A study in press at the journal Biological Psychiatry asked 103 people about how often they had experienced stressful events, both recently and over the course of their lifetimes, as well as about their chronic ongoing stress, and then took functional magnetic resonance images of their brain. The more stress, the smaller the brain...in several particular cortical areas.
• "Cumulative adversity (a combination of recent stressful events and the lifetime total of stressful events) was associated with smaller volume in medial prefrontal cortex (PFC), insular cortex, and subgenual anterior cingulate regions."
• "Recent stressful life events were associated with smaller volume in two clusters: the medial PFC and the right insula."
• "Life trauma (total stressful events over a lifetime) was associated with smaller volume in the medial PFC, anterior cingulate, and subgenual regions."
• "The interaction of greater subjective chronic stress and greater cumulative stressful life events was associated with smaller volume in the orbitofrontal cortex, insula, and anterior and subgenual cingulate regions.
And what do all those cortical areas have in common? They are all associated with reasoning and decision making, emotion, and self-control. The researchers were careful to say that "...lower volumes do not necessarily equate to poorer functioning," adding "...it may be that regions of lower volume represent greater efficiency in functioning." In other words, smaller brains may not mean less competent brains.
Except that other research suggests precisely that...that stress does have functional impacts on how well our brains work. It impairs formation and recall of long term memory, and stress is also strongly associated with clinical depression and with a decreased ability to cope with stressful experiences! So not only does the research on stress-associated brain shrinkage suggest that it causes functional mental impairments...one of the problems it appears to cause is the very ability to deal with further stress...which is a really scary positive feedback loop.
Now how, you might wonder, does that relate to the topics we talk about here, a blog about risk perception? Directly, because clinical stress is caused by, among other things, worrying. There are every day worries, and chronic worries, big worries, and small worries. But worrying of any sort is, essentially, feeling threatened, and that triggers the biology of the fight or flight response, which causes levels of stress-related steroid hormones like glucocorticoids to go up. If those levels persist for more than several days, they start to do permanent damage, including, it appears, shrinking the brain, especially the parts of the brain involved in higher order reasoning and decision making. So worrying more than the evidence says we need to, about child abduction or terrorism or industrial chemicals, is literally a risk factor for shrinking the part of the brain we need to be more thoughtful and rational about risk, rather than more emotional. Talk about a scary feedback loop!
There are all sorts of ways to reduce stress, whole industries that peddle various products and pills and processes to help you stay calm. May I humbly suggest one solution to this threat to the size of your brain, a solution that none of the meditation gurus and pill pushers talk about: understanding how the psychology of risk perception works. Research has identified specific characteristics that make some threats feel scarier than the evidence says they are. These are the emotional reasons why we sometimes worry too much. Knowing them can help us worry less.
• Risks imposed on us (those other drunk drivers) feel scarier than the same risk if we engage in it voluntarily (driving drunk ourselves, which is riskier).
• Risks that involve higher pain and suffering (cancer) are scarier than risks which involve relatively less pain and suffering (heart attacks, which is riskier).
• Risks that are human-made (nuclear radiation) are scarier than risks that are natural (carcinogenic radiation from the sun, which is riskier).
• Risks that are immediate (industrial pesticides) are scarier than those that are down the road (climate change, which is WAY riskier).
• (There are many more risk perception factors in Chapter 3 of my book, How Risky Is It, Really? Why Our Fears Don't Always Match the Facts, which is available free online.)
If we're aware of these risk perception factors, we can see how they contribute to our worries, and we can fight back, at least a little, against those disproportionate fears. We can protect ourselves, at least a little, against the dangers of what I call The Perception Gap, the risks that arise when our subjective/emotional risk perception system gets risk wrong. We can use that self-awareness as a sort of seat belt for when we drive in the dangerous environment of making subjective choices about risk, which sometimes can lead to dangerous errors, including worrying too much.
Our risk perception system mostly works pretty well to keep us alive, but it's subjective, and sometimes makes mistakes, judgments that feel right but just plain don't match the facts. Knowing why we make those mistakes can help us begin to avoid them. Which can help us protect ourselves, including from the risk that worrying too much will shrink our brains.