Effects of Episodic Memory Recall on Reinforcing Value of Physical Activity.

OBJECTIVE: Many people prefer a sedentary versus an active lifestyle and have difficulty completing sufficient physical activity to improve health. While exercise can be a powerful reinforcer for some people, many prefer to be sedentary. The relative reinforcing value of physical activity (RRVPA) is influenced by a person's learning history with positive experiences strengthening the motivation to be active. Episodic memories may be critical to determining RRVPA, or RRV of different types of positive behaviors. METHOD: As a potential way to increase RRVPA we examined if recalling a positive episodic memory would affect RRVPA. One hundred and thirty seven adult participants completed measures of reinforcement history and memory functions and then recalled a single positive episode of either a physical activity or of a cognitively enriching activity, rated subjective memory qualities, and completed tasks to measure the RRV of both types of activity. RESULTS: Recalling a positive episodic memory increased RRV for the respective activity, and changes in RRVPA were moderated by how much the memory satisfies a basic psychological need. CONCLUSIONS: This research demonstrates the impact of episodic memory on RRVPA, which could be leveraged to aid behavior change efforts.

Insulin Resistance and Glycated Hemoglobin in Obesity Are Associated With Preference for Sugar-Sweetened Yogurt: A Pilot Study.

OBJECTIVE: Insulin resistance is associated with elevated activation of food reward, which should be associated with an increased reinforcing value of food. Research has also shown that sugar is a macronutrient strongly associated with reward and reinforcing value of food. This research is designed to assess whether insulin resistance is associated with a stronger preference for sugar-sweetened, thus elevating blood glucose responses in obese people with varying degrees of insulin resistance. METHODS: Thirteen people with obesity (body mass index, 39.1 kg/m 2 ; range, 30.0-45.1 kg/m 2 ) with varying degrees of insulin resistance (Homeostatic Model Assessment of Insulin Resistance, 5.2; range, 0.7-11.6) consumed novel flavored-colored yogurts that were sweetened with either sugar or monkfruit daily for 6 days to assess whether when given the choice of sugar-sweetened versus monkfruit-sweetened yogurts to consume, participants preferred sugar-sweetened yogurts. RESULTS: Participants consumed a greater amount ( p = .009) and percentage ( p = .04) of sugar-sweetened yogurt earned than monkfruit-sweetened yogurt. The percent of sugar-sweetened versus monkfruit-sweetened yogurt consumed in relationship to amount earned was related to insulin resistance ( r = 0.64, p = .019), glycated hemoglobin ( r = 0.61, p = .027), insulin ( r = 0.58, p = .007), and glucose ( r = 0.56, p = .048). CONCLUSIONS: Insulin resistance is associated with preference for sugar-sweetened foods in participants with obesity, which may make it hard to make dietary changes. Research is needed to assess whether treatments that improve insulin resistance also change the preference for sugar-sweetened or high-glycemic-index foods.

Effects of 6-month episodic future thinking training on delay discounting, weight loss and HbA1c changes in individuals with prediabetes.

People with prediabetes are at risk for type 2 diabetes. They may discount the future delay discounting (DD), and not engage in preventive health behaviors. Episodic future thinking (EFT) can reduce DD when future scenarios are cued, but research is needed to assess long-term effects of EFT and when EFT is not cued. This study tested EFT training compared to control for people with prediabetes enrolled in a 6-month weight loss program on DD, weight, HbA1c, and physical activity. Results showed a reliable EFT effect on reducing DD in cued (p = 0.0035), and uncued DD tasks (p = 0.048), and significant overall changes in weight (p < 0.001), HbA1c (p, 0.001) and physical activity (p = 0.003), but no significant differences in these outcomes by group (p's > 0.05). Sixty-eight percent of the sample ended below the prediabetes HbA1c range. These results suggest that DD can be modified over extended periods, and the effects of EFT can be observed without EFT cues. However, these data do not suggest that changes in weight, HbA1c or physical activity were due to EFT training. The study was initiated before the COVID-19 pandemic which provided the opportunity to compare differences for people treated in-person or remotely. Analyses showed no differences in DD, weight, HBA1c or physical activity outcomes were observed between in-person and remote treatment, suggesting telehealth is a scalable approach to treating prediabetes.

A story to tell: the role of narratives in reducing delay discounting for people who strongly discount the future.

Delay Discounting (DD) or devaluing a future, larger reward in favour of a smaller, more immediate reward, has been linked to negative health behaviours. One intervention that reduces DD is Episodic Future Thinking (EFT). EFT has participants generate cues representing positive future events that correspond to temporal windows during the DD task. The current study examined if incorporating EFT cues into narratives would strengthen effects on DD. One hundred and sixty adults were recruited from Amazon Mechanical Turk and were randomised to traditional or narrative EFT. Results showed that participants in narrative EFT discounted the future less (p = 0.034) than participants who engaged in traditional EFT. This novel approach to EFT is well grounded in research and theory on the power of narratives to influence behaviour and can open a new window into ways to reduce DD to strengthen engagement in positive choices.

Comparing the reinforcing value of high intensity interval training versus moderate intensity aerobic exercise in sedentary adults.

Exercise is a reinforcer for both animals and humans, as they will work progressively harder to gain access for the opportunity to exercise. Exercise activates brain reward pathways similar to drugs of abuse, and the magnitude of the reinforcing value of exercise is a predictor of exercise behavior. The majority of research on exercise reinforcement has studied moderate intensity aerobic exercise (MIAE) or resistance training. There is limited research on the relative reinforcing value (RRV) of high intensity interval training (HIIT), which is often reported to be a preferred form of exercise in comparison to MIAE. Experiment 1 was a pilot study of 20 sedentary females designed to compare the reliability of differences in RRVHIIT vs RRVMIAE over two sessions, assess protocols comparing different volumes of HIIT in comparison to MIAE, and estimate sample sizes needed for a fully powered study to assess which type of exercise protocol was a better substitute for a highly liked sedentary activity. Experiment 2 studied 44 participants to assess whether HIIT or MIAE would be better substitutes for highly liked sedentary activities. Experiment 1 showed that measures of RRVHIIT or RRVMIAE were reliable, and that volume of HIIT did not influence RRVHIIT, even if it was of equal amount or duration to MIAE. Experiment 2 showed that HIIT was a more preferred substitute for sedentary behaviors than MIAE. Predictors of RRVMIAE were liking of MIAE and pleasantness of affect post MIAE. These results suggest inactive people may find interval training to be more reinforcing than MIAE, and may be more likely to adopt and maintain an exercise program involving HIIT rather than MIAE. The next stage of research should be to understand how to sensitize the RRV of exercise to motivate sedentary people to be more active.

Delay Discounting, Glycemic Regulation and Health Behaviors in Adults with Prediabetes.

The majority of people with prediabetes transition to type 2 diabetes. Research has suggested that persons with type 2 diabetes are likely to discount the future and focus on immediate rewards. This study was designed to assess whether this process of delay discounting (DD) is associated with glycemic regulation, medication adherence and eating and exercise behaviors in adults with prediabetes. Participants included 81 adults with prediabetes who were also prescribed hypertension or dyslipidemia drugs, which is common for people with prediabetes. Participants completed adjusting amount DD $100 and $1000 tasks, as well assessments of glycemic control (Hemoglobin (Hb) A1c), medication adherence, diet quality, and objectively measured physical activity. Relationships between DD and these variables were assessed. Results showed higher rates of DD were related to higher HbA1c; as well as poorer medication adherence, lower diet quality and lower physical activity. Hierarchical regression showed that the association between minority status, a known risk factor for type 2 diabetes, was moderated by DD, as minorities with higher DD had greater HbA1c values. Delay discounting may represent a novel target to prevent progression from prediabetes to type 2 diabetes.

Using memories to motivate future behaviour: an experimental exercise intervention.

This study tested a novel memory-based experimental intervention to increase exercise activity. Undergraduate students completed a two-part online survey ostensibly regarding college activity choices. At Time 1, they completed questionnaires that included assessments of exercise-related attitudes, motivation and self-reported behaviours. Next, they described a memory of a positive or negative experience that would increase their motivation to exercise; students in a control condition did not receive a memory prompt. Finally, they rated their intentions to exercise in the future. Eight days following Time 1, students received a Time 2 survey that included an assessment of their self-reported exercise during the prior week. Students in the positive memory condition reported higher levels of subsequent exercise than those in the control condition; students in the negative memory condition reported intermediate levels of exercise. Activating a positive motivational memory had a significant effect on students' self-reported exercise activity even after controlling for prior attitudes, motivation and exercise activity.