Sex Differences in the Impact of BDNF Genotype on the Longitudinal Relationship between Physical Activity and Cognitive Performance

Working memory performance predicts, but does not reduce, cocaine- and cannabinoid-seeking in adult male rats

Background

Cognitive deficits reflecting impaired executive function are commonly associated with psychiatric disorders, including substance use. Cognitive training is proposed to improve treatment outcomes for these disorders by promoting neuroplasticity within the prefrontal cortex, enhancing executive control, and mitigating cognitive decline due to drug use. Additionally, brain derived neurotrophic factor (BDNF) can facilitate plasticity in the prefrontal cortex and reduce drug-seeking behaviors. We investigated whether working memory training could elevate BDNF levels in the prefrontal cortex and if this training would predict or protect against cocaine or cannabinoid seeking.

Methods

Adult male rats were trained to perform a 'simple' or 'complex' version of a delayed- match-to-sample working memory task. Rats then self-administered cocaine or the synthetic cannabinoid WIN55,212-2 and were tested for cued drug-seeking during abstinence. Tissue from the prefrontal cortex and dorsal hippocampus was analyzed for BDNF protein expression.

Results

Training on the working memory task enhanced endogenous BDNF protein levels in the prelimbic prefrontal cortex but not the dorsal hippocampus. Working memory training did not impact self-administration of either drug but predicted the extent of WIN self-administration and cocaine seeking during abstinence.

Conclusions

These results suggest that working memory training promotes endogenous BDNF but does not alter drug-seeking or drug-taking behavior. However, individual differences in cognitive performance prior to drug exposure may predict vulnerability to future drug use.

SuperAgers and centenarians, dynamics of healthy ageing with cognitive resilience

Graceful healthy ageing and extended longevity is the most desired goal for human race. The process of ageing is inevitable and has a profound impact on the gradual deterioration of our physiology and health since it triggers the onset of many chronic conditions like dementia, osteoporosis, diabetes, arthritis, cancer, and cardiovascular disease. However, some people who lived/live more than 100 years called 'Centenarians" and how do they achieve their extended lifespans are not completely understood. Studying these unknown factors of longevity is important not only to establish a longer human lifespan but also to manage and treat people with shortened lifespans suffering from age-related morbidities. Furthermore, older adults who maintain strong cognitive function are referred to as "SuperAgers" and may be resistant to risk factors linked to cognitive decline. Investigating the mechanisms underlying their cognitive resilience may contribute to the development of therapeutic strategies that support the preservation of cognitive function as people age. The key to a long, physically, and cognitively healthy life has been a mystery to scientists for ages. Developments in the medical sciences helps us to a better understanding of human physiological function and greater access to medical care has led us to an increase in life expectancy. Moreover, inheriting favorable genetic traits and adopting a healthy lifestyle play pivotal roles in promoting longer and healthier lives. Engaging in regular physical activity, maintaining a balanced diet, and avoiding harmful habits such as smoking contribute to overall well-being. The synergy between positive lifestyle choices, access to education, socio-economic factors, environmental determinants and genetic supremacy enhances the potential for a longer and healthier life. Our article aims to examine the factors associated with healthy ageing, particularly focusing on cognitive health in centenarians. We will also be discussing different aspects of ageing including genomic instability, metabolic burden, oxidative stress and inflammation, mitochondrial dysfunction, cellular senescence, immunosenescence, and sarcopenia.

Hormonal and psychological influences on performance anxiety in adolescent female volleyball players: a multi-approach study

Background

The neuroendocrine system has important implications for affiliation behavior among humans and can be used to assess the correlation between social relationships, stress, and health. This can be influenced by social closeness; this aspect is the closeness towards another individual or a group of individuals such as a sports team. Sports performance anxiety is considered an unpleasant emotional reaction composed of physiological, cognitive, affective, and behavioral components. This motivates us to learn about the process that can influence the outcome of competition. Hormones and genetics would seem to influence outcome and performance. In this regard, many studies have focused on the exercise response as a function of ovarian hormones and it has been observed that progesterone is a hormone that plays a key role in reducing anxiety, and thus stress, in humans and other animals. On the other hand, high cortisol concentrations are known to contribute to increased anxiety levels. However, the salivary alpha-amylase (sAA) enzyme has been suggested as marker of acute stress than cortisol. Genetics also seem to influence anxiety and stress management as in the case of brain-derived neurotrophic factor (BDNF) and striatal dopamine transporter (DAT). Therefore, the study aims to investigate social closeness, as a measure of sports team cohesion that can influence athletes' performance results, and its ability to influence the secretion of hormones, such as progesterone and cortisol, that affect the management of sports anxiety while also taking into account genetic background during a volleyball match.

Methods

Twenty-six female volleyball players who volunteered participated in this study (mean ± SD: age, 12.07 ± 0.7 years), and played in the final of the provincial volleyball championship in Palermo. All girls were during the ovarian cycle, in detail between the follicular and early ovulatory phases.

Results

The results showed a significant decrease in salivary cortisol only in the winning group (p < 0.039). In fact, whilst in the latter the pre-match level was 7.7 ng/ml and then decreased to 4.5 ng/ml after the match, in the losers group change was not statistically significant (7.8 ng/ml vs 6.6 ng/ml pre- and post-match). As to the sAA concentration, the winning team showed a statistically significant variation between pre- and post-match than the losers (166.01 ± 250 U/ml vs 291.59 ± 241 U/ml) (p = 0.01).

Conclusion

Analyzing the results of the SAS-2 psychological test it is highlighted that, on average, the loser group was more anxious than the winning group, and this contributed to the final result. In conclusion, there is strong evidence supporting the state of the art that many factors can affect performance anxiety and thus the performance itself.

A longitudinal study of polygenic score and cognitive function decline considering baseline cognitive function, lifestyle behaviors, and diabetes among middle-aged and older US adults

BACKGROUND

Genomic study of cognition decline while considering baseline cognition and lifestyle behaviors is scarce. We aimed to evaluate the impact of a polygenic score for general cognition on cognition decline rate, while considering baseline cognition and lifestyle behaviors, among the general population and people with diabetes, a patient group commonly affected by cognition impairment.

METHODS

We tested associations of the polygenic score for general cognition with annual changing rates of cognition measures in 8 years of follow-up among 12,090 White and 3100 Black participants of the Health and Retirement Study (HRS), a nationally representative sample of adults aged 50 years and older in the USA. Cognition measures including word recall, mental status, and total cognitive score were measured biannually. To maximize sample size and length of follow-up, we treated the 2010 wave of survey as baseline, and follow-up data until 2018 were analyzed. Baseline lifestyle behaviors, APOE status, and measured cognition were sequentially adjusted. Given racial differences in polygenic score, all analyses were conducted by race.

RESULTS

The polygenic score was significantly associated with annual changing rates of all cognition measures independent of lifestyle behaviors and APOE status. Together with age and sex, the polygenic score explained 29.9%, 15.9%, and 26.5% variances of annual changing rates of word recall, mental status, and total cognitive scores among Whites and explained 17.2%, 13.9%, and 18.7% variance of the three traits among Blacks. Among both White and Black participants, those in the top quartile of polygenic score had the three cognition measures increased annually, while those in the bottom quartile had the three cognition measures decreased annually. After further adjusting for the average cognition assessed in 3 visits around baseline, the polygenic score was still positively associated with annual changing rates of all cognition measures for White (P ≤ 2.89E - 19) but not for Black (P ≥ 0.07) participants. In addition, among participants with diabetes, physical activity offset the genetic susceptibility to decline of mental status (interaction P ≤ 0.01) and total cognitive scores (interaction P = 0.03).

CONCLUSIONS

Polygenic score predicted cognition changes in addition to measured cognition. Physical activity offset genetic risk for cognition decline among diabetes patients.

Impaired fear memory in a rat model of the Brain-Derived Neurotrophic Factor Val66Met polymorphism is reversed by chronic exercise

The brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with reduced activity-dependent BDNF release in the brain and has been implicated in fear and anxiety disorders, including post-traumatic stress disorder. Exercise has been shown to have benefits in affective disorders but the role of BDNF Val66Met remains unclear. Male and female BDNF Val66Met rats were housed in automated running-wheel cages from weaning while controls were housed in standard cages. During adulthood, all rats underwent standard three-day fear conditioning testing, with three tone/shock pairings on day 1 (acquisition), and extinction learning and memory (40 tones/session) on day 2 and day 3. Expression of BDNF and stress-related genes were measured in the frontal cortex. Extinction testing on day 2 revealed significantly lower freezing in response to initial cue exposure in control Met/Met rats, reflecting impaired fear memory. This deficit was reversed in both male and female Met/Met rats exposed to exercise. There were no genotype effects on acquisition or extinction of fear, however chronic exercise increased freezing in all groups at every stage of testing. Exercise furthermore led to increased expression of Bdnf in the prefrontal cortex of females and its isoforms in both sexes, as well as increased expression of FK506 binding protein 51 (Fkpb5) in females and decreased expression of Serum/glucocorticoid-regulated kinase (Sgk1) in males independent of genotype. These results show that the Met/Met genotype of the Val66Met polymorphism affects fear memory, and that chronic exercise selectively reverses this genotype effect. Chronic exercise also led to an overall increase in freezing in all genotypes which may contribute to results.

Aerobic exercise improves executive functions in females, but not males, without the BDNF Val66Met polymorphism

BACKGROUND

Aerobic exercise promotes cognitive function in older adults; however, variability exists in the degree of benefit. The brain-derived neurotropic factor (BDNF) Val66Met polymorphism and biological sex are biological factors that have been proposed as important modifiers of exercise efficacy. Therefore, we assessed whether the effect of aerobic exercise on executive functions was dependent on the BDNFval66met genotype and biological sex.

METHODS

We used data from a single-blind randomized controlled trial in older adults with subcortical ischemic vascular cognitive impairment (NCT01027858). Fifty-eight older adults were randomly assigned to either the 6 months, three times per week progressive aerobic training (AT) group or the usual care plus education control (CON) group. The secondary aim of the parent study included executive functions which were assessed with the Trail Making Test (B-A) and the Digit Symbol Substitution Test at baseline and trial completion at 6 months.

RESULTS

Analysis of covariance, controlling for baseline global cognition and baseline executive functions performance (Trail Making Test or Digit Symbol Substitution Test), tested the three-way interaction between experimental group (AT, CON), BDNFval66met genotype (Val/Val carrier, Met carrier), and biological sex (female, male). Significant three-way interactions were found for the Trail Making Test (F(1,48) = 4.412, p < 0.04) and Digit Symbol Substitution Test (F(1,47) = 10.833, p < 0.002). Posthoc analyses showed female Val/Val carriers benefited the most from 6 months of AT compared with CON for Trail Making Test and Digit Symbol Substitution Test performance. Compared with CON, AT did not improve Trail Making Test performance in male Val/Val carriers or Digit Symbol Substitution Test performance in female Met carriers.

CONCLUSIONS

These results suggest that future randomized controlled trials should take into consideration BDNF genotype and biological sex to better understand the beneficial effects of AT on cognitive function in vascular cognitive impairment to maximize the beneficial effects of exercise and help establish exercise as medicine for cognitive health.

Methylation of BDNF gene in association with episodic memory in women

Brain-derived neurotrophic factor (BDNF) gene regulation plays an important role in long-term memory formation, and the DNA methylation (DNAm) level of BDNF promoters has been associated with episodic memory deficits. Our aim was to explore the association between DNAm levels in BDNF promoter IV with verbal learning and memory performance in healthy women. We conducted a cross-sectional study by recruiting 53 individuals. Episodic memory was assessed by using the Rey Auditory Verbal Learning Test (RAVLT). Clinical interviews, RAVLT, and blood sample collection were assessed in all participants. DNAm was measured on DNA from whole peripheral blood using pyrosequencing. According to generalized linear model (GzLM) analyses, cytosine guanine dinucleotide (CpG) site 5 showed significant associations between learning capacity (LC, p &lt; 0.035), that is, every 1% of DNA methylation at CpG site 5 results in a 0.068 reduction in verbal learning performance. To the best of our knowledge, the current study is the first to show that BDNF DNAm plays an important role in episodic memory.

Brain-derived neurotrophic factor rs6265 (Val66Met) single nucleotide polymorphism as a master modifier of human pathophysiology

Brain-derived neurotrophic factor is the most prevalent member of the nerve growth factor family. Since its discovery in 1978, this enigmatic molecule has spawned more than 27,000 publications, most of which are focused on neurological disorders. Brain-derived neurotrophic factor is indispensable during embryogenesis and postnatally for the normal development and function of both the central and peripheral nervous systems. It is becoming increasingly clear, however, that brain-derived neurotrophic factor likewise plays crucial roles in a variety of other biological functions independently of sympathetic or parasympathetic involvement. Brain-derived neurotrophic factor is also increasingly recognized as a sophisticated environmental sensor and master coordinator of whole organismal physiology. To that point, we recently found that a common nonsynonymous (Val66→Met) single nucleotide polymorphism in the brain-derived neurotrophic factor gene (rs6265) not only substantially alters basal cardiac transcriptomics in mice but subtly influences heart gene expression and function differentially in males and females. In addition to a short description of recent results from associative neuropsychiatric studies, this review provides an eclectic assortment of research reports that support a modulatory role for rs6265 including and beyond the central nervous system.

Memory Modulation by Exercise in Young Adults Is Related to Lactate and Not Affected by Sex or BDNF Polymorphism

Currently, high-intensity interval exercise (HIIE) is on the rise compared to moderate-intensity exercise (MIE) due to its similar benefits for health and performance with low time requirements. Recent studies show how physical exercise can also influence cognitive function, although the optimal dose and underlying mechanisms remain unknown. Therefore, in our study, we have compared the effects on visuospatial and declarative memory of different exercise intensities (HIIE vs. MIE), including possible implicated factors such as lactate released after each session and the Brain-Derived Neurotrophic Factor (BDNF) genotype. Thirty-six undergraduate students participated in this study. The HIIE session consisted of a 3 min warm-up, four 2 min sets at 90−95% of the maximal aerobic speed (MAS) with 2 min of passive recovery between sets, and a 3 min cooldown, and the MIE session implies the same total duration of continuous exercise at 60% of the MAS. Better improvements were found after HIIE than MIE on the backward condition of the visuospatial memory test (p = 0.014, ηp2 = 0.17) and the 48 h retention of the declarative memory test (p = 0.04; d = 0.34). No differences were observed in the forward condition of the visuospatial memory test and the 7-day retention of the declarative memory test (p > 0.05). Moreover, non-modifiable parameters such as biological sex and BDNF polymorphism (Val/Val, Val/Met, or Met/Met) did not modulate the cognitive response to exercise. Curiously, the correlational analysis showed associations (p < 0.05) between changes in memory (visuospatial and declarative) and lactate release. In this sense, our results suggest an important role for intensity in improving cognitive function with exercise, regardless of genetic factors such as biological sex or BDNF Val66Met polymorphism.

Exercise Effects on Cognition in Older African Americans: A Pilot Randomized Trial

Introduction

Regular physical activity lowers risk for cognitive decline and neurodegenerative disorders. Older African Americans (AAs) have been underrepresented in trials that increased physical activity to improve cognitive outcomes.

Methods

56 sedentary, older, cognitively healthy AAs (avg. 69.2 ± 3.4 yrs. old) were randomized in 1:1 ratio into either a 12-week successful aging group (SAG) or a 12-week physical activity group (PAG). Participants in SAG attended weekly 60-min educational sessions in which healthy aging topics were discussed. Participants in PAG attended supervised physical activity sessions twice per week at local YMCAs (90-120 min/week) and were prescribed 2-3 days per week of home-based activity. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) assessed cognitive function. ANCOVA models compared mean 12-week change in global cognition and subdomain scores between groups with secondary analyses for sex differences. Effect sizes for RBANS were calculated.

Results

The RBANS global cognition score (SAG Est. 5.6 ± 1.8, effect size = 0.37, p = 0.003) and several subdomain scores (one-sample T tests, all p < 0.05) increased significantly within the SAG. Scores for global cognition increased more in SAG than in PAG (Change Estimate, PAG minus SAG: -4.6 ± 2.5 points, effect size = 0.31) at a trend level (p = 0.072). SAG females increased their global cognition score more than PAG females and more than males in either PAG or SAG (all p < 0.035).

Discussion

A 12-week physical activity intervention (PAG) did not improve cognitive functioning among older AAs but a comparator healthy aging education program did. Inadequate physical activity dosage or duration, SAG members acting on health-related information from educational sessions, and/or social stimulation within the SAG may have contributed to these results. Future studies should combine socially engaging activities with vigorous physical activity for cognitive enhancement among cognitively healthy older African Americans.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT03474302.

Interaction Effect between Physical Activity and the BDNF Val66Met Polymorphism on Depression in Women from the PISMA-ep Study

The relationship between depression and the Val66Met polymorphism at the brain-derived neurotrophic factor gene (BDNF), has been largely studied. It has also been related to physical activity, although the results remain inconclusive. The aim of this study is to investigate the relationship between this polymorphism, depression and physical activity in a thoroughly characterised sample of community-based individuals from the PISMA-ep study. A total of 3123 participants from the PISMA-ep study were genotyped for the BDNF Val66Met polymorphism, of which 209 had depression. Our results are in line with previous studies reporting a protective effect of physical activity on depression, specifically in light intensity. Interestingly, we report a gene-environment interaction effect in which Met allele carriers of the BDNF Val66Met polymorphism who reported more hours of physical activity showed a decreased prevalence of depression. This effect was observed in the total sample (OR = 0.95, 95%CI = 0.90–0.99, p = 0.027) and was strengthened in women (OR = 0.93, 95%CI = 0.87–0.98, p = 0.019). These results highlight the potential role of physical activity as a promising therapeutic strategy for preventing and adjuvant treatment of depression and suggest molecular and genetic particularities of depression between sexes.

FEASibility testing a randomized controlled trial of an exercise program to improve cognition for T2DM patients (the FEAST trial): A study protocol

While cognitive dysfunction is an important concern in persons with type 2 diabetes mellitus (T2DM), it has received little attention in the T2DM literature. Although it often remains unrecognized, cognitive dysfunction associated with T2DM can lead to severe consequences. Prior research studies have consistently shown that aerobic exercise enhances cognitive function among healthy subjects. However, very few studies have examined the effects of aerobic exercise on cognitive function in persons with T2DM. In addition, one important single-nucleotide polymorphism that influences cognition in humans is the brain-derived neurotrophic factor (BDNF) Val66Met variant. Despite strong evidence suggesting aerobic exercise has a beneficial effect on cognitive function, there is significant variability in individual response to exercise programs on cognitive outcomes among Val/Val versus Met carriers. However, the evidence on how the BDNF Val66Met variant influences cognitive outcomes following an aerobic exercise intervention among individuals with T2DM is currently lacking. Therefore, the purpose of this randomized controlled trial is to pilot-test a 3-month supervised exercise program to improve plasma BDNF levels and cognition, overall and according to genotypes of the BDNF Val66Met variant. A total of 81 patients with T2DM will be randomly assigned to either aerobic exercise group (n = 54) or attention control group (n = 27) for 3 months. Outcomes of interest include postintervention changes in plasma BDNF levels, fasting blood glucose, hemoglobin A1c, body mass index, executive function, memory, and processing speed. This study will provide further evidence on use of exercise as a non-pharmaceutical, low-cost intervention to improve cognition in this population.

Met carriers of the BDNF Val66Met polymorphism show reduced Glx/NAA in the pregenual ACC in two independent cohorts

The Met allele of the Val66Met SNP of the BDNF gene (rs6265) is associated with impaired activity-dependent release of brain-derived neurotrophic factor (BDNF), resulting in reduced synaptic plasticity, impaired glutamatergic neurotransmission, and morphological changes. While previous work has demonstrated Val66Met effects on magnetic resonance spectroscopy (MRS) markers of either glutamatergic metabolism (Glx) or neuronal integrity (NAA), no study has investigated Val66Met effects on these related processes simultaneously. As these metabolites share a metabolic pathway, the Glx/NAA ratio may be a more sensitive marker of changes associated with the Val66Met SNP. This ratio is increased in psychiatric disorders linked to decreased functioning in the anterior cingulate cortex (ACC). In this study, we investigated the correlation of the Val66Met polymorphism of the BDNF gene with Glx/NAA in the pregenual anterior cingulate cortex (pgACC) using MRS at 3 Tesla (T) (n = 30, all males) and 7 T (n = 98, 40 females). In both cohorts, Met carriers had lower Glx/NAA compared to Val homozygotes. Follow-up analyses using absolute quantification revealed that the Met carriers do not show decreased pgACC glutamate or glutamine levels, but instead show increased NAA compared to the Val homozygotes. This finding may in part explain conflicting evidence for Val66Met as a risk factor for developing psychiatric illnesses.

Blood Brain-Derived Neurotrophic Factor (BDNF) and Major Depression: Do We Have a Translational Perspective?

Major depressive disorder (MDD) affects millions of people worldwide and is a leading cause of disability. Several theories have been proposed to explain its pathological mechanisms, and the “neurotrophin hypothesis of depression” involves one of the most relevant pathways. Brain-derived neurotrophic factor (BDNF) is an important neurotrophin, and it has been extensively investigated in both experimental models and clinical studies of MDD. Robust empirical findings have indicated an association between increased BDNF gene expression and peripheral concentration with improved neuronal plasticity and neurogenesis. Additionally, several studies have indicated the blunt expression of BDNF in carriers of the Val66Met gene polymorphism and lower blood BDNF (serum or plasma) levels in depressed individuals. Clinical trials have yielded mixed results with different treatment options, peripheral blood BDNF measurement techniques, and time of observation. Previous meta-analyses of MDD treatment have indicated that antidepressants and electroconvulsive therapy showed higher levels of blood BDNF after treatment but not with physical exercise, psychotherapy, or direct current stimulation. Moreover, the rapid-acting antidepressant ketamine has presented an early increase in blood BDNF concentration. Although evidence has pointed to increased levels of BDNF after antidepressant therapy, several factors, such as heterogeneous results, low sample size, publication bias, and different BDNF measurements (serum or plasma), pose a challenge in the interpretation of the relation between peripheral blood BDNF and MDD. These potential gaps in the literature have not been properly addressed in previous narrative reviews. In this review, current evidence regarding BDNF function, genetics and epigenetics, expression, and results from clinical trials is summarized, putting the literature into a translational perspective on MDD. In general, blood BDNF cannot be recommended for use as a biomarker in clinical practice. Moreover, future studies should expand the evidence with larger samples, use the serum or serum: whole blood concentration of BDNF as a more accurate measure of peripheral BDNF, and compare its change upon different treatment modalities of MDD.

Longitudinal Associations of Midlife Accelerometer Determined Sedentary Behavior and Physical Activity With Cognitive Function: The CARDIA Study

Background To determine if accelerometer measured sedentary behavior (SED), light-intensity physical activity (LPA), and moderate-to-vigorous-intensity physical activity (MVPA) in midlife is prospectively associated with cognitive function. Methods and Results Participants were 1970 adults enrolled in the CARDIA (Coronary Artery Risk Development in Young Adults) study who wore an accelerometer in 2005 to 2006 (ages 38-50 years) and had cognitive function assessments completed 5 and/or 10 years later. SED, LPA, and MVPA were measured by an ActiGraph 7164 accelerometer. Cognitive function tests included the Digit Symbol Substitution Test, Rey Auditory Verbal Learning Test, and Stroop Test. Compositional isotemporal substitution analysis examined associations of SED, LPA, and MVPA with repeated measures of the cognitive function standardized scores. In men, statistical reallocation of 30 minutes of LPA with 30 minutes of MVPA resulted in an estimated difference of SD 0.07 (95% CI, 0.01-0.14), SD 0.09 (95% CI, 0.02-0.17), and SD -0.11 (95% CI, -0.19 to -0.04) in the Digit Symbol Substitution Test, Rey Auditory Verbal Learning Test, and Stroop scores, respectively, indicating better performance. Associations were similar when reallocating time in SED with MVPA, but results were less robust. Reallocation of time in SED with LPA resulted in an estimated difference of SD -0.05 (95% CI, -0.06 to -0.03), SD -0.03 (95% CI, -0.05 to -0.01), and SD 0.05 (95% CI, 0.03- 0.07) in the Digit Symbol Substitution Test, Rey Auditory Verbal Learning Test, and Stroop scores, respectively, indicating worse performance. Associations were largely nonsignificant among women. Conclusions Our findings support the idea that for men, higher-intensity activities (MVPA) may be necessary in midlife to observe beneficial associations with cognition.

Physical Activity and Trajectory of Cognitive Change in Older Persons: Mayo Clinic Study of Aging

BACKGROUND

Little is known about the association between physical activity (PA) and cognitive trajectories in older adults.

OBJECTIVE

To examine the association between PA and change in memory, language, attention, visuospatial skills, and global cognition, and a potential impact of sex or Apolipoprotein E (APOE) ɛ4 status.

METHODS

Longitudinal study derived from the population-based Mayo Clinic Study of Aging, including 2,060 cognitively unimpaired males and females aged ≥70 years. Engagement in midlife (ages 50-65) and late-life (last year) PA was assessed using a questionnaire. Neuropsychological testing was done every 15 months (mean follow-up 5.8 years). We ran linear mixed-effect models to examine whether mid- or late-life PA at three intensities (mild, moderate, vigorous) was associated with cognitive z-scores.

RESULTS

Light intensity midlife PA was associated with less decline in memory function compared to the no-PA reference group (time x light PA; estimate [standard error] 0.047 [0.016], p = 0.004). Vigorous late-life PA was associated with less decline in language (0.033 [0.015], p = 0.030), attention (0.032 [0.017], p = 0.050), and global cognition (0.039 [0.016], p = 0.012). Females who were physically inactive in midlife experienced more pronounced cognitive decline than females physically active in midlife and males regardless of PA (p-values for time interaction terms with midlife PA levels and sex were all p < 0.05 for global cognition). APOE ɛ4 carriership did not moderate the association between PA and cognition.

CONCLUSION

Engaging in PA, particularly of vigorous intensity in late-life, was associated with less pronounced decline in global and domain-specific cognition. This association may differ by sex.

Does the Brain-Derived Neurotrophic Factor Val66Met Polymorphism Modulate the Effects of Physical Activity and Exercise on Cognition?

The Val66Met is a polymorphism of the brain-derived neurotrophic factor (BDNF) gene that encodes a substitution of a valine (Val) to methionine (Met) amino acid. Carrying this polymorphism reduces the activity-dependent secretion of the BDNF protein, which can potentially affect brain plasticity and cognition. We reviewed the biology of Val66Met and surveyed 26 studies (11,417 participants) that examined the role of this polymorphism in moderating the cognitive response to physical activity (PA) and exercise. Nine observational studies confirmed a moderating effect of Val66Met on the cognitive response to PA but differences between Val and Met carriers were inconsistent and only significant in some cognitive domains. Only five interventional studies found a moderating effect of Val66Met on the cognitive response to exercise, which was also inconsistent in its direction. Two studies showed a superior cognitive response in Val carriers and three studies showed a better response in Met carriers. These results do not support a general and consistent effect of Val66Met in moderating the cognitive response to PA or exercise. Both Val and Met carriers can improve specific aspects of cognition by increasing PA and engaging in exercise. Causes for discrepancies among studies, effect moderators, and future directions are discussed.

The Influence of the BDNF Val66Met Polymorphism on the Association of Regular Physical Activity With Cognition Among Individuals With Diabetes

INTRODUCTION

Diabetes is associated with cognitive dysfunction that comes with substantial lifetime consequences, such as interference with diabetes self-management and reduced quality of life. Although regular physical activity has been consistently shown to enhance cognitive function among healthy subjects, significant interpersonal differences in exercise-induced cognitive outcomes have been reported among brain-derived neurotrophic factor (BDNF) Val/Val vs. Met carriers. However, the evidence on how the BDNF Val66Met variant influences the relationship between regular physical activity and cognition among individuals with diabetes is currently lacking.

METHODS

A total of 3,040 individuals with diabetes were included in this analysis using data from the Health and Retirement Study. Associations among moderate and vigorous physical activities (MVPA) and measures of cognitive function were evaluated using multivariable linear regression models within each stratum of the Val66Met genotypes.

RESULTS

MVPA was more strongly associated with total cognitive score, mental status, and words recall among Met/Met carriers, compared to Val/Val and Val/Met carriers.

CONCLUSIONS

This study provided preliminary findings on how BDNF variants may modulate the exercise-induced cognitive benefits among mid-aged and older adults with diabetes. Given the limitations of the current study, it is necessary for randomized controlled trials to stratify by BDNF genotypes to more conclusively determine whether Met carriers benefit more from increased physical activity. In addition, future research is needed to examine how the interplay of BDNF Val66Met variants, DNA methylation, and physical activity may have an impact on cognitive function among adults with diabetes.

The BDNF Val66Met Polymorphism Modulates Resilience of Neurological Functioning to Brain Ageing and Dementia: A Narrative Review

Brain-derived neurotropic factor (BDNF) is an abundant and multi-function neurotrophin in the brain. It is released following neuronal activity and is believed to be particularly important in strengthening neural networks. A common variation in the BDNF gene, a valine to methionine substitution at codon 66 (Val66Met), has been linked to differential expression of BDNF associated with experience-dependent plasticity. The Met allele has been associated with reduced production of BDNF following neuronal stimulation, which suggests a potential role of this variation with respect to how the nervous system may respond to challenges, such as brain ageing and related neurodegenerative conditions (e.g., dementia and Alzheimer’s disease). The current review examines the potential of the BDNF Val66Met variation to modulate an individual’s susceptibility and trajectory through cognitive changes associated with ageing and dementia. On balance, research to date indicates that the BDNF Met allele at this codon is potentially associated with a detrimental influence on the level of cognitive functioning in older adults and may also impart increased risk of progression to dementia. Furthermore, recent studies also show that this genetic variation may modulate an individual’s response to interventions targeted at building cognitive resilience to conditions that cause dementia.

Sex Moderates the Effect of Aerobic Exercise on Some Aspects of Cognition in Cognitively Intact Younger and Middle-Age Adults

We recently reported the results of a randomized, parallel-group, observer-masked, community-based clinical trial of 132 cognitively normal individuals aged 20–67 with below median aerobic capacity who were randomly assigned to one of two 6-month, four-times-weekly conditions: aerobic exercise and stretching/toning. We now assessed potential sex moderation on exercise-related changes in aerobic capacity, BMI and cognitive function. There was no sex moderation of the effect of aerobic exercise on aerobic capacity or BMI. We had previously reported an effect of aerobic exercise on executive function that was moderated by age. We found additional moderation by sex, such that in any age range men improved more than women. Processing speed showed significant sex moderation but not significant age moderation. In men, processing speed significantly improved by week 12 (b = 0.35, p = 0.0051), but the effect was diminished relative to week 12 at week 24 (b = 0.24, p = 0.0578). In women, there was no exercise effect at either time point (week 12: b = −0.06, p = 0.4156; week 24: b = −0.11, p = 0.1841). Men benefited cognitively more than women from aerobic exercise. This study highlights the importance of using sex-disaggregated analyses when assessing the impact of physical exercise intervention, and the need to ascertain the underlying mechanisms for differential cognitive benefit by sex.

Acute high-intensity aerobic exercise affects brain-derived neurotrophic factor in mild cognitive impairment: a randomised controlled study

OBJECTIVE

To investigate the brain-derived neurotrophic factor (BDNF) and cognitive response to a short bout of high-intensity aerobic exercise in older adults with mild cognitive impairment (MCI).

METHODS

Participants were randomised to one of two testing schedules, completing either a standardised exercise test (group A) or a resting control condition (group B). Blood sampling and cognitive measures (visuospatial learning and memory, sustained attention and executive function) were collected at baseline (T1) and postintervention (T2). An additional measurement of study outcomes was collected after exercise (T3) in group B only.

RESULTS

64 participants (female 53.2%, mean age 70.5±6.3 years) with MCI were recruited. From T1 to T2, serum BDNF (sBDNF) concentration increased in group A (n=35) (median (Md) 4564.61±IQR 5737.23 pg/mL to Md 5173.27±5997.54 pg/mL) and decreased in group B (Md 4593.74±9558.29 pg/mL to Md 3974.66±3668.22 pg/mL) (between-group difference p=0.024, effect size r=0.3). The control group made fewer errors on the sustained attention task compared with the exercise group (p=0.025). Measures of visuospatial learning and memory or executive function did not change significantly between groups.

CONCLUSION

This study is the first to show that a short bout of high-intensity aerobic exercise increases peripheral sBDNF in a population with MCI. However, acute exercise did not improve cognitive performance.

Effect of BDNFVal66Met on disease markers in dominantly inherited Alzheimer's disease

OBJECTIVE

Previous studies suggest that the brain-derived neurotrophic factor (BDNF) Val66Met (rs6265) polymorphism may influence symptom onset in Alzheimer's disease (AD). Our recent cross-sectional findings suggest that Met66 may influence clinical expression in dominantly inherited AD (DIAD) through its effects on tau. However, it remains unclear whether carriage of Met66 in DIAD results in faster increases in cerebrospinal fluid (CSF) tau and ptau₁₈₁ , and whether these increases are associated with accelerated brain volume loss and memory decline.

METHODS

A total of 211 subjects (101 mutation noncarriers, 110 mutation carriers), who were cognitively normal, as defined by a Clinical Dementia Rating global score of 0, completed assessments of cognitive function, neuroimaging, and CSF sampling over 3.5 years as part of the Dominantly Inherited Alzheimer's Network.

RESULTS

In mutation carriers, Met66 carriers showed faster memory decline (4×), hippocampal volume loss (16×), and CSF tau and ptau₁₈₁ increases (6×) than Val66 homozygotes. BDNF did not influence rates of cortical β-amyloid accumulation or change in CSF Aβ₄₂ levels in mutation carriers. In mutation noncarriers, BDNF genotype had no effect on change in cognition, brain volume, cortical β-amyloid accumulation, or change in any CSF measures of tau, ptau₁₈₁ , and CSF Aβ₄₂ .

INTERPRETATION

As in sporadic AD, the deleterious effects of β-amyloid on cognitive function, brain volume loss, and CSF tau in DIAD mutation carriers are less in Val66 homozygotes. The BDNF Val66Met polymorphism should be considered as a potential moderator of clinical trial outcomes in current treatment and prevention trials in DIAD and sporadic AD. Ann Neurol 2018;84:424-435.