How To Preserve Your Memory

A friend of mine recently asked me how I stay motivated to workout, especially during quarantine - how to avoid the "Quarantine 15." As important as exercise is for staying in shape physically, it is just as important for you to stay in shape mentally and not just when it comes to handling stress, anxiety, and/or emotions. Research has found that there is a hormone released during exercise called Irisin, which may have beneficial effects including weight loss, thermoregulation, and neuro-cognitive protection. This includes protecting your memories in hopes of fighting neurodegenerative diseases like Alzheimer's dementia through synaptic plasticity (strengthening the pattern of communication between neurons) and neurogenesis (forming new neurons). Recognizing the impact that fitness has on not just the body but the brain motivates me to stay active and holds me accountable to protect my memories along with all that I have learned (medical school tuition isn't cheap).

Fun fact: Irisin comes from the name Iris, the Greek goddess known as the messenger of the gods. Can you tell I was a Classics major in college? Initially discovered in the skeletal muscle tissue of mice, it is a cleavage protein also found in humans derived from fibronectin type III domain 5 (FNDC5). This means when you exercise, FNDC5 is converted to irisin. In terms of weight loss, irisin has been shown to influence the browning of adipose (fat) cells.

When you think of fat, there are two main types: white and brown (there is also visceral and subcutaneous but we won't get into that). White fat is responsible for the standard large deposits that store energy and produce hormones but also can lead to obesity. In contrast, brown fat has smaller "droplets" with large amounts of mitochondria (think of these as engines), meaning this tissue can generate a LOT of energy. For us, this comes through as heat. Thus, brown fat is used to keep us warm, so, in addition to decreasing white fat, irisin has a thermoregulation benefit (Irisin: An Overview). Other studies have found irisin improves insulin sensitivity and glucose metabolism, which may play a role in preventing metabolic syndrome and diabetes (Kim & Song, 2018).

While exercise is known to improve cognitive function, especially in neurodegenerative diseases such as Alzheimer's and Parkinson's, understanding how has been and continues to be under investigation. From increasing blood flow to the hippocampus, a part of the brain that helps form new memories, to synaptic plasticity, neurogenesis and decreasing neuro-inflammation, physical activity improves outcomes for the mind as well as the body (Kim & Song, 2018). "The beneficial effects of exercise seem to depend on crosstalk between muscles and nervous tissue through the increased release of muscle irisin during exercise," (Bristot, 2019). This crosstalk plays into memory and is most closely associated with endurance and aerobic routines. "Irisin enhances brain function by modulating neurotransmitter secretion," (Kim & Song, 2018; Mattson, 2012). Because of its brain boosting capabilities, irisin has been purported to be an agent for fighting dementia and memory impairment after being studied in mouse models with Alzheimer's. So, the best way to protect your memory? Well, if you have time to read this blog post, it means you have time to exercise - get out there and get moving!

References:

Bristot, V., et al. "The Role of PGC-1α/UCP2 Signaling in the Beneficial Effects of Physical Exercise on the Brain." Fronteirs in Neuroscience. 2019 March. Retrieved August 26, 2020 from https://www.researchgate.net/publication/332074712_The_Role_of_PGC-1aUCP2_Signaling_in_the_Beneficial_Effects_of_Physical_Exercise_on_the_Brain.

"Irisin: An Overview." ScienceDirect. Retrieved August 26, 2020 from https://www.sciencedirect.com/topics/neuroscience/irisin.

Kim, O. & Song, J. "The Role of Irisin in Alzheimer’s Disease." Journal of Clinical Medicine. 2018 Nov. Retrieved August 26, 2020 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262319/.

Lourenco, M., et al. "Exercise-linked FNDC5/irisin rescues synaptic plasticity and memory defects in Alzheimer’s models. Nature. 2019 Jan. Retrieved August 26, 2020 from https://www.nature.com/articles/s41591-018-0275-.

Mattson M.P. "Energy intake and exercise as determinants of brain health and vulnerability to injury and disease." Cell Metabolism. 2012;16:706–722. doi: 10.1016/j.cmet.2012.08.012. Retrieved August 26, 2020 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3518570/.