Having frequent bad dreams may be an early sign that someone is going to develop Alzheimer's, new research says. A study has found that nightmares can be linked to a risk of dementia - and scientists now think they could be used as a way of identifying the need for treatments to slow down the disease.
The phenomenon is strongest in men - raising the risk fivefold. In women, the number of dementia cases increased by 41%.
Lead author Dr Abidemi Otaiku, of Birmingham University's Centre for Human Brain Health, said: "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. This is important because there are very few risk indicators for dementia that can be identified as early as middle age."
Dr Otaiku and colleagues analysed data on people across the US - more than 600 aged 35 to 64 and 2,600 over 79s. They were tracked for an average of nine and five years respectively.
In the younger group, those who experienced bad dreams on a weekly basis were four times more likely to experience cognitive decline over the following decade. The study published in EClinicalMedicine found older volunteers with the same sleep problem were twice as likely to get dementia.
Participants completed a range of questionnaires including the Pittsburgh Sleep Quality Index which asks how often individuals experienced bad dreams. Statistical software was used to identify associations between higher frequency and cognitive decline and dementia.
Dr Otaiku said: "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."
The researchers next plan to investigate if the same applies to young people and whether remembering dreams and how vivid they are could also be used to identify at-risk patients. They also hope to use EEG (electroencephalography) skulls caps and MRI (magnetic resonance imaging) brain scans to investigate the biological basis of bad dreams in both healthy people and those with dementia.
The number of dementia cases worldwide will triple to more than 150 million by 2050 because of ageing populations. In June the same team found older men who have nightmares are over three times as likely to develop Parkinson's.
They tracked more than 3,800 participants in the US for an average of 12 years. Like Alzheimer's, the neurological disorder affects memory, movement and communication.
With no cure in sight, there's an increasing focus on earlier diagnosis and behaviours that reduce the risk. Alzheimer's and other forms of dementia affect more than 940,000 people in the UK - a figure that will reach two million within three decades.
In June the same team found older men who have nightmares are over three times as likely to develop Parkinson's, after tracking more than 3,800 participants in the US for an average of 12 years. Like Alzheimer's, the neurological disorder affects memory, movement and communication.
