It is important to monitor our brain health
We spend a third of our lives sleeping. And a quarter of the time we sleep is spent dreaming. So, for someone with a life expectancy of about 73 years, that's just over six years of sleep.
Yet, considering the central role sleep plays in our lives, we still know very little about why we dream, how the brain creates dreams and, most importantly, how important our dreams may be to.
In the study, I analyzed data from three large U.S. studies on health and aging. They involved more than 600 people aged 35 to 64, and 2,600 people aged 79 and older.
All participants were free of dementia at the start of the study and were followed for an average of nine years for the middle-aged group and five years for the older participants.
At the beginning of the study (2002-2012), participants completed a series of questionnaires, including one that asked about how often they experienced bad dreams and nightmares.
I analyzed the data to find out whether participants with a higher frequency of nightmares at the beginning of the study were more likely to experience cognitive decline (a rapid decline in memory and thinking skills over time) and be diagnosed with dementia.
I found that middle-aged participants who experienced nightmares every week were four times more likely to experience cognitive decline (a precursor to dementia) over the next decade. Older participants, meanwhile, were twice as likely to be diagnosed with dementia.
Interestingly, the connection between nightmares and future dementia was much stronger for men than for women. For example, older men who had nightmares every week were five times more likely to develop dementia compared to older men who did not have nightmares. In women, however, the increased risk was only 41%. In the middle-aged group, a very similar pattern was found.
Symptom or cause of dementia?
Overall, these results suggest that frequent nightmares may be one of the first signs of dementia, which may precede the development of memory problems and thinking skills by several years or even decades, especially in men. Moreover, it is not unreasonable to suspect that having bad dreams and nightmares on a regular basis may even be a cause of dementia.
Given the nature of this study, it is not possible to be certain which of these theories is correct (although I suspect it is the former). However, regardless of which theory turns out to be true, the main implication of the study remains the same, i.e., that having bad dreams and nightmares regularly during middle and old age may bear some relationship to an increased risk of developing dementia as we age.
Recurrent nightmares can be treated
The good news is that recurrent nightmares are treatable. And first-line medical treatment for nightmares has already been shown to decrease the accumulation of abnormal proteins associated with Alzheimer's disease. There have also been case reports showing improvements in memory and thinking skills after treating nightmares.
These findings suggest that treating nightmares may help slow cognitive decline and prevent the development of dementia in some people. This will be an important avenue to explore in future research.
The next steps in my research will include studying whether nightmares in young people may also be related to an increased risk of dementia. This could help determine whether nightmares are the cause of dementia or whether they are simply an early sign in some people.
According to a publication made by eClinicalmedicine of the Lancet.