How?
Avoid toxins. Besides the obvious actions – like don’t sniff glue, and stand upwind when pumping gas – be careful about alcohol, which works by depriving brain cells of oxygen: that buzz is the feeling of neurons drowning.
Minimize inflammation. When your immune system activates to deal with an infection or allergen, it sends chemical messengers called cytokines throughout your body. Unfortunately, cytokines can linger in your brain, leading to a slump in mood and even depression (Maier and Watkins 1998; Schiepers, Wichers, and Maes 2005).
So take practical steps to reduce colds and flu, such as washing your hands often, and avoid any foods that set off your immune system. For example, many people have inflammatory reactions to gluten grains (e.g., wheat, oats, rye) and/or dairy products; it’s not surprising, since these foods were introduced just 10,000 years ago, a tiny moment in the 200 million-year evolution of the mammalian, primate, and human diet. You don’t need overt symptoms of allergies for a medical lab blood test to show that gluten or dairy foods aren’t good for you. On your own, try going to zero with both these food groups for two weeks and see if you notice a difference in your mental or physical health; if you do, keep staying away from them: I do myself, and there are plenty of delicious alternatives.
Get regular exercise, which promotes the growth of new neural structures, including via the birth of new brain cells.
Relax. The stress hormone cortisol both sensitizes the fight-or-flight alarm bell of the brain – the amygdala – and weakens (even shrinks) a region called the hippocampus, which helps put the brakes on stress reactions. Consequently, in a vicious cycle, stress today makes you more sensitive to stress tomorrow. Additionally, since the hippocampus is also critical for making memories, a daily diet of stress (even from just feeling frustrated, irritated, or anxious) makes it harder to learn new things or put your feelings in context. One major antidote to stress is relaxation, which activates the soothing and calming parasympathetic wing of the nervous system; see chapter 4 in Just One Thing for good ways to relax.
