Stress affects the mental ability
The high level of the stress hormone associated with decreased brain volume and weaker results in the thinking and memory tests.
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American doctors have analyzed the results of a large study, using data on 4244 men (mean age - 76 years) without dementia. By scanning the brain brain volume was determined for each of them, after they have been tested, which tested their thinking and memory. Pensioners took analyzes of saliva in the morning and evening, to determine the level of cortisol (stress hormone). According to the analysis of study participants were divided into three groups - high, medium and low levels of cortisol.
Those older people who have found high levels of cortisol, the average had lower brain volume (especially the gray matter) than in those who have levels of this hormone was lower, the difference was about 16 milliliters. They also showed lower results on tests of thinking and memory. However, this association was only valid for the evening performance analysis of cortisol. High levels of this hormone in the morning, on the contrary, has been associated with an increased amount of white (not gray) matter of the brain and produces better results of some tests (but not a memory test). It is believed that the evening analysis shows baseline cortisol at rest, on the morning of a recent analysis of the effect of stress awakening. Studies show that depression increases the risk of dementia, but scientists are not yet known mechanisms of this process. People with depression increased cortisol levels, and there is a theory that this hormone has a toxic effect on the region of the brain called the hippocampus, which plays an important role in memory performance.
"As we have seen the results of only one analysis, we can not tell what's going on before - an increase in cortisol levels or a decrease in brain volume. It is possible that the decrease in brain volume in aging process reduces its ability to withstand the effects of cortisol, which in turn leads to further loss of brain cells. A deeper understanding of this relationship, we will try to find ways to reduce the negative impact of cortisol in the brain and mind "- says one of the authors of the study, neurologist Lohner Lenor (Lenore J. Launer).
See. M. Geerlings et al. "Salivary cortisol, brain volumes, and cognition in community-dwelling elderly without dementia", Neurology, August 2015.