Older people whose cholesterol levels change over time may be 60% more likely to develop dementia than those whose cholesterol is stable, a study suggests.

Researchers tracked almost 10,000 people for an average of five years and gave them regular memory tests.

The typical difference between consecutive yearly cholesterol measurements was 91 mg/dL in the group who saw the biggest changes, compared with 22 mg/dL in the group with the smallest.

Those whose levels changed the most were 60% more likely to be diagnosed with dementia.

Study author Dr Zhen Zhou, of Monash University in Melbourne,  Australia, said: “These results suggest that fluctuating cholesterol, measured annually, may be a new biomarker for identifying people at risk of dementia, providing more information than the actual cholesterol levels measured at a single time point.”

Participants in the study had an average age of 74 and were split into four groups depending on how much their cholesterol changed.

Some 509 were diagnosed with dementia, including 147 in the group with the biggest changes and 98 in the smallest change group.

When they looked at different types of cholesterol, the researchers found the link was only present for “bad” LDL cholesterol, not “good” HDL cholesterol or triglycerides.

Eating too many foods high in saturated and trans fats can increase LDL cholesterol. Fatty meats, dairy, and many processed foods are common sources.

Dr Zhou added: “Older people’s cholesterol should be monitored for changes over time to help identify people who may be at risk of cognitive impairment or dementia and could benefit from interventions.

“[This] could include lifestyle changes or making sure they start or keep taking statin to prevent fluctuations in their cholesterol and potentially reduce the risk of dementia.”

The findings were published in Neurology, the medical journal of the American Academy of Neurology.