As a nation, we’re all feeling a little anxious right now. In the uncertain days following the Brexit vote, Mark Carney, Governor of the Bank of England, warned that “economic post-traumatic stress” might sweep Britain.
Sweaty palms, racing heart and queasy feelings in times of crisis are a primitive, natural reaction known as the stress response and, in small doses, a healthy thing. They give us the get-up-and-go to fight an impending challenge – we did, after all, evolve to fight or flee predators in the wild.
But when stress never relents, such as an overwhelming job or financial pressures, it can lead to a catalogue of health problems, from obesity and acne to heart disease. Last month, Australian research found high stress levels can cause cancer cells to spread six times faster.
Now, a burgeoning field of medical study known as psychoneuroendoimmunology (PNEI) is exploring the links between what goes on in our nervous systems and the development of illness. Here, then, is exactly how stress affects us:
Your body on stress
When your body senses danger, it triggers a stress response that starts in your brain’s hypothalamus gland, which sends signals to the adrenals (two glands that sit on top of the kidneys) to release stress hormones such as cortisol, adrenalin and noradrenalin. These raise blood pressure and give your body a hit of glucose to help you outrun the immediate danger.
“Cortisol and other stress hormones are important because they prime our bodies to react to threat,” says Dr Valeria Mondelli, senior lecturer in psychological medicine at King’s College London. “But when our cortisol is too high for too long, it can lead to physical and mental health problems in many areas of our bodies.”
The cancer connection
It is not helpful to tell people that stress caused their cancer – or any other condition – because, according to Angela Clow, professor of psychophysiology at the University of Westminster, that creates guilt and self-blame. Moreover, this conclusion was drawn from an Australian study performed on mice, which were put through extreme forms of physical stress, so it cannot be considered conclusive.
“Having said that,” says Prof Clow, “we know that though stress doesn’t cause cancer, it can slow down recovery and increase its progression.”
There are two main branches of your immune system: daytime immunity, which targets potential infections such as germs picked up on public transport; and night-time immunity, which releases natural killer cells that fight more covert invaders, such as cancer cells.
“Chronic, prolonged stress can lead to a deficiency in your night-time immunity, which is crucial for cancer protection,” says Prof Clow. “Studies looking at lifetime survival in breast cancer have shown that after treatment, those with high cortisol levels die statistically earlier and survive less than those with lower levels.” A 2016 review published in the journal Integrated Cancer Therapy found that elevated cortisol was the most common biomarker found in breast cancer patients and concluded that mindfulness, breathing and stretching techniques could offer potential improvement in immune activity in survivors.
Fat, cravings – and that spare tyre
If you crave fatty or sweet foods under stress, you’re not alone; repeated studies show how stressed-out rats make bad food choices. “High cortisol can affect the transmission of dopamine in the brain, a neurotransmitter linked to our reward system,” says Dr Mondelli. “That makes us more susceptible to seek rewards by eating more and leads to increased cravings.”
Cortisol also inhibits the breaking down of fat; storing it to fight a future threat would once have been essential from an evolutionary perspective.
It may also affect where our fat is deposited on our bodies. “The way people distribute their fat seems to be related to how they respond to stress,” says Dr Leigh Gibson, a lecturer in psychology and physiology at the University of Roehampton. “It’s been argued that people who adapt better to stress are less likely to put on visceral fat [fat around the middle].” Visceral fat is associated with increased risk of cardiovascular disease and Type-2 diabetes.
Memory, Alzheimer’s and dementia
Chronic stress could be a risk factor for dementia, says Dr Laura Phipps, of Alzheimer’s Research UK. “People with Alzheimer’s disease have been shown to have higher levels of cortisol in the blood, and, over time, this can cause damage to the hippocampus, an area of the brain involved in memory and one of the first areas affected by the disease.”
Dr Phipps explains some studies have shown that more psychological stress in a person’s life is linked to a higher risk of developing dementia, though exactly how this happens isn’t clear. One explanation could be inflammation, says Dr Mondelli. When our bodies are under stress, they produce pro-inflammatory cytokines, immune factors that fight infections. When these cytokines are elevated over a period of time, inflammation can result and affect not only our bodies’ ability to fight infection, its risk of heart disease and cancer, but also our brains. “Inflammation can decrease the number of neuron cells in our brains and affect the way they network with each other and the way we memorise things.”
During the stress response, your breathing increases and heart beats faster in an effort to pump more oxygen and blood to your muscles, preparing it for fight or flight. Stress hormones also cause your blood vessels to constrict and raise your blood pressure. Indeed, earlier this month German researchers found that those who were constantly exposed to traffic noise were at higher risk of heart attack because of the increased stress noise pollution put on their bodies.
But there’s more to it than the consequences of an increased heartbeat, says Dr Mondelli. “Elevated stress hormones over time lead to inflammation that damages the internal lining of the blood vessels which can facilitate the production of artherosclerotic plaques that clog up the arteries, increasing risk of heart attack,” she explains.
Stress and the skin
Pimples or skin-flaking that flares up when you’re stressed are not your imagination, says Dr Anthony Bewley, consultant dermatologist at Bart’s Hospital Trust, London. In fact, he’s seen a rise in adult onset acne in stressed-out, middle-aged women. “Stress not only delays wound healing, stress hormones also lead to the production of more oil in the skin and the blocking of hair follicles that lead to acne,” Dr Bewley explains.
Conditions such as eczema and psoriasis are also closely linked to stress. “The brain is connected through nerves to the skin, so when you get stressed, you release chemicals in the brain that can be pro-inflammatory and lead to flare-ups,” he explains.
A growing area of treatment on the NHS is psychodermatology, in which skin conditions are treated holistically with mindfulness or cognitive behavioural therapy (CBT) alongside medical interventions. “We’ve found that if you give a group of psoriasis patients the standard sunlight treatment with mindfulness tapes to relax them, they heal in half the time, compared to those that have the sunlight treatment alone,” says Dr Bewley. Talk to your GP about getting a referral.