BDNF levels and genotype are associated with antipsychotic-induced weight gain in patients with chronic schizophrenia

Novel ketamine and zinc treatment for anorexia nervosa and the potential beneficial interactions with the gut microbiome

Anorexia nervosa (AN) is a severe illness with diverse aetiological and maintaining contributors including neurobiological, metabolic, psychological, and social determining factors. In addition to nutritional recovery, multiple psychological and pharmacological therapies and brain-based stimulations have been explored; however, existing treatments have limited efficacy. This paper outlines a neurobiological model of glutamatergic and γ-aminobutyric acid (GABA)-ergic dysfunction, exacerbated by chronic gut microbiome dysbiosis and zinc depletion at a brain and gut level. The gut microbiome is established early in development, and early exposure to stress and adversity contribute to gut microbial disturbance in AN, early dysregulation to glutamatergic and GABAergic networks, interoceptive impairment, and inhibited caloric harvest from food (e.g., zinc malabsorption, competition for zinc ions between gut bacteria and host). Zinc is a key part of glutamatergic and GABAergic networks, and also affects leptin and gut microbial function; systems dysregulated in AN. Low doses of ketamine in conjunction with zinc, could provide an efficacious combination to act on NMDA receptors and normalise glutamatergic, GABAergic and gut function in AN.

Pharmacogenetics of Antipsychotic Treatment in Schizophrenia

Antipsychotics are the mainstay treatment for schizophrenia. There is large variability between individuals in their response to antipsychotics, both in efficacy and adverse effects of treatment. While the source of interindividual variability in antipsychotic response is not completely understood, genetics is a major contributing factor. The identification of pharmacogenetic markers that predict antipsychotic efficacy and adverse reactions is a growing area of research and holds the potential to replace the current trial-and-error approach to treatment selection in schizophrenia with a personalized medicine approach.In this chapter, we provide an overview of the current state of pharmacogenetics in schizophrenia treatment. The most promising pharmacogenetic findings are presented for both antipsychotic response and commonly studied adverse reactions. The application of pharmacogenetics to schizophrenia treatment is discussed, with an emphasis on the clinical utility of pharmacogenetic testing and directions for future research.

BDNF, GDNF, NGF and Klotho levels and neurocognitive functions in acute term of schizophrenia

BACKGROUND

Klotho and its relationship with neurotrophic factors and cognition in schizophrenia has not yet been investigated. In this study, the hypothesis that the blood serum levels of BDNF, GDNF, NGF and Klotho in schizophrenia patients and healthy controls would be related to cognitive functions was investigated.

METHODS

In this study, two groups were assessed: schizophrenia patients (case group) who were hospitalised in the Psychiatry Clinic of Sakarya University Training and Research Hospital and healthy volunteers (control group). The patients were evaluated on the 1st and 20th days of their hospitalisation with the Positive and Negative Syndrome Scale (PANSS), the Brief Psychiatric Rating Scale (BPRS), the General Assessment of Functioning Scale (GAF) and the Clinical Global Impression Scale (CGI). For cognitive assessment, both groups were evaluated with the Wechsler Memory Scale-Visual Production Subtest (Wechsler Memory Scale III-Visual Reproduction Subtest) and the Stroop test.

RESULTS

BDNF, GDNF, NGF and Klotho levels were lower in schizophrenia patients than in healthy controls. In the schizophrenia patients, on the 20th day of treatment, there was a statistically significant increase in BDNF compared to the 1st day of treatment. BDNF, GDNF and Klotho showed positive correlations with some cognitive functions in the healthy controls. BDNF, GDNF, NGF and Klotho levels were intercorrelated and predictive of each other in both groups.

CONCLUSION

This study suggests a relationship between cognitive functions, neurotrophic factors and Klotho. Most of the results are the first of their kind in the extant literature, while other results are either similar to or divergent from those generated in previous studies. Therefore, new, enhanced studies are needed to clarify the role of Klotho and neurotrophic factors in schizophrenia.

Negative Correlation between Serum Brain-derived Neurotrophic Factor Levels and Obesity Predictor Markers and Inflammation Levels in Females with Obesity

BACKGROUND: Obesity has been widely associated with structural and functional changes in the brain, whereas inflammation is one of the potential mechanisms involved in these changes. OBJECTIVE: This study aims to prove the relationship between serum brain-derived neurotrophic factor (BDNF) levels and obesity predictor markers (body mass index and waist to hip ratio) and inflammation (interleukin-6 and Tumor Necrosis Factor-alpha) levels in females with obesity. METHODS: This study used a cross-sectional study method using 33 females with obesity aged 19-23 years, body mass index (BMI) > 27.5 kg/m2, normal blood pressure, normal resting heart rate (RHR), normal hemoglobin (Hb), and fasting blood glucose (FBG) ≤ 100 mg/dL. The examination of serum BDNF, IL-6, and TNF-α levels using the Enzyme-Linked Immunosorbent Assay (ELISA) method. The data were analyzed using Pearson product-moment test with a significant levels p<0.05. RESULTS: The results indicated that there is a negative correlation between serum BDNF levels and BMI (r = –0.759; p<0.001), WHR (r = –0.675; p<0.001), IL-6 levels (r = –0.530; p<0.001) and TNF-α levels (r = –0.561; p<0.001). CONCLUSION: Based on the results of the study, there is a negative correlation between serum BDNF levels and BMI, waist to hip ratio, and inflammation (interleukin-6 and Tumor Necrosis Factor-alpha) levels in females with obesity. Further studies are needed to confirm the present findings.

The association between BDNF levels and risperidone-induced weight gain is dependent on the BDNF Val66Met polymorphism in antipsychotic-naive first episode schizophrenia patients: a 12-week prospective study

A growing number of studies have shown that brain-derived neurotrophic factor (BDNF) is associated with weight gain during antipsychotic treatment in schizophrenia patients. However, there is still a lack of research results in the initial stage of antipsychotic treatment. This study aimed to evaluate the relationship between weight gain caused by risperidone monotherapy for 12 weeks and BDNF level in antipsychotic-naive and first-episode (ANFE) patients with schizophrenia, and we hypothesize that this may depend on BDNF Val66Met gene polymorphism. In a 12-week longitudinal trial, 225 ANFE patients were enrolled and treated with risperidone. Body weight was measured at baseline and during the 12-week follow-up. After treatment, the average weight of ANFE patients increased by 2.6 kg. Furthermore, we found that in patients with Val/Val genotype, the increase in serum BDNF levels was negatively correlated with risperidone-induced weight gain (r = -0.44, p = 0.008). Regression analysis showed that the baseline BDNF level was a predictor of weight gain after treatment (β = -0.45, t = -3.0, p = 0.005). Our results suggest that the BDNF signaling may be involved in weight gain caused by risperidone treatment. Furthermore, the negative association between weight gain and increased BDNF levels during risperidone treatment in ANFE schizophrenia depends on the BDNF Val66Met polymorphism.

Genetic Testing for Antipsychotic Pharmacotherapy: Bench to Bedside

There is growing research interest in learning the genetic basis of response and adverse effects with psychotropic medications, including antipsychotic drugs. However, the clinical utility of information from genetic studies is compromised by their controversial results, primarily due to relatively small effect and sample sizes. Clinical, demographic, and environmental differences in patient cohorts further explain the lack of consistent results from these genetic studies. Furthermore, the availability of psychopharmacological expertise in interpreting clinically meaningful results from genetic assays has been a challenge, one that often results in suboptimal use of genetic testing in clinical practice. These limitations explain the difficulties in the translation of psychopharmacological research in pharmacogenetics and pharmacogenomics from bench to bedside to manage increasingly treatment-refractory psychiatric disorders, especially schizophrenia. Although these shortcomings question the utility of genetic testing in the general population, the commercially available genetic assays are being increasingly utilized to optimize the effectiveness of psychotropic medications in the treatment-refractory patient population, including schizophrenia. In this context, patients with treatment-refractory schizophrenia are among of the most vulnerable patients to be exposed to the debilitating adverse effects from often irrational and high-dose antipsychotic polypharmacy without clinically meaningful benefits. The primary objective of this comprehensive review is to analyze and interpret replicated findings from the genetic studies to identify specific genetic biomarkers that could be utilized to enhance antipsychotic efficacy and tolerability in the treatment-refractory schizophrenia population.

Brain-Derived Neurotrophic Factor Modulates the Effect of Sex on the Descending Pain Modulatory System in Healthy Volunteers

OBJECTIVES

We investigated sex differences and the influence of brain-derived neurotrophic factor (BDNF) in the descending pain modulatory system (DPMS), as measured by change on the numerical pain scale (NPS; 0-10) during conditioned pain modulation (CPM task; primary outcome) and by function of the corticospinal motor pathway and heat pain thresholds (HPTs; secondary outcomes).

METHODS

This cross-sectional study included healthy volunteers ranging in age from 18 to 45 years (32 male and 24 female). Assessment included serum BDNF, HPT, change on the NPS (0-10) during the CPM task, and motor-evoked potential (MEP) using transcranial magnetic stimulation (TMS).

RESULTS

The MEP (Mv) amplitude was larger in male participants compared with female participants (mean [SE] = 1.55 [0.34] vs mean [SE] = 1.27 [0.27], respectively, P = 0.001). The mean NPS (0-10) during CPM task changed more substantially for female compared with male participants (mean [SE] = -3.25 [2.01] vs mean [SE] = -2.29 [1.34], respectively, P = 0.040). In addition, a higher serum BDNF (adjusted index for age) was associated with a larger decrease of the NPS during CPM task (P = 0.003), although further regression analyses by sex showed that this was only significant for females (P = 0.010).

CONCLUSIONS

Significant sex differences were identified in DPMS function and corticospinal motor pathway integrity. Nevertheless, BDNF was associated with the function of the DPMS in female but not male participants, indicating that sex and neuroplasticity state are crucial factors for pain perception in healthy subjects.

The Burden of Antipsychotic-Induced Weight Gain and Metabolic Syndrome in Children

Antipsychotic medications are critical to child and adolescent psychiatry, from the stabilization of psychotic disorders like schizophrenia, bipolar disorder, and psychotic depression to behavioral treatment of autism spectrum disorder, tic disorders, and pediatric aggression. While effective, these medications carry serious risk of adverse events-most commonly, weight gain and cardiometabolic abnormalities. Negative metabolic consequences affect up to 60% of patients and present a major obstacle to long-term treatment. Since antipsychotics are often chronically prescribed beginning in childhood, cardiometabolic risk accumulates. An increased susceptibility to antipsychotic-induced weight gain (AIWG) has been repeatedly documented in children, particularly rapid weight gain. Associated cardiometabolic abnormalities include central obesity, insulin resistance, dyslipidemia, and systemic inflammation. Lifestyle interventions and medications such as metformin have been proposed to reduce risk but remain limited in efficacy. Furthermore, antipsychotic medications touted to be weight-neutral in adults can cause substantial weight gain in children. A better understanding of the biological underpinnings of AIWG could inform targeted and potentially more fruitful treatments; however, little is known about the underlying mechanism. As yet, modest genetic studies have nominated a few risk genes that explain only a small percentage of the risk. Recent investigations have begun to explore novel potential mechanisms of AIWG, including a role for gut microbiota and microbial metabolites. This article reviews the problem of AIWG and AP metabolic side effects in pediatric populations, proposed mechanisms underlying this serious side effect, and strategies to mitigate adverse impact. We suggest future directions for research efforts that may advance the field and lead to improved clinical interventions.

Gut microbiota: An intermediary between metabolic syndrome and cognitive deficits in schizophrenia

Gut microbiome interacts with the central nervous system tract through the gut-brain axis. Such communication involves neuronal, endocrine, and immunological mechanisms, which allows for the microbiota to affect and respond to various behaviors and psychiatric conditions. In addition, the use of atypical antipsychotic drugs (AAPDs) may interact with and even change the abundance of microbiome to potentially cause adverse effects or aggravate the disorders inherent in the disease. The regulate effects of gut microbiome has been described in several psychiatric disorders including anxiety and depression, but only a few reports have discussed the role of microbiota in AAPDs-induced Metabolic syndrome (MetS) and cognitive disorders. The following review systematically summarizes current knowledge about the gut microbiota in behavior and psychiatric illness, with the emphasis of an important role of the microbiome in the metabolism of schizophrenia and the potential for AAPDs to change the gut microbiota to promote adverse events. Prebiotics and probiotics are microbiota-management tools with documented efficacy for metabolic disturbances and cognitive deficits. Novel therapies for targeting microbiota for alleviating AAPDs-induced adverse effects are also under fast development.

Association study of the BDNF gene polymorphism (G196A) with overweight/obesity among women from Northwest of Iran

Background

Obesity is a health problem defined by surplus body fat accumulation and is one of the leading causes of morbidity and mortality. Earlier studies indicated the influence of brain-derived neurotrophic factor (BDNF) molecular alterations in the development of obesity. One of these variations is the G196A single nucleotide polymorphism (Val66Met; SNP rs6265), which impairs intracellular trafficking and reduces the secretion of BDNF. In this study, we evaluated the possible association of G196A polymorphism of the BDNF gene with body mass index (BMI) among women from the Iranian Azeri Turkish ethnic group. Four hundred eighty-four women including 343 women with obesity or overweight and 141 age-sex and ethnically matched healthy controls were genotyped for G196A SNP of BDNF gene by applying polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) method. The association of this polymorphism with BMI was evaluated using analysis of covariance (ANCOVA), and the comparison of alleles and genotypes frequencies between patients (obese and/or overweight participants) and healthy controls was carried out using logistic regression models.

Results

Individuals carrying Met-Met genotype have a significantly lower mean of BMI in comparison to those carrying non-Met/Met polymorphisms (P = 0.0138).

Conclusions

In this study, the association of the Val66Met polymorphism of the BDNF gene with BMI as an obesity trait has been confirmed among the women from the Northwest of Iran.

Pharmacogenetics of Antipsychotic Drug Treatment: Update and Clinical Implications

Numerous genetic variants have been shown to be associated with antipsychotic response and adverse effects of schizophrenia treatment. However, the clinical application of these findings is limited. The aim of this narrative review is to summarize the most recent publications and recommendations related to the genetics of antipsychotic treatment and shed light on the clinical utility of pharmacogenetics/pharmacogenomics (PGx). We reviewed the literature on PGx studies with antipsychotic drugs (i.e., antipsychotic response and adverse effects) and commonly used commercial PGx tools for clinical practice. Publications and reviews were included with emphasis on articles published between January 2015 and April 2018. We found 44 studies focusing on antipsychotic response and 45 studies on adverse effects (e.g., antipsychotic-induced weight gain, movement disorders, hormonal abnormality, and clozapine-induced agranulocytosis/granulocytopenia), albeit with mixed results. Overall, several gene variants related to antipsychotic response and adverse effects in the treatment of patients with schizophrenia have been reported, and several commercial pharmacogenomic tests have become available. However, further well-designed investigations and replication studies in large and well-characterized samples are needed to facilitate the application of PGx findings to clinical practice.

Progress in Genetic Polymorphisms Related to Lipid Disturbances Induced by Atypical Antipsychotic Drugs

Metabolic side effects such as weight gain and disturbed lipid metabolism are often observed in the treatment of atypical antipsychotic drugs (AAPDs), which contribute to an excessive prevalence of metabolic syndrome among schizophrenic patients. Great individual differences are observed but the underlying mechanisms are still uncertain. Research on pharmacogenomics indicates that gene polymorphisms involved in the pathways controlling food intake and lipid metabolism may play a significant role. In this review, relevant genes (HTR2C, DRD2, LEP, NPY, MC4R, BDNF, MC4R, CNR1, INSIG2, ADRA2A) and genetic polymorphisms related to metabolic side effects of AAPDs especially dyslipidemia were summarized. Apart from clinical studies, in vitro and in vivo evidence is also analyzed to support related theories. The association of central and peripheral mechanisms is emphasized, enabling the possibility of using peripheral gene expression to predict the central status. Novel methodological development of pharmacogenomics is in urgent need, so as to provide references for individualized medication and further to shed some light on the mechanisms underlying AAPD-induced lipid disturbances.

Does metabolic status affect serum levels of BDNF and MMP-9 in patients with schizophrenia?

The purpose of the article: Brain-derived neurotrophic factor (BDNF) and matrix metalloproteinase-9 (MMP-9) are involved in the processes of neurogenesis, synaptic plasticity, learning and memory. Growing number of studies shows a relationship between BDNF or MMP-9 and schizophrenia. Also, BDNF and MMP-9 levels may be affected by metabolic parameters, such as obesity or dyslipidemia. Our hypothesis is that alterations of BDNF or MMP-9 levels in schizophrenia might be secondary to metabolic abnormalities, often found among schizophrenia patients. Materials and methods: We have compared BDNF and MMP-9 between patients with schizophrenia (n = 64, age 49 ± 8.2 y) and healthy controls (n = 32, age 51 ± 8.9 y) in the context of cardio-metabolic parameters. Serum levels of BDNF and MMP-9 were measured using ELISA test, body composition parameters were determined using bioelectric impedance analysis. Results and conclusions: Our results showed significantly lowered serum BDNF concentration in the schizophrenia group (schizophrenia: 23.8 ± 7.83 ng/mL, control: 27.69 ± 8.11 ng/mL, p = 0.03). Serum MMP-9 concentration in schizophrenia group did not differ compared with the control group (schizophrenia: 456.8 ± 278.4 ng/mL, control: 341.5 ± 162.4 ng/mL, p = 0.07). After adjusting for age, all anthropometric parameters, body composition and laboratory tests BDNF were still significantly lower in the schizophrenia group. However, MMP-9 became significantly elevated in the schizophrenia group after adjusting for several anthropometric and body composition covariates. Our results confirmed reduced serum BDNF concentration in patients with schizophrenia. Also, this reduction seems to be independent of metabolic abnormalities. On the other hand, our hypothesis that MMP-9 level in schizophrenia is altered due to metabolic abnormalities might be true.

Health Benefits of Endurance Training: Implications of the Brain-Derived Neurotrophic Factor-A Systematic Review

This article presents a concept that wide expression of brain-derived neurotrophic factor (BDNF) and its receptors (TrkB) in the nervous tissue, evoked by regular endurance training (ET), can cause numerous motor and metabolic adaptations, which are beneficial for human health. The relationships between the training-evoked increase of endogenous BDNF and molecular and/or physiological adaptations in the nervous structures controlling both motor performance and homeostasis of the whole organism have been presented. Due to a very wide range of plastic changes that ET has exerted on various systems of the body, the improvement of motor skills and counteraction of the development of civilization diseases resulting from the posttraining increase of BDNF/TrkB levels have been discussed, as important for people, who undertake ET. Thus, this report presents the influence of endurance exercises on the (1) transformation of motoneuron properties, which are a final element of the motor pathways, (2) reduction of motor deficits evoked by Parkinson disease, and (3) prevention of the metabolic syndrome (MetS). This review suggests that the increase of posttraining levels of BDNF and its TrkB receptors causes simultaneous changes in the activity of the spinal cord, the substantia nigra, and the hypothalamic nuclei neurons, which are responsible for the alteration of the functional properties of motoneurons innervating the skeletal muscles, for the enhancement of dopamine release in the brain, and for the modulation of hormone levels involved in regulating the metabolic processes, responsively. Finally, training-evoked increase of the BDNF/TrkB leads to a change in a manner of regulation of skeletal muscles, causes a reduction of motor deficits observed in the Parkinson disease, and lowers weight, glucose level, and blood pressure, which accompany the MetS. Therefore, BDNF seems to be the molecular factor of pleiotropic activity, important in the modulation processes, underlying adaptations, which result from ET.

Testing the role of genetic variation of the MC4R gene in Chinese population in antipsychotic-induced metabolic disturbance

Antipsychotic-induced metabolic disturbance (AIMD) is a common adverse effect of antipsychotics with genetics partly underpinning variation in susceptibility among schizophrenia patients. Melanocortin4 receptor (MC4R) gene, one of the candidate genes for AIMD, has been under-studied in the Chinese patients. We conducted a pharmacogenetic study in a large cohort of Chinese patients with schizophrenia. In this study, we investigated the genetic variation of MC4R in Chinese population by genotyping two SNPs (rs489693 and rs17782313) in 1,991 Chinese patients and examined association of these variants with the metabolic effects that were often observed to be related to AIMD. Metabolic measures, including body mass index (BMI), waist circumference (WC), glucose, triglyceride, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels were assessed at baseline and after 6-week antipsychotic treatment. We found that interaction of SNP×medication status (drug-naïve/medicated) was significantly associated with BMI, WC, and HDL change %, respectively. Both SNPs were significantly associated with baseline BMI and WC in the medicated group. Moderate association of rs489693 with WC, Triglyceride, and HDL change % were observed in the whole sample. In the drug-naïve group, we found recessive effects of rs489693 on BMI gain more than 7%, WC and Triglyceride change %, with AA incurring more metabolic adverse effects. In conclusion, the association between rs489693 and the metabolic measures is ubiquitous but moderate. Rs17782313 is less involved in AIMD. Two SNPs confer risk of AIMD to patients treated with different antipsychotics in a similar way.

Sex difference in the association of body mass index and BDNF levels in Chinese patients with chronic schizophrenia

RATIONALE AND OBJECTIVE

Schizophrenia displays sex differences in many aspects. Decreased brain-derived neurotrophic factor (BDNF) levels have been reported to be associated with high body weight or obesity as well as other psychopathological aspects in schizophrenia patients. This study aimed to explore sex differences in the relationship between serum BDNF levels and obesity in patients with chronic schizophrenia.

METHODS

We recruited 132 Chinese patients with chronic schizophrenia (98 males and 34 females) and compared sex differences in the body mass index (BMI), obesity, serum BDNF levels, and their associations. Psychopathology symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). A regression model with various demographic and clinical variables was applied to predict the serum levels of BDNF.

RESULTS

Female patients had a higher rate of obesity and higher BMI, but lower BDNF levels than male schizophrenia patients. A significantly negative correlation was observed between BMI and BDNF levels only in female patients but not in male patients. The multiple regression model with demographic and clinical variables significantly predicted BDNF levels only in female patients, with a medium size effect. And only in female patients, BMI made a significant contribution to this prediction.

CONCLUSION

Our results indicate significant sex differences in the obesity, BMI, BDNF levels, and their association in chronic patients with schizophrenia, showing a significant inverse correlation between BMI and BDNF levels only in female patients. Thus, sex needs to be considered when assessing the relationship between BDNF and metabolic syndromes in schizophrenia.

Effects of smoking on cognition and BDNF levels in a male Chinese population: relationship with BDNF Val66Met polymorphism

Recent studies demonstrate that brain-derived neurotrophic factor (BDNF) might be associated with nicotine addiction, and circulating BDNF is a biomarker of memory and general cognitive function. Moreover, studies suggest that a functional polymorphism of the BDNF Val66Met may mediate hippocampal-dependent cognitive functions. We aimed to explore the relationships between smoking, cognitive performance and BDNF in a normal Chinese Han population. We recruited 628 male healthy subjects, inducing 322 smokers and 306 nonsmokers, and genotyped them the BDNF Val66Met polymorphism. Of these, we assessed 114 smokers and 98 nonsmokers on the repeatable battery for the assessment of neuropsychological status (RBANS), and 103 smokers and 89 nonsmokers on serum BDNF levels. Smokers scored lower than the nonsmokers on RBANS total score (p = 0.002), immediate memory (p = 0.003) and delayed memory (p = 0.021). BDNF levels among the smokers who were Val allele carriers were correlated with the degree of cognitive impairments, especially attention, as well as with the carbon monoxide concentrations. Our findings suggest that smoking is associated with cognitive impairment in a male Chinese Han population. The association between higher BDNF levels and cognitive impairment, mainly attention in smokers appears to be dependent on the BDNF Val66Met polymorphism.

Pharmacogenetic Correlates of Antipsychotic-Induced Weight Gain in the Chinese Population

Antipsychotic-induced weight gain (AIWG) is a common adverse effect of this treatment, particularly with second-generation antipsychotics, and it is a major health problem around the world. We aimed to review the progress of pharmacogenetic studies on AIWG in the Chinese population to compare the results for Chinese with other ethnic populations, identify the limitations and problems of current studies, and provide future research directions in China. Both English and Chinese electronic databases were searched to identify eligible studies. We determined that > 25 single-nucleotide polymorphisms in 19 genes have been investigated in association with AIWG in Chinese patients over the past few decades. HTR2C rs3813929 is the most frequently studied single-nucleotide polymorphism, and it seems to be the most strongly associated with AIWG in the Chinese population. However, many genes that have been reported to be associated with AIWG in other ethnic populations have not been included in Chinese studies. To explain the pharmacogenetic reasons for AIWG in the Chinese population, genome-wide association studies and multiple-center, standard, unified, and large samples are needed.

BDNF as a pharmacogenetic target for antipsychotic treatment of schizophrenia

Antipsychotic drugs remain the mainstay of pharmacotherapy for schizophrenia. As there are large individual variations in efficacy and side-effects of antipsychotic drugs, there is a strong demand for personalized medication to treat schizophrenia. Pharmacogenetic research into antipsychotic drugs has examined a number of genetic variants and only a few polymorphisms have been found which promise to be associated with the therapeutic efficacy and side-effects of antipsychotic drugs. Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a major role in neurogenesis and neuroplasticity, and in the modulation of several neurotransmitter systems including the dopaminergic system involved in the pathophysiology of schizophrenia. This review focused on the association between the BDNF gene Val66Met polymorphism and antipsychotic drugs. The BDNF Val66Met polymorphism has been related to the pathophysiology of schizophrenia, psychotic symptomatology, cognition, efficacy and side-effects of antipsychotic drugs. The BDNF Val66Met variants could be a promising target for antipsychotic medication options or developing next generation antipsychotic drugs. However, some studies showed inconsistent results due to sample size, ethnic differences and different antipsychotic drugs. Further studies will be required in this area to confirm the effect of the BDNF Val66Met polymorphism in the pathophysiology of schizophrenia and patients' response to antipsychotic drugs, especially in a larger sample size and in different ethnic populations.

Bidirectional Microglia-Neuron Communication in Health and Disease

Microglia are ramified cells that exhibit highly motile processes, which continuously survey the brain parenchyma and react to any insult to the CNS homeostasis. Although microglia have long been recognized as a crucial player in generating and maintaining inflammatory responses in the CNS, now it has become clear, that their function are much more diverse, particularly in the healthy brain. The innate immune response and phagocytosis represent only a little segment of microglia functional repertoire that also includes maintenance of biochemical homeostasis, neuronal circuit maturation during development and experience-dependent remodeling of neuronal circuits in the adult brain. Being equipped by numerous receptors and cell surface molecules microglia can perform bidirectional interactions with other cell types in the CNS. There is accumulating evidence showing that neurons inform microglia about their status and thus are capable of controlling microglial activation and motility while microglia also modulate neuronal activities. This review addresses the topic: how microglia communicate with other cell types in the brain, including fractalkine signaling, secreted soluble factors and extracellular vesicles. We summarize the current state of knowledge of physiological role and function of microglia during brain development and in the mature brain and further highlight microglial contribution to brain pathologies such as Alzheimer’s and Parkinson’s disease, brain ischemia, traumatic brain injury, brain tumor as well as neuropsychiatric diseases (depression, bipolar disorder, and schizophrenia).

Brain-derived neurotrophic factor as a biomarker for cognitive recovery in acute schizophrenia: 12-week results from a prospective longitudinal study

RATIONALE

It is generally accepted that impaired cognitive function is a core feature of schizophrenia. There is evidence for the role of brain-derived neurotrophic factor (BDNF) in cognitive function. Olanzapine was reported to yield cognitive improvement in patients with schizophrenia.

OBJECTIVES

In this study, we performed a prospective, open-label, 12-week observation trial to investigate whether peripheral BDNF may represent a potential biomarker for the effect of cognitive improvement induced by olanzapine in patients with schizophrenia.

METHODS

In total, 95 patients with acute schizophrenia were enrolled in the study. We also recruited 72 healthy individuals for a control group. The Positive and Negative Syndrome Scale (PANSS) was used to evaluate symptom severity and treatment response. Cognitive function was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plasma BDNF levels were measured with an enzyme-linked immunosorbent assay.

RESULTS

Of the 95 patients consented into the study, 68 completed the 12-week follow up. Our results showed that schizophrenia patients with acute exacerbation had significantly poorer performance than that of the controls (Ps < 0.01). A significantly decreased plasma level of BDNF in patients was observed compared with the controls (F = 7.77, P = 0.006). A significant improvement in each PANSS subscore and total score was observed when the patients completed this study (Ps < 0.01). Additionally, 12-week olanzapine treatment exhibited significant improvements in RBANS immediate memory, attention, and total scores (P = 0.018, 0.001, and 0.007, respectively). Along with the clinical improvement, plasma BDNF levels after 12-week olanzapine monotherapy (4.67 ± 1.74 ng/ml) were also significantly increased compared with those at baseline (3.38 ± 2.11 ng/ml) (P < 0.01). Spearman's correlation analysis showed that the increase in plasma levels of BDNF is significantly correlated with the change in the RBANS total scores (r = 0.28, P = 0.02) but not with the change in the PANSS total scores (r = - 0.18, P = 0.13). There is a significant correlation of BDNF increase with the change of RBANS attention subscore (r = 0.27, P = 0.028).

CONCLUSIONS

Our findings suggest that olanzapine improves psychiatric symptoms and cognitive dysfunction, particularly attention and immediate memory, in patients with acute schizophrenia, in parallel with increased plasma BDNF levels. Plasma BDNF levels may be a potential biomarker for cognitive recovery in acute schizophrenia.

Cognition, serum BDNF levels, and BDNF Val66Met polymorphism in type 2 diabetes patients and healthy controls

Background and aims

Type 2 diabetes (T2DM) is associated with cognitive deficits. However, their pathophysiological mechanisms are still unknown. Recent study suggests that brain-derived neurotrophic factor (BDNF) is correlated with cognitive deficits in T2DM patients. This study was to determine whether altered serum BDNF levels and cognitive deficits depended on the BDNF Val66Met polymorphism in T2DM.

Results

The BDNF Val66Met polymorphism may not contribute directly to the susceptibility to T2DM. The total and nearly all index scores (all p < 0.01) except for the attention and visuospatial/constructional indexes (both p > 0.05) of RBANS were markedly decreased in T2DM compared with healthy controls. Serum BDNF levels were significantly lower in patients than that in controls (p < 0.001), and BDNF was positively associated with delayed memory in patients (p < 0.05). The Met variant was associated with worse delayed memory performance among T2DM patients but not among normal controls. Moreover, serum BDNF was positively associated with delayed memory among Met homozygote patients (β = 0.29, t = 2.21, p = 0.033), while serum BDNF was negatively associated the RBANS total score (β = –0.92, t = –3.40, p = 0.002) and language index (β = −1.17, t = –3.54, p = 0.001) among Val homozygote T2DM patients.

Conclusions

BDNF gene Val66Met variation may be associated with cognitive deficits in T2DM, especially with delayed memory. The association between lower BDNF serum levels and cognitive impairment in T2DM is dependent on the BDNF Val66Met polymorphism.

Methods

We recruited 311 T2DM patients and 346 healthy controls and compared them on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), serum BDNF levels, and the BDNF Val66Met polymorphism.

Val66Met functional polymorphism and serum protein level of brain-derived neurotrophic factor (BDNF) in acute episode of schizophrenia and depression

BACKGROUND

Brain-derived neurotrophic factor (BDNF) influences neuron differentiation during development as well as the synaptic plasticity and neuron survival in adulthood. BDNF has been implicated in the pathogenesis of schizophrenia and depression. Val66Met polymorphism and BDNF serum level are potential biomarkers in neuropsychiatric disorders. The aim of this study was to determine the effect of BDNF gene Val66Met functional polymorphism on serum BDNF concentration in patients with schizophrenia, during depression episode and in healthy control group.

METHODS

183 participants were recruited (61 patients with depressive episode, 56 females with schizophrenia, 66 healthy controls) from Polish population. Serum BDNF levels were measured using ELISA method. Val66Met polymorphism was genotyped using PCR- RFLP method.

RESULTS

Serum BDNF levels were not associated with Val66Met polymorphism in either of the groups. A significant increase of BDNF level in schizophrenia (p = 0.0005) and depression (p = 0.026) comparing to the control group has been observed.

CONCLUSIONS

Our results suggest that the functional Val66Met BDNF polymorphism is not associated with BDNF serum levels, which is in line with previous findings. Replication studies on larger groups are needed.

Metabolic adverse effects of olanzapine on cognitive dysfunction: A possible relationship between BDNF and TNF-alpha

OBJECTIVE

There is accumulating evidence indicating that long-term treatment with second-generation antipsychotics (SGAs) results in metabolic syndrome (MetS) and cognitive impairment. This evidence suggests an intrinsic link between antipsychotic-induced MetS and cognitive dysfunction in schizophrenia patients. Olanzapine is a commonly prescribed SGA with a significantly higher MetS risk than that of most antipsychotics. In this study, we hypothesized that olanzapine-induced MetS may exacerbate cognitive dysfunction in patients with schizophrenia.

METHODS

A sample of 216 schizophrenia patients receiving long-term olanzapine monotherapy were divided into two groups, MetS and non-MetS, based on the diagnostic criteria of the National Cholesterol Education Program's Adult Treatment Panel III. We also recruited 72 healthy individuals for a control group. Cognitive function was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plasma brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-alpha (TNF-alpha) were measured by an enzyme-linked immunosorbent assay for 108 patients and 47 controls.

RESULTS

Among the 216 schizophrenia patients receiving olanzapine monotherapy, MetS was found in 95/216 (44%). Patients with MetS had more negative symptoms, higher total scores in PANSS (Ps<0.05) and lower immediate memory, attention, delayed memory and total scores in RBANS (Ps<0.01). Stepwise multivariate linear regression analysis revealed that increased glucose was the independent risk factor for cognitive dysfunction (t=-2.57, P=0.01). Patients with MetS had significantly lower BDNF (F=6.49, P=0.012) and higher TNF-alpha (F=5.08, P=0.026) levels than those without MetS. There was a negative correlation between the BDNF and TNF-alpha levels in the patients (r=-0.196, P=0.042).

CONCLUSION

Our findings provide evidence suggesting that the metabolic adverse effects of olanzapine may aggravate cognitive dysfunction in patients with schizophrenia through an interaction between BDNF and TNF-alpha.

Oxidative and nitrosative stress biomarkers in chronic schizophrenia

There is evidence that the acute phase of schizophrenia (SCZ) is accompanied by specific changes in oxidative and nitrosative stress (O&NS) biomarkers. There are, however, no firm data regarding these biomarkers in chronic SCZ. Therefore, this study aimed to delineate O&NS biomarkers in patients with chronic SCZ. 125 outpatients with SCZ and 118 controls were enrolled. The markers included lipid hydroperoxides (LOOH), advanced oxidation protein products (AOPP), nitric oxide metabolites (NOx), total radical-trapping antioxidant parameter (TRAP) and paraoxonase 1 (PON-1) activity. Immune-inflammatory markers known to be altered in SCZ were also measured: leptin, IL-6, soluble TNF receptors (sTNF-Rs) and the chemokines CCL-11 and CCL-3. There were no significant associations between chronic SCZ and the O&NS markers (AOPP, NOx, LOOH) and the anti-oxidants PON-1 and TRAP. Leptin, sTNF-R, CCL-3 and CCL-11 were significantly higher in SCZ. There were significant associations between pro-inflammatory and O&NS biomarkers (leptin/CCL-8 and AOPP; IL-6 and NOx; CCL-3 and LOOH; CCL-3/IL-6/NOx and TRAP). In conclusion, there were significant intercorrelations between inflammatory and O&NS pathways, which play a role in the pathophysiology of chronic SCZ. O&NS markers and the enzyme PON-1 are not useful as biomarkers in chronic stable polymedicated SCZ patients.

Theranostic Biomarkers for Schizophrenia

Schizophrenia is a highly heritable, chronic, severe, disabling neurodevelopmental brain disorder with a heterogeneous genetic and neurobiological background, which is still poorly understood. To allow better diagnostic procedures and therapeutic strategies in schizophrenia patients, use of easy accessible biomarkers is suggested. The most frequently used biomarkers in schizophrenia are those associated with the neuroimmune and neuroendocrine system, metabolism, different neurotransmitter systems and neurotrophic factors. However, there are still no validated and reliable biomarkers in clinical use for schizophrenia. This review will address potential biomarkers in schizophrenia. It will discuss biomarkers in schizophrenia and propose the use of specific blood-based panels that will include a set of markers associated with immune processes, metabolic disorders, and neuroendocrine/neurotrophin/neurotransmitter alterations. The combination of different markers, or complex multi-marker panels, might help in the discrimination of patients with different underlying pathologies and in the better classification of the more homogenous groups. Therefore, the development of the diagnostic, prognostic and theranostic biomarkers is an urgent and an unmet need in psychiatry, with the aim of improving diagnosis, therapy monitoring, prediction of treatment outcome and focus on the personal medicine approach in order to improve the quality of life in patients with schizophrenia and decrease health costs worldwide.

TOX and ADIPOQ Gene Polymorphisms Are Associated with Antipsychotic-Induced Weight Gain in Han Chinese

To find the genetic markers related to the antipsychotic-induced weight gain (AIWG), we analyzed associations among candidate gene single-nucleotide polymorphisms (SNPs) and quantitative traits of weight changes and lipid profiles in a Chinese Han population. A total of 339 schizophrenic patients, including 86 first-episode patients (FEPs), meeting the entry criteria were collected. All patients received atypical antipsychotic drug monotherapy and hospitalization and were followed for 12 weeks. Forty-three SNPs in 23 candidate genes were calculated for quantitative genetic association with AIWG, performed by PLINK. The TOX gene SNP rs11777927 (P = 0.009) and the ADIPOQ gene SNP rs182052 (P = 0.019) were associated with AIWG (in body mass index, BMI). In addition, the BDNF SNP rs6265 (P = 0.002), BDAF SNP rs11030104 SNP (P = 0.001), and ADIPOQ SNPs rs822396 (P = 0.003) were significantly associated with the change of waist-to-hip ratio (WHR) induced by atypical antipsychotics. These results were still significant after age and gender adjustments. These findings provide preliminary evidence supporting the role of TOX, ADIPOQ and BDNF in weight and WHR gain induced by atypical antipsychotics.

Pharmacogenetic Associations of Antipsychotic Drug-Related Weight Gain: A Systematic Review and Meta-analysis

Although weight gain is a serious but variable adverse effect of antipsychotics that has genetic underpinnings, a comprehensive meta-analysis of pharmacogenetics of antipsychotic-related weight gain is missing. In this review, random effects meta-analyses were conducted for dominant and recessive models on associations of specific single nucleotide polymorphisms (SNP) with prospectively assessed antipsychotic-related weight or body mass index (BMI) changes (primary outcome), or categorical increases in weight or BMI (≥7%; secondary outcome). Published studies, identified via systematic database search (last search: December 31, 2014), plus 3 additional cohorts, including 222 antipsychotic-naïve youth, and 81 and 141 first-episode schizophrenia adults, each with patient-level data at 3 or 4 months treatment, were meta-analyzed. Altogether, 72 articles reporting on 46 non-duplicated samples (n = 6700, mean follow-up = 25.1wk) with 38 SNPs from 20 genes/genomic regions were meta-analyzed (for each meta-analysis, studies = 2-20, n = 81-2082). Eleven SNPs from 8 genes were significantly associated with weight or BMI change, and 4 SNPs from 2 genes were significantly associated with categorical weight or BMI increase. Combined, 13 SNPs from 9 genes (Adrenoceptor Alpha-2A [ADRA2A], Adrenoceptor Beta 3 [ADRB3], Brain-Derived Neurotrophic Factor [BDNF], Dopamine Receptor D2 [DRD2], Guanine Nucleotide Binding Protein [GNB3], 5-Hydroxytryptamine (Serotonin) Receptor 2C [HTR2C], Insulin-induced gene 2 [INSIG2], Melanocortin-4 Receptor [MC4R], and Synaptosomal-associated protein, 25kDa [SNAP25]) were significantly associated with antipsychotic-related weight gain (P-values < .05-.001). SNPs in ADRA2A, DRD2, HTR2C, and MC4R had the largest effect sizes (Hedges' g's = 0.30-0.80, ORs = 1.47-1.96). Less prior antipsychotic exposure (pediatric or first episode patients) and short follow-up (1-2 mo) were associated with larger effect sizes. Individual antipsychotics did not significantly moderate effect sizes. In conclusion, antipsychotic-related weight gain is polygenic and associated with specific genetic variants, especially in genes coding for antipsychotic pharmacodynamic targets.

Association of the BDNF Val66Met polymorphism with BMI in chronic schizophrenic patients and healthy controls

Several lines of evidence suggest that a functional variant of the brain-derived neurotrophic factor gene (BDNF Val66Met) correlates with a number of eating disorders. Studies have also shown that the BDNF Val66Met polymorphism was associated with weight gain in patients with schizophrenia on long-term antipsychotic treatment. This study aimed to determine whether there was a relationship between the BDNF Val66Met polymorphism and BMI values in patients with chronic schizophrenia. We compared 308 Han Chinese patients with schizophrenia on long-term antipsychotic medication with 304 healthy normal controls on BDNF polymorphism. Body weight and BMI were measured before breakfast on the day blood samples were taken. The symptomatology of schizophrenia was assessed using the Positive and Negative Syndrome Scale. The results showed that the BDNF Val66Met polymorphism was associated with the BMI value, with genotype having a strong effect on the mean BMI value in male but not in female patients. Our results suggest that variation in the BDNF gene may be a risk factor for weight gain in male patients with schizophrenia on long-term antipsychotic treatment.

Niveles séricos del factor neurotrófico derivado del cerebro durante la gestación normal y la preeclampsia

<p>Introducción. La preeclampsia (PE) es una de las principales causas de mortalidad materna y perinatal en el mundo, aparece en la segunda mitad de la gestación y actualmente no hay marcadores que la detecten en forma temprana. Dadas las propiedades angiogénicas del factor neurotrófico derivado del cerebro (BDNF) y la disfunción endotelial de los vasos sanguíneos presente en la PE, se ha propuesto una posible asociación entre el BDNF y PE. Objetivo. Determinar si existe asociación entre niveles séricos de BDNF durante el embarazo y la preeclampsia. Materiales y métodos. Estudio de cohorte prospectivo longitudinal. Se seleccionaron 13 pacientes quienes desarrollaron PE y 31 gestantes de curso normal. Se midieron variables antropométricas y niveles de BDNF, glicemia, insulina y perfil lipídico en la gestación temprana, media y tardía. Se practicó un modelo de regresión logística para verificar si los niveles de BDNF, en conjunto con otras variables, pueden explicar el desarrollo de PE. Resultados. Los niveles de BDNF no variaron significativamente entre el grupo de gestantes que desarrollaron preeclampsia y las que no: en gestación temprana 25.3 y 23.3ng/ml, en gestación media 28 y 24.7ng/ml y en gestación tardía 25.4 y 27.4ng/ml, respectivamente. Se hallaron diferencias entre los dos grupos en el peso, la insulina y la evaluación del modelo homeostático (HOMA). Se encontró asociación entre niveles de BDNF y peso e IMC y glucemia en las gestantes que no desarrollaron PE. Se practicó un modelo de regresión logística en el que la PE se explicó mejor con variables como IMC, PAS y HOMA, pero no con BDNF. Conclusiones. El BDNF puede participar en la regulación del peso corporal y el metabolismo de la glucosa en mujeres gestantes, pero el nivel de BDNF, solo o en conjunto con otras variables, no puede explicar la preeclampsia.</p>

A Lack of Correlation between Brain-Derived Neurotrophic Factor Serum Level and Verbal Memory Performance in Healthy Polish Population

Brain derived neurotrophic factor (BDNF) is considered to be connected with memory and learning through the processes of long term synaptic potentiation and synaptic plasticity. The aim of the study was to examine the relationship between precursor BDNF (proBNDF) and mature BDNF (mBDNF) serum levels and performance on Rey Auditory-Verbal Learning Test (RAVLT) in 150 healthy volunteers. In addition, we have verified the relationships between serum concentration of both forms of BDNF and RAVLT with sociodemographic and lifestyle factors.We found no strong evidence for the correlation of proBDNF and mBDNF serum levels with performance on RAVLT in healthy Polish population in early and middle adulthood. We observed the mBDNF serum concentration to be higher in women compared with men. Moreover, we revealed higher mBDNF level to be connected with lower body mass index (BMI). In turn, the results of RAVLT correlated with sociodemographic and lifestyle factors, such as: age, education, gender, BMI and smoking.

Association between obesity and the brain-derived neurotrophic factor gene polymorphism Val66Met in individuals with bipolar disorder in Mexican population

BACKGROUND

The brain-derived neurotrophic factor (BDNF) has been considered as an important candidate gene in bipolar disorder (BD); this association has been derived from several genetic and genome-wide studies. A polymorphic variant of the BDNF (Val66Met) confers some differences in the clinical presentation of affective disorders. In this study, we evaluated a sample population from Mexico City to determine whether the BDNF (rs6265) Val66Met polymorphism is associated with the body mass index (BMI) of patients with BD.

METHODS

This association study included a sample population of 357 individuals recruited in Mexico City. A total of 139 participants were diagnosed with BD and 137 were classified as psychiatrically healthy controls (all individuals were interviewed and evaluated by the Diagnostic Interview for Genetic Studies). Genomic DNA was extracted from peripheral blood leukocytes. The quantitative polymerase chain reaction (qPCR) assay was performed in 96-well plates using the TaqMan Universal Thermal Cycling Protocol. After the PCR end point was reached, fluorescence intensity was measured in a 7,500 real-time PCR system and evaluated using the SDS v2.1 software, results were analyzed with Finetti and SPSS software. Concerning BMI stratification, random groups were defined as follows: normal <25 kg/m(2), overweight (Ow) =25.1-29.9 kg/m(2), and obesity (Ob) >30 kg/m(2).

RESULTS

In the present work, we report the association of a particular BMI phenotype with the presence of the Val66Met allele in patients with BD (P=0.0033 and odds ratio [95% confidence interval] =0.332 [157-0.703]), and correlated the risk for valine allele carriers with Ow and Ob in patients with BD.

CONCLUSION

We found that the methionine allele confers a lower risk of developing Ow and Ob in patients with BD. We also confirmed that the G polymorphism represents a risk of developing Ow and Ob in patients with BD. In future studies, the haplotype analysis should provide additional evidence that BDNF may be associated with BD and BMI within the Mexican population.

Pharmacogenetics of clozapine treatment response and side-effects in schizophrenia: an update

INTRODUCTION

Clozapine (CLZ) is the most effective treatment for treatment-resistant schizophrenia (SCZ) patients, with potential added benefits of reduction in suicide risk and aggression. However, CLZ is also mainly underused due to its high risk for the potentially lethal side-effect of agranulocytosis as well as weight gain and related metabolic dysregulation. Pharmacogenetics promises to enable the prediction of patient treatment response and risk of adverse effects based on patients' genetics, paving the way toward individualized treatment.

AREA COVERED

This article reviews pharmacogenetics studies of CLZ response and side-effects with a focus on articles from January 2012 to February 2015, as an update to the previous reviews. Pharmacokinetic genes explored primarily include CYP1A2, while pharmacodynamic genes consisted of traditional pharmacogenetic targets such as brain-derived neurotrophic factor as well novel mitochondrial genes, NDUFS-1 and translocator protein.

EXPERT OPINION

Pharmacogenetics is a promising avenue for individualized medication of CLZ in SCZ, with several consistently replicated gene variants predicting CLZ response and side-effects. However, a large proportion of studies have yielded mixed results. Large-scale Genome-wide association studies (e.g., CRESTAR) and targeted gene studies with standardized designs (response measurements, treatment durations, plasma level monitoring) are required for further progress toward clinical translation. Additionally, in order to improve study quality, we recommend accounting for important confounders, including polypharmacy, baseline measurements, treatment duration, gender, and age at onset.

The brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with increased body mass index and insulin resistance measures in bipolar disorder and schizophrenia

OBJECTIVES

We tested the hypothesis that a common functional variant in brain-derived neurotrophic factor (BDNF), Val66Met, which has been shown to be associated with increased body mass index (BMI) in schizophrenia (SCZ) and schizoaffective disorder (SAD), is also associated with antipsychotic-induced weight gain in bipolar disorder (BPD). Association of Val66Met with other metabolic measures, including high- and low-density cholesterol, triglycerides, total cholesterol, fasting blood glucose, and hemoglobin A1c, was also tested.

METHODS

This was a 12-month, prospective, randomized trial of two atypical antipsychotic drugs (APDs) with moderate (risperidone) or high (olanzapine) risk to cause weight gain. Subjects were diagnosed as having BPD (n = 90) and SCZ or SAD (n = 76).

RESULTS

BMI was significantly greater in all diagnoses for Met66 allele carriers at six months (p = 0.01). Met66 carriers with BPD showed a greater increase in the triglycerides/high-density (HDL) cholesterol ratio (p = 0.01), a key marker for metabolic syndrome related to insulin resistance, and log-triglycerides (p = 0.04), after three or six months of treatment. Met66 carriers had the greatest increase in log-triglycerides (p = 0.03) and triglycerides/HDL cholesterol ratio after three months of treatment with risperidone (p = 0.003), and the highest BMI at six months (p = 0.01).

CONCLUSIONS

The positive association of BNDF Val66Met with high BMI values replicates previous findings in patients with SCZ and indicates the BDNF Val66Met genotype as a potential risk factor for obesity and insulin resistance measures in patients with BPD receiving antipsychotics as well.

Fat mass- and obesity-associated (FTO) gene and antipsychotic-induced weight gain: an association study

OBJECTIVES

Genetic variation in the fat mass- and obesity-associated gene (FTO) has been associated with obesity in the general population. In this study we have investigated these variants for association with antipsychotic-induced weight gain (AIWG).

METHODS

A total of 218 patients with chronic schizophrenia or schizoaffective disorder treated mostly with clozapine or olanzapine for up to 14 weeks were included in the study. We analyzed 4 polymorphisms in intron 1 of the FTO gene (rs1421085, rs8050136, rs9939609, rs9930506) for association with AIWG using ANCOVA.

RESULTS

No statistically significant associations were observed between the single nucleotide polymorphisms and AIWG. However, patients homozygous for the A-allele of rs9939609 gained numerically higher weight than the other genotypic groups (AA: 5.26 ± 6.7%; TA: 4.66 ± 5.6%; TT: 4.21 ± 5.3%).

CONCLUSION

Our current observations suggest that the FTO gene variants investigated may not play a major role in AIWG.

The role of genetic variation across IL-1β, IL-2, IL-6, and BDNF in antipsychotic-induced weight gain

OBJECTIVES

Antipsychotics with high weight gain-inducing propensities influence the expression of immune and neurotrophin genes, which have been independently related to obesity indices. Thus, we investigated whether variants in the genes encoding interleukin (IL)-1β, IL-2, and IL-6 and brain-derived neurotrophic factor (BDNF) Val66Met are associated with antipsychotic-induced weight gain (AIWG).

METHODS

Nineteen polymorphisms were genotyped using Taqman(®) assays in 188 schizophrenia patients on antipsychotic treatment for up to 14 weeks. Mean weight change (%) from baseline was compared across genotypic groups using analysis of covariance (ANCOVA). Epistatic effects between cytokine polymorphisms and BDNF Val66Met were tested using Model-Based Multifactor Dimensionality Reduction.

RESULTS

In European patients, IL-1β rs16944*GA (P = 0.013, Pcorrected = 0.182), IL-1β rs1143634*G (P = 0.001, Pcorrected = 0.014), and BDNF Val66Met (Val/Val, P = 0.004, Pcorrected = 0.056) were associated with greater AIWG, as were IL-1β rs4849127*A (P = 0.049, Pcorrected = 0.784), and IL-1β rs16944*GA (P = 0.012, Pcorrected = 0.192) in African Americans. BDNF Val66Met interacted with both IL-1β rs13032029 (Val/Met+ TT, PPerm = 0.029), and IL-6 rs2069837 (Val/Val+ AA, PPerm = 0.021) in Europeans, in addition to IL-1β rs16944 (Val/Val+ GA, PPerm = 0.006) in African Americans.

CONCLUSIONS

SNPs across IL-1β and BDNF Val66Met may influence AIWG. Replication of these findings in larger, independent samples is warranted.

Smoking and BDNF Val66Met polymorphism in male schizophrenia: a case-control study

Some recent studies show an association between a functional polymorphism of BDNF gene (Val66Met) and the susceptibility to nicotine dependence and we hypothesized that this polymorphism was associated with smoking in both schizophrenia patients and healthy controls. The BDNF Val66Met gene polymorphism was genotyped in 690 chronic male schizophrenia patients (smoker/nonsmoker = 522/169) and 628 male controls (smoker/nonsmoker = 322/306) using a case-control design. Nicotine dependence (ND) was assessed by the cigarettes smoked per day (CPD), the Heaviness of Smoking Index (HSI), and the Fagerstrom Test for ND (FTND). Patients also were rated on the Positive and Negative Syndrome Scale (PANSS). The results showed no significant differences in BDNF Val66Met genotype and allele distributions between the patients and healthy controls or between smokers and nonsmokers in either patients or healthy controls alone. In patient groups, however, the smokers with the Met allele had significantly higher HSI scores (Met/Met: 2.8 ± 1.7 vs. Met/Val: 2.2 ± 1.7 vs. Val/Val: 2.0 ± 1.6, p < 0.01) and a trend toward a significantly higher FTND score (p = 0.09) than those with the Val/Val genotype. In addition, the smokers showed significantly lower PANSS negative symptom and total scores, longer duration of illness and more hospitalizations (all p < 0.05). In the control group, the smokers with the Met allele started smoking significantly earlier than those with the Val/Val genotype (both p < 0.05). These results suggest that the BDNF Val66Met polymorphism may affect a smoker's response to nicotine in both schizophrenia and healthy controls from a Chinese Han population, but with differential effects in different aspects of smoking behaviors.

Increase of circulating BDNF levels and its relation to improvement of physical fitness following 12 weeks of combined exercise in chronic patients with schizophrenia: a pilot study

Brain-derived neurotrophic factor (BDNF), the most abundant of neurotrophins in the brain, is known to be responsible for maintenance of neurons has been implicated in the pathology of schizophrenia. In the present pilot study, we investigated the effect of a combined exercise program on circulating BDNF expression and the relationship between BDNF and improvements in physical fitness. Twenty-four patients with schizophrenia participated in the exercise intervention, three nonconsecutive days per week for 12 weeks. The resistance exercise program used the elastic band for eight different exercises for 25 min, and the aerobic exercise consisted of moderate walking for 25 min. After the training program, there were positive improvements in body composition and blood pressure. Also, there was significant improvement in leg strength, cardiovascular fitness, balance, and jump. Serum BDNF values had significantly increased following the combined exercise program. The elevation in serum BDNF concentrations correlated significantly with improvements in cardiovascular fitness and leg strength. These results suggest that exercise induced modulation of BDNF may play an important role in developing non-pharmacological treatment for chronic schizophrenic patients. In addition, these preliminary results serve to generate further hypothesis and facilitate the planning the exercise training program and management of participants.

Serum brain-derived neurotrophic factor levels and cocaine-induced transient psychotic symptoms

BACKGROUND

Cocaine-induced psychosis (CIP) is among the most serious adverse effects of cocaine. Reduced serum brain-derived neurotrophic factor (BDNF) levels have been reported in schizophrenia and psychosis; however, studies assessing the involvement of BDNF in CIP are lacking.

METHODS

A total of 22 cocaine-dependent patients (aged 33.65 ± 6.85) who had never experienced psychotic symptoms under the influence of cocaine (non-CIP) and 18 patients (aged 34.18 ± 8.54) with a history of CIP completed a 2-week detoxification program in an inpatient facility. Two serum samples were collected from each patient at baseline and at the end of the protocol. Demographic, consumption and clinical data were recorded for all patients. A paired group of healthy controls was also included.

RESULTS

At the beginning of the detoxification treatment, serum BDNF levels were similar in both the non-CIP and the CIP groups. During early abstinence, the non-CIP group exhibited a significant increase in serum BDNF levels (p = 0.030), whereas the CIP group exhibited a decrease. Improvements in depression (Beck Depression Inventory, BDI, p = 0.003) and withdrawal symptoms (Cocaine Selective Severity Assessment, CSSA, p = 0.013) show a significant positive correlation with serum BDNF levels in the non-CIP group, whereas no correlation between the same variables was found in the CIP group.

CONCLUSIONS

This study suggests that BDNF plays a role in the transient psychotic symptoms associated with cocaine consumption. In the non-CIP group, the increase in serum BDNF appears to be driven by the effects of chronic cocaine consumption and withdrawal. In contrast, patients with CIP share some of the neurotrophic deficiencies that characterize schizophrenia and psychosis.

Brain-derived neurotrophic factor blood levels are decreased in schizophrenia patients and associate with rs6265 genotypes

OBJECTIVES

A growing number of studies implicate brain-derived neurotrophic factor (BDNF), an important promoter of synaptic transmission and neural plasticity, in the pathogenesis of schizophrenia. However, the existing data are controversial, that may reflect population differences between studied groups.

DESIGN AND METHODS

In the present study we performed a comparative analysis of BDNF plasma levels and its relation with rs6265 (G196A; Val66Met) polymorphism of BDNF gene (BDNF) in schizophrenia-affected and healthy subjects (controls) of the Armenian population. To check the influence of antipsychotics on BDNF plasma levels both medicated and non-medicated patients were involved in this study. Patients with paranoid form of schizophrenia chronically treated with typical antipsychotics (n=103), age- and sex-matched controls (n=105), and 25 antipsychotic-naive first-episode schizophrenia patients were involved. The levels of BDNF in the blood plasma were measured with a solid-phase enzyme-linked immunosorbent assay.

RESULTS

Decreased plasma levels of BDNF in both medicated and non-medicated schizophrenia patients compared to controls were observed. No significant difference in BDNF levels between medicated and non-medicated patients was detected. It was also detected that, compared to individuals homozygous for the standard allele (G/G) of rs6265, carriers of the rs6265 minor allele (A/G+A/A), which is significantly more frequent in schizophrenia patients than in controls, had decreased BDNF levels.

CONCLUSIONS

The data obtained suggested that the pathogenesis of schizophrenia is characterized by genetically predetermined decreased blood levels of BDNF. These results indicated that genetically determined alterations of neuroimmune modulators may be among the risk factors of schizophrenia and contribute to disease-specific pathologic changes in functional activity of both the neuronal synaptic plasticity and the immune system.

A longitudinal study of alterations of hippocampal volumes and serum BDNF levels in association to atypical antipsychotics in a sample of first-episode patients with schizophrenia

Background

Schizophrenia is associated with structural and functional abnormalities of the hippocampus, which have been suggested to play an important role in the formation and emergence of schizophrenia syndrome. Patients with schizophrenia exhibit significant bilateral hippocampal volume reduction and progressive hippocampal volume decrease in first-episode patients with schizophrenia has been shown in many neuroimaging studies. Dysfunction of the neurotrophic system has been implicated in the pathophysiology of schizophrenia. The initiation of antipsychotic medication alters the levels of serum Brain Derived Neurotrophic Factor (BDNF) levels. However it is unclear whether treatment with antipsychotics is associated with alterations of hippocampal volume and BDNF levels.

Methods

In the present longitudinal study we investigated the association between serum BDNF levels and hippocampal volumes in a sample of fourteen first-episode drug-naïve patients with schizophrenia (FEP). MRI scans, BDNF and clinical measurements were performed twice: at baseline before the initiation of antipsychotic treatment and 8 months later, while the patients were receiving monotherapy with second generation antipsychotics (SGAs).

Results

We found that left hippocampal volume was decreased (corrected left HV [t = 2.977, df = 13, p = .011] at follow-up; We also found that the higher the BDNF levels change the higher were the differences of corrected left hippocampus after 8 months of treatment with atypical antipsychotics (Pearson r = 0.597, p = 0.024).

Conclusions

The association of BDNF with hippocampal volume alterations in schizophrenia merits further investigation and replication in larger longitudinal studies.

Pharmacogenetics of antipsychotic treatment in schizophrenia

Antipsychotics are the mainstay treatment for schizophrenia. There is large variability between individuals in their response to antipsychotics, both in efficacy and adverse effects of treatment. While the source of interindividual variability in antipsychotic response is not completely understood, genetics is a major contributing factor. The identification of pharmacogenetic markers that predict antipsychotic efficacy and adverse reactions is a growing area of research, and holds the potential to replace the current trial-and-error approach to treatment selection in schizophrenia with a personalized medicine approach.In this chapter, we provide an overview of the current state of pharmacogenetics in schizophrenia treatment. The most promising pharmacogenetic findings are presented for both antipsychotic response and commonly studied adverse reactions. The application of pharmacogenetics to schizophrenia treatment is discussed, with an emphasis on the clinical utility of pharmacogenetic testing and directions for future research.

Pharmacological mechanisms underlying the association of antipsychotics with metabolic disorders

Obesity and metabolic syndrome in association with an increased risk of cardiovascular disease and type II diabetes are significant problems that contribute to lower life expectancy of patients with schizophrenia. Understanding the pharmacological mechanisms of the current antipsychotic treatment is clearly the key to the improvement of pharmacotherapy, to avoid or to mitigate the metabolic adverse effects.

Genetics of serum BDNF: meta-analysis of the Val66Met and genome-wide association study

OBJECTIVES

Lower levels of serum brain derived neurotrophic factor (BDNF) is one of the best known biomarkers of depression. To identify genetic variants associated with serum BDNF, we tested the Val66Met (rs6265) functional variant and conducted a genome-wide association scan (GWAS).

METHODS

In a community-based sample (N = 2054; aged 19-101, M = 51, SD = 15) from Sardinia, Italy, we measured serum BDNF concentration and conducted a GWAS.

RESULTS

We estimated the heritability of serum BDNF to be 0.48 from sib-pairs. There was no association between serum BDNF and Val66Met in the SardiNIA sample and in a meta-analysis of published studies (k = 13 studies, total n = 4727, P = 0.92). Although no genome-wide significant associations were identified, some evidence of association was found in the BDNF gene (rs11030102, P = 0.001) and at two loci (rs7170215, P = 4.8 × 10⁻⁵ and rs11073742 P = 1.2 × 10⁻⁵) near and within NTRK3 gene, a neurotrophic tyrosine kinase receptor.

CONCLUSIONS

Our study and meta-analysis of the literature indicate that the BDNF Val66Met variant is not associated with serum BDNF, but other variants in the BDNF and NTRK3 genes might regulate the level of serum BDNF.

Lifestyle modification and behavior therapy effectively reduce body weight and increase serum level of brain-derived neurotrophic factor in obese non-diabetic patients with schizophrenia

The goal of the study was to elucidate the relationship between serum circulating brain-derived neurotrophic factor (BDNF) and body weight reduction via lifestyle modification and behavior therapy in obese non-diabetic patients with chronic schizophrenia. Thirty-three obese non-diabetic subjects with schizophrenia treated with stable antipsychotic medication in a day-care unit for at least 3 months were recruited. Thirty age-, body weight-matched subjects without psychiatric disorders were enrolled as controls. All participants underwent a 10-week weight reduction program, including lifestyle modification, psychosocial treatment, behavior therapy and exercise in the day-care unit. Blood biochemistry, serum BDNF, adipokine (adiponectin), inflammatory markers (C-reactive protein, tumor necrosis factor-alpha and interleukin-6) and oral glucose tolerance test were evaluated before and after the program. Serum BDNF concentrations were significantly lower among patients with schizophrenia compared to control subjects. Serum BDNF levels were significantly increased following the weight reduction program. Elevations in serum BDNF levels were positively correlated with body weight and body mass index reduction. Altogether, our results demonstrate that a non-pharmacological weight reduction program effectively reduces body weight with significant elevation of serum BDNF levels in obese non-diabetic patients with schizophrenia.

Association study of Val66Met polymorphism in brain-derived neurotrophic factor gene with clozapine-induced metabolic syndrome: preliminary results

The prevalence of the metabolic syndrome (MetS) is higher among patients receiving atypical antipsychotics (AAPs) treatment, and even among AAPs, treatment with clozapine has been shown to be associated with a higher long-term incidence rate of MetS. Likewise, brain-derived neurotrophic factor (BDNF) deficiency has been reported to result in metabolic traits, such as increased food intake, hyperphagia and obesity, etc. In this study, we hypothesized that a functional polymorphism (Val66Met) in the BDNF gene may confer susceptibility to clozapine-induced MetS, potentially in a sex-specific manner, since an interaction between Val66Met polymorphism and sex was observed in our previous studies. A total of 199 schizophrenia patients being treated with clozapine were divided into two groups, MetS and non-MetS, based on the diagnostic criteria of the National Cholesterol Education Program's Adult Treatment Panel III. We genotyped the Val66Met polymorphism, and measured the serum levels of fasting glucose (GLU), triglyceride (TG) and high density lipoprotein cholesterol (HDL). There was a trend indicating a significant association between the homozygous Met/Met genotype and MetS in male patients (OR = 2.39; 95% CI: 1.05–5.41; p = 0.039; corrected p = 0.078). Among the six risk factors listed in the ATPIII criteria, we found a significant association between fasting GLU levels and Val66Met polymorphism in males (p = 0.005; corrected p = 0.03), but not in females (p = 0.65). Post-hoc analysis in males revealed that the Met/Met carriers had significant higher levels of fasting GLU than those with Val/Val or Val/Met genotypes (p = 0.007; corrected p = 0.042 and p = 0.002; corrected p = 0.012, respectively). In conclusion, we observed a weak association between the Val66Met polymorphism and clozapine-induced MetS in a sex-specific manner. While preliminary, such findings prompt further, large-scale longitudinal studies to replicate these findings.