Simple cholesterol checks could help predict dementia up to six years before a diagnosis, promising research suggested today.
Previous studies have long linked having high cholesterol in middle age with a higher risk of developing the memory-robbing condition.
But now scientists in Australia, who tracked almost 10,000 adults in their 70s, found those with stable levels had a ‘significantly’ lower likelihood of receiving a diagnosis or showing cognitive decline.
Experts hope routine cholesterol checks could now be used to flag people with fluctuating cholesterol levels allowing patients to get treated earlier.
But the researchers, who labelled the findings ‘important’ did acknowledge the paper was merely observational and could not prove why fluctuating rates may raise the risk of the condition.
Study lead author and expert in public health at at Monash University in Melbourne, Zhen Zhou, said: ‘Older people with fluctuating cholesterol levels unrelated to whether they were taking lipid-lowering medications may warrant closer monitoring and proactive preventive interventions.’
Professor Fernando Testai, an expert in neurology and rehabilitation at the University of Illinois Chicago added: ‘This study adds an important piece to the puzzle of preserving brain health by providing evidence that increasing variability in cholesterol levels is associated with cognitive decline.
‘The study did not include people who started or stopped taking lipid-lowering medications during the study period.
‘So, the results cannot be explained by the effect of statins.
‘From a practical standpoint, not sticking to strategies that improve the lipid profile, such as following a healthy diet and exercising, can worsen the negative impact of harmful lipids on the brain.’
In the study, researchers tracked almost 10,000 adults in their 70s — none of whom made any changes to taking cholesterol-lowering medication.
Over a follow-up of six years, they found 509 participants developed dementia and another 1,760 developed cognitive decline without dementia.
Those with the highest fluctuations in cholesterol — who ranked in the top 25 per cent — were 60 per cent more likely to have a dementia diagnosis, the scientists said.
They were also at a 23 per cent higher chance of suffering cognitive decline.
Volunteers with higher levels of low-density lipoprotein cholesterol — LDL cholesterol or ‘bad’ cholesterol — were most likely to see significantly faster declines in cognitive health test scores and tests involving memory and reaction speed.
High-density lipoprotein cholesterol (HDL), meanwhile, has long been considered good because of the swathe of evidence showing it protects the heart.
Around 900,000 Brits are currently thought to have the memory-robbing disorder. But University College London scientists estimate this will rise to 1.7million within two decades as people live longer. It marks a 40 per cent uptick on the previous forecast in 2017
Alzheimer’s disease is the most common cause of dementia. The disease can cause anxiety, confusion and short-term memory loss
It removes cholesterol from the arteries and carries it to the liver to be broken down and removed from the body — reducing the risk of heart attacks and strokes.
But some research has since started to challenge the traditional view that more is better when it comes to HDL levels.
Yet the scientists discovered that high fluctuations in HDL were not associated with dementia or cognitive decline.
The scientists, however, acknowledged the research had ‘some limitations’ including involving predominantly white adults (96 per cent), meaning the results may not apply to other population groups.
The findings will be presented in full at American Heart Association’s Scientific Sessions 2024 in Chicago.
Cholesterol is a fatty, waxy substance found in the blood that is vital for bodily functions including digestion, making vitamin D and hormones.
However, too much can build up in the blood due to eating fatty food, not exercising enough, being overweight, smoking and drinking alcohol.
Having high LDL cholesterol doesn’t trigger any symptoms but can lead to blocked blood vessels and raise the risk of heart problems and strokes.
Meanwhile, HDL cholesterol has been shown to protect against heart disease, with the NHS stating that levels above 18mg/dL for men and 21.6mg/dL for women are healthy.
Recent analysis by the Alzheimer’s Society estimates the overall annual cost of the dementia to the UK is £42billion a year, with families bearing the brunt.
An ageing population means these costs – which include lost earnings of unpaid carers – are set to soar to £90billion in the next 15 years.
Around 944,000 in the UK are thought to be living with dementia, while the figure is thought to be around 7million in the US.
Alzheimer’s affects around six in 10 people with dementia.
It is thought to be caused by a build-up of amyloid and tau in the brain, which clump together and from plaques and tangles that make it harder for the brain to work properly.
Eventually, the brain struggles to cope with this damage and dementia symptoms develop.
Memory problems, thinking and reasoning difficulties and language problems are common early symptoms of the condition, which then worsen over time.
Alzheimer’s Research UK analysis found 74,261 people died from dementia in 2022 compared with 69,178 a year earlier, making it the country’s biggest killer.
