Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
Nightmares can cause a person to wake up during the night frightened and experience difficulty falling back asleep. Frequent bad dreams can negatively affect sleep quality, mood, and thinking.
Researchers started investigating the link between nightmares and cognitive decline, which is associated with dementia.
A recent study showed that experiencing disturbing dreams every week can increase the risk of mental decline and dementia in middle-aged and older individuals.
These findings can help doctors find new ways to diagnose dementia in its early phases, slow its progress, and even prevent it in some cases.
What Is Dementia?
Dementia is a clinical condition characterized by a deterioration in a person’s cognitive functions. People suffering from dementia experience mental impairment that can affect their:
● Communication and language
● Judgment and reasoning
● Ability to perform learned tasks
● Ability to recognize objects
Several injuries and illnesses may cause the cognitive impairment associated with dementia. These include an ischemic brain injury, accumulation of tau protein in the gray and white matter of the brain, and an abnormal buildup of the synaptic protein αlpha-synuclein in the brain.
Nightmares In Adults
A nightmare is a bad dream that wakes you up. Frequent nightmares lead to poor sleep quality and negatively affect waking lives.
We often associate nightmares with childhood. However, older people often have disturbing dreams. Around 50 to 85 percent of adults report experiencing nightmares at least once a year.
A large community-based study reported that around 5 percent of adults had nightmares weekly.
Another population-based study suggested that nightmares become more frequent as people grow older.
Recently, scientists began investigating the relationship between bad dreams and degenerative diseases associated with mental deterioration.
A study was done in 2021 and demonstrated that patients with Parkinson’s disease who frequently have disturbing dreams have a higher risk for worsening cognitive and motor function.
Can Nightmares Predict Dementia?
A new study published in The Lancet Discovery Science investigated the link between distressing dreams and the risk of dementia and cognitive deterioration.
The study analyzed data from studies done on 600 middle-aged people (between the ages of 35 and 64) and 2,600 older people (79 years and older), all of which were dementia-free at the beginning of the study.
The study followed the middle-aged group for an average of 9 years and the older group for an average of 5.
The data analysis revealed that in the following decade, middle-aged adults who experienced bad dreams weekly were four times more likely to experience mental impairment, a characteristic of dementia.
Moreover, older participants who experienced nightmares every week were twice as likely to develop dementia over the following five years compared with participants who never had bad dreams.
Therefore, a higher frequency of bad dreams might indicate a more progressive stage of neurodegeneration, which is associated with a more advanced phase of dementia.
Interestingly, the association between dementia and bad dreams was stronger in men than in women. As a result, the study concluded that frequent nightmares might be one of the earliest signs of dementia, especially in men.
Can Bad Dreams Increase The Risk Of Dementia?
Several theories can explain how frequent distressing dreams can cause dementia.
1) Increased Blood Pressure
Frightening dreams can increase the heart rate during sleep, which increases blood pressure.
That may explain why nightmares can increase the risk of dementia, especially in men.
In a longitudinal study published in the medical journal Hypertension, researchers found that older men with higher blood pressure at night were at a higher risk for developing dementia.
Consequently, elevated blood pressure at night due to nightmares can increase the risk of dementia.
2) Elevated Levels of Tau Protein
Another explanation is that people who frequently experience bad dreams have poor sleep quality, which leads to an accumulation of proteins associated with dementia in the brain.
An animal study on mice showed that sleep disturbances increase memory impairments and the levels of tau protein in the brain.
As mentioned above, dementia can result from high tau protein levels in the brain. Therefore, constantly waking up from nightmares can increase tau deposits in the brain, which leads to a type of dementia.
Another theory is that there may exist a common genetic factor that increases the likelihood of both experiencing nightmares and developing dementia.
Researchers found that genetic factors can affect how much a person experiences disturbing dreams during childhood and adulthood.
These genetic factors may also determine a person’s risk for dementia and mental decline.
How Are These New Findings Helpful?
This new research suggests that doctors may be able to slow mental deterioration and prevent dementia in some people by treating their nightmares. If bad dreams are an early sign of cognitive decline, this helps with the early diagnosis and management of dementia.
Moreover, these findings pave the way for future research into the risk of dementia in young people.
After this study, researchers can investigate if nightmares can increase cognitive decline and the risk of dementia in younger individuals. That will help scientists establish whether bad dreams cause dementia or whether they’re the consequence of mental decline.
All in all, this new data provides insight into the relationship between dementia and dreams, provides a novel opportunity for early dementia diagnosis, suggests a new possible way to prevent dementia, and sheds more light on the untapped territory of the dream world.
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