Perceived chronic stress, health and cognition

The aim of this licentiate thesis was to examine consequences of chronic stress for stressrelated diseases and to investigate the chronic stress – cognition relationship. In the first study data covering ten years was used from the Betula Prospective Cohort Study (Nilsson et al., 1997). Based on the ratings on a stress scale, matched samples between 40 and 65 years of age were divided into a high and low stress group. The reported incidence of cardiovascular, diabetes, psychiatric, tumor, and musculoskeletal diseases wasassessed five and ten years after a baseline assessment. The incidence of diseases five years after baseline assessment showed no differences between the groups. After ten years, there was a higher incidence of psychiatric diseases in the high stress group as well as a significant effect for tumors. These results indicated that moderately elevated stress levels may have an impact on psychiatric diseases, especially depression, and possibly also some tumor diseases, but it was concluded that prolonged moderate stress does not appear to be very harmful to health in general. In the second study cognitive performance was studied in chronic stress outpatients and matched controls. A battery of cognitive tests assessing processing speed, attention, episodic-, semantic- and working memory was used. Performance decrements for thechronic stress patients were found in episodic memory, particularly in learning across repeated trials, and in tasks requiring divided attention under either encoding or retrieval of words. Performance differences were also seen in aspects of working memory, mental tempo, semantic access (letter fluency) and prospective memory. It was concluded that executive functioning may be suboptimal in chronic stress patients and that letter fluency and prospective memory tests can be useful as clinical tools when evaluating chronic stressstates. Taken together, the findings indicate that there is no clear association between moderately elevated chronic stress and increased incidence of stress related diseases, whereas certain cognitive functions such as executive functioning appear vulnerable to chronic stress