Stress raises the risk of memory loss and cognitive decline among older people with diabetes, research suggests.
Researchers at the University of Edinburgh studied more than 900 men and women aged between 60 and 75 with type-2 diabetes, which tends to be common after the age of 40.
They found that brain function slowed in participants with higher levels of the stress hormone cortisol.
Dr Rebecca Reynolds, of the University of Edinburgh's Centre for Cardiovascular Science, said: "We know that type-2 diabetes is linked to problems with memory, but the reason behind this is unclear.
"This study shows that older people with diabetes who have higher levels of stress hormones in their blood are more likely to have experienced cognitive decline. It may be that by regulating cortisol levels, we could help improve cognitive decline in patients with type-2 diabetes."
The research published by Diabetes Care is part of the Edinburgh Type-2 Diabetes Study, set up four years ago to better understand why people with diabetes may have memory problems.
Scientists evaluated mental abilities with a range of tests, which included looking at memory and assessing how quickly participants processed information. They compared this with general intelligence levels, using vocabulary tests, to work out whether brain function in participants had diminished over time. Factors such as education, cardiovascular disease, smoking and mood were also taken into account.
Blood samples were taken from participants in the morning to assess levels of cortisol.
The researchers, who have been funded by the Medical Research Council, will now look at other factors which may also impact on memory problems.
They are now inviting people who enrolled when the Edinburgh Type-2 Diabetes Study was set up to take part in follow-up research to repeat the memory tests.