Chronic stress and anxiety increases risk of developing depression and dementia

New research has warned people to find ways to reduce chronic stress and anxiety or they may be at an increased risk of developing depression and even dementia.

Led by the Rotman Research Institute at Baycrest Health Sciences, the research suggests that chronic stress and anxiety damage key brain regions involved in emotional responses, thinking and memory.

Dr Linda Mah, lead author of the study, said: “Pathological anxiety and chronic stress are associated with structural degeneration and impaired functioning of the hippocampus and the prefrontal cortex (PFC).

"This may account for the increased risk of developing neuropsychiatric disorders, including depression and dementia.”

Researchers examined brain areas impacted by chronic anxiety, fear and stress from existing animal and human studies.

The team looked specifically at neural circuits linked to fear and anxiety in three brain regions; the amygdala, medial prefrontal cortex (PFC) and hippocampus, which are impacted during exposure to chronic stress.

They found an 'extensive overlap' of the brain’s neurocircuitry in all three conditions, which could explain the link between chronic stress and the development of neuropsychiatric disorders, including depression and Alzheimer’s disease.

The researchers also noted similar patterns of abnormal brain activity with fear,anxiety and chronic stress – specifically an overactive amygdala (associated with emotional responses) and an under-active PFC (thinking areas of the brain that help regulate emotional responses through cognitive appraisal).

Experiencing anxiety, fear and stress is considered a normal part of life when it is occasional and temporary, such as feeling anxious and stressed before an exam or a job interview.

However, when those acute emotional reactions become more frequent or chronic, they can significantly interfere with daily living activities such as work, school and relationships.

Scientists have suggested that when such acute emotional reactions become chronic they can 'wreak havoc' on immune, metabolic and cardiovascular systems, and damage the brain’s hippocampus (crucial for long-term memory and spatial navigation).

However, Dr Mah believes stress-induced damage to the brain may not be completely irreversible. Treatment with anti-depressant drugs and physical activity have been found to boost regeneration of 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,” she added.

The Rotman Research Institute at Baycrest Health Sciences is an international centre for the study of human brain function. The institute is helping to illuminate the causes of cognitive decline in older people and identify promising approaches to treatment and lifestyle practices that will protect brain health.