A middle aged woman’s risk of developing Alzheimer’s disease later on in life does not appear to be affected by her levels of cholesterol, researchers from Johns Hopkins University School of Medicine wrote in the medical journal Neurology. The authors are now questioning previous research which did point towards a link. Significant drops on cholesterol levels during old age are much better predictors of Alzheimer’s risk, say the authors.

Alzheimer’s disease, also known as simply Alzheimer’s or Senile Dementia of the Alzheimer Type (SDAT) is a progressive neurologic brain disease which leads to irreversible loss of neurons and cognitive abilities, including reasoning and memory. Signs and symptoms eventually become so severe that the patient cannot function socially or occupationally. Plaques and tangles develop within the structure of the brain, causing cells to die. Alzheimer’s patients have abnormally low levels of some crucial brain chemicals which are involved in the transmission of messages within the brain – neurotransmitters.

Michelle M. Mielke, PhD, said:

    “While some studies suggest that cholesterol is a risk factor for dementia, others have not replicated this finding, so the possible association has been under debate.”

In this study, 1,462 Swedish females aged 38 to 60 were followed-up for a total of 32 years. Monitoring involved heart tests, chest x-rays, blood tests and a physical exam. None of them had dementia at the beginning of the study.

Data was also gathered regarding lifestyle and personal histories, including smoking status, education, medical history and what medications they had been taking. Regular measurements were also taken of each individual’s BMI (body mass index), as well as blood pressure. On four occasions during the follow-up period they were tested for dementia.

During the 32-year period 161 females developed dementia.

The researchers were surprised at not being able to find any link between cholesterol levels during middle or old age and dementia risk, as previous studies had.

They did find that women with the highest falls in cholesterol levels from middle to old age had double the risk of developing dementia compared to those whose levels either had gone up or remained unchanged. Those with the highest cholesterol falls had a 17.5% risk of developing dementia compared to 8.9% of the women with no change or a rise.

Higher-than-expected declines in blood cholesterol levels during old age appears to be a more accurate predictor of dementia risk than levels during middle age, Meilke explained. Mailke said:

    “Cholesterol should still be monitored and treated through diet, exercise and medication for cardiovascular and overall health.”

Dementia, unlike Alzheimer’s, is not a disease in itself. Dementia is a set of signs and symptoms, while Alzheimer’s is the name for a specific disease. Put it another way, all patients with Alzheimer’s eventually have symptoms of dementia, but not the other way round, not all individuals with dementia have Alzheimer’s. Dementia can be caused by many illnesses and conditions, such as Alzheimer’s disease, stroke, Dementia with Lewy bodies, progressive supranuclear palsy, Korsakoff’s syndrome, Binswanger’s disease, HIV and AIDS, and Creutzfeldt-Jakob disease (CJD).

“The 32-year relationship between cholesterol and dementia from midlife to late life”
M.M. Mielke, PhD, P.P. Zandi, PhD, H. Shao, MS, M. Waern, MD, PhD, S. Ostling, MD, PhD, X. Guo, MD, PhD, C. Björkelund, MD, PhD, L. Lissner, PhD, I. Skoog, MD, PhD andD.R. Gustafson, PhD
Published online before print November 10, 2010, doi: 10.1212/WNL.0b013e3181feb2bf
Neurology November 10, 2010 WNL.0b013e3181feb2bf

Written by Christian Nordqvist