Persistent stress can shrink the brain and even lead to dementia, say researchers.
Chemicals released by the body during prolonged stress are toxic to brain tissue, they found.
Types of stress linked to the condition include that suffered by those in loveless marriages, dead end jobs and post traumatic situations.
The research suggests chemicals - called corticosteroids - can kill off brain cells if concentrations remain high over long periods.
Corticosteroids help the body in 'fight or flight' situations - suppressing the immune system and increasing the amount of sugar in the bloodstream.
The hippocampus, a part of the brain involved in the formation of memories, is particularly susceptible - which leads doctors to believe stress may lead to dementia.
"The sample size is too small to draw conclusions but the implication is that stress had affected the hippocampus," the Daily Mail quoted T Byram Karasu, professor of psychiatry at the Albert Einstein College of Medicine in New York, as saying.
The study has been published in the Journal of Neuroimaging.