It is now possible to detect the first signs of brain decline before symptoms appear by using a wearable device that monitors heartbeat during sleep.
The research was conducted by an international team including Agustin Ibanez, professor in global brain health at Trinity College Dublin.
“During sleep, your autonomic nervous system modulates your heart rhythm in complex ways,” Prof Ibanez said. “If your heart’s rhythm becomes too predictable, too rigid, it can reflect diminished adaptability in your cardiovascular and nervous systems.”
The new study developed a way to measure the flexibility – technically referred to as complexity – of the heart rate while we are asleep.
“We found that reduced complexity during sleep predicted faster cognitive decline, equivalent to being three years older,” Prof Ibanez said.
The less complex, or variable, the night-time pulse rate, he said, the less adaptable the heart was to the environmental conditions the body found itself in, and the more susceptible it would be to earlier brain decline, and dementia. “This suggests that your sleeping heartbeat may partially reveal how resilient your brain is to ageing,” he said.
The study – which also included scientists across the US and Canada – is reported in The Journal of the American Heart Association.
With enough data, we can personalise predictions, accounting for sleep, stress and lifestyle changes
The research suggests development of a low-cost non-invasive device that can monitor pulse rate at night could help authorities detect dementia earlier.
“With further development, it could become a tool for early screening using everyday wearables,” Prof Ibanez said. “With enough data, we can personalise predictions, accounting for sleep, stress and lifestyle changes.”
The early detection of dementia would mean that the advice people are offered could go beyond the usual “sleep well, exercise and eat right” medical mantra.
“We can tailor interventions,” Prof Ibanez said. “For instance, someone with reduced pulse complexity could receive targeted stress-reduction programmes, cognitive training or even medication trials. The device used for early detection can also track how well these interventions work.”
The global economic burden of dementia is more than €1bn per year and is expected to double by 2050.
“Understanding how our brains stay healthy as we age is one of the most important questions of our day, as we become older as a population,” Prof Ibanez said.
The costs to society include caregiver burden and lost productivity, while for individuals it can mean identity loss, social withdrawal and emotional toll.
Our brains age together with our bodies and our environments
Prof Ibanez believes that because of the costs to society as a whole, the Irish Government and others should support the development of a device that monitors night-time heart rate and make it available free to people over 50.
“The data generated would enable predictive models customised by country, region, sex, ethnicity and socio-economic status,” he said. “Our brains age together with our bodies and our environments.”
This research proves that algorithms can be used to pick up subtle changes that indicate brain decline years before symptoms show up.
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