Exercise for Improving Memory
Lifestyle Health Wrap #14
If you’re new here, I recommend reading my first post about why I started this publication.
After a week off, I’m back with another lifestyle health research wrap!
The title of this wrap refers to the study I cover in the exercise section.
But first, some housekeeping…
For the past two weeks, I’ve been wrapping up work for my class finals for the first quarter of my MS in Precision Health program. Most of this time was devoted to background research and data analysis for a cross-sectional study I conducted using data from the National Health and Nutrition Examination Survey (NHANES).
NHANES is a massive ongoing research project run by the CDC that publishes health data from thousands of Americans every 2 years. These datasets are designed to be representative of the US population and are used by a lot of health researchers in the US. I’ve even covered a few studies that used NHANES data in previous posts.1
Although the user experience on the site is pretty bad, anyone can access NHANES data to conduct research, which is what I did for my Healthcare Data Science class. All this to say, I’m planning on sharing my findings with you all in next week’s post! So next week’s post won’t be a “wrap” but a presentation of my research.
And with that being said, I’ve decided that from here out I’m going to make these wrap posts bi-weekly. I might still post other things on off weeks (like next week!), but I feel the need to reduce the frequency of these and prioritize quality over quantity to make this more sustainable for myself.
Alright, enough preamble, let’s get into this week’s wrap…
Sections
DIET & SLEEP | EXERCISE | STRESS | CONNECTION
Diet & Sleep
Sometimes I combine sections if a study I cover falls into two categories, I’ve done a Diet & Sleep combo once before, and here it is again…
Sleep and Diet: Mounting Evidence of a Cyclical Relationship | August 04, 2021 | https://doi.org/10.1146/annurev-nutr-120420-021719
Review2
Over 1/3 of US adults fail to get adequate sleep; not enough and poor sleep are both linked to increased risk of cardiometabolic diseases including type 2 diabetes and obesity. Moreover, poor sleep negatively influences dietary choices, leading people to eat more fatty and sweet foods and less healthy foods, which also increases the risk of cardiometabolic diseases. Whereas prior research has mostly focused on how sleep negatively influences diet, this review focused more on the less explored topic of how diet can influence sleep, thus the article's title.
The underlying mechanisms of poor sleep leading to poor dietary choices are changes in appetite-regulating hormones and increased sensitivity to food rewards, leading to cravings for energy-dense foods.
Dietary intake of tryptophan and its influence on the synthesis of melatonin is a primary way in which diet influences sleep. “In humans, endogenous melatonin is exclusively produced from dietary tryptophan (132), but only a small portion (1–2%) of this dietary tryptophan is converted to melatonin via the serotonin pathway (8).” The article includes a table of foods rich in tryptophan, including dairy, fish, nuts, and meats.
Tryptophan transport into the brain competes with other large neutral amino acids (LNAAs). It’s mentioned that the consumption of tryptophan-rich foods alongside carb-rich foods may improve tryptophan entry into the brain and enhance the biosynthesis of serotonin and melatonin. This is because the release of insulin in response to carbs promotes protein synthesis in the muscle, which shunts those other LNAAs away from the brain and toward the muscles. A controlled experiment cited in the review that supports this theory fed elderly people tryptophan-enriched cereals for a week and found that their sleep improved significantly on a number of metrics. This topic is explored further in a section of the paper about whether or not the glycemic index of meals influences sleep quality.
The glycemic index (GI) of a food is a “standardized measure of circulating glucose levels following consumption of 50 g of that food, measured on a scale of 0–100 with 100 representing the GI of pure glucose'.” Two experimental studies suggest that meals with higher GI’s may improve sleep, however, this may be unrelated to melatonin biosynthesis and was contradicted by a large epidemiological study of US women. More research is needed to understand the influence of GI on sleep.
Two sections of the paper review research on whether or not dietary intake of serotonin and melatonin influences sleep quality and they conclude that the evidence is weak and lacking.
Another section covered how adherence to a Mediterranean diet–characterized by high fruit, vegetable, nut, and legume consumption–has been consistently associated with improved sleep quality in several observational studies, however, clinical trials are needed to establish causality.
Finally, the article touches on some early research that suggests that dietary approaches stop hypertension, measured by the DASH index, and anti-inflammatory dietary patterns, measured by the dietary inflammatory index (DII), may also positively influence sleep, but more research is needed. Notably, these dietary patterns “include nutrients or food sources similar to” the Meditarnian Diet and low-GI diets.
Overall, the review emphasizes the potential of dietary modifications as a safe and effective strategy to improve sleep. While more research is needed, adopting a balanced diet rich in fruits, vegetables, legumes, and other sources of tryptophan may contribute to better sleep quality and overall health.3
Exercise
Movement boosts memory: Investigating the effects of acute exercise on episodic long-term memory | November 5, 2024
https://doi.org/10.1016/j.jsams.2024.10.011
N = 51 college-aged students (males/females = 35/16)
Within-Participant Comparison Crossover Intervention
I found this study from Dr. Rhonda Patrick’s Instagram Reel about it.
A within-participant comparison crossover intervention study is a study in which participants act as their own controls. The control condition in this study simply was no activity but simply seated rest before a memorization task. The treatment condition was 20 minutes of moderate-intensity cycling before the memorization task.
The memorization task consisted of 15 unique words. “Participants encoded each word during five study-test encoding sessions, and then received an immediate recall test.” Retention of these words was then assessed at 24-h, 4, 6, 8 weeks, and 11 months after encoding.
Exercise did not improve encoding, but retention was significantly improved at 6 and 8 weeks for the exercise condition. This study suggests that exercising before learning may improve long-term retention of information.
Potential mechanisms for how exercise could improve memory retention were explored in the discussion section of the paper. An increase in hormones and growth factors like brain-derived neurotrophic factor (BDNF) triggered by exercise could enhance memory post-exercise via their role in synaptic plasticity. Also, improved sleep quality following exercise might contribute to better memory consolidation.
Stress
Central effects of stress hormones in health and disease: Understanding the protective and damaging effects of stress and stress mediators | Jan 30, 2008
https://doi.org/10.1016/j.ejphar.2007.11.071
Review
Stress begins in the brain and affects the brain, as well as the rest of the body. Acute stress responses promote adaptation and survival via responses of neural, cardiovascular, autonomic, immune and metabolic systems. Chronic stress can promote and exacerbate pathophysiology through the same systems that are dysregulated. The burden of chronic stress and accompanying changes in personal behaviors (smoking, eating too much, drinking, poor quality sleep; otherwise referred to as "lifestyle") is called allostatic overload.
This study reviews the relevant literature investigating the effects of chronic stress on the brain. Negative effects can include impaired memory as a result of changes in the hippocampus and impaired executive function and attention due to changes in the prefrontal cortex. The details of the neuroscientific mechanisms that control the influence of stress on the brain are complex and I won’t bore you with the details. Importantly, chronic life stress is associated with changes in brain regions such as the hippocampus, prefrontal cortex, and amygdala, which are implicated in disorders like depression, anxiety, and PTSD. These changes are influenced by factors like cortisol dysregulation and HPA-axis imbalance.
Positive affect, self-esteem, and social support mitigate stress-related effects. For instance, positive outlooks are associated with lower cortisol levels and better physiological responses to stress, while social interactions reduce markers of allostatic load. Conversely, poor self-esteem and loneliness amplify stress responses, linking them to hippocampal volume reduction and greater physiological dysregulation.
Effective strategies to counteract stress include lifestyle changes (e.g., better sleep, diet, exercise, and social support) and societal changes (e.g., public health policies addressing education, housing, and community development). While medications (e.g., anxiolytics, and antidepressants) can help manage stress-related symptoms, they come with limitations and side effects. Behavioral changes, lifestyle interventions, and policy efforts to reduce stress and burn-out are needed to sustainably mitigate the negative effects of chronic stress.
This review is rich in detail and well-written. I encourage anyone seeking to better understand this topic to give it a read. Though be prepared, it is dense.
Connection
Positive Social Mentalities and Quality of Spiritual Living in Old Age: Roles of Social Participation and Life Meaning | September 21, 2024
https://doi.org/10.1177/00469580241282061
N = 512 Chinese adults over the age of 60 (56.2% females)
Cross-Sectional
Quality of spiritual living (QSL) in old age is closely related to the health and well-being of older adults. It is necessary to explore the psychosocial factors and mechanisms that affect the QSL of older adults. The researchers investigated 512 older Chinese people using the positive social mentalities scale, social participation scale, sense of life meaning scale, and spiritual living self-assessment questionnaire.
The authors describe spiritual living as “a way of life centered on spiritual growth and practice, emphasizing systematic spiritual pursuit, which may include esthetic-creating practice, moral practice, or personal growth.” QSL was measured with a 30-item survey that assesses 5 factors: esthetic creation, leisure and entertainment, adaptive learning, social values, and moral beliefs. “Positive social mentalities (PSMs) refer to an individual’s positive social cognitions, feelings, and responses to social relations and their reality, such as life satisfaction, social security, social trust, social justice, or social identity.”
The researchers found that “Positive social mentalities (PSMs), social participation (SP), and life meaning (LM) had significant positive correlations with QSL.” Importantly, “SP and LM had serial mediating effects between PSMs and QSL.” This means that positive social mentalities improved participants’ quality of spiritual living (QSL) scores indirectly by improving social participation and life meaning, which both improve QSL scores.
It suggests that we should pay more attention to the spiritual living of older adults and improve their [quality of spiritual living] by enhancing their psychological construction and social functions.
Disclaimer: This newsletter provides health information and research for educational purposes only. It is not a substitute for professional medical advice. Consult a healthcare professional for guidance on your health-related decisions. We are not medical professionals.
I try not to cover too many reviews that don’t also include meta-analyses because I find that they are often difficult to succinctly summarize and often lack clear takeaways/conclusions, but this felt like a review worth covering. And the same goes for the study in the stress section.
NotebookLM, an AI tool from Google that I’ve been testing out, wrote this and also helped me draft other sentences. I let nothing it wrote go unedited or unverified.