Low cholesterol levels are associated with a higher risk of Alzheimer's

This study was published in the Archives of Neurology 2004 May;61(5):705-14

Study title and authors:
Relation of plasma lipids to Alzheimer disease and vascular dementia.

Reitz C, Tang MX, Luchsinger J, Mayeux R.
Gertrude H. Sergievsky Center, Columbia University College of Physicians and Surgeons, New York, NY, USA.

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/15148148

This study investigated the relationship between cholesterol levels and Alzheimer disease and vascular dementia. (Vascular dementia is caused by problems in the supply of blood to the brain usually from a stroke). The study included 4,316 participants aged 65 years and older.

The study found:
(a) The risk of prevalent Alzheimer's was 28% higher in those who had low cholesterol, under 172 mg/gL (4.4 mmol/L), compared to those with cholesterol levels between 197-225 mg/dL (5.1-5.8 mmol/L).
(b) The risk of prevalent Alzheimer's was 34% higher in those who had low levels of high density lipoprotein (HDL) cholesterol, under 37 mg/gL (.95 mmol/L), compared to those with high density lipoprotein (HDL) cholesterol levels over 55 mg/dL (1.4 mmol/L).
(c) The risk of prevalent vascular dementia was 20% higher in those who had low cholesterol, under 172 mg/gL (4.4 mmol/L), compared to those with cholesterol levels between 197-225 mg/dL (5.1-5.8 mmol/L).
(d) The risk of prevalent vascular dementia was 40% higher in those who had low levels of high density lipoprotein (HDL) cholesterol, under 37 mg/gL (.95 mmol/L), compared to those with high density lipoprotein (HDL) cholesterol levels over 55 mg/dL (1.4 mmol/L).

The data from the study reveals that low cholesterol levels are associated with a higher risk of Alzheimer's.

Alzheimer’s patients have significantly reduced levels of cholesterol and fats in the brain

This study was published in Alzheimer Disease and Associated Disorders 1998 Sep;12(3):198-203

Study title and authors:
Reduced levels of cholesterol, phospholipids, and fatty acids in cerebrospinal fluid of Alzheimer disease patients are not related to apolipoprotein E4.

Mulder M, Ravid R, Swaab DF, de Kloet ER, Haasdijk ED, Julk J, van der Boom JJ, Havekes LM.
Gaubius Laboratory, TNO-PG, Leiden, The Netherlands.

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/9772023

The study compared levels of cholesterol and fats in cerebrospinal fluid (cerebrospinal fluid is found in the brain and spinal canal) in Alzheimers patients and subjects without Alzheimers. The study assessed the brain tissue at postmortem in 30 Alzheimers cases and 31 age-matched control patients.

The study found:
(a) Cholesterol levels in the cerebrospinal fluid of patients without alzheimer's was 55% higher than in patients with Alzheimer's.
(b) Fatty acid levels (fat molecules) in the cerebrospinal fluid of patients without alzheimer's was 522% higher than in patients with Alzheimer's.
(c) Phospholipid levels (phospholipids contain two molecules of fat and are a major component of cell membranes) in the cerebrospinal fluid of patients without alzheimer's was 1650% higher than in patients with Alzheimer's.

The results of the study show that Alzheimer’s patients have significantly reduced levels of cholesterol and fats in the cerebrospinal fluid.