Stress and the Brain: It’s all about balance

Why do we like music so much? Music can be often very relaxing. Life is not always so. We all experience our share of stressful times and anxiety. The life of a young scientist, for example, who is trying to make her, or his, name in the academic world and consolidate their own independent research, can be extremely stressful. There is, however, one scientist on campus who decided to take stress one step further and turn it into the focus of his research. Profesor Alon Chen from the Department of Neurobiology, is asking a profound question. We all know that we are affected by stress, but can stress change our genetics? Can we inherit our parents fear or move our own personal traumas onwards to our children? The answer, as you are soon going to discover, can be a little bit stressful. Good evening, everyone. Please, sit back and relax, make yourself comfortable because we are going to have a little talk about stress. We all know what stress is, we recognize the feeling inside us, we recognize it around us. Regardless of age, gender, occupation or lifestyle. But what is stress? do you really need stress-related feelings? Why would our brain do this to us? Haven’t the Jewish people suffered enough? Imagine that you are walking on one of the beautiful green pathways of the Weizmann Institute and from nowhere a lion starts running straight toward you. There is probably a better chance you will meet a rattlesnake at the Weizmann ground, but let’s stick with the lion, I think it’s more exotic. In the millisecond you notice this lion, your brain will activate what is known as the stress response. This response initiates many changes in your brain and body that collectively aim to allow you to cope with the stressor, with this challenge. Your heart rate and blood pressure will increase, your blood glucose will rise, your fear and anxiety level will go skyrocketing. Your memory and focus attention will change. Your movement, your locomotion will change. Your immune system will kick in. Your appetite and reproductive function will be inhibited. Of course sex and food is the last thing you need to think about while out-running a lion. So, almost every system in your brain and body will respond to this stressor, to this challenge. Is it good for you to respond this way? Yes, it is. The stress response is a survival response, its conservatory evolution from fish to human, to allow the organism to cope and survive. But all these changes that I just described take many of the body’s systems out of a homeostasis, out of balance, which is good and necessary when the lion is still around. But when we realize that what is running toward us is actually not a lion – in fact is Prof. Daniel Zajfman in a lion’s costume, Daniel. The stress response has to switch off all systems and restore homeostasis, restore balance, bringing all systems to the initial steady state. Now, we can all breathe. So, why am I telling you all this? Why is it important to study? To investigate the brain’s response to stress? One argument will be our desire, our curiosity or, I would even say our obligation as a scientist, to study how their brain functions. To learn how this amazing machine actually works. The second, and not less important, is our knowledge when this response is not properly regulated, when it’s not properly controlled, it’s strongly associated with a variety of pathologies, including depression and anxiety disorders, PTSD, eating disorders. But not only psychiatric disorders, also metabolic disorders such as type 2 diabetes and obesity, immune-related, reproductive-related and even cancer. However, we all know that many of us do expose to stressful event for or even chronic stress, but we do not necessarily develop one of the diseases or disorders that I just mentioned. So, what are we missing here? Why some of us are more resilient than others? Why some of us are more susceptible to develop a disease when they’re exposed to stress? So stress is an environmental factor. It’s similar to what we drink, eat, breathe or smoke. In most of these cases, the environmental factor will not directly cause a disease, but will interact with our genes and many of us do carry genetic predispositions – small changes in your DNA that make us more vulnerable to develop a disease, when we’re faced with the right environmental factor. So, and this is the good news, it’s not always our fault. We can always blame our parents, from which we inherited of course our DNA. Let’s take, for example, identical twins separated at birth, they have identical genetic makeup, carrying the exact same genetic predisposition. But one will grow on the shores of Hawaii’s big island and the other one in a Kibbutz next to Gaza strip. Chances are that the one who will grow in the stressful environment will develop a stress-related disease is significantly higher. So our genetic make-up, our genes, will interact with the environment via a different mechanism, known as epigenetic mechanism, that we and many others at the Weizmann Institute are studying extensively, in order to study the effect of the environment on our health and pave new ways for better treatment. [music] As you all know, stress can come in different flavors and shapes: it can be acute but very strong and traumatic, it can be chronic, but relatively mild, it can be purely psychological or purely physiological, or a mixture of both. You can see someone getting hurt or getting hurt yourself. It doesn’t have to be a lion, it could be your boss at work, it could be a family member, a traffic in the morning, a loved one you just lost and many more. Stress can also affect you at different stages of your life: as an adult, as a teenager, as a young kid, a baby, or even as an embryo in your mother’s body, when she is the one that is exposed to stress. Is the fact you were exposed to stress early in life, even as an embryo, will change your ability to respond to stress later in life, or increase your sensitivity to stress-related diseases? Try to picture this, a pregnant woman living in a war zone, missiles and sirens. What are the signals she is transmitting to her baby? It’s crazy outside, you better be small and fast, you should always look for the danger, program your brain to respond faster and quicker, and increase your vigilance. So Mazal Tov, the baby is born and after few years, we put him in a classroom for eight hours per day, in addition together with additional 30 or 40 kids, but he cannot concentrate for eight hours – he was designed, he was programmed to focus his attention on the surrounding, to look for danger. He cannot sit long on the same chair and listen to the same teacher. He probably will be classified as having ADHD, an attention deficit, but he is totally fine. This is the way he was designed, this is the way he was programmed. He is not a problem, the environment is. What about men and women? The differences between the sexes. Do men and women respond similar to stress? No, no, they don’t. Their behavioral and emotional and hormonal response to stress are different between males and females. For example, female, woman, the cortisol levels are significantly higher. I will not go into the mechanism or the reasons, why are these differences taking place. I will just mentioned in this case the female, the woman, have the normal response and the men are the ones which are inhibited by this testosterone. But why I’m telling you all this in a 10 minute presentation? In addition to the fact that talking about sex always makes people sit up in their seats, the reason is that the prevalence of stress-linked psychopathologies, such as anxiety and depression, are two-to-three times higher in females than in males. Therefore, it’s very important to study both sexes, which have partially different brain mechanisms that regulate the response and may need a totally different type of treatment. It’s also important to know that the number of individual worldwide that are suffering from stress-mediated psychopathologies are huge and are growing with time. The available pharmacological treatments are not efficient in a large percentage of the patients. Approximately, 30 percent of individuals suffering from this type of disorder, don’t have any available drug or treatment, and many more that do respond suffer from severe side effects. So the medical need is immense and solutions will come only from a high quality, state-of-the-art basic science. So before I finish, I have to be a bit more positive. What can we do about it? How can we reduce the stress level and even treat or improve our state of anxiety or depression? Today, psychotherapy is good as any available drug, and many times, combining both is the best solution. Scientifically, the proven method is exercise, not in any specific way. Everyone according to his or her ability. Less scientific but not necessarily less effective is meditation, social activities. Any type of enrichment that will make you feel good, like walking on the beach, working on your garden, listening to this beautiful music or just visiting the beautiful Weizmann Institute. Thank you very much and enjoy the rest of the evening.

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