher order chromatin compromised by the disease process, together with exploration of locus-specific epigenetic interventions in animal models, could pave the way for future treatments of psychosis and schizophrenia.

Single event-related changes in cerebral oxygenated hemoglobin using word game in schizophrenia

Neuroimaging studies have been conducted using word generation tasks and have shown greater hypofrontality in patients with schizophrenia compared with healthy subjects. In this study, we compared the characteristics of oxygenated hemoglobin changes involved in both phonological and categorical verbal fluency between 35 outpatients with schizophrenia and 35 healthy subjects during a Japanese "shiritori" task using single-event-related near-infrared spectroscopy. During this task, the schizophrenic patients showed significantly smaller activation in the prefrontal cortex area than the controls. In addition, a significant positive correlation was obtained between oxygenated hemoglobin changes (prefrontal cortex area, inferior parietal area) and the severity of positive psychiatric symptoms. It is possible that hypofrontality of patients may be a diagnostic assistance tool for schizophrenia, and that the relationship between activation and positive syndrome scores may be of help in predicting functional outcome in patients.