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Key points
- Modern life makes significant, persistent cognitive demands. This somehow leads to increased mental illness and less well-being.
- The human prefrontal cortex manages these demands, usually without difficulty.
- When the demands become chronic and stressful the prefrontal cortex struggles and may fail.
- The result is a broadened vulnerability to mental disorders for all citizens of modernity.
In February of this year a medical case report appeared in the Washington Post. It described a young woman whose mental health had been declining dramatically since college. Initially diagnosed as ADHD, this was changed to bipolar disorder, and finally, at age 24, she became psychotic. She did not recognize her parents, was paranoid, and generally incoherent. She was taken to the hospital to be admitted to a psychiatric unit.
Fortunately, an observant ER doctor noticed that her gait was unstable. This was odd for her age, so he ordered a CT of the brain. And there it was, hydrocephalus, or fluid on the brain. A congenitally narrow duct prevented adequate drainage of fluid and it built up to the point that the Prefrontal Cortex (or PFC) was compressed. Surgeons opened the duct and the next day she was herself for the first time in years.
I tell this story not because hydrocephalus is common in young people, but to show what happens when the PFC is damaged or unable to work properly. Unlike other parts of the brain, functions do not shut down, they change. Some combination of thinking, feeling, and behavior inevitably become altered. This is vital information as it turns out that the PFC is the bridge between our modern ways and our modern maladies.
In my last post I discussed the increases in mental illness that plague the industrial world, and how modern life appears to underlie these changes. Managing life as if it were a device, constantly figuring out what to do instead of having skills, memories, and other people to guide us typify our days. These are the demands of modern life, and they are causing us harm. The pace and intensity of these demands are like no other time in our history and are surely part of the picture. But what is it exactly that is being harmed and how does that translate into mental illness and poor well-being?
The Seat of Executive Function
Research in neuroscience over the past 30 years provides us with an answer in the workings of the PFC. The demands of modern life I mentioned above can only be managed by the PFC – the most advanced brain system we have. The PFC is the last thing to evolve in the human brain and the most powerful. It is how we built our technological world.
The PFC has an amazing repertoire of abilities, and like anything else, a few weak points. The most potent functions of the PFC come under the umbrella of executive function. These are things like selective attention (the ability to choose where to put your attention despite distractions), mental shifting (changing focus and activity on a dime, when circumstances demand it) and making mental representations (seeing things in our mind’s eye that don’t exist in the world). These abilities stack on top of one another to give us even higher functions like getting the subtle gist of a conversation and imagining what another person thinks or feels. People with PFC illnesses, such as autism, notably cannot do these last two things.
Two more functions deserve mention. One is working memory. This is like RAM on a computer. It is all the things we can keep in mind for easy access of conscious thought. The second is our ability to inhibit reactions to emotions. Some real-life examples are in order.
A good illustration of executive function is cooking. Our cook has four pots on the stove and a pan in the oven. She knows the different plan for each dish. Suddenly, the doorbell rings. She forgot a repairman was scheduled to come over. Using her PFC, she accesses the cooking data, which is already in working memory, quickly shifts plans, has a representation of everything in her mind, then executes the plan for each dish. Lower the heat on this, take that off, put the other in the fridge, keep cooking the other two for ten more minutes. All in under a minute. She makes it look easy, but children, people who are sleep-deprived or ill, and other animals cannot do this.
To illustrate the other two functions, it will be easier to discuss their impaired function. A common complaint in mental health and medical offices these days is memory. Where did I put my pen? Why did I walk into this room? What is the name of that person or the word for this? I have reassured many patients that this is not early Alzheimer’s. It is the result of stress on the PFC and a consequent impairment in working memory.
The second function, inhibition of response to emotion, is also known to commonly breakdown. You are in a bad mood and the kids are too loud. You raise your voice. The irritation that you normally control with ease breaks through. There are other less obvious examples. We do not grab a delicious looking ice cream cone from a stranger. Nor do we put our bodies up against an attractive person walking down the street. My dog does both (with other dogs and food)—if allowed—because her PFC is not well developed.
Fault Lines in the PFC
As mentioned, the PFC has two defining fault lines. One, is that the PFC does not work well, or at all, under stress. The other is that both brain-imaging and brain-injury studies tell us that mental illness will result from damaging or chronically impairing the PFC (as we saw in the case of the young woman who'd been chronically misdiagnosed).
The PFC was meant for quiet contemplation, not frenzied work. It can do the latter, but not for long. As I discussed in my last post, modern life demands that we be able to manage complex and abstract things in most of what we do (and be ready for the inevitable reformatting). We use it all day, every day, in normal work and under stress. We see the fault lines when it’s difficult to concentrate, we can’t find words, or irritability constantly breaks through. This is the PFC under stress.
By doing this all our lives we make ourselves vulnerable to any mental disorder we may carry genetically or be prone to for other reasons. Scientists can now see the actual change of a normal PFC to one producing mental illness(1) by stressing(2) the PFC. Here is where the harm is done.
Modern life, with its incessant work, cognitive demands and lack of social connection all meet in the PFC. Once you have a mental disorder, you will always be more prone to a recurrence. The more episodes, the more prone you become. But the stress on the PFC can be undone or at least minimized. This is where our work lies.
In my final post in this series, I’ll discuss where this leaves us as a society and as individuals, and what we can do about it.
References
(1) Manning, Elizabeth E., and Susanne E. Ahmari. “How Can Preclinical Mouse Models Be Used to Gain Insight into Prefrontal Cortex Dysfunction in Obsessive-Compulsive Disorder?” Brain and Neuroscience Advances 2 (January 2018): 239821281878389. https://doi.org/10.1177/2398212818783896.
(2) Sullivan, Ron M., and François Laplante. “Stress, Prefrontal Cortex Asymmetry, and Depression.” In The Handbook of Stress, 505–23. John Wiley & Sons, Ltd, 2011. https://doi.org/10.1002/9781118083222.ch25.
