Primary deficit schizophrenia (DS) is characterized by enduring negative symptoms and represents a qualitatively different disease entity with respect to non-deficit schizophrenia (NDS). No studies investigated the association between the enzyme paraoxonase 1 (PON1) and DS and its phenomenology.

In this case-control study, Thai women and men, aged 18 to 65 years, were divided in DS (n = 40) and NDS (n = 40) and were compared to controls (n = 40). PON1 activities against 4-(chloromethyl)phenyl acetate (CMPA) and phenylacetate were determined. Moreover, subjects were genotyped for their PON1 Q192R polymorphism and immunoglobulin A (IgA) levels responses directed to Gram-negative bacteria were measured.

DS is significantly associated with the QQ genotype and the Q allele as compared with NDS and controls. PON1 activities are significantly and inversely associated with negative symptoms, formal thought disorders, psychomotor retardation, excitation and DS. The presence of the Q allele is associated with increased IgA responses to Pseudomonas aeruginosa, Morganella morganii, and Pseudomonas putida as compared with RR carriers.

The PON1 Q allele and lower PON1 activities especially against CMPA are associated with DS, indicating lowered quorum quenching abilities as well as lowered defenses against lipoperoxidation and immune activation. It is suggested that lowered PON1 activity in DS constitutes an impairment in the innate immune system which together with lowered natural IgM may cause lower immune regulation thereby predisposing toward greater neurotoxic effects of immune-inflammatory, oxidative and nitrosative pathways and Gram-negative microbiota.

Previous studies have shown that the function of hypothalamic-pituitary-adrenal (HPA) axis is involved in the characterization of personality traits. FK506-binding protein 51 (FKBP51 or FKBP5) is a co-chaperone of heat-shock protein 90, and plays an important role in the negative feedback regulation of HPA axis function. It has been reported that a C/T single nucleotide polymorphism in the intron 2 of FKBP5 gene (rs1360780) affects FKBP5 protein levels and cortisol response to dexamethasone and psychological stress tests. Therefore, it is hypothesized that the FKBP5 polymorphism affects personality traits. In the present study, we studied the association between this polymorphism and personality traits in healthy subjects.

Subjects were 826 Japanese healthy volunteers. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the FKBP5 genotype was detected by a real-time PCR and cycling probe technology for SNP typing.

In total subjects, the group with the T allele predictive of impaired negative feedback regulation of the HPA axis had higher scores of harm avoidance (p = 0.043) and lower scores of cooperativeness (p = 0.019) compared to that without the T allele. The T allele was associated with higher scores of harm avoidance in females (p = 0.020) and lower scores of cooperativeness in males (p = 0.015).

The present study thus suggests that the FKBP5 polymorphism affects harm avoidance and cooperativeness in healthy subjects, with gender specificity.

Dopamine and norepinephrine are implicated in the characterization of personality traits. Dopamine-β-hydroxylase (DBH) is the enzyme responsible for conversion of dopamine to norepinephrine. Previous studies have shown that the -1021C/T polymorphism of the DBH gene promoter influences plasma DBH activity. Few studies investigated the association between this polymorphism and personality traits.

To examine the association between the -1021C/T DBH polymorphism and personality traits in healthy volunteers.

The participants were 627 Japanese unrelated volunteers. The subjects with present psychiatric disorders or past history of psychiatric disorders according to the DSM-IV were excluded. The DBH genotypes were identified by a PCR-RFLP method, and personality traits were assessed by the Temperament and Character Inventory (TCI). The study protocol was approved by the Ethics Committee of Yamagata University School of Medicine, and all subjects provided written informed consent to participate.

In the two-factor analysis of covariance with the DBH genotype and sex as factors and with age as a covariate, there was no main effect of the DBH genotype on any TCI score, while the interaction between the factors was significant in harm avoidance. In the post-hoc analysis, the group with the T allele predictive of lower DBH activity had higher scores of harm avoidance than that without the T allele in females (p=0.006), but not in males.

The present study suggests that the -1021C/T DBH polymorphism affects the personality trait of harm avoidance in healthy females.

Previous studies have shown that the function of hypothalamic-pituitary-adrenal (HPA) axis is involved in the characterization of personality traits. Glucocorticoid receptor (GR) is the most important regulator of the HPA axis negative feedback system, and several polymorphisms of the GR gene are associated with altered glucocorticoid sensitivity. In the present study, we examined the associations between the GR polymorphisms and personality traits in healthy subjects.

Subjects were 880 Japanese healthy volunteers. Personality traits were assessed by the Temperament and Character Inventory (TCI). Two polymorphisms of the GR gene, i.e., G/C SNP in the intron 2 (BcII polymorphism, rs41423247) and A/G SNP in the exon 9β (9β polymorphism, rs6198), were detected by a real-time PCR and cycling probe technology for SNP typing.

The genotype distributions were G/G = 614, G/C = 240, and C/C = 26 for the BcII polymorphism, and A/A = 879 and A/G = 1 for the 9β polymorphism, respectively. There were no significant associations between the BcII genotype groups in any TCI dimension score.

The present study suggests that these two GR polymorphisms (BcII and 9β polymorphism) are not involved in the characterization of personality traits in healthy subjects.

Neurocognitive and functional neuroimaging studies point to frontal lobe abnormalities in schizophrenia. Molecular and behavioural genetic studies suggest that the frontal lobe is under significant genetic influence. We carried out structural magnetic resonance imaging (MRI) of the frontal lobe in monozygotic (MZ) twins concordant or discordant for schizophrenia and healthy MZ control twins.

The sample comprised 21 concordant pairs, 17 discordant affected and 18 discordant unaffected twins from 19 discordant pairs, and 27 control pairs. Groups were matched on sociodemographic variables. Patient groups (concordant, discordant affected) did not differ on clinical variables. Volumes of superior, middle, inferior and orbital frontal gyri were calculated using the Cavalieri principle on the basis of manual tracing of anatomic boundaries. Group differences were investigated covarying for whole-brain volume, gender and age.

Results for superior frontal gyrus showed that twins with schizophrenia (i.e. concordant twins and discordant affected twins) had reduced volume compared to twins without schizophrenia (i.e. discordant unaffected and control twins), indicating an effect of illness. For middle and orbital frontal gyrus, concordant (but not discordant affected) twins differed from non-schizophrenic twins. There were no group differences in inferior frontal gyrus volume.

These findings suggest that volume reductions in the superior frontal gyrus are associated with a diagnosis of schizophrenia (in the presence or absence of a co-twin with schizophrenia). On the other hand, volume reductions in middle and orbital frontal gyri are seen only in concordant pairs, perhaps reflecting the increased genetic vulnerability in this group.

There is a growing body of data suggesting the gene-environment interaction in the characterization of personality traits, but variation in ordinary parental rearing among environmental factors has not been focused yet. We examined the effects of the interaction between the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and parental rearing on personality traits.

Subjects were 710 Japanese healthy volunteers. Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which consists of the care and protection factors. Personality assessment was performed by the Temperament and Character Inventory (TCI), which has 7 dimensions, i.e., novelty seeking, harm avoidance, reward dependence, persistence, self-directedness, cooperativeness, and self-transcendence. The BDNF Val66Met polymorphism was detected by the PCR-RFLP method.

Parental rearing has significant main effects on all TCI dimensions except novelty seeking, while no significant main effects of the BDNF genotype on the TCI scores were found. The interaction between the BDNF genotype and maternal care of the PBI had significant effects on harm avoidance and self-directedness of the TCI. Post-hoc analyses showed that decreased maternal care was correlated with increased harm avoidance and decreased self-directedness in most of the genotype groups, and for both personality traits the correlation was highest in the Met/Met genotype and lowest in the Val/Val genotype and that for the Val/Met genotype was in between the two values.

The present study suggests that the BDNF Val66Met polymorphism moderates the effects of parenting rearing, especially maternal care, on harm avoidance and self-directedness in healthy subjects.

It has been shown that certain personality traits are related to mortality and disease morbidity, but the biological mechanism linking them remains unclear. Telomeres are tandem repeat DNA sequences located at the ends of chromosomes, and shorter telomere length is a predictor of mortality and late-life disease morbidity. Thus, it is possible that personality traits influence telomere length. In the present study, we examined the relationship of leukocyte telomere length with personality traits in healthy subjects.

The subjects were 209 unrelated healthy Japanese who were recruited from medical students at 4th–5th grade. Assessment of personality traits was performed by the Revised NEO Personality Inventory (NEO-PI-R) and the Temperament and Character Inventory (TCI). Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene.

In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of neuroticism (P < 0.01) and conscientiousness (P < 0.05) of the NEO-PI-R, and lower scores of harm avoidance (P < 0.05) and reward dependence (P < 0.05) of the TCI.

The present study suggests that leukocyte telomere length is associated with some personality traits, and this association may be implicated in the relationship between personality traits and mortality.

Transnasal inferior meatal antrostomy is increasingly used for the treatment of post-Caldwell–Luc mucoceles in maxillary sinus. This study aimed to report the outcomes after inferior meatal antrostomy with a mucosal flap for recurrent mucoceles.

The records of patients who had undergone transnasal inferior meatal antrostomy with or without a mucosal flap were reviewed.

Transnasal endoscopic inferior meatal antrostomy with or without a mucosal flap was performed in 21 and 49 patients, respectively. No complications were observed. A closing of the antrostomy was found in 9 (18.4 per cent) of the 49 patients who underwent antrostomy without a mucosal flap. No closings were observed in the 21 patients who underwent antrostomy with a mucosal flap. There was a significant difference in the rate of closing for surgery with and without the mucosal flap.

Transnasal endoscopic inferior meatal antrostomy with a mucosal flap is a safe method for the treatment of post-Caldwell–Luc maxillary mucoceles that effectively prevents recurrence.