Brain-derived neurotrophic factor (BDNF) gene not associated with antidepressant-induced mania

A genome-wide association study of antidepressant-induced mania

Antidepressant-induced mania (AIM) is a side effect of antidepressant treatment that is characterized by mania or hypomania after the start of medication. It is likely polygenic, but its genetic component remains largely unexplored. We aim to conduct the first genome-wide association study of AIM in 814 bipolar disorder patients of European ancestry. We report no significant findings from our single-marker or gene-based analyses. Our polygenic risk score analyses also did not yield significant results with bipolar disorder, antidepressant response, or lithium response. Our suggestive findings on the hypothalamic-pituitary-adrenal axis and the opioid system in AIM require independent replications.

Antidepressants that increase mitochondrial energetics may elevate risk of treatment-emergent mania

Preclinical evidence suggests that antidepressants (ADs) may differentially influence mitochondrial energetics. This study was conducted to investigate the relationship between mitochondrial function and illness vulnerability in bipolar disorder (BD), specifically risk of treatment-emergent mania (TEM). Participants with BD already clinically phenotyped as TEM+ (n = 176) or TEM- (n = 516) were further classified whether the TEM associated AD, based on preclinical studies, increased (Mito+, n = 600) or decreased (Mito-, n = 289) mitochondrial electron transport chain (ETC) activity. Comparison of TEM+ rates between Mito+ and Mito- ADs was performed using generalized estimating equations to account for participants exposed to multiple ADs while adjusting for sex, age at time of enrollment into the biobank and BD type (BD-I/schizoaffective vs. BD-II). A total of 692 subjects (62.7% female, 91.4% White, mean age 43.0 ± 14.0 years) including 176 cases (25.3%) of TEM+ and 516 cases (74.7%) of TEM- with previous exposure to Mito+ and/or Mito- antidepressants were identified. Adjusting for age, sex and BD subtype, TEM+ was more frequent with antidepressants that increased (24.7%), versus decreased (13.5%) mitochondrial energetics (OR = 2.21; p = 0.000009). Our preliminary retrospective data suggests there may be merit in reconceptualizing AD classification, not solely based on monoaminergic conventional drug mechanism of action, but additionally based on mitochondrial energetics. Future prospective clinical studies on specific antidepressants and mitochondrial activity are encouraged. Recognizing pharmacogenomic investigation of drug response may extend or overlap to genomics of disease risk, future studies should investigate potential interactions between mitochondrial mechanisms of disease risk and drug response.

Association between thyroid autoimmunity and antidepressant treatment-emergent mania in pediatric mood disorders

Risk factors associated with antidepressant treatment-emergent mania(ATEM) are poorly characterized in child and adolescent populations. To identify better biomarkers, we aimed to explore whether thyroid autoimmunity is associated with ATEM in pediatric mood disorders. We enrolled two groups of pediatric mood disorders, those with ATEM+ (n = 29) and those with ATEM- controls (n = 31). All diagnoses were made according to structured interviews by the clinicians. Autoimmune thyroiditis (anti-thyroid peroxidase antibodies [TPO-abs] and thyroid function (thyroid-stimulating hormone [TSH] and free thyroxin [FT4]) were assessed. Logistic regression was used to explore the relationship between TPO-abs seroprevalence and ATEM+ while controlling for covariates. Group comparisons showed that the patient with ATEM+ had significantly higher seroprevalence and titer of TPO-abs compared to ATEM- controls. In logistic regression analysis adjusting for age, gender, Tanner stage, body mass index, antipsychotic treatments, smoking status and family history of thyroid disorder, the seroprevalence of TPO-abs (>60 U/mL) was significantly associated with ATEM+ (OR = 3.67, 95% confidence interval [CI] = 1.2-11.1, p = 0.022). Our findings demonstrated that seroprevalence and titer of TPO-abs in pediatric mood disorders are associated with ATEM+ status. TPO-abs could potentially serve as a biomarker when assessing the risk of ATEM in the child and adolescent population.

Antidepressant-Associated Mania in Bipolar Disorder: A Review and Meta-analysis of Potential Clinical and Genetic Risk Factors

PURPOSES/BACKGROUND

Antidepressants (ADs) play a valuable role in treating the depressive episodes of bipolar disorder. However, 14% of these individuals taking ADs experience AD-associated mania (AAM) within a few weeks of starting treatment. Numerous studies have suggested potential clinical and genetic risk factors. We aimed to conduct a comprehensive systematic review and meta-analysis that integrates the past literature with the recent studies and identifies important predictors for AAM.

METHODS/PROCEDURES

The review was limited to experimentally designed studies that contain the relevant search terms in PubMed and PsychInfo. After removing studies that were in discordance with our criteria, the review included 24 reports examining clinical risk factors and 10 investigating genetic risk factors. Our meta-analysis was conducted on 5 clinical risk factors, each of which had at least 4 articles with extractable data.

FINDINGS/RESULTS

The only clinical factors in the literature that have been shown to be more indicative of AAM risk are AD monotherapy and tricyclic ADs. Among genetic factors, the serotonin transporter gene polymorphism may play a minor role in AAM. Our meta-analysis provided support for the number of prior depressive episodes.

IMPLICATIONS/CONCLUSION

Prevention of AAM may be served by early detection of recurrent depression episodes. Further large-scale longitudinal studies are required to determine the underpinnings of AAM.

Dan-Lou Prescription Inhibits Foam Cell Formation Induced by ox-LDL via the TLR4/NF-κB and PPARγ Signaling Pathways

Atherosclerosis is the major worldwide cause of mortality for patients with coronary heart disease. Many traditional Chinese medicine compound prescriptions for atherosclerosis treatment have been tried in patients. Dan-Lou prescription, which is improved from Gualou-Xiebai-Banxia decoction, has been used to treat chest discomfort (coronary atherosclerosis) for approximately 2,000 years in China. Although the anti-inflammatory activities of Dan-Lou prescription have been proposed previously, the mechanism remains to be explored. Based on the interaction between inflammation and atherosclerosis, we further investigated the effect of Dan-Lou prescription on macrophage-derived foam cell formation and disclosed the underlying mechanisms. In the oxidative low-density lipoprotein (ox-LDL) induced foam cells model using murine macrophage RAW 264.7 cells, the ethanol extract from Dan-Lou prescription (EEDL) reduced ox-LDL uptake and lipid deposition by inhibiting the protein and mRNA expression of Toll-like receptor (TLR)4 and scavenger receptor (SR)B1. After stimulation with ox-LDL, the metabolic profile of macrophages was also changed, while the intervention of the EEDL mainly regulated the metabolism of isovalerylcarnitine, arachidonic acid, cholesterol, aspartic acid, arginine, lysine, L-glutamine and phosphatidylethanolamine (36:3), which participated in the regulation of the inflammatory response, lipid accumulation and cell apoptosis. In total, 27 inflammation-related gene targets were screened, and the biological mechanisms, pathways and biological functions of the EEDL on macrophage-derived foam cells were systemically analyzed by Ingenuity Pathway Analysis system (IPA). After verification, we found that EEDL alleviated ox-LDL induced macrophage foam cell formation by antagonizing the mRNA and protein over-expression of PPARγ, blocking the phosphorylation of IKKα/β, IκBα and NF-κB p65 and maintaining the expression balance between Bax and Bcl-2. In conclusion, we provided evidences that Dan-Lou prescription effectively attenuated macrophage foam cell formation via the TLR4/NF-κB and PPARγ signaling pathways.

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.

Pharmacogenetics of antidepressant drugs: current clinical practice and future directions

While antidepressants are widely used to treat mood and anxiety disorders, only half of the patients will respond to antidepressant treatment and only one-third of patients experience a full remission of symptoms. The identification of genetic biomarkers that predict antidepressant-treatment response can improve current clinical practice. This is an emerging field known as pharmacogenetics, which comprises of genetic studies on both the pharmacokinetics and pharmacodynamics of treatment response. Recent studies on antidepressant-treatment response have focused on both aspects of pharmacogenetics research, identifying new candidate genes that may predict better treatment response for patients. This paper reviews recent findings on the pharmacogenetics of antidepressant drugs and future clinical applications. Ultimately, these studies should lead to the use of genetic testing to guide the use of antidepressants in clinical practice.

Pharmacogenomics of antidepressant induced mania: a review and meta-analysis of the serotonin transporter gene (5HTTLPR) association

BACKGROUND

Antidepressants can trigger a rapid mood switch from depression to mania. Identifying genetic risk factors associated with antidepressant induced mania (AIM) may enable individualized treatment strategies for bipolar depression. This review and meta-analysis evaluates the evidence for association between the serotonin transporter gene promoter polymorphism (5HTTLPR) and AIM.

METHODS

Medline up to November 2009 was searched for key words bipolar, antidepressant, serotonin transporter, SLC6A4, switch, and mania.

RESULTS

Five studies have evaluated the SLC6A4 promoter polymorphism and AIM in adults (total N=340 AIM+ cases, N=543 AIM- controls). Although a random effects meta-analysis showed weak evidence of association of the S allele with AIM+ status, a test of heterogeneity indicated significant differences in estimated genetic effects between studies. A similar weak association was observed in a meta-analysis based on a subset of three studies that excluded patients on mood stabilizers; however the result was again not statistically significant.

LIMITATIONS

Few pharmacogenomic studies of antidepressant treatment of bipolar disorder have been published. The completed studies were underpowered and often lacked important phenotypic information regarding potential confounders such as concurrent use of mood stabilizers or rapid cycling.

CONCLUSIONS

There is insufficient published data to confirm an association between 5HTTLPR and antidepressant induced mania. Pharmacogenomic studies of antidepressant induced mania have high potential clinical impact provided future studies are of adequate sample size and include rigorously assessed patient characteristics (e.g. ancestry, rapid cycling, concurrent mood stabilization, and length of antidepressant exposure).

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.

The role of BDNF genetic polymorphisms in bipolar disorder with psychiatric comorbidities

BACKGROUND

Bipolar disorder (BD) is a complex disorder where genetic factors play a major role in its etiology. Probably, no other axis I diagnosis has a co-morbidity prevalence as high as BD. Since BDNF is involved in different ways in various psychiatric disorders we hypothesized that its genetic polymorphisms could be associated with the co-morbidity phenomenon in BD.

METHODS

We studied 320 subjects (160 BD patients and 160 healthy controls). Genotyping was performed using made-to-order TaqMan genotyping assays (rs4923463, rs6265, rs2049045, and rs7103411). Statistical analyses were performed using UNPHASED version 3.0.12 and Haploview 4.1.

RESULTS

No genotypic, allelic or haplotype differences were found between bipolar patients and healthy controls. Concerning exclusively the rs4923463 (G/G) there was a significant association with alcoholism (p=0.009), smoking (p=0.006) and violent suicide attempt (p=0.03). We further found that the G-G haplotype (rs4923463-rs2049045) (adjusted p=0.029) and the G-T haplotype (rs4923463-rs7103411) (adjusted p=0.029) were significantly more frequent in the group with alcoholism co-morbidity when compared with the group without this co-morbidity.

LIMITATIONS

Sample size and retrospective assessment of suicide behavior and psychiatric comorbidities.

CONCLUSIONS

The results obtained in our study indicate that BDNF variants may confer susceptibility to additional psychiatric diagnosis in BD.

Effects of BDNF polymorphisms on antidepressant action

Evidence suggests that the down-regulation of the signaling pathway involving brain-derived neurotrophic factor (BDNF), a molecular element known to regulate neuronal plasticity and survival, plays an important role in the pathogenesis of major depression. The restoration of BDNF activity induced by antidepressant treatment has been implicated in the antidepressant therapeutic mechanism. Because there is variability among patients with major depressive disorder in terms of response to antidepressant treatment and since genetic factors may contribute to this inter-individual variability in antidepressant response, pharmacogenetic studies have tested the associations between genetic polymorphisms in candidate genes related to antidepressant therapeutic action. In human BDNF gene, there is a common functional polymorphism (Val66Met) in the pro-region of BDNF, which affects the intracellular trafficking of proBDNF. Because of the potentially important role of BDNF in the antidepressant mechanism, many pharmacogenetic studies have tested the association between this polymorphism and the antidepressant therapeutic response, but they have produced inconsistent results. A recent meta-analysis of eight studies, which included data from 1,115 subjects, suggested that the Val/Met carriers have increased antidepressant response in comparison to Val/Val homozygotes, particularly in the Asian population. The positive molecular heterosis effect (subjects heterozygous for a specific genetic polymorphism show a significantly greater effect) is compatible with animal studies showing that, although BDNF exerts an antidepressant effect, too much BDNF may have a detrimental effect on mood. Several recommendations are proposed for future antidepressant pharmacogenetic studies of BDNF, including the consideration of multiple polymorphisms and a haplotype approach, gene-gene interaction, a single antidepressant regimen, controlling for age and gender interactions, and pharmacogenetic effects on specific depressive symptom-clusters.

The role of BDNF as a mediator of neuroplasticity in bipolar disorder

The cognitive impairment and neuroanatomical changes that takes place among patients with bipolar disorder (BD) patients has been well described. Recent data suggest that changes in neuroplasticity, cell resilience and connectivity are the main neuropathological findings in BD. Data from differential lines of research converges to the brain-derived neurotrophic factor (BDNF) as an important contributor to the neuroplasticity changes described among BD patients. BDNF serum levels have been shown to be decreased in depressive and manic episodes, returning to normal levels in euthymia. BDNF has also been shown to decrease as the disorder progresses. Moreover, factors that negatively influence the course of BD, such as life stress and trauma have been shown to be associated with a decrease in BDNF serum levels. These findings suggest that BDNF plays a central role in the progression of BD. The present review discusses the role of BDNF as a mediator of the neuroplastic changes that occur in portion with mood episodes and the potential use of serum BDNF as a biomarker in BD.

The role of genetic variation of BDNF gene in antidepressant-induced mania in bipolar disorder

The occurrence of mania during antidepressant treatment is a key issue in the clinical management of bipolar disorder (BD). Brain-derived neurotrophic factor (BDNF) has been implicated in the pathogenesis of mood disorders. Moreover, antidepressants increase the expression of BDNF and its overactivity may be involved in the mechanism of development of the manic state. The aim of the present study was to test the influence of BDNF gene alterations in antidepressant-induced mania in bipolar patients. A case-control study was performed to analyse genotype and allele frequencies for the BDNF polymorphisms between two groups [37 patients with antidepressant-induced mania (AIM+) and 55 patients without antidepressant-induced mania (AIM-)]. No significant differences were found between AIM+ and AIM- groups. Our results did not support the BDNF gene link to antidepressant-induced mania, like a previous study with a smaller sample has already suggested.

The pharmacogenetics of antidepressant-induced mania: a systematic review and meta-analysis

OBJECTIVE

Antidepressant-induced mania (AIM) has been associated with the serotonin-transporter-linked promoter region (5-HTTLPR) polymorphism in some studies but not in others. We conducted a meta-analysis of those studies and other studies of genetic predictors of AIM.

METHODS

MEDLINE-based searches of genetic studies of AIM were conducted, and a meta-analysis of six studies of 5-HTTLPR was performed. Other polymorphisms were insufficiently studied to allow for meta-analysis.

RESULTS

There was an association of the short (s) variant of 5-HTTLPR and AIM [risk ratio (RR) = 1.35, 95% confidence interval (CI): 1.04-1.76, p=0.02]. There was a higher frequency of s carriers (sl and ss genotypes) in those who developed AIM [RR = 1.38, 95% CI: 0.98-1.93), p=0.06].

CONCLUSION

The 5-HTTLPR polymorphism appears to have a moderate effect size association with AIM in patients with bipolar disorder.

BDNF gene: functional Val66Met polymorphism in mood disorders and schizophrenia

The brain-derived neurotrophic factor (BDNF) gene has become a candidate gene for molecular-genetic studies of mood disorders and schizophrenia, and also for pharmacogenomics of drugs used in the treatment of these conditions, such as mood-stabilizers in bipolar mood disorder, antidepressants in depression, and antipsychotics in schizophrenia. It has been demonstrated that the functional Val66Met polymorphism of the gene can be associated with a number of clinical and pharmacological phenomena in these illnesses.

The role of 5-HTTLPR polymorphism in antidepressant-associated mania in bipolar disorder

BACKGROUND

The occurrence of mania during antidepressant treatment is a key issue in the clinical management of bipolar disorder (BD). The serotonin transporter gene is a candidate to be associated with antidepressant-associated mania (AAM) in some patients. This gene has a polymorphism within the promoter region (5-HTTLPR) with two allelic forms, the long (L) and the short (S) variants.

METHODS

We performed a case-control study to compare 5-HTTLPR genotype and allelic frequencies between 43 patients with a DSM-IV diagnosis of BD, with at least one manic/hypomanic episode associated with treatment with proserotonergic antidepressants (AAM+) and 69 unrelated, matched bipolar patients, who had been exposed to proserotonergic antidepressants without development of manic symptoms (AAM-(*)). Furthermore, we performed this comparison between a subgroup of 23 AAM+ patients that, when they presented AAM, were not using mood stabilizer (AAM+(*)) and 25 AAM- patients who used antidepressant without the concomitant use of a mood stabilizer (AAM-(*)). 5-HTTLPR genotyping was performed using PCR.

RESULTS

No significant differences were found between AAM+ and AAM-. Within the subgroups, our results show that S-carriers (LS+SS Genotypes) are more prone to make a manic/hypomanic episode associated with antidepressant (P=0.017).

LIMITATIONS

Our study is retrospective.

CONCLUSIONS

The 5-HTTLPR polymorphism may be considered a predictor of abnormal response to antidepressant in patients with BP, but this action is influenced by the presence of a mood stabilizer. Such observations reinforce that a correct diagnosis of bipolarity before the beginning of the treatment is essential, mainly for S-carriers patients.