UNDER EMBARGO:12.00am 18/3 AEDT | 9am 17/3 EST
A large international study led by UNSW Sydney’s Centre for Healthy Brain Ageing (CHeBA), has found that older adults who experience frequent disturbing dreams may have a higher risk of developing dementia - particularly men and people in their 60s.
The research, involving an international collaboration of scientists from Brazil, China, France, Italy, South Korea, and Taiwan and published in Psychiatry and Clinical Neurosciences, analysed data from more than 10,000 adults aged 60 to 89 years who were followed over time. The study is part of the CHeBA-led COSMIC collaboration (Cohort Studies of Memory in an International Consortium).
Lead author and Research Fellow at CHeBA, Dr Darren Lipnicki, said the findings build on earlier research but extend it to a much broader and more diverse population.
“Previous studies suggested a link between disturbing dreams and dementia risk, but they were conducted in more limited samples,” Dr Lipnicki said. “By bringing together data from multiple countries and regions, we were able to test whether this association holds across different cultures and populations,” says Dr Lipnicki.
What are “disturbing dreams”?
Disturbing dreams include nightmares and “bad dreams.” Nightmares are typically intense, distressing dreams that wake the sleeper, often involving threats or danger. However, many distressing dreams do not wake the sleeper. In this study, researchers used the term “disturbing dreams” to cover both types.
About one in four participants (24%) reported experiencing disturbing dreams. Over the follow-up period, researchers tracked who developed dementia. They looked at both all-cause dementia and Alzheimer’s disease (the most common form of dementia).
After accounting for a wide range of factors - including sleep problems, medications, physical and mental health, cognitive performance, and genetic risk (APOE ε4 status) - the researchers found:
- Adults aged 60–69 who reported disturbing dreams had nearly four times the risk of developing dementia compared with those who did not report such dreams;
- Among men, having disturbing dreams at least once a week was associated with more than three times the risk of developing Alzheimer’s disease;
- These associations were not seen consistently in older age groups (70+ years).
Overall rates of dementia in the study were relatively low, with about 11 cases per 1,000 person-years for all-cause dementia and 5 cases per 1,000 person-years for Alzheimer’s disease.
Dr Lipnicki said the age-specific findings were particularly noteworthy.
“We found the strongest association in people in their 60s, which may suggest that disturbing dreams could be an early marker of dementia risk for some individuals,” he said. “It’s important to emphasise that not everyone who experiences disturbing dreams will go on to develop dementia.”
Why might dreams be linked to dementia?
Researchers say the reasons are not yet clear. Several possible explanations are being explored:
- Early brain changes: Some types of dementia are linked to abnormal protein build-up in the brain. These changes may affect areas involved in regulating emotion during dreaming;
- Brain networks involved in threat detection: A brain network that helps detect important or threatening information may be overactive in people who experience frequent disturbing dreams;
- Stress and cortisol regulation: Chronic stress is linked to both nightmares and cognitive decline. Disturbing dreams may reflect changes in the body’s stress system that are also associated with dementia risk.
Importantly, the study does not prove that disturbing dreams cause dementia. They may instead be an early warning sign of underlying brain changes. Previous research linking nightmares and dementia was based mainly on older, predominantly white participants in the United States. This new study extends the findings to a much more diverse, international sample of community-dwelling adults across Asia, Europe, and South America.
The researchers also examined Alzheimer’s disease specifically, rather than dementia in general.
What does this mean for people who have nightmares?
According to co-author and Co-Director of CHeBA, “disturbing dreams are common and do not mean someone will definitely develop dementia. However, the findings suggest that frequent disturbing dreams - particularly in men and adults in their 60s - may warrant further investigation in future research.”
The team says more work is needed to understand the biological mechanisms behind the association and whether treating disturbing dreams could have any impact on long-term brain health.
Contact details:
Heidi Douglass
(02) 9385 0410