Wellness
Bad sleep harms old-age memory by disrupting the brain’s ‘waste removal system’
Poor sleep among older adults is linked to disruptions in the brain’s “waste removal system”, according to a recent study, offering valuable insight into how sleep quality impacts brain functioning.
For the study, the researchers focused on the glial-lymphatic (glymphatic) system, a fluid transport pathway that plays a vital role in clearing waste from the brain. The system’s efficiency is a critical determinant of brain health, particularly in ageing populations.
Study lead, Professor Lee at The University of Hong Kong (HKU) and her team sought to understand the glymphatic-brain relationship in poor sleepers, which underlies memory decline.
Dysfunction of the glymphatic system leads to the accumulation of toxic proteins, and this process has recently been implicated in several neurological disorders, such as Alzheimer’s disease, Parkinson’s disease and epilepsy.
“Sleep quality, brain activities, and glyphamtic functioning are related. Understanding how sleep quality influences the glymphatic system and human brain networks offers valuable insight into the neurophysiological mechanisms underpinning age-related memory change,” Professor Lee said.
The research team studied 72 older adults using functional MRI scans and sleep recordings. The findings indicate that poor sleep quality adversely affects normal brain function by deactivating the restorative glymphatic system.
“The results clearly reveal the effect of sleep on the human brain’s network through the glymphatic system, which in turn affects memory performance in older adults,” said Professor Lee.
“Therefore, maintaining efficient glymphatic functioning seems crucial for promoting healthy ageing.”
The results of the study add important evidence that sleep quality affects cognitive health through the underlying neural relationships.
“Impaired memory is a common complaint among older adults with poor sleep quality,” Professor Lee said.
“Our results provide a novel perspective on the interplay between sleep, the glymphatic system and multimodal brain networks.”
Routine vaccines for adults may reduce dementia risk, a review of more than 100 million people suggests.
The research found both flu and shingles vaccines were associated with a lower risk in adults aged 50 and over.
The shingles (herpes zoster) jab was linked to a 24 per cent lower risk of any dementia and a 47 per cent lower risk of Alzheimer’s disease.
A joint Italian-Canadian neuroscience review points to a pattern that public health experts say is hard to ignore, suggesting vaccines against common infections may offer long-term protection against the UK’s leading cause of death.
With an ageing population, about two million people are projected to be living with dementia in the UK by 2050.
Prof Sir Andrew Pollard is director of the Oxford Vaccine Group and former chair of the Joint Committee on Vaccination and Immunisation.
He said: “Vaccines for pneumonia, shingles, and influenza in older adults have been shown to reduce the risk of serious infections and hospitalisation caused by these diseases.
“But studies in the past few years have raised the intriguing possibility that vaccination could also provide a welcome reduction in the risk of dementia, a disease which places a huge burden on society and the NHS.”
A separate large-scale randomised trial in Wales compared shingles vaccines Zostavax and Shingrix to address the “healthy user effect”, where people who get vaccinated tend to be more health-conscious. As both groups were vaccinated, this helped control for that bias.
The results showed those receiving the newer Shingrix vaccine had a substantially lower risk of developing dementia over subsequent years.
Dr Maxime Taquet, clinical lecturer in psychiatry at Oxford, who led that study, said: “The size and nature of this study makes these findings convincing, and should motivate further research.”
Higher intake of some food preservatives is linked with increased risks of type 2 diabetes and cancer, two studies suggest.
The findings were based on diet and health data from more than 100,000 French adults in the NutriNet-Santé study between 2009 and 2023.
Of 17 preservatives analysed individually, higher consumption of 12 was associated with an increased risk of type 2 diabetes.
Higher intake overall was linked to a 47 per cent increase in incidence.
In the cancer research, several preservatives were linked to higher risk. Potassium sorbate was associated with a 14 per cent higher risk of overall cancer and a 26 per cent higher risk of breast cancer, while sodium nitrite was linked to a 32 per cent higher risk of prostate cancer.
Overall preservative intake was not linked to cancer incidence in the cohort.
Researchers said several compounds could alter immune and inflammatory pathways, possibly triggering cancer development.
Both were observational studies, so they show association rather than cause.
Mathilde Touvier, a coordinator of the diabetes study, said: “This is the first study in the world on the links between preservative additives and the incidence of type 2 diabetes.
“Although the results need to be confirmed, they are consistent with experimental data suggesting the harmful effects of several of these compounds.”
Prof William Gallagher, of University College Dublin, who was not involved with the research, said: “These higher rates of cancer are modest but are significant when taken at a population-based level in terms of potential impact.”
The researchers called on manufacturers to limit unnecessary preservatives and backed advice for consumers to eat fresh, minimally processed foods.
Weaker, fragmented body clocks are linked to higher dementia risk, new research suggests.
The study also found that people whose activity levels peaked later in the day, rather than earlier, faced a higher risk.
Circadian rhythm is the body’s internal clock, regulating the 24-hour sleep-wake cycle and other processes including hormones, digestion and body temperature.
With a strong rhythm, the body clock aligns well with the 24-hour day, sending clear signals for body functions.
Researchers at UT Southwestern Medical Center in Texas studied 2,183 people with an average age of 79 who did not have dementia.
Participants wore small heart monitors for an average of 12 days to measure rest and activity patterns.
Over an average follow-up of three years, 176 people developed dementia. Those with weaker rhythms had nearly 2.5 times the risk of dementia compared to those with the strongest rhythms.
People whose activity peaked at 2.15pm or later had a 45 per cent increased risk compared to those peaking earlier in the afternoon.
Wendy Wang, the study author, said: “Changes in circadian rhythms happen with ageing, and evidence suggests that circadian rhythm disturbances may be a risk factor for neurodegenerative diseases like dementia.
“Disruptions in circadian rhythms may alter body processes like inflammation, and may interfere with sleep, possibly increasing amyloid plaques linked to dementia, or reducing amyloid clearance from the brain.
“Future studies should examine the potential role of circadian rhythm interventions, such as light therapy or lifestyle changes, to determine if they may help lower a person’s risk of dementia.”
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Routine vaccines may protect against dementia, research finds
Food preservatives linked to increased diabetes and cancer risk, study finds
Weaker body clock linked to increased dementia risk
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