Cognitive performance in elderly women: significance of the 19bp insertion/deletion polymorphism in the 5' flank of the dopamine beta-hydroxylase gene, educational level, body fat measures, serum triglyceride, alcohol consumption and age

Association between dopamine beta-hydroxylase polymorphism and attention function in suicide attempters with chronic schizophrenia

BACKGROUND

Patients with schizophrenia are at a higher risk for suicide compared with the general population. Dopamine beta-hydroxylase (DβH) plays a key role in the conversion of dopamine to norepinephrine, which is related to suicidal behavior and cognitive regulation.

OBJECTIVE

To examine whether there is the effect of DβH 5'-insertion/deletion (Ins/Del) polymorphism on cognitive performance in suicide attempters with chronic schizophrenia.

METHODS

This polymorphism was detected in 114 suicide attempters and 617 non-suicide attempters with chronic schizophrenia. Cognitive performance was assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS).

RESULTS

The allelic and genotypic frequencies of this polymorphism between two groups did not differ after controlling for covariates (both, p > .05). There were no differences in RBANS scores between two groups after adjusting for covariates (all, p > .05). However, based on the genotype grouping in suicide attempters and non-attempters, the attention score significantly differed after adjusting for covariates (both, p < .05). Further analysis indicated that this polymorphism was associated with attention score in suicide attempters (p < .05), but not in non-suicide attempters (p > .05).

CONCLUSIONS

DβH 5'-Ins/Del polymorphism was not a risk locus of suicide attempters, but it was implicated in attention regulation in suicide attempters with chronic schizophrenia.

Dopaminergic gene methylation is associated with cognitive performance in a childhood monozygotic twin study

Individual differences in cognitive function are due to a combination of heritable and non-heritable factors. A large body of evidence from clinical, cognitive, and pharmacological neuroscience implicates dopaminergic gene variants as modulators of cognitive functions. Neuroepigenetic studies demonstrate environmental factors also influence complex phenotypes by affecting gene expression regulation. To evaluate the mechanism of environmental influence on cognitive abilities, we examined if epigenetic regulation of dopaminergic genes plays a role in cognition. Using a DNA methylation profiling microarray, we used a monozygotic (MZ) twin difference design to evaluate if co-twin differences in methylation of CpG sites near six dopaminergic genes predicted differences in response inhibition and memory performance. Studying MZ twins allows us to assess if environmentally driven differences in methylation affect differences in phenotype while controlling for the influence of genotype and shared family environment. Response inhibition was assessed with the flanker task and short-term and working memory were assessed with digit span recall. We found MZ co-twin differences in DRD4 gene methylation predicted differences in short-term memory. MZ differences in COMT, DBH, DAT1, DRD1, and DRD2 gene methylation predicted differences in response inhibition. Taken together, findings suggest methylation status of dopaminergic genes may influence cognitive functions in a dissociable manner. Our results highlight the importance of the epigenome and environment, over and above the influence of genotype, in supporting complex cognitive functions.

Association between DBH 19bp insertion/deletion polymorphism and cognition in schizophrenia with and without tardive dyskinesia

Long-term antipsychotic treatment for schizophrenia is associated with the development of tardive dyskinesia (TD), which is involved in increased cognitive impairment. Dopamine beta-hydroxylase (DBH) gene associated with dopamine and norepinephrine systems influences cognition. Schizophrenia with TD have higher DBH activity than those without TD. This study examined whether DBH5'-insertion/deletion (-Ins/Del) polymorphism could influence cognitive function in schizophrenia with and without TD. The presence of DBH5'-Ins/Del polymorphism was determined in 345 schizophrenia with TD and 397 schizophrenia without TD. The Abnormal Involuntary Movement Scale and Repeatable Battery for Assessment of Neuropsychological Status (RBANS) were used to assess TD severity and cognition. The allele and genotype frequencies of DBH5'-Ins/Del polymorphism did not differ between patients with and without TD (both p>0.05). RBANS total score and subscales did not differ by DBH5'-Ins/Del genotype groups in patients with TD (all p>0.05). However, attention score significantly differed by DBH5'-Ins/Del genotype groups in those without TD (p<0.05). Patients without TD who were Del homozygous had significantly lower attention score than those without TD who were Ins alleles (p<0.05). Immediate memory and attention scores were lower in patients with TD than without TD (both p<0.05). This study indicated that DBH5'-Ins/Del polymorphism may not play a role in the susceptibility to TD and cognitive deficits in schizophrenia with TD, but it may influence cognitive function in schizophrenia with non-TD. Moreover, schizophrenia with TD experienced greater cognitive deficits than those with non-TD, especially in immediate memory and attention.

The interaction of polymorphisms of IL10 and DBH was associated with general symptoms of PANSS with TD in Chinese Han schizophrenic patients

OBJECTIVE

Tardive dyskinesia (TD) is a human hyperkinetic movement disorder as a result of potentially irreversible long-term chronic first-generation antipsychotic medications. Unfortunately, mechanisms involved in the development of TD have been poorly understood. Previous studies have indicated that some genetic polymorphisms of immune system and dopamine beta-hydroxylase (DBH) genes may be involved in the pathogenesis of TD. Rs1800872 and rs72393728 are located on the promoter of interleukin-10 (IL10) and DBH gene, respectively. The genetic association between the rs1800872 and TD is unclear. Previous studies have indicated that genetic variations of IL 10 and DBH are implicated in the positive and negative symptoms in schizophrenia. However, the interaction of two variations with severity of TD and symptoms of schizophrenic patients with TD has not been reported. The present study investigated whether these variations and their interaction were associated with clinical phenotypes of TD with schizophrenia in a genetically homogeneous northern Chinese Han population.

METHODS

Rs1800872 and rs72393728 were genotyped in schizophrenic patients with TD (n = 372) and without TD (NTD; n = 412). The Abnormal Involuntary Movement Scale (AIMS) and Positive and Negative Syndrome Scale (PANSS) were applied to assess the severity of TD and psychopathology of schizophrenia, respectively.

RESULTS

The allele and genotype frequencies of rs1800872 and rs72393728 did not significantly differ between TD and NTD patients (p>0.05). No significant difference was found in the AIMS total score among the genotypes of two loci (p>0.05). Interestingly, the interaction of rs1800872 and rs72393728 showed a significant association with the PANSS general score (p = 0.011), and a trend toward to the PANSS total score (p = 0.055).

CONCLUSION

These findings suggest that the interaction of rs1800872 and rs72393728 variants may play a role in psychopathology of the general symptoms on PANSS in schizophrenic patients with TD in a northern Chinese Han population.

Association between DBH 19 bp insertion/deletion polymorphism and cognition in first-episode schizophrenic patients

Many genes associated with dopamine (DA) and norepinephrine (NE) systems influence cognitive deficits of schizophrenia patients, but one key enzyme is dopamine beta-hydroxylase (DBH), which converts DA to NE and whose activity and levels are under strong genetic control. This study examines the association of the 19 bp insertion/deletion (Ins/Del) polymorphism in the 5' flank of the DBH gene with cognitive deficits in first-episode schizophrenic patients (FEP). We assessed the cognitive function in 195 FEP and 304 healthy controls using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The 19 bp Ins/Del polymorphism of DBH gene was genotyped. Our results showed that the allelic and genotypic frequencies of the 19 bp Ins/Del polymorphism significantly differed between FEP and healthy controls (both p < 0.05). Cognitive test scores were significantly lower in FEP than healthy controls on all scales (all p < 0.001) except for the visuospatial/constructional index (p > 0.05). Immediate memory abilities significantly differed by genotype (p<0.05) but not genotype×diagnosis. Immediate memory score was lower in FEP with DBH5'-Del/Del genotype (61.3 ± 17.2) than those with DBH5'-Ins/Ins genotype (68.6 ± 16.2; p < 0.05). The 19 bp Del allele was associated with poorer immediate memory performance than the Ins allele in FEP (p < 0.05). However, healthy controls did not show any differences in cognitive function indices between the Ins and Del for either the allele or genotype of the 19 bp Ins/Del polymorphism. Our findings suggest that the DBH5'-Ins/Del polymorphism may play a role in susceptibility to FEP. The DBH5'-Ins/Del polymorphism may also influence immediate memory in FEP. Moreover, FEP had poorer cognitive function than healthy controls in all examined cognitive domains except for the visuospatial/constructional index.

The dopamine b-hydroxylase 19 bp insertion/deletion polymorphism was associated with first-episode but not medicated chronic schizophrenia

BACKGROUND

Numerous studies report dysfunctional dopaminergic and noradrenergic neurotransmission in the pathogenesis of schizophrenia. Dopamine beta-hydroxylase (DBH) is an intracellular enzyme catalyzing the conversion of dopamine to noradrenaline. Functional polymorphisms have been reported in the promoter region of DBH gene, including a 19 bp insertion/deletion polymorphism. The purpose of this study was to investigate whether there was an association between the functional polymorphism (DBH5'-Ins/Del) and schizophrenia in a Han Chinese population.

METHODS

This polymorphism was genotyped in 221 first-episode schizophrenics, 360 chronic schizophrenics and 318 healthy controls using a case-control design. We assessed their psychopathology using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

We showed that the DBH5'-Ins/Del deletion (Del) allelic and genotypic frequencies were significantly lower in controls than first-episode of schizophrenics (FES) (both p < 0.001), but controls were not different from chronic schizophrenics. Furthermore, the PANSS positive symptom and total scores were significantly higher in FES with the Del/Del genotype than those with Ins/Del and Ins/Ins genotypes (all p < 0.05).

CONCLUSIONS

The DBH5'-Ins/Del polymorphism may play a role in susceptibility to the positive symptoms of FES and to these FES not progressing on to chronic schizophrenia.

Biomarkers in geriatric psychiatry: searching for the holy grail?

PURPOSE OF REVIEW

Biomarkers in clinical medicine are used to detect or diagnose specific illnesses, predict disease progression, and predict the response to treatment. As the proportion of adults over 65 years of age rises, there is a growing need to detect neurodegenerative disease at an earlier stage with the goal of improving treatment for highly prevalent illnesses such as late-life depression and dementia.

RECENT FINDINGS

The search for biomarkers of late-life mental disorders includes the exploration of structural neuroimaging, functional neuroimaging, genomics, proteomics, noninvasive neurophysiology, cerebrospinal fluid, and plasma analysis. Novel structural and functional neuroimaging techniques that have recently been developed show promise as biomarkers of both late-life depression and specific dementia syndromes. The fields of proteomics and genomics are advancing our ability to identify genes and aberrant proteins that detect preclinical dementia. As depression is often a harbinger of dementia in late life, recent studies are beginning to elucidate the relationship between different types of late-life depression and the subsequent emergence of dementia.

SUMMARY

Biomarker research in late-life mental disorders is progressing at a rapid pace. The application of current biomarkers to clinical practice may be on the horizon with further research that refines their sensitivity and specificity.

The -1021 C/T DBH polymorphism is associated with neuropsychological performance among children and adolescents with ADHD

Catecholaminergic imbalance has increasingly been implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). The enzyme dopamine-beta-hydroxylase (D beta H)-critical to catecholaminergic regulation-is under strong genetic control, with the -1021 C/T polymorphism accounting for up to 50% of the enzymatic activity. This work aimed to investigate association between this functional polymorphism and the performance of children and adolescents with ADHD in neuropsychological measures of executive function (EF). Sixty-four drug-naive patients with ADHD undertook a Continuous Performance Test and the Wisconsin Card Sorting Test. By means of a factorial analysis, a composite measure of EF was extracted. Performance according to genotypic group was analyzed, including age as a confounder. In addition, a family-based association test was conducted as a confirmatory analysis. Principal components analysis of neuropsychological measures loaded two factors that explained 83.8% of total variance. Cognitive performance, as measured by the composite score, showed significant difference between genotypic groups after adjustment for age (P = 0.002). The CC homozygosity was associated with a diminished global EF performance, a result that was corroborated by the intra-familial analysis. The present study demonstrated an association between the neuropsychological performance of children with ADHD and a functional polymorphism in the promoter region of the DBH gene. The refinement of the ADHD phenotype by means of composite measures of EF can contribute to uncover the molecular underpinnings of ADHD.