How stress affects our brain
Today we look at how stress affects the brain, when it is bad and how exercise can alleviate its effects.
The word stress covers such a wide range of emotions that whether it is negative or positive has to be defined depending on the situation. What is clear is that we need stimuli in order to develop: Muscles need exercise to grow and our brains need stimuli to stay functional or get better. If these stimuli are missing, our abilities atrophy.
It is equally clear that too much at once can also do us serious harm. There is no strictly scientific limit to when stress begins to have a negative effect. But if this limit has been exceeded for a long time, there are processes in our brain that are clearly detectable.
Flight or fight - also in our heads!
We all have the "flight and fight" mechanism in us when a dangerous situation arises. The hypothalamic-pituitary-adrenal axis in our brain becomes active. This will become important again later.
It is remarkable and unique for the human species that thoughts alone are enough to bring us into such a stress reaction: Just thinking about an exam, Monday or our boss is enough to activate this axis and make us feel uncomfortable.
John Ratey says that if our body responds to our thoughts, we can conversely influence our thoughts through physical activity. In other words, exercise can help reduce the effects of stress. So we should exercise, but also because stress can make you fat.
What happens in our brain?
When the hypothalamic-pituitary-adrenal axis becomes active, our body first releases adrenaline and then cortisol. This acts more slowly and via the bloodstream and then takes over the tasks of providing energy. At the same time, it makes the body insulin-resistant and already works on fat storage. If stress lasts too long, two things happen: physically we put on fat and lose muscle, and in the brain the stress axis described earlier (hypothalamus-pituitary-adrenal cortex) gets more weight than is good for us. Cortisol itself is neither good nor bad, but: in the right dose it helps us to form memories (i.e. to learn). But if we have too much of it, we have difficulty learning new things or even accessing old memories. This can be shown in imaging techniques in that the hippocampus shrinks.
What is the best way to deal with these effects?
Exercise starts recovery processes not only in the body, but also in the brain on a neuronal level. Regular moderate exercise raises our stress resistance. We remember the growth factors from last week: moderate exercise helps build them better than any other stimulus. BDNF, IFG 1, FGF2 and VEGF initiate recovery processes that are just started by exercise.
Which training is the right one?
As described last week, a combination of coordinative (tennis, for example) and endurance sports is ideal for the processes in our brain. Since another source of stress is isolation from the social environment, group activities (with the right people) are another measure to reduce stress.
The question of the right dose is easily answered: it should be measured in such a way that you sweat and still enjoy what you are doing.