Stress and anxiety are associated with different psychological consequences. Now, researchers found that some parts of the brain can also be damaged, causing depression and even dementia.

Scientists from the Rotman Research Institute studied brain areas that are widely affected by fear, anxiety and stress in both animal and human subjects. They found that there is an extensive overlap in the brain circuits of those who have the three conditions.

"Chronic stress increases risk of major psychiatric disorders such as depression, and more recently has been linked with onset of dementia," the authors wrote.

While occasional stress and anxiety are normal, experiencing it more frequently can lead to disruptions in relationships and daily activities. That's where chronic stress comes in.

Chronic stress is defined as the prolonged presence of physiological stress response, which can damage various bodily systems. Such condition may also cause the shrinkage of the hippocampus, which is the part of the brain responsible for long-term memory and spatial navigation.

The researchers reviewed existing studies that looked into stress and fear conditioning in animals. The studies analyzed also include results of neuroimaging tests of stress and anxiety in both healthy and clinically affected humans.

More specifically, the authors looked into the connections in the brain parts responsible for fear and anxiety, which include amygdala, medial prefrontal cortex and hippocampus.

The researchers discovered similar patterns of abnormal brain activity with chronic stress and fear or anxiety. The amygdala or emotional center was overactive while the prefrontal cortex or cognitive center was under active.

The study findings is not entirely bad news. Lead author Linda Mah says damages in the identified parts of the brain are not completely irreversible. She says antidepressants and physical activity were both proven to hasten development of the hippocampus.

Mah says their future studies should identify whether measures like exercise, mind training and cognitive-behavioral therapy will not only reduce stress, but the risk of developing neuropsychiatric conditions as well.

The study was published in Current Opinion in Psychiatry.

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