Sleep problems could double risk of dementia in later life

People diagnosed with sleep disorders are at a significantly higher risk of developing dementia and other neurodegenerative conditions later in life, new research shows.

The study revealed strong associations between sleep disorders and several major neurodegenerative conditions, including Alzheimer’s disease (AD), Parkinson’s disease (PD), vascular dementia, general dementia, and amyotrophic lateral sclerosis (ALS).

People with a diagnosed sleep disorder were found to be twice as likely to develop a neurodegenerative condition within 15 years of their diagnosis than those without sleep issues, suggesting that sleep disorders may be a predictive marker of future neurodegeneration.

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The findings, published in npj dementia, highlight the importance of detecting and managing sleep disorders that could potentially reduce the risk of neurodegeneration.

The collaborative study between researchers at the UK Dementia Research Institute (UK DRI) at Cardiff University and the NIH Intramural Center for Alzheimer’s and Related Dementias (CARD) in the US examined data from three biobanks: the Secure Anonymised Information Linkage (SAIL) databank, the UK Biobank, and FinnGen. Across the three biobanks, the researchers analysed the electronic health records of over a million people, examining sleep disorders related to circadian rhythms, such as narcolepsy, sleep apnea, hypersomnia, and parasomnias, as well as non-organic sleep disorders, including generalised insomnia and nightmares.

Using statistical methods, the researchers analysed relationships between different neurodegenerative diseases and sleep disorders, and determined whether disrupted sleep is an early sign of cognitive decline or whether it leads to the development of dementia.

The results show that having a sleep disorder significantly increases the risk of going on to develop a neurodegenerative disease later in life, and this risk was greater for people who experienced recurrent sleep disorders.

For people with a general diagnosis of dementia or Parkinson’s, incidences of circadian sleep disorders and non-organic sleep disorders were associated with an increased risk of dementia in the 10 to 15 years that followed.

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For those with a diagnosis of Alzheimer’s disease, circadian sleep disorders increased the risk of Alzheimer’s in the 10 to 15 years following sleep disorder diagnosis and for those with vascular dementia, circadian sleep disorders and non-organic sleep disorders increased risk of developing vascular dementia in the 5 to 10 years following sleep disorder diagnosis.

Dr Emily Simmonds, from UK DRI at Cardiff University, said: ‘Our results are compelling, indicating a clear increased risk of neurodegenerative disease following a sleep disorder, across three large biobank datasets. Through analysing over one million people’s health records, we have found evidence to suggest that having a sleep disorder significantly increases someone’s risk of going on to later develop a neurodegenerative disease.’

The study also revealed that sleep disorders increased the risk of Alzheimer’s and Parkinson’s, independently of genetic risk.

Professor Valentina Escott-Price, group leader at the UK DRI, explained: ‘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. 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.’

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Future research will study the impact of sleep medications and whether improving sleep through medication will decrease the risk of developing dementia.