High cholesterol in middle age linked to dementia

Higher levels of low-density lipo-protein, sometimes called “bad cholesterol”, were linked to an increased risk of developing the conditions. While elevated levels of total cholesterol were also associated with an increased risk, this link was weaker. High levels of LDL cholesterol are already known to raise the risk of heart disease and stroke.

The latest study provides the strongest evidence so far of the relationship between blood cholesterol and dementia and Alzheimer’s.

It was led by the London School of Hygiene & Tropical Medicine with the University of Tsukuba, Japan, and OXON Epidemiology, which is based in London and Madrid.

Study lead Dr Nawab Qizilbash explained: “While the link between LDL cholesterol and dementia and Alzheimer’s disease is modest, and found in people followed up from middle age for over 10 years, any modifiable risk factor is welcome for this huge, burgeoning and devastating disease.

“Most of the known risk factors are difficult to modify and convincing evidence that their modification can prevent dementia or Alzheimer’s disease is scarce.

“Likewise, long-term follow-up of randomised and non-randomised studies are needed to assess if the benefits of LDL cholesterol-lowering interventions – which greatly reduce coronary heart disease – may additionally reduce the risk of dementia or Alzheimer’s disease.”

Funded by Alzheimer’s UK, researchers used anonymised data from the UK Clinical Practice Research Database on more than 1.8 million UK adults.

Lead author Dr Masao Iwagami, assistant professor at the University of Tsukuba, said: “Our study dwarfs in size all previous studies and provides really precise results.”

However, the authors acknowledged the limitations of the study, including a lack of information on diet or physical activity.

So, they said, it was not possible to assess the influence of these factors on blood cholesterol and how it might affect observed associations.

The study is published in Lancet Healthy Longevity.