thirty minutes of isolation
Cortisol levels rise sixfold in some mammals after just thirty minutes of isolation.
tags /cortisol /
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on swinging between extremes
Because of my health issues I have had to experiment a lot with my diet and exercise, so I go into semi-strict regimes to see if something works. I say “semi-strict” because…
on learning to be slow
I was doing my routine reading of “on this day” entries when itt made me realise how recent it was that I learned how to run: I started running regularly sometime in…
the invisible threshold
I wanted to write on sunday, but I was having my monthly migraine, so only today I seem to be slowly recovering. I still feel like shit though. This month’s menstrual cycle…
hippocampal shrinkage and memory loss
The scientific name for the disorder speaks volumes: hypercortisolism. Its symptoms are eerily similar to those of chronic stress: weight gain around the midsection; breaking down muscle tissue to produce unnecessary glucose and then fat; insulin resistance and possibly diabetes; panic attacks, anxiety, depression, and increased risk of heart disease. One of the many correlations Starkman has shown is that the extent of hippocampal shrinkage and memory loss is directly proportional to elevations in cortisol.
There are a number of scenarios in which the body fails to shut off the flow of stress hormones. The most obvious is simply unrelenting stress. If we never get a break, the recovery process never gets started, the amygdala keeps firing, and the production of cortisol spills over healthy levels. Sometimes the fight-or-flight switch gets stuck in the on position. It can be a function of genetics, according to epidemiological surveys: if you put a random group of people in a stressful public speaking situation, those whose parents suffered from hypertension still show elevated levels of cortisol twenty-four hours after the speech.
excess cortisol can block access to existing memories
Human studies also show that excess cortisol can block access to existing memories, which explains how people can forget where the fire exit is when there’s actually a fire—the lines are down, so to speak. With too much stress, we lose the ability to form unrelated memories, and we might not be able to retrieve the ones we have.
people who are depressed have trouble learning
It also helps explain why constantly high levels of cortisol—due to chronic stress—make it hard to learn new material, and why people who are depressed have trouble learning. It’s not just lack of motivation, it’s because the hippocampal neurons have bolstered their glutamate machinery and shut out less important stimuli. They’re obsessed with the stress.
the action of cortisol amasses a surplus fuel supply
Cortisol takes over for epinephrine and signals the liver to make more glucose available in the bloodstream, while at the same time blocking insulin receptors at nonessential tissues and organs and shutting down certain intersections so the fuel flows only to areas important to fight-or-flight. The strategy is to make the body insulin-resistant so the brain has enough glucose. Cortisol also begins restocking the shelves, so to speak, replenishing energy stores depleted by the action of epinephrine. It converts protein into glycogen and begins the process of storing fat...If this process continues unabated, as in chronic stress, the action of cortisol amasses a surplus fuel supply around the abdomen in the form of belly fat.