Association of BDNF risk variant and dorsolateral cortical thickness with long-term treatment response to valproate in type I bipolar disorder: An exploratory study

Valproate is among the most prescribed drugs for bipolar disorder; however, 87% of patients do not report full long-term treatment response (LTTR) to this medication. One of valproate's suggested mechanisms of action involves the brain-derived neurotrophic factor (BDNF), expressed in the brain areas regulating emotions, such as the prefrontal cortex. Nonetheless, data about the role of BDNF in LTTR and its implications in the structure of the dorsolateral prefrontal cortex (dlPFC) is scarce. We explore the association of BDNF variants and dorsolateral cortical thickness (CT) with LTTR to valproate in bipolar disorder type I (BDI). Twenty-eight BDI patients were genotyped for BDNF polymorphisms rs1519480, rs6265, and rs7124442, and T1-weighted 3D brain scans were acquired. LTTR to valproate was evaluated with Alda's scale. A logistic regression analysis was conducted to evaluate LTTR according to BDNF genotypes and CT. We evaluated CT differences by genotypes with analysis of covariance. LTTR was associated with BDNF rs1519480 and right dlPFC thickness. Insufficient responders with the CC genotype had thicker right dlPFC than TC and TT genotypes. Full responders reported thicker right dlPFC in TC and TT genotypes. In conclusion, different patterns of CT related to BDNF genotypes were identified, suggesting a potential biomarker of LTTR to valproate in our population.

Looking for factors affecting functioning in euthymic patients with bipolar I disorder: the importance of cognitive complaints and BDNF's Val66Met polymorphism

INTRODUCTION

Functioning in Bipolar Disorder (BD) is affected in a substantial proportion of patients. The impact of demographic, clinical, cognitive, and genetic factors on functioning has been shown individually; however, as a complex phenomenon, a global approach to identify the most relevant as well as possible interactions is needed.

METHODS

102 patients with type I BD in euthymia were invited for evaluation of demographic, clinical, and cognitive characteristics as well as genotype for Val66Met polymorphism of BDNF gene to determine those associated with poor functioning according to the FAST scale cut-off score. Clinical evaluation included assessment of residual affective symptoms and anxiety. Cognitive evaluation included the COBRA scale, verbal memory, and executive functions testing.

RESULTS

Residual depressive symptoms, anxiety, cognitive complaints and being a Met carrier were more frequent in the poor functioning group and were entered in a logistic regression model. Being a Met carrier (OR=4.46, CI=1.19-16.67) and cognitive complaints (OR=1.29, CI= 1.13-1.46) were the most important predictors of poor functioning in type I BD.

LIMITATIONS

Cross-sectional study, with select population limiting generalizability of findings.

CONCLUSIONS

A better understanding of underlying factors affecting cognition, including the possible involvement of BDNF Val66Met polymorphism, its systematic evaluation and a continued search for targeted treatment, along with recognition and attention of residual affective and anxious symptoms might improve psychosocial outcomes such as functioning in this population.

Prefrontal cortical thickness and clinical characteristics of long-term treatment response to valproate in bipolar disorder

Valproate compositions are frequently used to treat bipolar disorder (BD); however, 87% of patients do not report full response in the long-term. There is scarce information about the clinical features and brain structural characteristics of long-term treatment response (LTTR) to this medication. In this study, we aim to evaluate the clinical characteristics and prefrontal cortical thickness (CT) of LTTR to valproate in BD. We evaluated 30 BD outpatients on valproate treatment, and 20 controls with a 3T T1-weighted 3D brain scan and Alda's scale for LTTR. An analysis of covariance was used to evaluate CT measures and a logistic regression was conducted to predict the full response (FR) using clinical features and CT measures. Patients with an insufficient response (IR) reported thinner right frontal eye fields, anterior and dorsolateral prefrontal cortexes compared with controls. FR patients presented thicker right dorsolateral prefrontal cortex than IR and no differences with controls. Patients with mixed features presented increased odds of achieving FR, while CT measures reported non-significant results. This is the first study to report mixed features as a clinical predictor of valproate LTTR. Our findings also suggest better preservation of the right prefrontal cortex of subjects with FR to valproate.

[Role of Serotonin Transporter Gene in Eating Disorders]

BACKGROUND

The serotoninergic system has been implicated in mood and appetite regulation, and the serotonin transporter gene (SLC6A4) is a commonly studied candidate gene for eating disorders. However, most studies have focused on a single polymorphism (5-HTTLPR) in SLC6A4.

OBJECTIVE

We present the studies published on the association between eating disorders (ED) and 5-HTTLPR polymorphism in anorexia nervosa (AN), bulimia nervosa (BN), and eating disorders not otherwise specified (EDNOS).

METHOD

Search of databases: MEDLINE, ISI, and PubMed for SLC6A4 and ED.

CONCLUSIONS

From a review of 37 original articles, it was suggested that carriers of S allele is a risk factor for eating disorders, especially for AN. However, BN did not show any association. Also, BMI, impulsivity, anxiety, depression, and age of onset have been associated with S allele in ED patients.