Chronic Stress Linked to Depression, Dementia

People who suffer from chronic stress and anxiety may be at increased risk for developing depression and even dementia, according to a new Canadian review led by the Rotman Research Institute at Baycrest Health Sciences in Toronto.

The researchers observed how chronic anxiety, fear, and stress can impact various parts of the brain in both humans and animals. The findings show an “extensive overlap” of the brain’s neurocircuitry in all three conditions, which may explain the link between chronic stress and the development of neuropsychiatric disorders, including depression and Alzheimer’s disease.

Everyone experiences anxiety, fear, and stress, and when these negative emotions are occasional and temporary, they are considered a normal part of life. However, when these emotional reactions become more frequent or chronic, they can significantly interfere with daily living activities such as work, school, and relationships.

Chronic stress is defined as a prolonged activation of the normal acute physiological stress response. Chronic stress can wreak havoc on immune, metabolic, and cardiovascular systems, and lead to atrophy of the brain’s hippocampus (crucial for long-term memory and spatial navigation).

“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,” said Dr. Linda Mah, clinician scientist with the institute and lead author of the review.

For the review, the investigators looked specifically at key structures in the neurocircuitry of fear and anxiety (amygdala, medial prefrontal cortex, hippocampus) which are impacted during exposure to chronic stress.

The researchers noted similar patterns of abnormal brain activity with 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 judgment).

“Looking to the future, we need to do more work to determine whether interventions, such as exercise, mindfulness training, and cognitive behavioral therapy, can not only reduce stress but decrease the risk of developing neuropsychiatric disorders,” said Mah

The scientific review paper follows on the heels of another major study by Mah which was recently published in the American Journal of Geriatric Psychiatry. In that study, Mah found some of the strongest evidence yet that anxiety may accelerate the development of Alzheimer’s disease in people diagnosed with mild cognitive impairment.

The findings are published online in the journal Current Opinion in Psychiatry.

Source: Baycrest Centre for Geriatric Care