Dementia rates are on the rise globally, with scientists working hard to improve our knowledge of the condition. Now, a new study has linked bad dreams in middle age to a greater risk of developing dementia later in life.
The study - published in The Lancet journal eClinicalMedicine and led by Dr Abidemi Otaiku of the University of Birmingham's Centre for Human Brain Health - suggested people who had frequent bad dreams in the mid-life years (35-64) were more likely to be diagnosed further down the line. Data from more than 600 adults in the US was examined, and none of the participants had dementia at the start of the study.
As Otaiku points out, more research is needed to get a clearer picture of what's going on when it comes to nightmares in middle age and dementia. However, he says the findings are potentially "important" because "there are very few risk indicators for dementia that can be identified as early as middle age" - and "bad dreams could be a useful way to identify individuals at high risk of developing dementia".
So, what else do we need to know at this point? We asked Dr Otaiku to talk us through...
What might these findings mean?
"If we can identify people who are at risk of getting dementia, several years or decades before memory and thinking problems start, doctors will be better placed to provide treatments that might delay or even prevent dementia from developing at all," says Dr Otaiku. "Therefore, finding out that nightmares in middle-aged adults might be linked to increased dementia risk later in life, might help contribute towards this strategy.
"A caveat is that such treatments are not yet available," he adds. "However, scientists are actively working on developing them. In addition, we already know that there are a number of things we can do right now to improve the health of our brain, and thereby reduce our risk of dementia, such as eating a healthy diet, having regular exercise, and keeping alcohol within recommended limits.
"And perhaps most intriguingly, given that nightmares are treatable, these findings raise the possibility that treating nightmares might even help to slow cognitive decline, and delay or prevent dementia."
So, what's going on - why could nightmares and dementia be linked?
"My theory is that frequent nightmares or bad dreams - in some adults - are a very early symptom of Alzheimer's disease or other dementias, which manifest for several years or even decades before memory and thinking problems arise," says Otaiku.
"We know that the same brain regions that regulate our emotions during wakefulness, also regulate our emotions during dreaming. Therefore, nightmares that develop before the onset of dementia, could be caused by neurodegeneration of frontal brain regions that normally 'down regulate' negative emotions across wakefulness and dreaming. This may result in depression and anxiety during the day, and nightmares and bad dreams during the night."
Could there be other factors at play? For example, we often associate bad dreams with times of high stress and anxiety
"In this study, participants were asked a range of questions about their physical health and psychological wellbeing, including how stressed they were, and also levels of anxiety and depression.
"Whilst those with frequent bad dreams were more stressed, and were more likely to have anxiety or be depressed, the link between bad dreams and future dementia remained strong even when taking these factors (and others) into account," says Otaiku. "This suggests that there may well be a direct link between dreams and dementia in some individuals."
I get lots of bad dreams - should I be worried?
As Dr Otaiku already pointed out, lots of things have been associated with a raised risk of dementia - and, generally speaking, many of these can be adjusted throughout our lives to help lower the risk, such as eating a healthy, balanced diet, keeping active, not smoking, watching our alcohol intake and treating issues like hearing loss and social isolation.
And if you are middle-aged and prone to nightmares? "Having frequent bad dreams can be due to things like stress, low mood, or anxiety. And for many people, having lots of bad dreams may just be a lifelong tendency," Otaiku reassures. "I suspect only a small proportion of frequent bad dreams are due to underlying dementia."