New research suggests that maintaining lower levels of 'bad' cholesterol in your bloodstream could significantly reduce your risk of developing dementia.

The study, published in the Journal of Neurology Neurosurgery & Psychiatry, reveals a strong connection between low LDL cholesterol and decreased dementia risk.

What the Research Found

Researchers analysed data from over 571,000 people in South Korea who had not been diagnosed with dementia.

The study compared two groups: 192,213 people with LDL cholesterol levels below 1.8 mmol/L and 379,006 people with levels above 3.4 mmol/L.

The results were striking:

• People with LDL-C levels below 1.8 mmol/L had a 26% lower risk of developing dementia compared to those with higher levels

• The risk of Alzheimer's disease specifically was reduced by 28% in the low LDL-C group

• For those already with low LDL cholesterol, taking statins provided an additional 13% reduction in dementia risk

  
  

Understanding Cholesterol and Dementia

LDL cholesterol, often referred to as 'bad' cholesterol, is known to cause plaque buildup in arteries, leading to cardiovascular disease. This increases the risk of strokes and heart attacks, which are known risk factors for dementia.

While the relationship between LDL cholesterol and heart disease has been well-established, its connection to dementia has been less clearly understood until recently.

A 2024 Lancet report found that 7% of dementia cases were linked to high levels of bad cholesterol in midlife. This new research strengthens the evidence that managing cholesterol levels could be an important strategy for brain health as we age.

NHS Guidelines for Cholesterol Levels

To understand the significance of the LDL-C levels mentioned in the study, it's helpful to know the NHS recommended cholesterol targets:

• Total cholesterol: 5 mmol/L or less for healthy adults; 4 mmol/L or less for those at high risk

• LDL (bad) cholesterol: 3 mmol/L or less for healthy adults; 2 mmol/L or less for those at high risk

• HDL (good) cholesterol: 1 mmol/L or more for men and 1.2 mmol/L or more for women

• Non-HDL cholesterol: 4 mmol/L or less for healthy adults; 2.5 mmol/L or less for those at high risk

• Total cholesterol to HDL ratio: should be below 4

  
  

The study found significant benefits when LDL-C levels were below 1.8 mmol/L, which is even lower than the NHS target for high-risk individuals.

This suggests that maintaining very low LDL cholesterol levels might provide additional protection against dementia beyond the current guidelines for cardiovascular health.

Implications for Public Health

With forecasts suggesting the number of people living with dementia worldwide could nearly triple to 153 million by 2050, these findings have significant public health implications.

Evidence suggests that almost half of all dementia cases could be prevented or delayed through modifiable risk factors. Managing cholesterol appears to be one such factor that could make a meaningful difference.

The Research Perspective

Dr Francesco Tamagnini, a neurophysiologist at the University of Reading not involved with the study, noted:

"There is clearly more to the story of Alzheimer's than we first thought. This paper looks at the correlation and potential causal relationship between high levels of bad cholesterol and dementia risk. The results give a convincing argument for researchers to consider LDL cholesterol in addition to the classic approaches."

While the study has limitations—including its observational nature, which cannot establish definitive cause and effect—it adds to a growing body of evidence connecting cardiovascular health to brain health.

Dr Julia Dudley of Alzheimer's Research UK cautioned that "dementia risk is complex and influenced by many factors," adding that clinical trials will be key to understanding the exact mechanisms at work.

Managing Your Cholesterol

To maintain healthy cholesterol levels, consider these approaches:

1. Eat a healthy, balanced diet low in saturated fats

2. Stay physically active with regular exercise

3. Maintain a healthy weight

4. Limit alcohol consumption

5. Quit smoking if you smoke

6. Increase dietary fibre intake

7. Include plant sterols and stanols in your diet

   
   

Plant sterols and stanols are naturally occurring substances found in plants that can help block cholesterol absorption in the intestines. Research shows that consuming 1.5-2.4g of plant sterols/stanols daily can lower LDL cholesterol by 7-10%.

Plant sterols are available in fortified foods like certain cholesterol lowering margarines, as well as supplements.

Remember: Age Matters Too

It's important to note that even with a healthy lifestyle, cholesterol can still be an issue because age is also a factor. As we get older, our bodies naturally produce more cholesterol, and our liver becomes less efficient at removing LDL cholesterol from the bloodstream.

This is why regular cholesterol monitoring becomes increasingly important as we age, regardless of how healthy our lifestyle may be.

Speak with your GP about having your cholesterol levels checked, particularly if you are over 40, have a family history of high cholesterol or heart problems, or have other risk factors such as high blood pressure or diabetes.