Ken Yamauchi

Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism in schizophrenia is associated with age at onset and symptoms

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor that promotes several functions of neurons and modulates neurotransmissions. It has been reported that there are alterations of BDNF levels in schizophrenic brains and that BDNF gene expressional changes would be responsible for the etiology of schizophrenia. Recent studies have shown that a variation of BDNF gene (Val66Met polymorphism) affects the function of neurons, and is associated with several neurological and psychiatrical disorders. We investigated the relationship between BDNF Val66Met polymorphism and the onset age as well as levels of clinical symptoms in 159 of chronic schizophrenia in-patients diagnosed by DSM-IV. The mean onset ages were 27.5+/-9.5 for BDNF Val/Val, 25.5+/-7.4 for BDNF Val/Met and 22.9+/-6.0 for BDNF Met/Met and this polymorphism was significantly associated with age at onset (P=0.023). The mean Brief Psychiatric Rating Scale scores (BPRS) were significantly different among those three groups (P=0.003). No significant differences were demonstrated comparing the BDNF genotype distributions of positive and negative family history (P=0.21). Our investigation indicates that the BDNF gene Val66Met polymorphism is related to the onset age of schizophrenia and the levels of clinical symptoms that remain after long-term antipsychotic treatment.

Gene expression and association analysis of vascular endothelial growth factor in major depressive disorder.

Vascular endothelial growth factor (VEGF) has been implicated in neuronal survival, neuroprotection, regeneration, growth, differentiation, and axonal outgrowth, which are known to be involved in the pathophysiology of major depressive disorder (MDD). Recently, the VEGF mRNA expression in the peripheral leukocytes from Alzheimers disease or cardiovascular disease was reported to be changed. We hypothesized that the expression of the VEGF mRNA in the peripheral leukocytes may be a good candidate for the biological marker for MDD. Thirty two patients with MDD and age- and sex-matched control subjects were included in this expression study. The VEGF mRNA levels in the peripheral leukocytes from drug-naive MDD patients were significantly higher than those from the control subjects and the magnitude of the decrease of VEGF mRNA after 8-week treatment significantly correlated with clinical improvement. Then, we genotyped two single nucleotide polymorphic markers of VEGF gene, which were reported to be associated with amyotrophic lateral sclerosis and Alzheimers disease, in patients with MDD and control subjects (n=154, each). We did not find any significant association between these markers and MDD or its clinical subtypes. Our investigation indicates that the higher expression levels of VEGF mRNA in the peripheral leukocytes are associated with the depressive state and their recovery after treatment may be associated with the clinical improvement.

The Val66Met polymorphism of the brain‐derived neurotrophic factor gene is associated with psychotic feature and suicidal behavior in Japanese major depressive patients

Recent researches have suggested that brain‐derived neurotrophic factor (BDNF) may be implicated in the pathophysiology of mood disorder. This study examined the association between the BDNF Val66Met polymorphism and major depressive disorder (MDD) in a Japanese population. We genotyped the BDNF Val66Met polymorphism in 154 major depressive patients and 154 age‐ and sex‐matched control subjects. The genotypic distributions and allele frequencies were similar among the patients and control subjects. When the relationships of the polymorphism with several clinical variables (i.e., age, sex, age of onset, number of episode, presence of psychotic features, suicidal behavior, and family history) were examined, the dose of Met allele had significant effects on psychotic feature and suicidal behavior and family history. These results suggest that the BDNF Val66Met polymorphism is not related to the development of MDD but related to clinical features of MDD in a Japanese population.

Predictors of subjective and objective quality of life in outpatients with schizophrenia

Aim:  In recent years, greater attention has been given to quality of life (QOL) in schizophrenia and several studies reported that negative and depressive symptoms and cognitive dysfunction are related to patient QOL. But because a variety of QOL measures have been used in the previous studies, there seems to be no unanimous predictors for subjective and objective QOL. The purpose of the present study was to elucidate the relationship between clinical variables and subjective and objective QOL in outpatients with schizophrenia, using schizophrenia disease‐specific QOL measures. Particular attention was paid to cognitive function as a predictor of QOL.

Serotonin transporter mRNA expression in peripheral leukocytes of patients with major depression before and after treatment with paroxetine

Serotonin transporter (5HTT) is thought to be involved in the pathophysiology of major depression and the target of antidepressants. We hypothesized that 5HTT mRNA levels in peripheral leukocytes may be associated with depressive states and the therapeutic response to antidepressant treatments. Fifteen patients with major depression and age-, sex-matched control subjects were studied. 5HTT mRNA levels were determined with quantitative real-time PCR method. 5HTT mRNA levels in leukocytes were significantly higher in depressive patients at baseline (before medication) than in control subjects. 5HTT mRNA levels were decreased significantly after 8 weeks of paroxetine medication compared with those at baseline. Our investigation suggested that the increased expression of 5HTT mRNA in peripheral leukocytes may be related with the pathophysiology of depression and its reduction after treatment may reflect the adaptive change induced by the antidepressant.

Subjective and Objective Measures of Quality of Life Have Different Predictors for People with Schizophrenia

This study investigated the relationship between subjective and objective quality of life and assessed predictors in people with schizophrenia. The study population consisted of 99 stabilized outpatients with schizophrenia (DSM-IV) who had been regularly receiving outpatient treatment at the Department of Psychiatry, The Tokushima University Hospital. Subjective and objective quality of life were estimated using the Schizophrenia Quality of Life Scale and the Quality of Life Scale, respectively. Psychiatric symptoms were also measured with the Brief Psychiatric Rating Scale and the Calgary Depression Scale for Schizophrenia. Scores on the Schizophrenia Quality of Life Scale Motivation and Energy scales significantly correlated with the Quality of Life Scale total scores –.40 (p <.001), and with the scores on Interpersonal Relations subscale –.42 (p <.001), Instrumental Role subscale –.28 (p = .005), Intrapsychic Foundations subscale –.39 (p <.001), and Common Objects and Activities subscale –.25 (p = .014). The Schizophrenia Quality of Life Scale Psychosocial scale significantly correlated with only the Quality of Life Scale total score –.20 (p = .05), and there was no significant correlation between the scores on the Schizophrenia Quality of Life Scale Symptoms and Side-effects scales and the Quality of Life Scale. Stepwise regression analyses showed that the Calgary Depression Scale for Schizophrenia score was the most important predictor of each scale of the Schizophrenia Quality of Life Scale, and the Brief Psychiatric Rating Scale Negative Symptoms score was the most important predictor of the Quality of Life Scale total score and each subscale. These results suggest that subjective and objective quality of life have different predictors and should be considered as separate and complementary outcome variables.

Interaction between catechol-O-methyltransferase (COMT) Val108/158Met and brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms in age at onset and clinical symptoms in schizophrenia

Summary.Catechol-O-methyltransferase (COMT) gene is one of the candidate genes for schizophrenia because it codes an enzyme that participates in the metabolic inactivation of dopamine and noradrenaline and a limiting factor of dopamine metabolism in the prefrontal cortex. COMT gene lies on chromosome 22q11.2, which has been associated with schizophrenia susceptibility. A single-nucleotide polymorphism of COMT gene at position 108/158 results in an amino acid substitution from valine (val) to methionine (met), which modifies its enzymatic activity and may change the brain morphology and expressional behaviors. On the other hand, brain-derived neurotrophic factor (BDNF) plays a critical role in the development of mesolimbic dopaminergic- related systems. BDNF also contains a functional single-nucleotide polymorphism at codon 66 (Val66Met) of its prodomain and this polymorphism is responsible for schizophrenia susceptibility. In this study, we first investigated the relationship between COMT Val108/158Met polymorphism and age at onset as well as levels of clinical symptoms in 158 of chronic schizophrenia inpatients and then we investigated the gene-by-gene interaction between COMT Val108/158Met polymorphism and BDNF Val66Met polymorphism with age- and sex-matched control subjects (n = 318). We concluded that the COMT Val108/158Met polymorphism was not related to either the onset at age or the levels of clinical symptoms after long-term antipsychotic treatment in schizophrenia.

Gene expression in the peripheral leukocytes and association analysis of PDLIM5 gene in schizophrenia

PDLIM5 modulates neuronal calcium signaling, co-localizes with synaptic vesicles of neurotransmitters and positive association between its gene and schizophrenia was reported but its relation is still ambiguous. The differential expression of the PDLIM5 gene both in the brain and in the lymphoblasts has been found in schizophrenia compared to control subjects. In this study, we measured the expression level of the PDLIM5 gene transcripts in the peripheral leukocytes from 19 medication-free and 21 chronically medicated schizophrenic patients as well as age- and sex-matched control subjects using a quantitative real-time PCR method. The mRNA levels of the PDLIM5 gene in the leukocytes of medication-free schizophrenic patients were significantly higher than those of control subjects. On the other hand, our group has previously shown that its mRNA expression in the leukocytes of medication-free major depressive patients was significantly lower compared with controls. There was no difference in the PDLIM5 mRNA levels between chronic schizophrenic patients with antipsychotic medication and their controls. Further, we failed to find any genetic association between the PDLIM5 gene and schizophrenia with six single nucleotide polymorphics (SNPs) of the PDLIM5 gene in Japanese subjects (279 subjects each) and there was no significant relation between PDLIM5 gene and schizophrenia with the haplotype analysis (P=0.48), either. We suggest that the higher expression levels of the PDLIM5 mRNA in the peripheral leukocytes may be a candidate marker for medication-free schizophrenic patients.

Clinical correlates associated with cognitive dysfunction in people with schizophrenia.

The purpose of the present study was to investigate the correlation between cognitive function and clinical variables in people with schizophrenia.

FKBP5, SERT and COMT mRNA expressions in the peripheral leukocytes during menstruation cycle in healthy reproductive females

There have been several evidences that the mRNA expressions in the peripheral leukocytes may indicate not only physical but also psychological states. The purpose of this study is whether the mRNA expressional changes in the leukocytes are related to the mental states across the menstrual cycle in reproductive healthy female subjects. Thirty-eight female subjects (22.4+/-1.4 year-old) were participated in this study at three menstruation cycle periods (menstrual, follicular and luteal phase). The FKBP5 (FK506-binding protein gene), SERT (serotonin transporter gene) and COMT (catechol-o-methyltransferase gene) mRNA expressions in the leukocytes were determined with hormonal data. The psychological changes were assessed with self-rating hospital anxiety and depression scale (HADS). Only one thirds of subjects (n=12) had regular menstrual cycles during the experiment. So we analyzed the data from these 12 subjects. The anxiety score of each subject was changed across the menstrual cycle (Friedman test: P<0.05). The FKBP5 mRNA expression was significantly lower in the follicular phase than in the other phases but no changes were seen in either SERT or COMT mRNA expressions among the phases. In conclusion, there are differences of HADS anxiety score and FKBP5 mRNA expression in the leukocytes across the menstrual cycle but there is no correlation between anxiety scores and FKBP5 mRNA.