Dementia warning: Scientists issue alert over alarming sign in women that could double their risk

Older women who experience increasing daytime sleepiness over a five-year period face double the risk of developing dementia, according to new research.

The study, published in Neurology, tracked women in their 80s and found clear links between changing sleep patterns and dementia risk.

Researchers from the University of California, San Francisco, observed that while the findings don’t prove daytime sleepiness causes dementia, they demonstrate a significant association between the two.

The team monitored sleep patterns in elderly women to determine how changes over time might serve as early markers or risk factors for cognitive decline.

The research adds to growing evidence that sleep health plays a crucial role in brain function and cognitive ageing.

The study involved 733 female participants with an average age of 83 who did not have mild cognitive impairment or dementia at the start.

Participants wore wrist devices to track their sleep and circadian rhythm patterns for three days at the beginning and end of the five-year study period.

During this time, 164 participants (22 per cent) developed mild cognitive impairment and 93 participants (13 per cent) developed dementia.

Researchers observed “large changes” in sleep patterns in more than half of the participants (56 per cent).

The women fell into three distinct groups: those with stable sleep or small improvements (44 per cent), those with declining night-time sleep (35 per cent), and those experiencing increasing sleepiness (21 per cent).

Those in the increasing sleepiness group slept longer during both day and night and had worsening circadian rhythms.

When researchers examined dementia outcomes, they found striking differences between the groups.

Only eight per cent in the stable sleep group developed dementia, compared to 15 per cent in the declining night-time sleep group and 19 per cent in the increasing sleepiness group.

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After adjusting for factors including age, education, race, diabetes and high blood pressure, those with increasing sleepiness had double the dementia risk compared to stable sleepers.

No association with dementia was found in the declining night-time sleep group.

Study author Dr Yue Leng said: “Sleep is essential for cognitive health, as it allows the brain to rest and rejuvenate, enhancing our ability to think clearly and remember information.

“However, little is known about how changes in sleep and cognition are connected over time and how these changes relate to dementia risk in the later decades of life.

“Our study found that sleep problems may be intertwined with cognitive ageing and may serve as an early marker or risk factor for dementia in women in their 80s.”