Regional cerebral blood flow in first break and chronic schizophrenic patients and normal controls

Auditory efferent suppression during alternate auditory attention in schizophrenia patients with auditory hallucinations

Auditory hallucination is a complex and not yet fully understood phenomenon, and further research is necessary to elucidate the underlying mechanisms. Previous research has shown the possible contribution of abnormal efferent auditory pathways to auditory hallucinations. Given the structural and functional top-down connection between the auditory cortex and the cochlea, this study investigated the efferent auditory system in schizophrenia patients experiencing verbal auditory hallucinations (VAHs). Alternate Auditory Attention (ALAUDIN©) tasks were integrated with Contralateral Suppression of Otoacoustic Emissions (CSOAE) tasks as an assessment method. A total of 57 healthy controls (HCs) and 10 schizophrenia patients-five with recent hallucinations (SRH group) and five with nonrecent hallucinations (SNRH group) participated. Contralateral suppressors, which included white noise (WN) alone and WN in combination with ALAUDIN© tasks, were integrated with an otoacoustic emission (OAE) system to measure the suppression of cochlear outer hair cells. While no significant differences in suppression were found between the left and right ears across all groups, the SRH group demonstrated significantly greater suppression than did the HC group for contralateral suppressor 4 (CS4). Notably, incorporating the ALAUDIN© tasks could be used to measure abnormalities in the efferent auditory pathway in patients with schizophrenia with VAHs. These results suggest that the ALAUDIN©-CSOAE test could be used to examine efferent auditory pathways and differentiate schizophrenia patients with recent VAHs from healthy individuals, but further research with larger sample sizes is warranted to validate these findings.

Neuropsychological performances and brain perfusion patterns in patients with first episode psychosis

Abnormalities in cognition are a pronounced feature in primary psychotic disorders and may appear long before the manifestation of the first-episode psychosis (FEP). Although brain functional changes may precede structural alterations, brain perfusion patterns in FEP and most importantly their correlations with cognition remain poorly understood. In the present study we assessed neurocognitive functions and regional cerebral blood flow (rCBF) in 53 patients with a diagnosis of FEP. A special emphasis was placed on the assessment of basic executive functions. Cerebral perfusion patterns were measured by SPECT rCBF scintigraphy in cerebral lobes bilaterally and Brodmann Areas (BAs). Patients showed impairments in long-term verbal memory, processing speed/response latency and executive cognition. Pathological perfusion was prominent in the limbic lobes bilaterally. BAs with the largest hypoperfusion, were the subgenual area (BA25) and hippocampal areas (BA 28 and 36). The left temporal lobe was also hypoperfused, and specifically the inferior temporal gyrus (BA 20), the left middle (BA 21) and superior (BA 22) temporal gyrus, and the temporal pole (BA 38). Hypoperfusion was limited in the frontal regions, although specific BAs displayed pathological perfusion (i.e., BA 24). Cerebral lobe perfusion was not correlated with compromised cognitive abilities.

Aberrant perfusion and its connectivity within default mode network of first-episode drug-naïve schizophrenia patients and their unaffected first-degree relatives

Neural substrates behind schizophrenia (SZ) and its heritability mediated by brain function are largely unknown. Cerebral blood flow (CBF), as a biomarker of activation in the brain, reflects the neuronal metabolism, and is promisingly used to detect cerebral alteration thereby shedding light on the features of individuals at high genetic risk. We performed a cross-sectional functional magnetic resonance imaging (MRI) study enrolling 45 first-episode drug-naïve patients with SZ, 32 unaffected first-degree relatives of these patients, and 51 healthy controls (HCs). We examined CBF, CBF connectivity, and CBF topological properties. SZ patients showed increased CBF in the left medial superior frontal gyrus and right precuneus compared with HCs, and decreased CBF in the left middle temporal gyrus compared with their relatives. Furthermore, unaffected relatives revealed higher level of CBF pronounced in regions within default mode network (DMN). Both SZ patients and their relatives exhibited dysconnectivity patterns. Notably, as for the network properties, unaffected relatives were with an intermediate level between SZ patients and HCs in the local efficiency and global efficiency. Our findings demonstrate the aberrant CBF of areas within DMN and the CBF connectivity pattern might be a familial feature in the brain of first-episode SZ patients and their relatives.

A systematic review and meta-analysis of the effects of antipsychotic medications on regional cerebral blood flow (rCBF) in schizophrenia: association with response to treatment

Evaluating the short- and long-term effects of antipsychotics on brain physiology is a key factor in advancing our understanding of neurophysiological changes in psychosis and improving prediction of treatment response. Understanding the nature of such changes is crucial to the interpretation of neuroimaging findings in patients with schizophrenia and psychoses in general. This review has systematically appraised existing evidence on resting cerebral blood flow (rCBF) in schizophrenia, before and after antipsychotic treatment, relating the findings to symptom severity. The review shows that antipsychotics exert regional effects on rCBF, particularly in frontal and basal ganglia regions, and that different antipsychotic generations have differential effects on rCBF. These findings are supported by an exploratory meta-analysis of a subset of studies. The review also highlights the relative lack of studies that use a priori definitions of treatment response, which is an important step in identifying testable hypotheses and ensuring clinical relevance of remission criteria. Finally, the review highlights important considerations for future psychopharmacological studies investigating the potential for rCBF to predict symptomatic improvement, which could inform the management of treatment in schizophrenia.

Hypofrontality in schizophrenia: a meta-analysis of functional imaging studies

OBJECTIVE

Hypofrontality is not a well-replicated finding in schizophrenia either at rest or under conditions of task activation.

METHOD

Studies comparing whole brain and frontal blood flow/metabolism in schizophrenic patients and normal controls were pooled. Voxel-based studies were also combined to examine the pattern of prefrontal activation in schizophrenia.

RESULTS

Whole brain flow/metabolism was reduced in schizophrenia to only a small extent. Resting and activation frontal flow/metabolism were both reduced with a medium effect size. Duration of illness significantly moderated resting hypofrontality, but the moderating effects of neuroleptic treatment were consistent with an influence on global flow/metabolism only. Pooling of voxel-based studies did not suggest an abnormal pattern of activation in schizophrenia.

CONCLUSION

Meta-analysis supports resting hypofrontality in schizophrenia. Task-activated hypofrontality is also supported, but there is little from voxel-based studies to suggest that this is associated with an altered pattern of regional functional architecture.

Wisconsin card sorting activated regional cerebral blood flow in first break and chronic schizophrenic patients and normal controls

Dynamic 133Xe single photon emission computed tomography (SPECT) was used to measure regional cerebral blood flow (rCBF) during the Wisconsin Card Sorting test (WCS) and the Number Matching task (NM) in six never-medicated first break schizophrenic and schizophreniform patients, seven chronic schizophrenic patients, and seven normal controls. Because of a difference in mean age between first break patients and normals, we adjusted rCBF data for age effects using ANCOVA. For age-adjusted absolute superior and middle frontal rCBF bilaterally, we found significantly less activation from NM to WCS in first break patients compared to normals. Similarly, for age-adjusted absolute and relative left middle frontal rCBF, we found significantly less activation in chronics compared to normals. Changes in age-adjusted global cerebral blood flow (gCBF) were not statistically significant among the three groups, but were in the same direction as activated absolute frontal rCBF. Because of the small number of subjects in each group, the results of this study should be regarded as preliminary and interpreted cautiously.