It’s no secret that physical activity is great for overall health and wellbeing. It helps decrease stress, improve mood, and have long lasting benefits on cardiovascular health and fitness as well cognitive abilities in healthy adults.
Emerging scientific evidence suggests that physical activity is neuroprotective, and may promote adult neurogenesis (the birth of new neurons in the adult brain) and delay or reverse cognitive decline in the aging adults. Walking, running, resistance training, and swimming are all affordable types of activities shown to maintain physical and mental health.
What if exercise is not an option?
Physical activity may be hindered in an older population that is injured, frail or in poor health, such as during advanced stages of neurodegenerative diseases. A recent article in Science (2020), Horowitz et al. identified a method to transfer the brain benefits of exercise to those who were sedentary through administration of blood plasma. They identified glycosylphosphatidylinositol (GPI)-specific phospholipase D (Gpld1), as a liver derived- blood factor that improved hippocampal function in aged sedentary mice.
The hippocampus is the region of the brain that plays a key role in memory, learning and mood. This is one of two regions that generates new neurons (adult neurogenesis) throughout life. This has been shown throughout the animal kingdom from rodents, primates, to humans. It’s believed that the benefits of exercise on cognition lies in the hippocampal circuitry. This circuitry is impaired in animal models and humans with neurodegenerative disorders such as Alzheimer disease.
Horowitz et al. show that infusing plasma from the blood of either exercised mature or aged mice can transfer the benefits of exercise to sedentary mice. The mice that received the plasma transfusions had increases in the survival and differentiation of new neurons in the hippocampus as well as enhanced learning abilities. In both mice and humans, the liver-derived molecule, Gpld1, is increased following physical activity. By manipulating the GPI-Gpld1 pathway, Horowitz et al. fully mimics the benefits of physical activity on cognition in sedentary aged mice.
Although this has not been done in humans, this study is still an extremely important proof of concept to demonstrate how important physical activity is, especially in the aging population. It sheds light on the molecular mechanism of how something like exercise can promote healthy cognition. Not only does it create a possible therapeutic strategy for neurodegenerative diseases, but also the opportunities for psychiatric disorders and traumatic brain injuries, where hippocampal circuitry and cognitive impairment may also be affected.
It doesn’t matter how old you are, regular physical activity is required for optimal functioning. Whatever exercise you choose, make that exercise a habit, your overall brain health depends on it.
Horowitz, A. M. et al. Blood factors transfer beneficial effects of exercise on neurogenesis and cognition to the aged brain. Science 369, 167 (2020).