Dementia: Can statins keep your brain sharp?

Irish Examiner

2 days ago

Statins are not the most popular drugs, with many people who take them as a matter of necessity to keep their cholesterol under control, often grumbling about muscle twinges and joint aches.
But earlier this year, a new study appeared to provide another compelling reason to take them.
Based on data collected from more than 570,000 South Koreans, it concluded that taking statins reduces your risk of dementia in later life by 13%.
With more than 64,000 people in Ireland currently suffering from dementia, figures which are predicted to more than double over the next 20 years, every little reduction in risk helps.
Dr Angie Brown, Irish Heart Foundation
According to Angie Brown, a consultant cardiologist and medical director for the Irish Heart Foundation, one of the main theories behind this benefit is because statins can improve so-called 'vascular health,' which refers to the functioning of the complex network of blood vessels which connect the brain with the rest of the body.
While they are best knowing for lowering the levels of LDL cholesterol — the harmful form of cholesterol — reducing risk of plaques forming and blocking veins and arteries, they are also believed to reduce inflammation, and improve function of endothelial cells, the thin layer of tissue lining blood vessels which helps your blood move smoothly through your body.
'Vascular health is important,' says Brown.
'Problems with blood vessels such as those caused by plaque build-up or the stiffening which can occur with age, can restrict blood flow to the brain, reducing oxygen supply which is crucial for cellular function. Narrowing of the carotid arteries [the pair of major blood vessels in the neck] can lead to mini strokes which can lead to dementia.'
While this may imply that statins might be most beneficial for stopping vascular dementia, the South Korean study found that the greatest benefit was actually seen in preventing Alzheimer's disease.
While deteriorating vascular health plays an often overlooked role in the development and progression of Alzheimer's, an additional possible explanation has been offered by other studies which have suggested that statins may limit production of the toxic beta amyloid protein, one of the underlying causes of Alzheimer's.
Another idea is linked to the so-called 'lipid invasion model' of Alzheimer's disease, an emerging theory based on research which has indicated that the blood-brain barrier, the protective layer of cells which shields the brain from the bloodstream, can become more permeable as we age, enabling excess LDL cholesterol molecules to slip through with damaging consequences.
'This is a newer idea but it's quite interesting,' says Professor Sean Kennelly, a consultant geriatrician at Tallaght University Hospital.
'As we get older, the weakening protective barrier between the brain and the rest of the body may allow harmful cholesterol particles to leak into the brain, where they could trigger damage and inflammation. It would explain why statins might protect the brain. It's still being studied but it's a possibility.'
So shouldn't we all get ourselves on statins in midlife, and accept the odd twinge in exchange for a sharper and healthier brain in old age?
Not so fast, says Kennelly, who points out that while statins are known to have clear benefits for heart health, doctors need more evidence to be convinced that they can do the same for the brain.
He explains that the South Korean study was a so-called observational study where large groups of people are tracked over time. However, such studies cannot conclusively prove that statins are driving benefits for the brain because other factors such as overall health may have proved a way.
'In contrast, clinical trials, which are the gold standard for testing treatments, where people have been randomly assigned to take statins or not, have not shown strong or consistent evidence that statins slow cognitive decline or prevent dementia,' says Kennelly.
'However, many didn't follow participants for long enough to fully assess dementia risk.'
With that in mind, Kennelly feels that for now, lifestyle measures such as regular exercise and healthy eating to manage your blood pressure and blood sugar, along with staying socially connected and looking after your hearing, remain the best strategies for protecting your brain health through midlife and old age.
Other research has also pointed out that the shingles vaccine seems to be another potential preventative measure against dementia.
His thoughts are echoed by Geir Selbæk, a professor at the Norwegian National Centre for Ageing and Health, commonly known as Norway's leading dementia expert.
Geir Selbæk, a professor at the Norwegian National Centre for Ageing and Health
While Selbæk, 61, does take statins, he did so only because of a family history of heart disease. Like Kennelly, he is not completely convinced that statins alone are enough to stave off dementia, and instead, he is focusing more on other measures such as starting to wear a hearing aid after noticing early signs of deafness, regularly running and doing strength training as both are linked with better brain health, and stimulating his mind by training to learn a new language.
'We also have to take into account whether taking statin in the hope of a 13% risk reduction of dementia in 20 years time is worth it for a person,' he says.
'Especially if you have side effects like stiff joints.'
However with the advent of AI in healthcare, Selbæk predicts that in future computer models will be able to predict with increasing accuracy, the midlifers who might be able to benefit most from these drugs for their brain health.
'In the future we'll also likely have better tests, maybe blood tests or brain scans, that can show who's most at risk,' says Kennelly.
'That could help doctors decide more precisely who would benefit from interventions like statins.'