Association study of BDNF and CNTF polymorphism to depression in non-demented subjects of the "VITA" study

Astrocyte focal adhesion kinase reduces passive stress coping by inhibiting ciliary neurotrophic factor only in female mice

Astrocytes have been implicated in stress responses and produce ciliary neurotrophic factor (CNTF), which we have shown in the mouse medial amygdala (MeA) to promote passive stress coping response only in females. Pharmacological inhibition of focal adhesion kinase (FAK) upregulates CNTF expression. Here, we found that inducible knockout of FAK in astrocytes or systemic treatment with an FAK inhibitor increased passive coping behavior, i.e., immobility, in an acute forced swim stress test in female, but not male, mice. Strikingly, four weeks of chronic unpredictable stress (CUS) did not further increase passive coping in female astrocytic FAK knockout mice, whereas it exacerbated it in female wildtype mice and male mice of both genotypes. These data suggest that astrocyte FAK inhibition is required for chronic stress-induced passive coping in females. Indeed, CUS reduced phospho-FAK and increased CNTF in the female MeA. Progesterone treatment after ovariectomy activated amygdala FAK and alleviated ovariectomy-induced passive coping in wildtype, but not astrocytic FAK knockout females. This suggests that progesterone-mediated activation of FAK in astrocytes reduces female stress responses. Finally, astrocytic FAK knockout or FAK inhibitor treatment increased CNTF expression in the MeA of both sexes, although not in the hippocampus. As mentioned, MeA CNTF promotes stress responses only in females, which may explain the female-specific role of astrocytic FAK inhibition. Together, this study reveals a novel female-specific progesterone-astrocytic FAK pathway that counteracts CNTF-mediated stress responses and points to opportunities for developing treatments for stress-related disorders in women.

The association between BDNF C270T genetic variants and smoking in patients with mental disorders and in healthy controls

Studies investigating the association between smoking and the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism have reported inconclusive results, while the studies on the association of smoking status with BDNF C270T polymorphism are missing. We aimed to determine the association of smoking and BDNF Val66Met and C270T genetic variants in control subjects and patients with mental disorders. This study included 3502 Caucasian subjects: 918 healthy controls and 2584 patients with mental disorders (519 individuals with posttraumatic stress disorder (PTSD), 419 patients with depression, 996 patients with schizophrenia, and 650 patients with alcohol dependence). The frequency of the BDNF Val66Met and C270T variants were presented in codominant, dominant and recessive models. BDNF C270T, but not BDNF Val66Met polymorphism, was significantly associated with smoking in all groups, since the presence of the C270T T allele was more frequently found in smokers compared to non-smokers. Significant predictors of smoking were sex, age and BDNF C270T genetic variants. However, after detailed analysis of the separate diagnostic entities, the significant association of BDNF C270T polymorphism was confirmed only in healthy subjects, but not in patients with mental disorders; and was not related to number of cigarettes smoked per day. In patients with alcohol dependence, the severity of smoking was significantly associated with BDNF Val66Met variants. This is a first report of the significant association between the BDNF C270T polymorphism and smoking status in the large groups of Caucasian cases/controls.

Acute stress response to a cognitive task in patients with major depressive disorder: potential metabolic and proinflammatory biomarkers

Responses of the hypothalamic-pituitary-adrenal axis (HPAA), immune system and metabolic pathways are involved in adaptation to stress, while alterations in these responses have been implicated in the development of major depressive disorder (MDD). Multiple laboratory indices are known to react in response to the acute stress, however, no valid biomarkers have been reported, which can differentiate stress response in depressed individuals. The aim of this study was to assess changes in a set of laboratory parameters in patients with MDD in response to a moderate mental stress and to find potential markers of altered stress reactivity associated with depression. A group of 33 MDD patients and 43 control subjects underwent clinical evaluation to assess depression and anxiety symptoms, as well as heart rate variability (HRV) analysis. Participants were asked to perform a time constrained cognitive task, and selected hormones (cortisol, ACTH), cytokines (IL-6, IL-1β, TNF-α), neurotrophic factors (BDNF, CNTF) and metabolic parameters (glucose, cholesterol, triglycerides) were measured before and 60 min after the task performance. HRV analysis showed increased sympathetic input in MDD patients. The MDD group manifested an elevated HPAA activity as well as IL-6 and CNTF levels at baseline. A specific stress-induced increase in glucose and TNF-α was revealed in the MDD group, which was absent in control subjects. The data confirm the impairments of stress response in MDD and suggest that the reaction of simple metabolic and pro-inflammatory indices to a mild stressogenic challenge may be indicative of a depressive state.

Explorative results from multistep screening for potential genetic risk loci of Alzheimer's disease in the longitudinal VITA study cohort

Alzheimer's disease (AD) is a neurodegenerative disorder that preferentially affects individuals of advanced age. Heritability estimates for AD range between 60 and 80%, but only few genetic risk factors have been identified so far. In the present explorative study, we aimed at characterizing the genetic contribution to late-onset AD in participants of the Vienna Transdanube Aging (VITA) longitudinal birth cohort study in a two-step approach. First, we performed a genome-wide screen of pooled DNA samples (n = 588) to identify allele frequency differences between AD patients and non-AD individuals using life-time diagnoses made at the age of 80 (t = 60 months). This analysis suggested a high proportion of brain-expressed genes required for cell adhesion, cell signaling and cell morphogenesis, and also scored in known AD risk genes. In a second step, we confirmed associations using individual genotypes of top-ranked markers examining AD diagnoses as well as the dimensional scores: FULD and MMSE determined up to the age of 82.5 (t = 90 months). Taken together, our study proposes genes ANKS1B, ENST00000414107, LOC100505811, SLC22A14, QRFPR, ZDHHC8P1, ADAMTS3 and PPFIA1 as possible new candidates involved in the etiology of late-onset AD, with further research being needed to clarify their exact roles.

Stress and the Emerging Roles of Chromatin Remodeling in Signal Integration and Stable Transmission of Reversible Phenotypes

The influence of early life experience and degree of parental-infant attachment on emotional development in children and adolescents has been comprehensively studied. Structural and mechanistic insight into the biological foundation and maintenance of mammalian defensive systems (metabolic, immune, nervous and behavioral) is slowly advancing through the emerging field of developmental molecular (epi)genetics. Initial evidence revealed that differential nurture early in life generates stable differences in offspring hypothalamic-pituitary-adrenal (HPA) regulation, in part, through chromatin remodeling and changes in DNA methylation of specific genes expressed in the brain, revealing physical, biochemical and molecular paths for the epidemiological concept of gene-environment interactions. Herein, a primary molecular mechanism underpinning the early developmental programming and lifelong maintenance of defensive (emotional) responses in the offspring is the alteration of chromatin domains of specific genomic regions from a condensed state (heterochromatin) to a transcriptionally accessible state (euchromatin). Conversely, DNA methylation promotes the formation of heterochromatin, which is essential for gene silencing, genomic integrity and chromosome segregation. Therefore, inter-individual differences in chromatin modifications and DNA methylation marks hold great potential for assessing the impact of both early life experience and effectiveness of intervention programs—from guided psychosocial strategies focused on changing behavior to pharmacological treatments that target chromatin remodeling and DNA methylation enzymes to dietary approaches that alter cellular pools of metabolic intermediates and methyl donors to affect nutrient bioavailability and metabolism. In this review article, we discuss the potential molecular mechanism(s) of gene regulation associated with chromatin modeling and programming of endocrine (e.g., HPA and metabolic or cardiovascular) and behavioral (e.g., fearfulness, vigilance) responses to stress, including alterations in DNA methylation and the role of DNA repair machinery. From parental history (e.g., drugs, housing, illness, nutrition, socialization) to maternal-offspring exchanges of nutrition, microbiota, antibodies and stimulation, the nature of nurture provides not only mechanistic insight into how experiences propagate from external to internal variables, but also identifies a composite therapeutic target, chromatin modeling, for gestational/prenatal stress, adolescent anxiety/depression and adult-onset neuropsychiatric disease.

Systematic review and meta-analysis of genetic studies of late-life depression

Late-life depression (LLD) is thought to be multifactorial in etiology, including a significant genetic component. While a number of candidate gene studies have been carried out, results remain inconclusive. We undertook a systematic review of all genetic association studies of depression or depressive symptoms in late life published before February 2016, and performed meta-analyses on polymorphisms investigated in three or more independent studies. A total of 46 candidate gene studies examining 56 polymorphisms in 23 genes as well as a genome-wide association study (GWAS) were included. Meta-analyses were conducted for four polymorphisms using random effects models, of which three (APOE, BDNF, SLC6A4) were associated with LLD. These genes are implicated in hippocampal plasticity and stress reactivity, suggesting that dysregulation of these pathways may contribute to LLD. Despite using a large sample, the only GWAS published to date identified only one genome-wide significant locus in the 5q21 region. In the future, larger genetic studies specifically examining LLD, including non-hypothesis-driven GWAS, are required to further identify genetic determinants of LLD.

Genetic polymorphisms and the adequacy of brain stimulation: state of the art

INTRODUCTION

Heterogeneity of therapeutic response to brain stimulation techniques has inspired scientists to uncover the secrets to success or failure of these projects. Genetic polymorphisms are one of the major causes of this heterogeneity.

AREAS COVERED

More than twenty genetic variants within more than ten genes (e.g. BDNF, COMT, DRD2, TRPV1, 5-HT1A, 5-HHT, P2RX7, VEGF, TPH1, TPH2, ACE, APOE, GNB3, NET, NMDA receptors, and RGS4) have been investigated, among which the BDNF gene and its polymorphism, Val66Met, is the best documented variant. We review the genotypic combinations, which are reported to interact with the work of brain stimulation, of which the DRD2 C957T polymorphism is the most prominent type. Finally, implications of transcranial magnetic stimulation in deciphering the interaction between genetic background (e.g. SCN1A and 5-HTT) and drugs (e.g. carbamazepine and citalopram) at the cortical excitability level is explained. Expert commentary: Studies are ongoing to find missing factors responsible for heterogeneity of response to brain stimulation techniques. Further knowledge about genetic factors affecting the therapeutic response to brain stimulation techniques might provide helpful guidelines for choosing ideal candidates for treatment.

Investigation of association of serotonin transporter and monoamine oxidase-A genes with Alzheimer's disease and depression in the VITA study cohort: a 90-month longitudinal study

Alzheimer's disease (AD) and depression (DE) are common psychiatric disorders strongly intertwined with one another. Nevertheless, etiology and early diagnosis of the disorders are still elusive. Several genetic variations have been suggested to associate with AD and DE, particularly in genes involved in the serotonergic system such as the serotonin transporter (SERT/SLC6A4), responsible for the removal from the synaptic cleft, and the monoamine-oxidase-A (MAOA), responsible for the presynaptic degradation of serotonin. Here, we attempt to characterize this pleiotropic effect for the triallelic SERT gene-linked polymorphic region (5HTTLPR) and for the MAOA-uVNTR, in participants in the Vienna-Transdanube-Aging (VITA)-study. The VITA-study is a community-based longitudinal study following a birth cohort (75 years old at baseline examination, n = 606) from Vienna for a period of 90 months with a regular follow-up interval of 30 months. Our main finding, confirming previous reports, is that the 5HTTLPR S-allele is a risk allele for DE (OR = 1.55 CI 95% 1.03-2.32) and its carriers had a steeper increase in SGDS sum score. No association to AD was found. MAOA-uVNTR did not associate with either AD or DE. However, in AD MAOA-uVNTR S-allele carriers a steeper increase of HAMD and STAI1 sum scores (P < 0.05) was observed. Although the VITA-study cohort is rather small with low power to detect gene alterations, the uniqueness of this very thoroughly investigated and homogenous cohort strengthens the results through exceptional data collection. Still, reinvestigation in a larger cohort similar to this, as well as a meta-analysis, is important to confirm these results.

Reprint of: Effects of BDNF polymorphisms on brain function and behavior in health and disease

Brain-derived neurotrophic factor (BDNF), the most abundant neurotrophin in the brain, serves an important role during brain development and in synaptic plasticity. Given its pleiotropic effects in the central nervous system, BDNF has been implicated in cognitive function and personality development as well as the pathogenesis of various psychiatric disorders. Thus, BDNF is considered an attractive candidate gene for the study of healthy and diseased brain function and behaviors. Over the past decade, many studies have tested BDNF genetic association, particularly its functional Val66Met polymorphism, with psychiatric diseases, personality disorders, and cognitive function. Although many reports indicated a possible role for BDNF genetic effects in mental problems or brain function, other reports were unable to replicate the findings. The conflicting results in BDNF genetic studies may result from confounding factors such as age, gender, other environmental factors, sample size, ethnicity and phenotype assessment. Future studies with more homogenous populations, well-controlled confounding factors, and well-defined phenotypes are needed to clarify the BDNF genetic effects on mental diseases and human behaviors.

Effects of BDNF polymorphisms on brain function and behavior in health and disease

Brain-derived neurotrophic factor (BDNF), the most abundant neurotrophin in the brain, serves an important role during brain development and in synaptic plasticity. Given its pleiotropic effects in the central nervous system, BDNF has been implicated in cognitive function and personality development as well as the pathogenesis of various psychiatric disorders. Thus, BDNF is considered an attractive candidate gene for the study of healthy and diseased brain function and behaviors. Over the past decade, many studies have tested BDNF genetic association, particularly its functional Val66Met polymorphism, with psychiatric diseases, personality disorders, and cognitive function. Although many reports indicated a possible role for BDNF genetic effects in mental problems or brain function, other reports were unable to replicate the findings. The conflicting results in BDNF genetic studies may result from confounding factors such as age, gender, other environmental factors, sample size, ethnicity and phenotype assessment. Future studies with more homogenous populations, well-controlled confounding factors, and well-defined phenotypes are needed to clarify the BDNF genetic effects on mental diseases and human behaviors.

Peculiarities of geriatric psychiatry: a focus on aging and depression

There is a debate on whether Geriatric Psychiatry stands for itself as a discrete specialty or whether it is an extension of clinical Geriatrics, Neurology, and Psychiatry. This review aims to outline some recent data and possible approaches to define peculiarities of Geriatric Psychiatry, focusing on certain characteristics that define the aging brain. Geriatric depression is discussed taking into consideration some data from translational research. The brain aging process is not uniform. Frontal areas show marked impairment in inhibiting irrelevant information in working memory as they age, and the recruitment of these areas occur differently than in young subjects. Executive functions also change in normal elderly. Geriatric depression is a general definition of a multidimensional disorder with multiple risk factors. Dysexecutive syndrome is considered as a key to the neuropsychology of geriatric depression, correlated with functional impairment in late life. Late-onset depression has a higher load of comordibity, of cerebrovascular disease, and of some genetic factors that may be different from early onset depression. Also, there are at least four clusters of treatment outcomes that are common in geriatric depression, which mirror the neuropsychological and clinical profiles. Research and practice in Geriatric Psychiatry should focus on the interaction of various dimensions and risk factors rather than on attempting to find a single cause to the disorders. Some answers may be found in comorbidity issues, in white matter lesions, which are more common in the elderly, and in genetic factors that impact on the aging process.

Troponin and S100 beta are associated with depression in healthy older adults

OBJECTIVES

Depression has a significant impact on the functioning of older adults and often precedes cognitive decline or dementia. The current study examines the association between biomarkers related to neurocognitive outcome and depression in this population.

METHOD

Thirty-five older adults without significant neurological or psychiatric history underwent fasting blood draw and psychological testing. Self-reported measures of current and history of depression and assays for brain-derived neurotrophic factor, S100-beta, amyloid beta, and troponin were analyzed.

RESULTS

Troponin levels were found to be inversely related to current depression (r = -0.35, p = 0.03), while individuals who reported having a past history of depression had significantly higher levels of S100 beta than those who did not report this (t (33) = -2.08, p < 0.05).

CONCLUSION

The current study shows some support for the association of neurocognitive biomarkers to depression, though the mechanisms for these relationships are unclear and warrant further investigation.

Genetic risk factors and markers for Alzheimer's disease and/or depression in the VITA study

OBJECTIVES

In ageing population, both Alzheimer's disease (AD) and depression are common. Significant depressive symptoms are often co-morbid with cognitive impairment and dementia. In this study, we attempted to find various factors and markers for both AD and depression in a longitudinal cohort, the Vienna-Transdanube-Aging (VITA)-study.

METHODS

The VITA-Study consisted of 305 healthy subjects, 174 subjects with depression only, 55 subjects diagnosed with AD only and 72 subjects with depression as well as AD. Associations between AD and/or depression to gene polymorphisms APO E (epsilon4), choline acetyltransferase (ChAT) 4G to A, serotonin-transporter gene promoter-length, dopamine-D4-receptor, ciliary-neurotrophic-factor-null mutation and brain-derived neurotrophic factor (C270T) and to various known factors were analyzed.

RESULTS

AD and depression were significant associated. Significant risk factors found for AD were low education, low folic acid and depressive-symptoms, while for depression were low education and higher nonsteroidal anti-inflammatory drugs (NSAID) consume. Moreover, the ChAT polymorphism associated significant to depression. Gender, education, and ChAT significantly associated with the combination AD and/or depression.

CONCLUSION

Such studies must be conducted cautiously, as co-morbidities and gene-environmental-social influences may sway the results dramatically. We found in the VITA-study significant association between depression and AD and between ChAT polymorphism and depression.

Genetic association study of BDNF in depression: finding from two cohort studies and a meta-analysis

Depression is common and a major cause of morbidity and mortality and is also known to have serious effects on quality of life. Both clinical and pharmacologic studies have implicated the role of brain-derived neurotrophic factor (BDNF) as a susceptibility locus for the development of mental illness, including depression, bipolar disorder, and schizophrenia. Population-based genetic studies have examined the association between BDNF and a variety of depression outcomes, but the results have not clearly established the role of BDNF in the development of this complex disorder. The aim of this study was to test for associations between two genetic variants in BDNF, Val66Met (rs6265) and -270 C > T, and depression measured in two independent samples. In this analysis we included 3,548 participants from British Women's Heart and Health Study (BWHHS) and 6,836 mothers from Avon Longitudinal Study of Parents and Children (ALSPAC) who had complete data on genotype and depression outcomes. We did not detect any strong evidence of associations between any of the two polymorphisms and indicators of depression in either BWHHS or ALSPAC samples. Further, we carried out a systematic review and meta-analysis of all association studies of these two BDNF polymorphisms and depression. The meta-analysis of Val66Met in depression obtained an overall summary OR of 1.06 (95% CI: 0.89-1.26, P = 0.537) comparing MM with VV genotypes and an OR of 0.97 (95% CI: 0.89-1.05, P = 0.403) comparing MV with VV genotypes. Our findings suggest that BDNF genotype does not exert a major influence on the development of depression.

Effects of medications on plasma amyloid beta (Abeta) 42: longitudinal data from the VITA cohort

In the course of cognitive deterioration leading to Alzheimer's disease (AD) the increase of amyloid beta (Abeta42) in cerebrospinal fluid or plasma might be an initial event. We previously reported about the associations between concomitant medication and plasma Abeta42 levels in the non-demented population cohort of the Vienna transdanube aging study at baseline. In the present study, the longitudinal influence of insulin, gingko biloba, non-steroidal anti-inflammatory drugs (NSAIDs), oral anti-diabetics (sulfonylurea and biguanides), estrogens, fibrates, and statins on plasma Abeta42 are presented. Associated with medial temporal lobe atrophy (MTA), users of insulin showed significantly increased levels of Abeta42. Long-term users of gingko biloba, independent of their MTA, had significantly decreased plasma Abeta42 and the age-dependent increase of plasma Abeta42 was significantly smaller in long-term gingko biloba treated subjects. The use of fibrates also decreased plasma Abeta42 levels. In multiple testing considering interactions between medications, gender, APOE-epsilon4 presence and creatinine, insulin long-term users again showed significantly increased levels; fibrate and gingko biloba users showed a trend to rather decreased plasma Abeta42 levels compared to the non-users (p=0.05-0.08). Neither statins nor NSAIDs showed a significant effect on plasma Abeta42 in this model. Measuring the effect on cognition, no single medication studied was a significant predictor of conversion to AD or mild cognitive impairment (MCI). Whether the use of gingko biloba might prevent the conversion to MCI or AD needs to be proven in prospective, clinical trials.

Meta-analyses of genetic studies on major depressive disorder

The genetic basis of major depressive disorder (MDD) has been investigated extensively, but the identification of MDD genes has been hampered by conflicting results from underpowered studies. We review all MDD case-control genetic association studies published before June 2007 and perform meta-analyses for polymorphisms that had been investigated in at least three studies. The study selection and data extraction were performed in duplicate by two independent investigators. The 183 papers that met our criteria studied 393 polymorphisms in 102 genes. Twenty-two polymorphisms (6%) were investigated in at least three studies. Seven polymorphisms had been evaluated in previous meta-analyses, 5 of these had new data available. Hence, we performed meta-analyses for 20 polymorphisms in 18 genes. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistically significant associations were found for the APOE varepsilon2 (OR, 0.51), GNB3 825T (OR, 1.38), MTHFR 677T (OR, 1.20), SLC6A4 44 bp Ins/Del S (OR, 1.11) alleles and the SLC6A3 40 bpVNTR 9/10 genotype (OR, 2.06). To date, there is statistically significant evidence for six MDD susceptibility genes (APOE, DRD4, GNB3, MTHFR, SLC6A3 and SLC6A4).