Saliva Test for Stress Hormone Levels

According to a study published in the journal Neurology, testing the saliva of healthy older people for their cortisol levels may help identify individuals who should be screened for problems with cognition. The study found that people with higher levels of cortisol in the evening were more likely to have a smaller total brain volume and to perform worse on tests of thinking and memory skills. “Studies have shown that depression increases the risk for dementia, but we don’t know much about how this relationship occurs,” said the study’s lead author. The study analyzed 4,244 people with an average age of 76 who did not have dementia. Participants underwent a brain scan so researchers could look at their brain volume and then took tests of their thinking and memory skills. Saliva samples were taken from the participants once in the morning and in the evening to determine cortisol levels, and were then divided into three groups based on cortisol levels of high, medium and low. Results showed that people with the highest level of cortisol were more likely to have a smaller overall brain volume compared to those with lower levels of cortisol, with a difference of 16 milliliters between the two groups. Those with the highest level of cortisol also performed worse on the memory and thinking tests compared to those with low levels of the hormone. “Since this study just looked at a snapshot in time, we don’t know which came first: the high levels of cortisol or the loss of brain volume,” the author said. It’s possible, the researchers said, that the loss of brain volume that occurs with aging can lead to a lesser ability of the brain to stop the effects of cortisol, which can lead to further loss of brain cells. To read more about this study, click here.