The real mental dangers of letting your stress go unchecked

The link between anxiety and Alzheimer's is just one reason to take care.

The link between anxiety and Alzheimer's is just one reason to take care

(Credit: Getty Images)

This article was originally published May 9, 2018 and was updated September 14, 2018.

I experienced my first anxiety attack when I was 20 years old, trapped on a cross-country flight bound for my freshman year of university. These onslaughts of suffocation and doom would persist for over a year, cultivating a downward spiral of weight-loss, isolation, and sleep deprivation. I eventually sought out the help that I needed, but, ashamed even years later, I did not discuss my experience with anyone else.

Social stigma, overlooking symptoms and more prevent many from seeking help, despite overwhelming evidence demonstrating the negative health effects of chronic anxiety and stress.

Here are some important studies that remind us we should take care, #GETLOUD this week, and stay loud next week, and the week after that.

High levels of anxiety may increase your chances of developing Alzheimer's

A 2015 study by Baycrest's Rotman Research Institute in Toronto, using data from 376 adults with mild cognitive impairment between the ages of 55 and 91, showed that the risk of developing Alzheimer's increases significantly in those who suffer from anxiety.

"Our findings suggest that clinicians should routinely screen for anxiety in people who have memory problems because anxiety signals that these people are at greater risk for developing Alzheimer's," says Dr. Linda Mah, the principal investigator on the study and an Assistant Professor of Psychiatry at the University of Toronto.

The researchers found that, in participants suffering from mild anxiety, the risk of Alzheimer's increased by 33%, while moderate anxiety increased the risk by 78%. Patients with severe anxiety saw their risk increase by an astounding 135%.

Dr. Mah explains that those who suffer from anxiety disorders have higher cortisol levels — a stress hormone which has been shown to damage the hippocampus, an area of the brain important in the processing of emotion and memory.

"Looking to the future, we need to do more work to determine whether interventions, such as exercise, mindfulness training and cognitive behavioural therapy, can not only reduce stress but decrease the risk of developing neuropsychiatric disorders," says Dr. Mah.

The neural effects of anxiety can be "contagious"

Scientists at the Cumming School of Medicine's Hotchkiss Brain Institute (HBI) at the University of Calgary have discovered that the stress of others can be "contagious", and that stress transmitted from one individual to another can affect both brains in the same way.

"Brain changes associated with stress underpin many mental illnesses including PTSD, anxiety disorders and depression," says Dr. Jaideep Bains, professor in the Department of Physiology and Pharmacology, and member of the HBI. "Recent studies indicate that stress and emotions can be 'contagious'. Whether this has lasting consequences for the brain is not known."

Bains and his team observed these shared stress patterns between pairs of male and female mice. When one mouse was removed and exposed to mild stress then returned to its partner, both mice exhibited the same neural response to said stress. Specifically, both mice experienced an alteration in their CRH neurons, which control the brain's response to stress.

Toni-Lee Sterley, the study's lead author, says, "What was remarkable was that CRH neurons from the partners, who were not themselves exposed to an actual stress, showed changes that were identical to those we measured in the stressed mice." (Interestingly, the effects of stress in female mice were reversed following a social interaction, while male mice did not see any correlating improvement.)

But could this also be true in humans? Bains believes it may. "We readily communicate our stress to others, sometimes without even knowing it," he says. "There is even evidence that some symptoms of stress can persist in family and loved ones of individuals who suffer from PTSD. On the flip side, the ability to sense another's emotional state is a key part of creating and building social bonds."

Chronic stress can lead to riskier decision-making

Neuroscientists at MIT have discovered, through the study of rats and mice, that chronic stress can induce riskier behaviour in decision-making. The study shows that animals experiencing chronic stress are far more likely, when weighing the pros and cons between two options, to choose actions with higher risks and greater rewards than their chill counterparts.

This change in behaviour has been attributed to underlying impairments in a specific brain circuit, which the study suggests could be corrected if "tuned" properly. Manipulating this circuit in humans could in theory help patients who exhibit similar stress-induced risky behaviour.

"One exciting thing is that by doing this very basic science, we found a microcircuit of neurons in the striatum that we could manipulate to reverse the effects of stress on this type of decision-making. This to us is extremely promising, but we are aware that so far these experiments are in rats and mice," says MIT Professor Ann Graybiel, a member of the McGovern Institute for Brain Research.

In a stress-free brain, risky decisions are suppressed by what's called high-firing interneurons in the prefrontal cortex. When stress is introduced, these inhibitors are activated too late and riskier decision-making occurs. Untreated, this imbalance remains in effect for months.

"It's as though the animals had lost their ability to balance excitation and inhibition in order to settle on reasonable behaviour," says Graybiel.

The researchers found that they could restore normal behaviour by artificially activating the high-firing interneurons, though this requires optogenetics, a technique which allows biologists to control specific neurons using light (not yet human-friendly!).

Chloe Rose Stuart-Ulin is a Montréal-based journalist and editor. Her work has appeared in Ha'aretz, CBC, Lilith, Maclean's, and The Garden Statuary. Follow her @chloerosewrites.