When I introduce myself as a neurobiology researcher focused on exploring genetic and environmental factors that lead to and protect against toxic stress, anxiety, depression and memory deficits, I consistently hear: “That’s me! I’m your perfect subject! Tell me what to do!” It is striking that the majority of people I meet disclose a genuine conscious struggle with chronic stress. My response is simple; invest some time building up your hippocampus! And everyone says hippo-what? Well I think we will all be better off if we get acquainted with a very special part of our brain. While many brain regions significantly contribute to mental health, the hippocampus stands out as a vital emotional brain area involved in stress regulation, the etiology of anxiety and depression and memory function. Remarkably, it is a dynamic structure that is highly influenced by environmental factors, so we can have control over its function. I believe that everyone should aspire to being young at hippocampus- and incidentally the heart will follow.
The hippocampus is a curious brain structure shaped and thus named after a seahorse. We have 2 hippocampi, one in each temporal lobe of our brain. Like most brain structures the majority of the hippocampus develops during pregnancy and infancy. However, unlike most brain structures, the hippocampus has the amazing ability to grow new brain cells and develop throughout life. The process of growing new brain cells is called neurogenesis (the birth of new neurons). There are many factors that promote the survival of new brain cells as well as several factors that prevent the survival of new brain cells. An abundance of scientific studies have highlighted the importance of adding as many new neurons as possible to the hippocampus to optimize brain and body health. The “old” hippocampus is primed and ready to learn new tricks!
The hippocampus is responsible for terminating stress. When we get stressed, stress hormones circulate in our brain and body. The hippocampus has receptors that detect stress hormones and shut off the system. The new brain cells in the hippocampus are particularly good at shutting off stress so the more neurogenesis you have the better you will be at decreasing stress quickly. The ability to rapidly shut off stress is very important because prolonged stress can be very harmful.
The hippocampus is also responsible for mediating anxiety and depression related behavior and storing new episodic (or autobiographical) memories (and more!). If neurogenesis is high and many new neurons survive, the hippocampus can efficiently turn off stress, reduce anxiety and depression and efficiently store memories. If neurogenesis is low and few new neurons survive, stress is prolonged, symptoms of anxiety and depression persist and memory storage is impaired. Neurogenesis is our friend. We can think of the new cells in the hippocampus as a mini army of little defenders fighting a battle and guarding us against chronic stress. The more defenders we have the better!
The two biggest factors that reduce neurogenesis are aging and chronic stress. Neurogenesis is highest at birth and gradually declines across the lifespan. If we could keep our young hippocampus with high neurogenesis throughout life we would be so much more relaxed! While a modest reduction in neurogenesis across aging is unavoidable, there are many things we can do to promote the survival of newborn cells as we age. Chronic stress potently impairs neurogenesis. Biologically chronic stress includes the prolonged release of the steroid hormone cortisol. New cells do not survive if they are continually bathed in this stress hormone. Realistically chronic stress is everyday life for most individuals. People do not thrive under stressed conditions. Fortunately there are many ways to reduce chronic stress to keep new hippocampal cells alive and fighting. Additional factors that reduce neurogenesis are sleep deprivation, social isolation and sedentariness. Sound familiar? These factors seem to be inherent in modern life and work. With the odds stacked against us we need to actively attend to our hippocampus to combat these factors.
Here’s the good news! There are several enjoyable practices that build your mini army against stress and promote neurogenesis. There are many things we can do to keep neurogenesis high and our hippocampus young! Stress management is key to keeping newborn cells alive. Any program that lowers stress is helpful and advised. Meditation is a great practice that has been shown to lower stress and boost cognition and attention. Cardiovascular exercise, in any enjoyable form, powerfully boosts neurogenesis. Yoga is an incredibly healthy practice for the brain as it increases neurogenesis through exercise and stress reduction. Learning and enrichment, of any kind, are important practices to promote neurogenesis. Engaging in something challenging and difficult, like a new language, musical instrument or art, is especially good for increasing neurogenesis. Traveling to a new place is also great for your brain. Navigating a new environment and new sensory experiences challenges your hippocampus and promotes cell survival. Enrichment through relationships also promotes neurogenesis. Friendships, romantic partners and parenting relationships make your hippocampus very happy. Adequate sleep is another factor that promotes neurogenesis. Sleep deprivation elevates stress hormones so making sleep a priority is essential for healthy hippocampal function. When you employ these healthy practices you will enjoy all of the new stress reducing cells you are adding to your hippocampus.
Life inevitably introduces many challenges that can lead to prolonged stress. Individuals with low neurogenesis will be challenged by stressors and can develop anxiety, depression and memory deficits. However, we can protect ourselves against chronic stress by building a healthy hippocampus with high levels of neurogenesis. A healthy hippocampus is resilient and can protect the brain against the effects of chronic stress. Moreover, a resilient stress system protects the body against other stress related disorders or metabolic disorders including heart disease, diabetes and obesity. We certainly do get a head start if we are among the very young at heart – but it starts with a healthy hippocampus.