Most of us consider nightmares pretty harmless, but apparently, they can be a bad sign. According to research at the University of Birmingham, people who experience frequent bad dreams in middle age are more likely to be diagnosed with dementia later in life.
New research suggests nightmares may become common several years or even decades before the characteristic memory and thinking problems of dementia set in. The study will be published today (September 21, 2022) in The Lancet journal, eClinicalMedicine.
“We’ve demonstrated for the first time that distressing dreams, or nightmares, can be linked to dementia risk and cognitive decline among healthy adults in the general population,” said Dr. Abidemi Otaiku, of the University of Birmingham’s Center for Human Brain Health.
“This is important because there are very few risk indicators for dementia that can be identified as early as middle age. While more work needs to be done to confirm these links, we believe bad dreams could be a useful way to identify individuals at high risk of developing dementia, and put in place strategies to slow down the onset of disease.”
Dr. Otaiku examined data from three community-based cohorts in the United States for the study. These included more than 600 adult men and women aged between 35 and 64; as well as 2,600 adults aged 79 and older. All the participants were dementia-free at the start of the study and followed up for an average of nine years for the younger group and five years for the older participants.
Data collection for the study began between 2002 and 2012. Participants completed a range of questionnaires, including the Pittsburgh Sleep Quality Index (PSQI), which includes a question on how frequently individuals experienced bad dreams.
This data was analyzed using statistical software to assess whether participants with a higher frequency of nightmares were more likely to go on to experience cognitive decline and be diagnosed with dementia.
According to the research results, middle-aged people (35-64) who experience bad dreams on a weekly basis are four times more likely to experience cognitive decline over the following decade, while older people were twice as likely to be diagnosed with dementia.
It’s especially interesting that the study found that the associations were much stronger for men than for women. For instance, older men experiencing nightmares on a weekly basis were five times more likely to develop dementia than older men reporting no bad dreams. However, in women, the increase in risk was only 41 percent.
Next steps for the research will include exploring whether nightmares among young people could be associated with future dementia risk, and whether other dream characteristics, such as how often we remember dreams and how vivid they are, could also be used to identify dementia risk. Using magnetic resonance imaging (MRI) and electroencephalography (EEG), the scientists also plan to investigate the biological basis of bad dreams in both healthy people and people with dementia.
Reference: “Distressing dreams, cognitive decline, and risk of dementia: A prospective study of three population-based cohorts” by Abidemi I. Otaiku, 21 September 2022, eClinicalMedicine.