Study links 'bad cholesterol' to dementia
Reducing levels of LDL-cholesterol can reduce the risk of dementia by 26%, according to a new study, which also suggests statin drugs could provide an additional protective effect.
The observational study, published in the Journal of Neurology, Neurosurgery & Psychiatry, comes from a cohort of 571,000 adult outpatients in South Korea with no previous diagnosis of dementia who were followed for at least 180 days after LDL-cholesterol testing.
The group was split into two groups, around 190,000 with LDL-cholesterol levels of 70mg/dL or less and 379,000 with a level of 130mg/dL or more. Analysis of subsequent diagnoses of dementia showed that patients in the lower group had a 26% reduction in dementia overall, and a 28% reduction in Alzheimer's diagnoses, compared to the higher group.
In the lower LDL-cholesterol cohort, the use of statins seemed to reduce their risk even further, although, there was a levelling off with no further benefit if their levels fell below 30mg/dL.
While observational studies can be hard to interpret as other factors may be at play, the authors conclude that their results "underscore the crucial role of managing LDL-cholesterol in lowering dementia risk and highlight the importance of targeted strategies in addressing cardiovascular and cognitive health outcomes by physicians."
The data also "support[s] the necessity of targeted lipid management as a preventive strategy against dementia, indicating the importance of personalised treatment approaches."
They nevertheless caution against drawing firm conclusions, given the potential for under-reporting of dementia, differences in diagnostic procedures between hospitals, and the focus on baseline LDL-cholesterol levels that could change over time.
One commentator – neurophysiologist Dr Francesco Tamagnini of the University of Reading, who was not involved with the study – said that the study indicates that "there is clearly more to the story of Alzheimer's than we first thought."
He added: "The results give a convincing argument for researchers to consider LDL cholesterol in addition to the classic approaches," and that means that the current focus on amyloid and tau – which have long been targeted by drug developers – "is now likely to fade."
Dr Julia Dudley, head of research at Alzheimer's Research UK, pointed out that high levels of LDL-cholesterol were identified as a risk factor for dementia in last year's Lancet Commission on dementia prevention, while other studies have suggested that statins may reduce dementia risk.
"However, dementia risk is complex and influenced by many factors," she cautioned. "Without a detailed picture of what's going on in the brain we do not know if there is a direct link between lower cholesterol and reduced dementia risk. Clinical trials will be key to understand what effects statins might be having on disease processes in the brain."
