Nathalie André

Effects of BDNF polymorphism and physical activity on episodic memory in the elderly: a cross sectional study

BackgroundThe brain-derived neurotrophic factor (BDNF) concentration is highest in the hippocampus compared with that in other brain structures and affects episodic memory, a cognitive function that is impaired in older adults. According to the neurotrophic hypothesis, BDNF released during physical activity enhances brain plasticity and consequently brain health. However, even if the physical activity level is involved in the secretion of neurotrophin, this protein is also under the control of a specific gene. The aim of the present study was to examine the effect of the interaction between physical activity and BDNF Val66Met (rs6265), a genetic polymorphism, on episodic memory.MethodsTwo hundred and five volunteers aged 55 and older with a Mini Mental State Examination score ≥ 24 participated in this study. Four groups of participants were established according to their physical activity level and polymorphism BDNF profile (Active Val homozygous, Inactive Val homozygous, Active Met carriers, Inactive Met carriers). Episodic memory was evaluated based on the delayed recall of the Logical Memory test of the MEM III battery.ResultsAs expected, the physical activity level interacted with BDNF polymorphism to affect episodic memory performance (p < .05). The active Val homozygous participants significantly outperformed the active Met carriers and inactive Val homozygous participants.ConclusionThis study clearly demonstrates an interaction between physical activity and BDNF Val66Met polymorphism that affects episodic memory in the elderly and confirms that physical activity contributes to the neurotrophic mechanism implicated in cognitive health. The interaction shows that only participants with Val/Val polymorphism benefited from physical activity.

Executive functions improvement following a 5-month aquaerobics program in older adults: Role of cardiac vagal control in inhibition performance

The aims of this study were to examine the effects of aerobic exercise on measures of executive performance and their relationships with changes in cardiorespiratory fitness, cardiac vagal control (heart rate variability) and psychological variables. Thirty-six sedentary seniors aged 60-75 years were randomly assigned to a swimming and aquaerobics program or a stretching program two times a week for 21 weeks. Executive functions (inhibition, updating of working memory and cognitive flexibility) and cardiorespiratory fitness (estimated VO2max) were assessed at the start, after 10 weeks of program and at the end of the program. Resting HRV and measures of psychological outcomes (depression, self-efficacy, decisional balance) were obtained at the start and at the end of the program. Participants of both groups significantly improved their VO2max level, their psychological state and their performance for the 2-back task. Only the participants in the aquaerobics group significantly improved their vagally-mediated HRV and their performance for the Stroop test and the verbal running-span test at the end of the program. Only improvements in cardiac vagal control and in inhibition were shown to be functionally related. These results are discussed in line with the model of neurovisceral integration.

The impact of physical activity and sex differences on intraindividual variability in inhibitory performance in older adults

ABSTRACT It is well-known that processing speed and executive functions decline with advancing age. However, physical activity (PA) has a positive impact on cognitive performances in aging, specifically for inhibition. Less is known concerning intraindividual variability (iiV) in reaction times. This study aims to investigate the influence of PA and sex differences on iiV in inhibitory performance during aging. Healthy adults were divided into active and sedentary groups according to PA level. To analyse iiV in reaction times, individual mean, standard deviation and the ex-Gaussian parameters were considered. An interaction between activity level and sex was revealed, sedentary females being slower and more variable than sedentary men. No sex differences were found in the active groups. These results indicate that the negative impact of sedentariness on cognitive performance in older age is stronger for females. The present findings underline the need to consider sex differences in active aging approaches.

I Am Not a Lucky Person: An Examination of the Dimensionality of Beliefs About Chance

The purpose of this article was to verify whether beliefs about chance are multi or unidimensional constructs. Traditionally, authors who assessed beliefs about chance postulated that individuals who perceive themselves as unlucky usually believe that chance is random and are less confident as well as more anxious. Curiously, it appears that sometimes these individuals act as if they were motivated to avoid negative consequences. In order to better understand these puzzling findings, two studies were performed to compare three instruments intended to assess beliefs about chance and to verify their causal properties. In total, 285 students filled out a battery of instruments, including chance questionnaires (LOC, BIGL and MBIC) and personality traits. Overall, results showed that luck, through perceived controllability, seems to be related to volitional control, whereas chance, which is more stable and less controllable than luck, can be associated with cognitive distortions. The implications of these results are discussed.

Interaction between BDNF Polymorphism and Physical Activity on Inhibitory Performance in the Elderly without Cognitive Impairment

Background: In the elderly, physical activity (PA) enhances cognitive performances, increases brain plasticity and improves brain health. The neurotrophic hypothesis is that the release of brain-derived neurotrophic factor (BDNF), which is implicated in brain plasticity and cognition, is triggered by PA because motoneurons secrete BDNF into the bloodstream during exercise. Individual differences in cognitive performance may be explained by individual differences in genetic predisposition. A single nucleotide polymorphism on the BDNF gene, BDNFVal66Met, affects activity-dependent BDNF secretion. This study investigated the influence of the BDNFVal66Met polymorphism on the relationship between PA and controlled inhibition performance in older adults. Methods: A total of 114 healthy elderly volunteers (mean age = 71.53 years old) were evaluated. Participants were genotyped for the BDNFVal66Met polymorphism. We evaluated inhibitory performance using choice reaction times (RT) and error rates from a Simon-like task and estimated their PA using two self-reported questionnaires. We established four groups according to PA level (active vs. inactive) and BDNFVal66Met genotype (Met carriers vs. Val-homozygous). The results were analyzed using ANOVA and ANCOVA, including age, gender and body mass index as covariates. Results: The BDNFVal66Met polymorphism interacted with PA on controlled inhibition performance. More specifically, inactive Val-homozygous participants exhibited a lower inhibition performance than active Val homozygotes and inactive Met carriers; the former had a higher error rate without differences in RT. Conclusion: Differences between individuals on inhibitory performance may be partially understood by the interaction between genetic influence in BDNF secretion and PA level. The results of this study clearly support the neurotrophic hypothesis that BDNF synthesis is an important mechanism underlying the influence of physical activity on brain structure and functions.

Using motivational interviewing as a supplement to physical activity program in obese adolescents: a RCT study

This study ascertained the combination of physical activity (PA) and motivational interviewing (MI) on weight gain prevention, weight loss and maintenance of weight loss in children and youth. There have been a relatively large number of studies examining the role of PA programs, defined as supervised exercise sessions, in children and adolescents in obesity treatment. These programs are consistently associated with positive obesity outcomes (e.g., BMI decrease). However, the positive impact of PA programs tends to fade over time when structured exercise programming is discontinued. As youth weight management is a multifactorial issue (International Conference on Physical Activity and Obesity Children), it is important to identify intervention modalities that promote long-term behavioral change. Among components for weight maintenance, self-efficacy and self-regulation strategies are considered as two effective determinants and were similarly evoked by individuals who succeeded or failed in making or maintain behavior changes [1]. MI is recognized as an efficient technique to promote self-efficacy and selfregulation intended to develop knowledge and skills that can help individuals to cope with environmental and psychological impediments. MI is a goal-oriented, clientcentered counseling style for eliciting behavior change by helping clients to explore and resolve conflicting beliefs or attitude. MI differs from cognitive behavioral therapy in that MI targets motivation for change [2]. Some studies have examined MI in obesity treatment and have showed promising results with obese populations [1, 2]. The effectiveness of MI combined with physical activity program has not been systematically investigated. On the other hand, no study clearly examined the relationship between self-efficacy and body shape. Yet, it is assumed that dissatisfaction with body shape can be considered as a risk factor for the development of some eating disorders and that physical activity is known as having positive effects on body shape [3]. Consequently, by enhancing self-efficacy in PA and body shape, the risk of relapse can be reduced. The aim of this pilot study was to compare a PA program with a program including both PA and MI focused on selfregulated strategies aimed at general self-efficacy. We expected that combining PA program with MI would be a significant supplement to maintain changes in youth’s behavior. This study also aims to obtain information that can be put to practice use in health education. We hypothesized that general self-efficacy and body shape satisfaction for the group receiving both MI and PA interventions would be higher than for PA program group alone in posttest and retention test.