People who live a stressful life could have a higher risk of developing depression or dementia, researchers have revealed.
A review of previous studies has revealed that chronic stress and anxiety can damage key brain regions involved in emotional responses, thinking and memory, Press Association reports.
Lead author of the review, Dr Linda Mah, said: "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."
The paper reviewed a variety of recent studies that focused on stress and fear in animals as well as brain scans of stress and anxiety in humans.
These studies focussed on the neural circuits linked to fear and anxiety in three brain regions, the amygdala, PFC, and hippocampus.
Dr Mah's team looked specifically at neural circuits linked to fear and anxiety in three brain regions, the amygdala, PFC, and hippocampus
A see-saw pattern was seen in response to chronic stress with the amygdala, associated with emotional responses, becoming over-active and the PFC under-active.
The PFC contains "thinking" areas of the brain that help to regulate emotional responses by appraising them in a rational way.
Temporary episodes of anxiety, fear and stress - experienced before an exam or job interview, for instance - are part of normal life. But the scientists point out that when such acute emotional reactions become chronic they can "wreak havoc" on immune, metabolic and cardiovascular systems, and damage the brain.
Dr Mah believes stress-induced damage to the brain may not be completely irreversible.
Treatment with anti-depressant drugs and physical activity had both been found to boost regeneration of the hippocampus, she said.
"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.
Emma Mamo, head of workplace wellbeing at UK mental health charity Mind, commented: "This research highlights just how damaging unmanageable stress can be.
"We already know that there is a link between long-term exposure to stress and both physical and mental health problems. We also know that stress is hugely prevalent in the workplace – over half of the workers (56 per cent) surveyed in our latest YouGov poll said that their work was very or fairly stressful.
"That’s why it’s so important that employers tackle the causes of stress and poor mental health at work, to ensure staff feel supported to help cope with workplace stress."
The review was published in the journal Current Opinion in Psychiatry and Dr Mah works at the Baycrest Centre for Geriatric Care in Toronto, Canada.