3 days ago
Nightmares linked to higher dementia risk, study finds
People who have nightmares or sleepwalk are twice as likely to develop vascular dementia than those who sleep soundly, a study has found.
Scientists have long known that serious sleep disorders increase the risk of neurodegenerative conditions, but the latest research has shed more light on the connection.
Analysis of more than a million people's medical records has found individuals with sleep problems who have not been diagnosed with anything physically wrong are also at increased risk.
So-called 'non-organic' sleep disorders which are not linked to a known physiological condition include night terrors, sleepwalking, nightmares, and forms of insomnia and hypersomnia.
Sufferers from these disorders were found to be more than twice as likely to be diagnosed with vascular dementia in later life, and to be at 67 per cent higher risk of dementia and 68 per cent higher risk of Parkinson's disease.
The study, led by Cardiff University, involved data from three biobanks containing the records of people in Britain and Finland. The research compared the subjects' sleeping patterns with their genes and their long-term health outcomes.
'By using biobank data, we had timestamped records of when people had sleep disorders, and exactly when they were subsequently diagnosed with a neurodegenerative disease – rather than relying on self-reporting,' said Dr Emily Simmonds, one of the study authors and a bioinformatician at the UK Dementia Research Institute at Cardiff University.
'Our results are compelling, indicating a clear increased risk of neurodegenerative disease following a sleep disorder, across three large biobank datasets.'
The scientists found people often experienced sleep disorder symptoms up to 15 years before they started seeing symptoms of the neurodegenerative conditions.
Kristin Levine, a study co-author from the US National Institutes of Health's (NIH) Centre for Alzheimer's and Related Dementias, said: 'One of the exciting things about identifying people at higher risk of developing a neurodegenerative disease 10-15 years before diagnosis, is that it gives us time to implement treatments that may delay or prevent development of disease.'
A link was seen between sleep problems and the neurodegenerative diseases even in people whose genes put them at low risk, the study authors found.
'Perhaps most interestingly, this increased risk was occurring independently of genetic risk factors for Alzheimer's and Parkinson's, with sleep disorders almost 'compensating' for low genetic risk,' said Hampton Leonard from the NIH Centre, the study's co-leader.
'One would expect that if sleep disorders were caused by neurodegeneration, genetic risk of sleep disorder and neurodegenerative disease would line up. Further investigation is needed, but this points towards sleep disorders as a risk factor for these conditions.'
The scientists hope future research will build on their findings, and investigate if any interventions that target sleep problems can improve the outlook for neurodegenerative conditions.
The study is published in npj Dementia.
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