Chronic stress can lead to several brain changes linked to depression and even Alzheimer’s, scientists warn.
Alzheimer’s disease, the most common form of dementia, is projected to affect 80 million people in the next 20 years, yet most of its causes remain uncharted territory.
Even though there are several triggers, one of its origins facilitating the leap from mild cognitive impairment (MCI) to full-blown dementia, holds an alarming percentage.
Women who had been through significant stressors in mid-life had a significantly (65 per cent) greater risk of developing dementia later on.
Stressful events can trigger a cascade of reactions involving the stress hormones (glucocorticoids) and eventually lead to atrophy in the brain’s hippocampus, which is responsible for memories and known to be most affected by Alzheimer’s disease.
Stress interrupts the normal function of the brain by triggering a cascade of reactions which involve glucocorticoids (stress hormones), disturbing the entire body.
Dr Linda Mah, from the Baycrest Centre for Geriatric Care in Toronto, Canada, and her team looked specifically at neural circuits linked to fear and anxiety.
The evidence from her research was published in the Current Opinion in Psychiatry journal, suggesting that “chronic stress and anxiety can damage key regions of the brain which deal with emotional responses, thinking and memory”.
The team studied the effects of stress in three brain regions – the amygdala (associated with emotional responses), the PFC (associated with thinking), and hippocampus (associated with memory).
Chronic stress would make the amygdala respond in a see-saw pattern, by becoming over-active whereas the PFC would become under-active.
“Pathological anxiety and chronic stress are associated with structural degeneration and impaired functioning of the hippocampus and the prefrontal cortex (PFC), which may account for the increased risk of developing neuropsychiatric disorders, including depression and dementia,” lead author Linda Mah said.
“Temporary episodes of anxiety, fear and stress – like how we feel before an exam or job interview, for instance – are part of normal life. But the scientists point out that when these emotional reactions become chronic they can ‘wreak havoc’ on immune, metabolic and cardiovascular systems, and cause damage to the brain.”
However, the researchers believe stress-induced damage to the brain may not be completely irreversible.
Physical activity, meditation and in some cases antidepressants were found to be effective forms of treatment, boosting cell regeneration in the hippocampus.
“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,” Dr Mah added.
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