Hippocampal volume in first-episode schizophrenia and longitudinal course of the illness

Hippocampus and amygdala volumes are reduced in patients with schizoaffective disorder

We aimed to examine the hippocampus and amygdala volumes in patients with schizoaffective disorder with the notion that schizoaffective disorder has strong resemblance of clinical presentation with schizophrenia and bipolar disorder and that there have been studies on regions of interest volumes in patients with schizophrenia and bipolar disorder but not in patients with schizoaffective disorder. Eighteen patients with schizoaffective disorder and nineteen healthy controls were included into the study. Hippocampus and amygdala volumes were examined by using the MRI. Both hippocampus and amygdala volumes were statistically significantly reduced in patients with schizoaffective disorder compared to those of the healthy control comparisons (p<0.001 for the hippocampus and p<0.001 for the amygdala). In summary, our findings of the present study suggest that patients with schizoaffective disorder seem to have smaller volumes of the hippocampus and amygdala regions and that our results were in accordance with those obtained both in patients with schizophrenia and bipolar disorder, considering that schizoaffective disorder might have neuroanatomic similarities with both schizophrenia and bipolar disorder. Beacuse of some limitations aforementioned especially age, it is required to replicate our present results in this patient group.

Volumes of hippocampal subfields suggest a continuum between schizophrenia, major depressive disorder and bipolar disorder

Objective

There is considerable debate as to whether the continuum of major psychiatric disorders exists and to what extent the boundaries extend. Converging evidence suggests that alterations in hippocampal volume are a common sign in psychiatric disorders; however, there is still no consensus on the nature and extent of hippocampal atrophy in schizophrenia (SZ), major depressive disorder (MDD) and bipolar disorder (BD). The aim of this study was to verify the continuum of SZ - BD - MDD at the level of hippocampal subfield volume and to compare the volume differences in hippocampal subfields in the continuum.

Methods

A total of 412 participants (204 SZ, 98 MDD, and 110 BD) underwent 3 T MRI scans, structured clinical interviews, and clinical scales. We segmented the hippocampal subfields with FreeSurfer 7.1.1 and compared subfields volumes across the three diagnostic groups by controlling for age, gender, education, and intracranial volumes.

Results

The results showed a gradual increase in hippocampal subfield volumes from SZ to MDD to BD. Significant volume differences in the total hippocampus and 13 of 26 hippocampal subfields, including CA1, CA3, CA4, GC-ML-DG, molecular layer and the whole hippocampus, bilaterally, and parasubiculum in the right hemisphere, were observed among diagnostic groups. Medication treatment had the most effect on subfields of MDD compared to SZ and BD. Subfield volumes were negatively correlated with illness duration of MDD. Positive correlations were found between subfield volumes and drug dose in SZ and MDD. There was no significant difference in laterality between diagnostic groups.

Conclusion

The pattern of hippocampal volume reduction in SZ, MDD and BD suggests that there may be a continuum of the three disorders at the hippocampal level. The hippocampus represents a phenotype that is distinct from traditional diagnostic strategies. Combined with illness duration and drug intervention, it may better reflect shared pathophysiology and mechanisms across psychiatric disorders.

The effect of initial antipsychotic treatment on hippocampal and amygdalar volume in first-episode schizophrenia is influenced by age

BACKGROUND

Antipsychotic treatment has been shown to yield hippocampal and amygdalar volumetric changes in first-episode schizophrenia (FES). However, whether antipsychotic induced volumetric changes interact with age remains unclear.

METHODS

The current study includes data from 120 medication naïve FES patients and 110 matched healthy controls (HC). Patients underwent MRI scans before (T1) and after (T2) antipsychotic treatment. HCs underwent MRI scans at baseline only. The hippocampus and amygdala were segmented via Freesurfer 7. General linear models were conducted to investigate the effect of age by diagnosis interaction on baseline volume. Linear mixed models (LMM) were used to detect the effect of age on volumetric changes from pre to post treatment in FES.

RESULTS

GLM revealed a trending effect (F = 3.758, p = 0.054) of age by diagnosis interaction on the baseline volume of the left (whole) hippocampus, with older FES patients showing smaller hippocampal volumes, relative to HC, when controlled sex, education years, and ICV. LMM showed a significant age by time-point interaction effect (F = 4.194, estimate effect = -1.964, p = 0.043) on left hippocampal volume in all FES and significant time effect(F = 6.608,T1-T2(estimate effect) = 62.486, p = 0.011), whereby younger patients showed greater hippocampal volumetric decreases following treatment. At the subfield level, a significant time effect emerged in left molecular_layer_HP (F = 4.509,T1-T2(estimate effect) = 12.424, p = 0.032, FDR corrected) and left cornu ammonis(CA)4 (F = 4.800,T1-T2(estimate effect) = 7.527, p = 0.046, FDR corrected), implying volumetric reduction after treatment in these subfields.

CONCLUSIONS

Our findings suggest that age plays an important role in the neuroplastic mechanisms of initial antipsychotics on the hippocampus and amygdala of schizophrenia.

Categorical and Dimensional Deficits in Hippocampal Subfields Among Schizophrenia, Obsessive-Compulsive Disorder, Bipolar Disorder, and Major Depressive Disorder

BACKGROUND

The hippocampus is a core region of interest for all major mental disorders, and its subfields implement distinctive functions. It is unclear whether the mental disorders exhibit common patterns of hippocampal impairments, and we lack knowledge on whether and how hippocampal subfields represent deficit spectra across mental disorders.

METHODS

Using brain images of 1123 individuals scanned on a single magnetic resonance imaging scanner, we examined the commonality, specificity, and symptom associations of the volume of hippocampal subfields across patients with schizophrenia, patients with obsessive-compulsive disorder, patients with bipolar disorder, patients with major depressive disorder, and healthy control subjects. We further performed a transdiagnostic analysis of the individual variability of the volume of hippocampal subfields to reflect cross-disease gradients in the hippocampus.

RESULTS

We found common and disease-specific abnormalities in a few hippocampal fields and identified 2 reliable transdiagnostic factors in the hippocampal subfields, each reflecting a spectrum of mental disorders. The plane spanned by the 2 most reliable factors provided a clearer view of hippocampal volume abnormality spectra among the major mental disorders. In addition, functional and genetic enrichment analyses supported the different roles of the 2 hippocampal factors in mental disorders.

CONCLUSIONS

The volume of hippocampal subfields reflected some commonality and specificity among the 3 major mental disorders. We propose a new pathophysiological dimensional view of the hippocampus, reflecting at least 2 spectra of mental disorders, suggesting multivariate links among the diseases. This work highlights the value of the complementary categorical and dimensional views of the hippocampal deficits in mental disorders.

Altered expression levels of miR-144-3p and ATP1B2 are associated with schizophrenia

Objectives: Schizophrenia is a devastating mental disease. Various microRNAs were proven to be associated with schizophrenia. Altered microRNA-144-3p (miR-144-3p) levels were found in various neurological and psychotic disorders. Beta2-subunit of Na(+)/K(+)-ATPase (ATP1B2) regulates neuronal migration and cell growth during brain development through the PI3K/Akt/mTOR pathway. The present study explored the associations of miR-144-3p and ATP1B2 with schizophrenia and their mutual interaction.Methods: A schizophrenic animal model employing repeated MK-801 administration was established and 293 T cells over-expressing miR-144-3p were constructed by lentivirus. The in vitro and in vivo levels of miR-144-3p, ATP1B2, and the PI3K/Akt/mTOR pathway were examined by qRT-PCR and Western Blots. The interaction between miR-144-3p and ATP1B2 was predicted and assessed by using bioinformatic methods and a luciferase reporter gene assay, respectively.Results: MiR-144-3p expression was elevated in the schizophrenic rat hippocampus. ATP1B2 was down-regulated in schizophrenic patients by analysing GEO datasets. Additionally, miR-144-3p can directly bind with ATP1B2. Furthermore, the ATP1B2 expression and PI3K/Akt/mTOR phosphorylation levels were down-regulated in the 293 T cells over-expressing miR-144-3p and schizophrenic rat hippocampus, which could be reversed by risperidone.Conclusions: This study revealed that up-regulated miR-144-3p might be associated with schizophrenia through down-regulating ATP1B2, implicating new targets of schizophrenia treatment.

Hippocampal circuit dysfunction in psychosis

Despite strong evidence of the neurodevelopmental origins of psychosis, current pharmacological treatment is not usually initiated until after a clinical diagnosis is made, and is focussed on antagonising striatal dopamine receptors. These drugs are only partially effective, have serious side effects, fail to alleviate the negative and cognitive symptoms of the disorder, and are not useful as a preventive treatment. In recent years, attention has turned to upstream brain regions that regulate striatal dopamine function, such as the hippocampus. This review draws together these recent data to discuss why the hippocampus may be especially vulnerable in the pathophysiology of psychosis. First, we describe the neurodevelopmental trajectory of the hippocampus and its susceptibility to dysfunction, exploring this region's proneness to structural and functional imbalances, metabolic pressures, and oxidative stress. We then examine mechanisms of hippocampal dysfunction in psychosis and in individuals at high-risk for psychosis and discuss how and when hippocampal abnormalities may be targeted in these groups. We conclude with future directions for prospective studies to unlock the discovery of novel therapeutic strategies targeting hippocampal circuit imbalances to prevent or delay the onset of psychosis.

Decreased resting-state neural signal in the left angular gyrus as a potential neuroimaging biomarker of schizophrenia: An amplitude of low-frequency fluctuation and support vector machine analysis

OBJECTIVE

Schizophrenia (SCH) is primarily diagnosed based on specific clinical symptoms, with the lack of any objective SCH-related biomarkers often resulting in patient misdiagnosis and the underdiagnosis of this condition. This study was developed to assess the utility of amplitude of low-frequency fluctuation (ALFF) values analyzed via support vector machine (SVM) methods as a means of diagnosing SCH.

METHODS

In total, 131 SCH patients and 128 age- and gender-matched healthy control (HC) individuals underwent resting-state functional magnetic resonance imaging (rs-fMRI), with the resultant data then being analyzed using ALFF values and SVM methods.

RESULTS

Relative to HC individuals, patients with SCH exhibited ALFF reductions in the left angular gyrus (AG), fusiform gyrus, anterior cingulate cortex (ACC), right cerebellum, bilateral middle temporal gyrus (MTG), and precuneus (PCu) regions. No SCH patient brain regions exhibited significant increases in ALFF relative to HC individuals. SVM results indicated that reductions in ALFF values in the bilateral PCu can be used to effectively differentiate between SCH patients and HCs with respective accuracy, sensitivity, and specificity values of 73.36, 91.60, and 54.69%.

CONCLUSION

These data indicate that SCH patients may exhibit characteristic reductions in regional brain activity, with decreased ALFF values of the bilateral PCu potentially offering value as a candidate biomarker capable of distinguishing between SCH patients and HCs.

Nonclinical psychotic-like experiences and schizotypy dimensions: Associations with hippocampal subfield and amygdala volumes

Schizotypy and psychotic-like experiences (PLE) form part of the wider psychosis continuum and may have brain structural correlates in nonclinical cohorts. This study aimed to compare the effects of differential schizotypy dimensions, PLE, and their interaction on hippocampal subfields and amygdala volumes in the absence of clinical psychopathology. In a cohort of 367 psychiatrically healthy individuals, we assessed schizotypal traits using the Oxford-Liverpool Inventory of Life Experiences (O-LIFE) and PLE using the short form of the Prodromal Questionnaire (PQ-16). Based on high-resolution structural MRI scans, we used automated segmentation to estimate volumes of limbic structures. Sex and total intracranial volume (Step 1), PLE and schizotypy dimensions (Step 2), and their interaction terms (Step 3) were entered as regressors for bilateral amygdala and hippocampal subfield volumes in hierarchical multiple linear regression models. Positive schizotypy, but not PLE, was negatively associated with left amygdala and subiculum volumes. O-LIFE Impulsive Nonconformity, as well as the two-way interaction between positive schizotypy and PLE, were associated with larger left subiculum volumes. None of the estimators for right hemispheric hippocampal subfield volumes survived correction for multiple comparisons. Our findings support differential associations of hippocampus subfield volumes with trait dimensions rather than PLE, and support overlap and interactions between psychometric positive schizotypy and PLE. In a healthy cohort without current psychosis risk syndromes, the positive association between PLE and hippocampal subfield volume occurred at a high expression of positive schizotypy. Further studies combining stable, transient, and genetic parameters are required.

FreeSurfer ‐based segmentation of hippocampal subfields: A review of methods and applications, with a novel quality control procedure for ENIGMA studies and other collaborative efforts

Structural hippocampal abnormalities are common in many neurological and psychiatric disorders, and variation in hippocampal measures is related to cognitive performance and other complex phenotypes such as stress sensitivity. Hippocampal subregions are increasingly studied, as automated algorithms have become available for mapping and volume quantification. In the context of the Enhancing Neuro Imaging Genetics through Meta Analysis Consortium, several Disease Working Groups are using the FreeSurfer software to analyze hippocampal subregion (subfield) volumes in patients with neurological and psychiatric conditions along with data from matched controls. In this overview, we explain the algorithm's principles, summarize measurement reliability studies, and demonstrate two additional aspects (subfield autocorrelation and volume/reliability correlation) with illustrative data. We then explain the rationale for a standardized hippocampal subfield segmentation quality control (QC) procedure for improved pipeline harmonization. To guide researchers to make optimal use of the algorithm, we discuss how global size and age effects can be modeled, how QC steps can be incorporated and how subfields may be aggregated into composite volumes. This discussion is based on a synopsis of 162 published neuroimaging studies (01/2013–12/2019) that applied the FreeSurfer hippocampal subfield segmentation in a broad range of domains including cognition and healthy aging, brain development and neurodegeneration, affective disorders, psychosis, stress regulation, neurotoxicity, epilepsy, inflammatory disease, childhood adversity and posttraumatic stress disorder, and candidate and whole genome (epi‐)genetics. Finally, we highlight points where FreeSurfer‐based hippocampal subfield studies may be optimized.

Decreased serum NCAM is positively correlated with hippocampal volumes and negatively correlated with positive symptoms in first-episode schizophrenia patients

BACKGROUND

Neural cell adhesion molecule (NCAM) plays an important role in neurodevelopmental processes and regulates hippocampal plasticity. This study investigated the relationship between the serum NCAM concentrations and hippocampal volume and psychotic symptoms in first-episode drug naïve schizophrenia (FES) patients.

METHODS

Forty-four FES patients and forty-four healthy controls (HC) were recruited in this study. Serum concentrations of NCAM were measured by ELISA. Psychiatric symptoms were assessed by the positive and negative syndrome scale (PANSS). Brain structural images were obtained using a 3T MRI Scanner and obtained T1 images were processed in order to determine hippocampal grey matter volumes.

RESULTS

Schizophrenia patients revealed significantly decreased serum NCAM concentrations (p = 0.017), which were positively correlated with the left (r = 0.523, p < 0.001) and right (r = 0.449, p = 0.041) hippocampal volumes, but negatively correlated with the PANSS positive symptom scores (r = -0.522 p = 0.001). However, no such correlations existed in the HC group.

CONCLUSIONS

This is the first time to report that decreased serum NCAM concentrations were associated with hippocampal volumes and symptom severity in FES patients. Our data indicate that the low NCAM is possible neuropathology that is associated with the decreased hippocampus in FES patients.

Integration analysis of methylation quantitative trait loci and GWAS identify three schizophrenia risk variants

Genome-wide association studies (GWAS) have identified hundreds of genetic variants associated with schizophrenia (SCZ). However, prioritizing risk variants and regulatory elements for follow-up functional studies remains a major challenge. Therefore, we performed an integrated analysis to identify variants who affect methylation levels of nearby genes and contribute to the risk of SCZ, and to explore the potential role of these variants in SCZ pathogenesis. First, we used the Summary data-based Mendelian Randomization (SMR) method to integrate GWAS and methylation quantitative trait loci data. Then, the SNP-methylation combinations as associated with SCZ were replicated across multiple samples. Totally, we identified and replicated 14 and one SNP-methylation combinations in blood and brain tissues, respectively, that significantly associated with SCZ. Furthermore, our expression quantitative trait loci analysis, differential methylation analysis, neuroimaging genetics, and cognitive genetics analysis consistently supported the potential roles of these 15 SNPs in the pathogenesis of SCZ. Finally, using the convergent functional genomics method, we prioritized three risk SNPs, including rs3765971 (RERE, P_SMR = 3.87 × 10^-8), rs55742290 (ARL6IP4, P_SMR = 1.50 × 10^-7), and rs7293091 (CENPM, P_SMR = 5.09 × 10^-7), may represent promising risk variants in SCZ. These convergent lines of evidence suggest that three risk variants may be involved in the pathogenesis of SCZ. Further investigation of the roles of these variants in the pathogenesis of SCZ is warranted.

Dentate gyrus volume deficit in schizophrenia

BACKGROUND

Schizophrenia is associated with robust hippocampal volume deficits but subregion volume deficits, their associations with cognition, and contributing genes remain to be determined.

METHODS

Hippocampal formation (HF) subregion volumes were obtained using FreeSurfer 6.0 from individuals with schizophrenia (n = 176, mean age ± s.d. = 39.0 ± 11.5, 132 males) and healthy volunteers (n = 173, mean age ± s.d. = 37.6 ± 11.3, 123 males) with similar mean age, gender, handedness, and race distributions. Relationships between the HF subregion volume with the largest between group difference, neuropsychological performance, and single-nucleotide polymorphisms were assessed.

RESULTS

This study found a significant group by region interaction on hippocampal subregion volumes. Compared to healthy volunteers, individuals with schizophrenia had significantly smaller dentate gyrus (DG) (Cohen's d = -0.57), Cornu Ammonis (CA) 4, molecular layer of the hippocampus, hippocampal tail, and CA 1 volumes, when statistically controlling for intracranial volume; DG (d = -0.43) and CA 4 volumes remained significantly smaller when statistically controlling for mean hippocampal volume. DG volume showed the largest between group difference and significant positive associations with visual memory and speed of processing in the overall sample. Genome-wide association analysis with DG volume as the quantitative phenotype identified rs56055643 (β = 10.8, p < 5 × 10-8, 95% CI 7.0-14.5) on chromosome 3 in high linkage disequilibrium with MOBP. Gene-based analyses identified associations between SLC25A38 and RPSA and DG volume.

CONCLUSIONS

This study suggests that DG dysfunction is fundamentally involved in schizophrenia pathophysiology, that it may contribute to cognitive abnormalities in schizophrenia, and that underlying biological mechanisms may involve contributions from MOBP, SLC25A38, and RPSA.

Anatomic abnormalities of hippocampal subfields in never-treated and antipsychotic-treated patients with long-term schizophrenia

Hippocampal volume deficits have been reported in chronically-treated schizophrenia patients, however, the longer-term effects of antipsychotic medications on hippocampal anatomy are unclear. This case-control study investigated volume differences in hippocampal subfields of never-treated and antipsychotic-treated patients with long-term schizophrenia. High spatial-resolution T1-weighted magnetic resonance images were collected from 29 never-treated and 40 antipsychotic-treated patients with long-term schizophrenia matched for illness duration (all ≥ 5 years), and 40 demographically-matched healthy controls. Hippocampal subfield volumes were measured using FreeSurfer v6.0, compared across groups and between hemispheres, and correlated with clinical features. Volume reductions were found in both patient groups compared to healthy controls in 8 of 26 hippocampal subfields (Cohen's d = 0.46 - 1.17, P = < .001 - .03), and more diffusely and obviously in never-treated than treated patients (Cohen's d = 0.50 - 0.90, P = < .001 - .04). Greater right-than-left volumes were seen in treated patients and healthy controls in 11 of 13 subfields (T = 2.30 - 7.29, P = < .001 - .03), but not in never-treated patients, in whom the volumes were reduced more on the right than on the left. Subfield volumes were negatively correlated with symptom severity and illness duration, and declined with age in never-treated patients. Findings indicate clinically-relevant and age-related volume reductions in hippocampal subfields of never-treated patients with long-term schizophrenia. Broader and greater subfield deficits in never-treated than treated patients, especially in the right hippocampus, suggest that long-term antipsychotic treatment may benefit hippocampal structures over the longer-term course of illness.

Study on the sub-regions volume of hippocampus and amygdala in schizophrenia

Background

Many studies have found volume changes in the hippocampus and amygdala in patients with schizophrenia, but these findings have not reached an agreement. Particularly, few results showed the volumes of the sub-regions of the amygdala. In this research, we aim to clarify volume changes of hippocampus and amygdala sub-regions in patients with schizophrenia.

Methods

The sample consisted of 69 patients with schizophrenia and 72 control subjects aged from 18 to 65 years. FreeSurfer 6.0 software was used on T1-weighted images to assess the volumes of hippocampus and amygdala and their sub-regions. The general linear model (GLM) was used to analyze the volume changes between the two groups. False discovery rate (FDR) correction was performed, and the significance level was set at 0.05.

Results

The hippocampus volume in schizophrenia showed reduction compared to healthy control (P<0.05). Several hippocampal subfields showed smaller volume in schizophrenia patients, including bilateral presubiculum and molecular layer, left hippocampal tail, subiculum and cornus ammonis (CA)1, and right parasubiculum (P<0.05). Left amygdala volume showed a decrease as well, sub-regions including the bilateral basal nucleus, anterior-amygdaloid-area (AAA), paralaminar nucleus and left lateral nucleus (P<0.05).

Conclusions

Several sub-regions of hippocampus and amygdala showed a volumetric decline in patients group, which suggest the key roles of these regions in the pathophysiology of schizophrenia. Based on these results, we speculate that these regions could be used to assess the early finding of schizophrenia.

Hippocampal subregion abnormalities in schizophrenia: A systematic review of structural and physiological imaging studies

Aim

The hippocampus is considered a key region in schizophrenia pathophysiology, but the nature of hippocampal subregion abnormalities and how they contribute to disease expression remain to be fully determined. This study reviews findings from schizophrenia hippocampal subregion volumetric and physiological imaging studies published within the last decade.

Methods

The PubMed database was searched for publications on hippocampal subregion volume and physiology abnormalities in schizophrenia and their findings were reviewed.

Results

The main replicated findings include smaller CA1 volumes and CA1 hyperactivation in schizophrenia, which may be predictive of conversion in individuals at clinical high risk of psychosis, smaller CA1 and CA4/DG volumes in first‐episode schizophrenia, and more widespread smaller hippocampal subregion volumes with longer duration of illness. Several studies have reported relationships between hippocampal subregion volumes and declarative memory or symptom severity.

Conclusions

Together these studies provide support for hippocampal formation circuitry models of schizophrenia. These initial findings must be taken with caution as the scientific community is actively working on hippocampal subregion method improvement and validation. Further improvements in our understanding of the nature of hippocampal formation subregion involvement in schizophrenia will require the collection of structural and physiological imaging data at submillimeter voxel resolution, standardization and agreement of atlases, adequate control for possible confounding factors, and multi‐method validation of findings. Despite the need for cautionary interpretation of the initial findings, we believe that improved localization of hippocampal subregion abnormalities in schizophrenia holds promise for the identification of disease contributing mechanisms.

The hippocampus is considered a key region in schizophrenia pathophysiology but the nature of hippocampal subregion abnormalities and how they contribute to disease expression remains to be fully determined. This study reviews findings from schizophrenia hippocampal subregion volumetric and physiological imaging studies published within the last decade.

Omega-3 fatty acid supplementation may prevent loss of gray matter thickness in the left parieto-occipital cortex in first episode schizophrenia: A secondary outcome analysis of the OFFER randomized controlled study

The aim of the study was to assess changes in cortical thickness related to the use of n-3 polyunsaturated fatty acids (PUFA) as add-on therapy in patients with first episode schizophrenia. A double-blind randomized controlled study was conducted using a 26-week intervention composed of concentrated fish oil containing 2.2g/d of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) or placebo (olive oil). Participants underwent MRI scanning twice to assess changes in cortical thickness: at the beginning and at the end of intervention. Data of suitable quality was obtained from 29 participants. The T1-weighted images for each participant were analyzed using FreeSurfer methodology for longitudinal pipeline. Significant differences in cortical thickness loss were observed between the groups in the parieto-occipital regions of Brodmann areas 7 and 19 of the left hemisphere, dysfunctions in which may be involved in schizophrenia symptomatology. The results of the study support the previous observations carried out in older individuals and patients with mild cognitive impairment, indicating that n-3 PUFA may have neuroprotective properties, especially at early stages of neurodegenerative diseases, such as schizophrenia. If replicated, the results of the present study may encourage clinicians to consider n-3 PUFA as a promising addition to antipsychotics for long-term treatment of schizophrenia.

Cognitive impairment in first-episode drug-naïve patients with schizophrenia: Relationships with serum concentrations of brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor

OBJECTIVES

Evidence suggests that brain-derived neurotrophic factor (BDNF) and glial cell line -derived neurotrophic factor (GDNF) are important in the regulation of synaptic plasticity, which plays a key role in the cognitive processes in psychiatric disorders. Our work aimed at exploring the associations between serum BDNF and GDNF levels and cognitive functions in first-episode drug-naïve (FEDN) patients with schizophrenia.

METHODS

The BDNF and GDNF levels of 58 FEDN patients and 55 age- and sex-matched healthy controls were measured and test subjects were examined using several neurocognitive tests including the verbal fluency test (VFT), the trail making test (TMT), the digit span test (DST), and the Stroop test.

RESULTS

Patients performed significantly worse than controls in nearly all neurocognitive performances except the forward subscale part of the DST. BDNF levels were inversely correlated to TMT-part B scores and positively correlated to VFT-action in the FEDN group. GDNF levels showed a positive correlation with VFT-action scores and a negative correlation with TMT-part B scores of these patients.

CONCLUSION

Current data suggests that cognitive dysfunction widely exists in the early stages of schizophrenia. BDNF and GDNF may be jointly contributed to the pathological mechanisms involved in cognitive impairment in FEDN patients with schizophrenia.

Influence of CFH gene on symptom severity of schizophrenia

OBJECTIVE

Recent advances have provided compelling evidence for the role of excessive complement activity in the pathophysiology of schizophrenia. In this study, we aimed to detect the association of the gene encoding complement factor H (CFH), a regulator in complement activation, with schizophrenia.

MATERIALS AND METHODS

A sample of 1783 individuals with or without schizophrenia was recruited for genetic analysis. Genomic DNA samples were extracted from peripheral blood cells using multiplex polymerase chain reaction and the SNaPshot assay. A Database for Schizophrenia Genetic Research (SZDB) was used to detect the association of brain CFH expression with schizophrenia. Next, we performed a genotype-phenotype analysis to identify the relationship between CFH Y402H polymorphism and clinical features of schizophrenia.

RESULTS

There was a significant association of hippocampal CFH expression with schizophrenia (P=0.017), whereas this significance did not survive after adjusting for false discovery rate (P=0.105). Comparing the genotype and allele frequencies of the genotyped single-nucleotide polymorphisms between case and control groups showed no significant difference. There were significant differences in the scores of negative symptoms and delayed memory between the patients with C allele and those without C allele (P<0.01 and P=0.04 after Bonferroni correction, respectively). Furthermore, we observed a marginally significant association between the Y402H polymorphism and CFH expression in the hippocampus (P=0.051); however, this significance was lost after multiple testing correction (P=0.51, after Bonferroni correction).

CONCLUSION

Our findings provide suggestive evidence for the role of CFH in the development of negative symptoms and cognitive dysfunction in schizophrenia.