BDNF and TNF-α polymorphisms in memory

Biomarkers of cognitive and memory decline in psychotropic drug users

Psychotropic drugs are vital in psychiatry, aiding in the management of mental health disorders. Their use requires an understanding of their pharmacological properties, therapeutic applications, and potential side effects. Ongoing research aims to improve their efficacy and safety. Biomarkers play a crucial role in understanding and predicting memory decline in psychotropic drug users. A comprehensive understanding of biomarkers, including neuroimaging, biochemical, genetic, and cognitive assessments, is essential for developing targeted interventions and preventive strategies. In this narrative review, we performed a comprehensive search on PubMed and Google using review-specific terms. Clinicians should use a multifaceted approach, including neurotransmitter analysis, neurotrophic factors, miRNA profiling, and cognitive tasks for early intervention and personalized treatment. Anxiolytics' mechanisms involve various neurotransmitter systems and emerging targets. Research on biomarkers for memory decline in anxiolytic users can lead to early detection and intervention, enhancing clinical practices and aligning with precision medicine. Mood stabilizer users can benefit from early detection of memory decline through RNA, neurophysiological, and inflammatory biomarkers, promoting timely interventions. Performance-enhancing drugs may boost athletic performance in the short term, but their long-term health risks and ethical issues make their use problematic. Long-term use of psychotropic performance enhancers in athletes shows changes in biomarkers of cognitive decline, necessitating ongoing monitoring and intervention strategies. Understanding these genetic influences on memory decline helps pave the way for personalized approaches to prevent or mitigate cognitive deterioration, emphasizing the importance of genetic screening and early interventions based on an individual's genetic profile. Future research should focus on refining these biomarkers and protective measures against cognitive deterioration. Overall, a comprehensive understanding of biomarkers in psychotropic drug users is essential for developing targeted interventions and preventive strategies.

Psycho-Cognitive Profile and NGF and BDNF Levels in Tears and Serum: A Pilot Study in Patients with Graves' Disease

Nerve Growth Factor (NGF) and Brain derived Neurotrophic Factor (BDNF) mature/precursor imbalance in tears and serum is suggested as a risk factor and symptomatology aggravation in ophthalmology and neuropsychiatric disturbances. Cognitive and mood alterations are reported by patients with Graves' Orbitopathy (GO), indicating neurotrophin alterations might be involved. To address this question, the expression levels of NGF and BDNF and their precursors in serum and tears of GO patients were analyzed and correlated with the ophthalmological and psycho-cognitive symptoms. Hamilton Rating Scale for Anxiety (HAM-A) and Depression (HAM-D), Temperament and Character Inventory (TCI), and Cambridge Neuropsychological Test Automated Battery (CANTAB) test were used as a score. NGF and BDNF levels were measured using ELISA and Western Blot and statistically analyzed for psychiatric/ocular variable trend association. GO patients show memorization time and level of distraction increase, together with high irritability and impulsiveness. HAM-A and CANTAB variables association, and some TCI dimensions are also found. NGF and BDNF expression correlates with ophthalmological symptoms only in tears, while mature/precursor NGF and BDNF correlate with the specific psycho-cognitive variables both in tears and serum. Our study is the first to show that changes in NGF and BDNF processing in tears and serum might profile ocular and cognitive alterations in patients.

The effect of brain-derived neurotrophic factor Val66Met polymorphism on adolescent activity and rest rhythms, circadian preferences and attentional performance

BACKGROUND

Variations in circadian regulating mechanisms generate different individual preferences in respect of sleep and activity timing, which are known as chronotypes. In this sense, specifically during adolescence, there is a greater tendency for an eveningness chronotype. One factor that has been shown to have an impact on circadian rhythm patterns, as well as on some aspects of cognitive function, is the relatively common Val66Met (rs6265) polymorphism in the human brain-derived neurotrophic factor gene.

OBJECTIVE

This study aimed to evaluate the effect of the BDNF Val66Met polymorphism on the performance of adolescents in attentional tests, circadian preferences and activity-rest rhythm.

METHODS

85 healthy high school students completed the Morningness-Eveningness Questionnaire to assess their circadian preferences; were evaluated using the Psychological Battery for Attention Assessment; and were categorized as carriers and non-carriers of the rs6265 polymorphism using the TaqMan rt-PCR technique. A subsample of 42 students had their activity/rest rhythm recorded by actigraphy for nine days from which sleep parameters were estimated.

RESULTS

Circadian preference did not affect attentional performance (p > 0.1), but the time that the students attended school had an impact on all types of attention with morning shift students scoring higher, regardless of chronotype (p < 0.05). The presence of the BDNF Val66Met polymorphism was associated only with alternate attention performance (p < 0.05). Regarding actigraphy evaluation, the carriers of the polymorphism demonstrated significantly higher total time in bed, total sleep time, social jetlag, and earlier sleep onset.

CONCLUSIONS

The results indicate some degree of adaptation in the students' attentional performance, according to their school schedules. The presence of BDNF polymorphism demonstrated a counterintuitive impact on attentional performance, comparing to previous findings. The findings reinforce the effect of genetic traits on sleep-wake rhythm parameters, when objectively evaluated.

BDNF Val66Met gene polymorphism modulates brain activity following rTMS-induced memory impairment

The BDNF Val66Met gene polymorphism is a relevant factor explaining inter-individual differences to TMS responses in studies of the motor system. However, whether this variant also contributes to TMS-induced memory effects, as well as their underlying brain mechanisms, remains unexplored. In this investigation, we applied rTMS during encoding of a visual memory task either over the left frontal cortex (LFC; experimental condition) or the cranial vertex (control condition). Subsequently, individuals underwent a recognition memory phase during a functional MRI acquisition. We included 43 young volunteers and classified them as 19 Met allele carriers and 24 as Val/Val individuals. The results revealed that rTMS delivered over LFC compared to vertex stimulation resulted in reduced memory performance only amongst Val/Val allele carriers. This genetic group also exhibited greater fMRI brain activity during memory recognition, mainly over frontal regions, which was positively associated with cognitive performance. We concluded that BDNF Val66Met gene polymorphism, known to exert a significant effect on neuroplasticity, modulates the impact of rTMS both at the cognitive as well as at the associated brain networks expression levels. This data provides new insights on the brain mechanisms explaining cognitive inter-individual differences to TMS, and may inform future, more individually-tailored rTMS interventions.

Tumour Necrosis Factor in Neuroplasticity, Neurogenesis and Alcohol Use Disorder

Alcohol use disorder is a pervasive and detrimental condition that involves changes in neuroplasticity and neurogenesis. Alcohol activates the neuroimmune system and alters the inflammatory status of the brain. Tumour necrosis factor (TNF) is a well characterised neuroimmune signal but its involvement in alcohol use disorder is unknown. In this review, we discuss the variable findings of TNF's effect on neuroplasticity and neurogenesis. Acute ethanol exposure reduces TNF release while chronic alcohol intake generally increases TNF levels. Evidence suggests TNF potentiates excitatory transmission, promotes anxiety during alcohol withdrawal and is involved in drug use in rodents. An association between craving for alcohol and TNF is apparent during withdrawal in humans. While anti-inflammatory therapies show efficacy in reversing neurogenic deficit after alcohol exposure, there is no evidence for TNF's essential involvement in alcohol's effect on neurogenesis. Overall, defining TNF's role in alcohol use disorder is complicated by poor understanding of its variable effects on synaptic transmission and neurogenesis. While TNF may be of relevance during withdrawal, the neuroimmune system likely acts through a larger group of inflammatory cytokines to alter neuroplasticity and neurogenesis. Understanding the individual relevance of TNF in alcohol use disorder awaits a more comprehensive understanding of TNF's effects within the brain.

Differential promoter methylation and G-712A polymorphism of brain-derived neurotrophic factor in post-traumatic stress disorder patients of Li and Han populations in Hainan province

This study aimed to explore the correlations of promoter methylation and single-nucleotide polymorphism (SNP) of brain-derived neurotrophic factor (BDNF) with post-traumatic stress disorder (PTSD) in Li and Han nationalities in Hainan province. Depression- and anxiety-related questionnaires were performed for PTSD-related information collection and analysis, with 164 PTSD patients and 141 healthy controls included. Serum BDNF level was measured and the methylation of BDNF promoter was evaluated. The BDNF SNP genotyping was performed, after which the risk genotypes for PTSD were detected and analyzed using logistic regression analysis. Our study found that the PTSD incidence was different in Li and Han nationalities. Serum BDNF level in PTSD patients in Li nationality was obviously lower than that in patients in Han nationality, while the methylation of BDNF promoter was higher in patients in Li nationality. The G-712A rather than rs6265 genotypes presented significant difference between PTSD patients and healthy controls. Meanwhile, the patients in Li nationality with AG genotype at G-712A inclined to depression, and patients with GG genotype had a greater degree of PTSD. G-712A and promoter methylation of BDNF were independent risk factors for PTSD. Our study demonstrated that the differences of PTSD patients between Li and Han nationalities were attributed by SNP G-712A genotypes and promoter methylation of BDNF.

Interaction of BDNF and cytokines in executive dysfunction in patients with chronic schizophrenia

Multiple lines of evidence indicate that patients with chronic schizophrenia (SCZ) display executive dysfunction across the illness course. However, the potential molecular pathophysiologic mechanisms remain poorly elucidated. Neurodevelopmental changes caused by alterations of inflammatory mediators and neurotrophins have been shown to occur in the earliest stages of SCZ, and be associated with executive dysfunction (ED) in SCZ. Therefore, the current study was to investigate whether the interplay between BDNF and inflammatory mediators was involved in the disruption of executive function of long-term hospitalized patients with chronic SCZ. Serum cytokines and BDNF levels were measured in 112 long-term hospitalized patients with chronic SCZ and 44 healthy normal controls. Executive functions were assessed by verbal fluency tests (VFT), the Stroop word-color test (Stroop), and the Wisconsin card sorting tests (WCST).The results showed that the patients had higher IL-2, IL-6, IL-8, but lower TNF-α and BDNF compared to control subjects. In the patient group, BDNF was positively associated with IL-2 and IL-8 levels, while lower BDNF levels were correlated with ED measured by VFT and WCST tests. Multiple stepwise regression analyses confirmed that BDNF × IL-8 and BDNF × TNF-α were factors influencing the total score of VFT, while BDNF × IL-8 and BDNF × TNF-α were recognized as influencing factors for WCST scores. Our results suggest complex interactions between BDNF and cytokines were involved in the pathophysiology of executive function impairments in patients with SCZ.

Brain-Derived Neurotrophic Factor: A Key Molecule for Memory in the Healthy and the Pathological Brain

Brain Derived Neurotrophic Factor (BDNF) is a key molecule involved in plastic changes related to learning and memory. The expression of BDNF is highly regulated, and can lead to great variability in BDNF levels in healthy subjects. Changes in BDNF expression are associated with both normal and pathological aging and also psychiatric disease, in particular in structures important for memory processes such as the hippocampus and parahippocampal areas. Some interventions like exercise or antidepressant administration enhance the expression of BDNF in normal and pathological conditions. In this review, we will describe studies from rodents and humans to bring together research on how BDNF expression is regulated, how this expression changes in the pathological brain and also exciting work on how interventions known to enhance this neurotrophin could have clinical relevance. We propose that, although BDNF may not be a valid biomarker for neurodegenerative/neuropsychiatric diseases because of its disregulation common to many pathological conditions, it could be thought of as a marker that specifically relates to the occurrence and/or progression of the mnemonic symptoms that are common to many pathological conditions.

Influence of childhood trauma and brain-derived neurotrophic factor Val66Met polymorphism on posttraumatic stress symptoms and cortical thickness

Interaction between childhood trauma and genetic factors influences the pathophysiology of posttraumatic stress disorder (PTSD). This study examined the interaction effect of childhood trauma and brain-derived neurotrophic factor (BDNF) Val66Met polymorphism on PTSD symptoms and brain cortical thickness. A total of 216 participants (133 healthy volunteers and 83 PTSD patients) were recruited. T1-weighted structural magnetic resonance imaging, BDNF rs6265 genotyping through blood sampling, and clinical assessments including the childhood trauma questionnaire (CTQ) and posttraumatic stress disorder Checklist (PCL) were performed. A moderated regression analysis, two-way multivariate analysis of covariance, and correlation analysis were conducted. An interaction between the CTQ and the BDNF polymorphism significantly influenced PTSD symptom severity. In fact, people with rs6265 Val/Val genotype and higher CTQ scores showed higher PCL scores. Additionally, this interaction was significant on both left fusiform and transverse temporal gyri thickness. Furthermore, the thickness of both brain regions was significantly correlated with psychological symptoms including depression, anxiety, rumination, and cognitive emotion regulation methods; yet this was mainly observed in people with the Val/Val genotype. The interaction between childhood trauma and BDNF polymorphism significantly influences both PTSD symptoms and cortical thickness and the Val/Val genotype may increase the risk in Korean population.

The association of BDNF gene polymorphism with cognitive impairment in insomnia patients

BACKGROUND

Reductions in BDNF activity have shown associations with depressed mood. Other evidence has demonstrated that the BDNF Val66Met polymorphism (rs6265) appears to reduce neural plasticity. A limited number of studies have investigated the influence of these genetic polymorphisms in insomnia. The present study sought to confirm the presence of associations between BDNF Val66Met polymorphism (rs6265) occurrence in normal sleepers and those with insomnia.

METHOD

The study subjects consisted of a patient group (n = 199) complaining of insomnia and a control group (n = 51). Each subject was clinically interviewed using questions taken from the Brief Insomnia Questionnaire. After the interview, the subjects were asked to complete the Insomnia Severity Index, The Hamilton Depression Rating Scale, and the Montreal Cognitive Assessment Test. An overnight polysomnography test was also administered. Blood samples were collected for genetic study.

RESULTS

The insomnia patients showed a greater prevalence of heterozygous (A/G) VAL/MET polymorphism than the normal controls (p = ≤ 0.0001). This finding confirmed that this genetic polymorphism, which impairs BDNF activity, is an important correlate of disturbed sleep. Further, the finding of significantly greater (p = ≤ 0.0001) depression scores among the insomnia group suggested that BDNF is an important factor in the development of depressive symptoms.

CLINICAL IMPLICATIONS

The results of the present study indicate that BDNF gene polymorphism plays a prominent role in the variation of symptoms among insomnia patients and, further, that this polymorphism is strongly related to the severity of depression.

Genetics of stroke recovery: BDNF val66met polymorphism in stroke recovery and its interaction with aging

Stroke leads to long term sensory, motor and cognitive impairments. Most patients experience some degree of spontaneous recovery which is mostly incomplete and varying greatly among individuals. The variation in recovery outcomes has been attributed to numerous factors including lesion size, corticospinal tract integrity, age, gender and race. It is well accepted that genetics play a crucial role in stroke incidence and accumulating evidence suggests that it is also a significant determinant in recovery. Among the number of genes and variations implicated in stroke recovery the val66met single nucleotide polymorphism (SNP) in the BDNF gene influences post-stroke plasticity in the most significant ways. Val66met is the most well characterized BDNF SNP and is common (40-50 % in Asian and 25-32% in Caucasian populations) in humans. It reduces activity-dependent BDNF release, dampens cortical plasticity and is implicated in numerous diseases. Earlier studies on the effects of val66met on stroke outcome and recovery presented primarily a maladaptive role. Novel findings however indicate a much more intricate interaction between val66met and stroke recovery which appears to be influenced by lesion location, post-stroke stage and age. This review will focus on the role of BDNF and val66met SNP in relation to stroke recovery and try to identify potential pathophysiologic mechanisms involved. The effects of age on val66met associated alterations in plasticity and potential consequences in terms of stroke are also discussed.

Genetic influences on creativity: an exploration of convergent and divergent thinking

Previous studies on the genetic basis of creativity have mainly focused on the biological mechanisms of divergent thinking, possibly limiting the exploration of possible candidate genes. Taking a cognition-based perspective, the present study investigated the genetic basis for both the divergent and the convergent thinking components of creativity. A total of 321 Chinese university students were recruited to complete the Guildford Unusual Using Test (UUT) for divergent thinking capability and the Remote Associates Test (RAT) for convergent thinking capability. The polymorphism of rs2576037 in KATNAL2 was related to the fluency and originality component scores of UUT, and the polymorphism of rs5993883 in COMT, rs362584 in SNAP25 was related to the RAT performance. These effects remained significant after considering the influence of age, gender and intelligence. Our results provide new evidence for the genetic basis of creativity and reveal the important role of gene polymorphisms in divergent and convergent thinking.

Impact of brain-derived neurotrophic factor genetic polymorphism on cognition: A systematic review

INTRODUCTION

Brain-derived neurotrophic factor (BDNF) has an important role in the neurogenesis and neuroplasticity of the brain. This systematic review was designed to examine the association between BDNF Val66Met (rs6265) polymorphism and four cognitive domains-attention and concentration, executive function, verbal fluency, and memory, respectively.

METHODOLOGY

Primary literature search was performed using search engines such as PubMed and Scopus. Observational studies that evaluated the neurocognitive performances in relation to BDNF polymorphism within human subjects were included in this review, while animal studies, overlapping studies, and meta-analysis were excluded.

RESULTS

Forty of 82 reviewed studies (48.8%) reported an association between Val66Met polymorphism and neurocognitive domains. The proportion of the studies showing positive findings in cognitive performances between Val/Val homozygotes and Met carriers was comparable, at 30.5% and 18.3%, respectively. The highest percentage of positive association between Val66Met polymorphism and neurocognition was reported under the memory domain, with 26 of 63 studies (41.3%), followed by 18 of 47 studies (38.3%) under the executive function domain and four of 23 studies (17.4%) under the attention and concentration domain. There were no studies showing an association between Val66Met polymorphism and verbal fluency. In particular, Val/Val homozygotes performed better in tasks related to the memory domain, while Met carriers performed better in terms of executive function, in both healthy individuals and clinical populations.

CONCLUSION

While numerous studies report an association between Val66Met polymorphism and neurocognitive changes in executive function and memory domains, the effect of Met allele has not been clearly established.

Significant association of BDNF rs6265 G>A polymorphism with susceptibility to epilepsy: a meta-analysis

INTRODUCTION

Previously published articles have suggested that BDNF rs6265 G>A polymorphism is a potential risk factor for epilepsy. However, the results were not consistent.

METHODS

We conducted a meta-analysis to explore the association between BDNF rs6265 G>A polymorphism and epilepsy risk. Four online databases were searched, and related studies were reviewed from their inception up to June 20, 2017. ORs and corresponding 95% CIs were used to calculate the associations of each genetic model. Overall, 10 case-control publications involving 9,512 subjects were included in this meta-analysis.

RESULTS

Significant associations were found between BDNF rs6265 G>A polymorphism and epilepsy (A vs G: OR=0.88, 95% CI=0.83-0.94, P<0.01, I²=0%; GA vs GG: OR=0.88, 95% CI=0.79-0.97, P=0.01, I²=0%; AA vs GG: OR=0.79, 95% CI=0.70-0.90, P<0.01, I²=0%; GA+AA vs GG: OR=0.85, 95% CI=0.77-0.94, P<0.01, I²=0%; AA vs GG+GA: OR=0.85, 95% CI=0.76-0.95, P=0.01, I²=0%). Subgroup analysis also showed similar results in an Asian population.

CONCLUSION

Our meta-analysis indicated that BDNF rs6265 G>A polymorphism might be involved in epilepsy susceptibility, especially in the Asian population.

Brain-Derived Neurotropic Factor Val66Met Polymorphism and Posttraumatic Stress Disorder among Survivors of the 1998 Dongting Lake Flood in China

OBJECTIVE

This study mainly aimed to explore the association between brain-derived neurotropic factor (BDNF) Val66Met polymorphism and posttraumatic stress disorder (PTSD) among flood survivors in China.

METHODS

Individuals who experienced the 1998 Dongting Lake flood in Southeast Huarong, China, were enrolled in this study. Qualified health personnel carried out face-to-face interviews with participants. PTSD was identified using PTSD Checklist-Civilian version (PCL-C). Blood samples were collected from the participants to extract DNA for genotyping.

RESULTS

A total of 175 participants were enrolled in this study. The prevalence of PTSD among flood survivors at 17-year follow-up was 16.0% (28/175). Individuals with PTSD were more likely to be female, experience at least three flood-related stressors, experience at least three postflood stressors, and carry the Met than those without PTSD. Compared with Val/Val homozygotes, Met carriers had higher scores of PCL-C (mean ± standard error: 23.60 ± 7.23 versus 27.19 ± 9.48, P < 0.05). Multivariable logistic regression analysis indicated that Met carriers (aOR = 4.76, 95% CI = 1.02-22.15, P < 0.05) were more likely to develop PTSD than Val/Val homozygotes.

CONCLUSIONS

Met carriers for BDNF rs6265 are at higher risk of developing PTSD and also exhibit more severe PTSD symptoms than Val/Val homozygotes among flood survivors in China.

BDNF Variants May Modulate Long-Term Visual Memory Performance in a Healthy Cohort

Brain-derived neurotrophic factor (BDNF) is involved in numerous cognitive functions including learning and memory. BDNF plays an important role in synaptic plasticity in humans and rats with BDNF shown to be essential for the formation of long-term memories. We previously identified a significant association between the BDNF Val66Met polymorphism (rs6265) and long-term visual memory (p-value = 0.003) in a small cohort (n = 181) comprised of healthy individuals who had been phenotyped for various aspects of memory function. In this study, we have extended the cohort to 597 individuals and examined multiple genetic variants across both the BDNF and BDNF-AS genes for association with visual memory performance as assessed by the Wechsler Memory Scale—Fourth Edition subtests Visual Reproduction I and II (VR I and II). VR I assesses immediate visual memory, whereas VR II assesses long-term visual memory. Genetic association analyses were performed for 34 single nucleotide polymorphisms genotyped on Illumina OmniExpress BeadChip arrays with the immediate and long-term visual memory phenotypes. While none of the BDNF and BDNF-AS variants were shown to be significant for immediate visual memory, we found 10 variants (including the Val66Met polymorphism (p-value = 0.006)) that were nominally associated, and three variants (two variants in BDNF and one variant in the BDNF-AS locus) that were significantly associated with long-term visual memory. Our data therefore suggests a potential role for BDNF, and its anti-sense transcript BDNF-AS, in long-term visual memory performance.

COMT, BDNF, and DTNBP1 polymorphisms and cognitive functions in patients with brain tumors

BACKGROUND

Cognitive dysfunction is common among patients with brain tumors and can be associated with the disease and treatment with radiotherapy and chemotherapy. However, little is known about genetic risk factors that may moderate the vulnerability for developing cognitive dysfunction. In this study, we examined the association of single nucleotide polymorphisms (SNPs) in the catechol-O-methyl transferase (COMT), brain-derived neurotrophic factor (BDNF), and dystrobrevin-binding protein 1 (DTNBP1) genes with cognitive functions and neuroimaging outcomes in patients with brain tumors.

METHODS

One hundred and fifty patients with brain tumors completed neuropsychological tests of attention, executive functions, and memory and were genotyped for polymorphisms in the COMT, BDNF, and DTNBP1 genes. Ratings of white matter (WM) abnormalities on magnetic resonance imaging scans were performed.

RESULTS

Multivariate regression shrinkage analyses, adjusted for age, education, treatment type, time since treatment completion, and tumor location, indicated a significant association between the COMT SNP rs4680 (Val158Met) and memory with lower scores in delayed recall (P < .01) among homozygotes (valine/valine). Additional COMT, BDNF and DTNBP1 SNPs were significantly associated with attention, executive functions, and memory scores.

CONCLUSION

This is the first study to suggest that known and newly described polymorphisms in genes associated with executive and memory functions in healthy individuals and other clinical populations may modulate cognitive outcome in patients with brain tumors.

The BDNF Val66Met Polymorphism Influences Reading Ability and Patterns of Neural Activation in Children

Understanding how genes impact the brain’s functional activation for learning and cognition during development remains limited. We asked whether a common genetic variant in the BDNF gene (the Val⁶⁶Met polymorphism) modulates neural activation in the young brain during a critical period for the emergence and maturation of the neural circuitry for reading. In animal models, the bdnf variation has been shown to be associated with the structure and function of the developing brain and in humans it has been associated with multiple aspects of cognition, particularly memory, which are relevant for the development of skilled reading. Yet, little is known about the impact of the Val⁶⁶Met polymorphism on functional brain activation in development, either in animal models or in humans. Here, we examined whether the BDNF Val⁶⁶Met polymorphism (dbSNP rs6265) is associated with children’s (age 6–10) neural activation patterns during a reading task (n = 81) using functional magnetic resonance imaging (fMRI), genotyping, and standardized behavioral assessments of cognitive and reading development. Children homozygous for the Val allele at the SNP rs6265 of the BDNF gene outperformed Met allele carriers on reading comprehension and phonological memory, tasks that have a strong memory component. Consistent with these behavioral findings, Met allele carriers showed greater activation in reading–related brain regions including the fusiform gyrus, the left inferior frontal gyrus and left superior temporal gyrus as well as greater activation in the hippocampus during a word and pseudoword reading task. Increased engagement of memory and spoken language regions for Met allele carriers relative to Val/Val homozygotes during reading suggests that Met carriers have to exert greater effort required to retrieve phonological codes.

Interaction of BDNF with cytokines in chronic schizophrenia

Brain-derived neurotrophic factor (BDNF) interacts with cytokines. Although both BDNF and cytokines occur at abnormal levels in schizophrenia patients, their interactions have not yet been examined. We therefore compared serum BDNF, TNF-α, interleukin (IL)-2, IL-6, and IL-8 levels in 92 chronically medicated schizophrenia patients and 60 healthy controls. We correlated these serum levels within these subject groups with each other and with clinical symptoms assessed according to the Positive and Negative Syndrome Scale (PANSS). Compared to the control group, the schizophrenia patients had significantly lower BDNF and TNF-α levels, and higher IL-2, IL-6, and IL-8 levels. The patients also showed a significant positive correlation between BDNF and both IL-2 and IL-8 levels, and low BDNF and TNF-α levels together were associated with poor performance on the PANSS cognitive factor. Thus, an interaction between cytokines and neurotrophic factors may be implicated in the pathophysiology of chronic schizophrenia. In particular, the cytokine TNF-α may interact with BNDF causing cognitive impairment.

Development of Neuropsychological Measures: Personal Experience and Lessons Learnt

This paper briefly reviews the history and purposes of neuropsychological assessment, as well as advancements in this area, and discusses the development of neuropsychological tests, using examples developed by the author and his colleagues to measure different aspects of human memory. These include the Shum Visual Learning Test, the Australian Retrograde Memory Test, the Comprehensive Assessment of Prospective Memory and the Virtual Reality Prospective Memory Task. The intended uses and psychometric properties of these tests, as well as examples of their use in research and clinical settings, will also be discussed. The paper will conclude with recommendations and advice on the development of neuropsychological tests based on the author's own experience.

Impact of repetitive transcranial magnetic stimulation on post-stroke dysmnesia and the role of BDNF Val66Met SNP

Background

Little is known about the effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) on dysmnesia and the impact of brain nucleotide neurotrophic factor (BDNF) Val66Met single-nucleotide polymorphism (SNP). This study investigated the impact of low-frequency rTMS on post-stroke dysmnesia and the impact of BDNF Val66Met SNP.

Material/Methods

Forty patients with post-stroke dysmnesia were prospectively randomized into the rTMS and sham groups. BDNF Val66Met SNP was determined using restriction fragment length polymorphism. Montreal Cognitive Assessment (MoCA), Loewenstein Occupational Therapy of Cognitive Assessment (LOTCA), and Rivermead Behavior Memory Test (RBMT) scores, as well as plasma BDNF concentrations, were measured at baseline and at 3 days and 2 months post-treatment.

Results

MoCA, LOTCA, and RBMT scores were higher after rTMS. Three days after treatment, BDNF decreased in the rTMS group but it increased in the sham group (P<0.05). Two months after treatment, RMBT scores in the rTMS group were higher than in the sham group, but not MoCA and LOTCA scores.

Conclusions

Low-frequency rTMS may improve after-stoke memory through various pathways, which may involve polymorphisms and several neural genes, but not through an increase in BDNF levels.

TNF-alpha G308A polymorphism and the susceptibility to Alzheimer's disease: an updated meta-analysis

BACKGROUND AND AIMS

Tumor necrosis factor (TNF)-alpha G308A polymorphism has been reported in the association with susceptibility to Alzheimer's disease (AD); however, results have been contradictory. We conducted an updated meta-analysis to evaluate the role of TNF-alpha G308A in the occurrence of AD.

METHODS

Relevant articles were retrieved from online databases. The combined odds ratio, odds ratio in different genetic models, and the related 95% confidence intervals were calculated. Publication bias and homogeneity among individual studies were estimated. Subgroup analyses and sensitivity analyses were also performed.

RESULTS

In overall analyses, no risk of AD was associated with TNF-alpha G308A under different genetic models. However, in the subgroup analyses, a significant association between TNF-alpha G308A and AD risk was observed in Chinese. In addition, a significant protective effect of TNF-alpha -308A was found in the occurrence of AD among North European populations under a dominant model.

CONCLUSIONS

The result of this meta-analysis suggests that TNF-alpha G308A polymorphism may be associated with the increased risk of AD in Chinese and decreased risk of AD in northern European populations.

Modulation of learning and memory by cytokines: signaling mechanisms and long term consequences

This review describes the role of cytokines and their downstream signaling cascades on the modulation of learning and memory. Immune proteins are required for many key neural processes and dysregulation of these functions by systemic inflammation can result in impairments of memory that persist long after the resolution of inflammation. Recent research has demonstrated that manipulations of individual cytokines can modulate learning, memory, and synaptic plasticity. The many conflicting findings, however, have prevented a clear understanding of the precise role of cytokines in memory. Given the complexity of inflammatory signaling, understanding its modulatory role requires a shift in focus from single cytokines to a network of cytokine interactions and elucidation of the cytokine-dependent intracellular signaling cascades. Finally, we propose that whereas signal transduction and transcription may mediate short-term modulation of memory, long-lasting cellular and molecular mechanisms such as epigenetic modifications and altered neurogenesis may be required for the long lasting impact of inflammation on memory and cognition.

BDNF val66met polymorphism affects aging of multiple types of memory

The BDNF val66met polymorphism (rs6265) influences activity-dependent secretion of brain-derived neurotrophic factor in the synapse, which is crucial for learning and memory. Individuals homozygous or heterozygous for the met allele have lower BDNF secretion than val homozygotes and may be at risk for reduced declarative memory performance, but it remains unclear which types of declarative memory may be affected and how aging of memory across the lifespan is impacted by the BDNF val66met polymorphism. This cross-sectional study investigated the effects of BDNF polymorphism on multiple indices of memory (item, associative, prospective, subjective complaints) in a lifespan sample of 116 healthy adults aged 20-93 years. Advancing age showed a negative effect on item, associative and prospective memory, but not on subjective memory complaints. For item and prospective memory, there were significant age×BDNF group interactions, indicating the adverse effect of age on memory performance across the lifespan was much stronger in the BDNF met carriers than for the val homozygotes. BDNF met carriers also endorsed significantly greater subjective memory complaints, regardless of age, and showed a trend (p<.07) toward poorer associative memory performance compared to val homozygotes. These results suggest that genetic predisposition to the availability of brain-derived neurotrophic factor, by way of the BDNF val66met polymorphism, exerts an influence on multiple indices of episodic memory - in some cases in all individuals regardless of age (subjective memory and perhaps associative memory), in others as an exacerbation of age-related differences in memory across the lifespan (item and prospective memory). This article is part of a Special Issue entitled Memory & Aging.