Evidence suggests that people who often have bad dreams at a middle age may suffer more rapidly from a decrease in cognitive functions and a higher risk of dementia as they grow older; ultimately, the study will lead to new ways of screening for dementia.
Most people have bad dreams from time to time, but about 5% of adults have nightmares — dreams that are unpleasant enough to wake them up — at least once a week. Stress, anxiety and under-sleep are all potential triggers, but previous research into people's Parkinson's disease has also linked frequent anxiety dreams to a faster decline in cognitive functions and an increased risk of dementia in the future.
To find out if it was true for healthy adults, Dr. Abidimi Otyku of Birmingham University referred to three earlier studies that examined the quality of people's sleep and then watched them for many years, assessing their brain health as well as other results, including more than 600 middle-aged adults and 2,600 people aged 79 and over.
Their data were analysed using statistical software, the aim being to see if those who had more trouble dreaming than others had reduced cognitive functions and diagnosed dementia.
A study published in eClinicalMedicine showed that middle-aged people who had bad dreams at least once a week were four times more likely to suffer from a decrease in cognitive functions in the next decade than those who had had very few dreams.
The working hypothesis of Otyku is that neurodegeneration in the right frontal lobe makes it difficult to control the emotions in a dream, which in turn leads to nightmares. "We know that neurodegenerative conditions, such as Parkinson's disease and Alzheimer's disease, often start years before diagnosis. Night nightmares can be one of the earliest signs," the scientist concludes.