Alzheimer’s is a devastating disease whose incidence is on the rise globally. ApoE-4, a particular allele of the apolipoprotein apoE, is a known risk factor. Since apoE plays a critical role in the transport of cholesterol and fats to the brain, it has been hypothesized that insufficient fat and cholesterol in the brain play a critical role in the disease process. Recently, it was found that Alzheimer’s patients have only a fraction of the concentration of free fatty acids in the cerebrospinal fluid compared to healthy individuals suggesting that a low-fat diet may increase the risk of Alzheimer’s disease.
Studies have also shown that cholesterol is pervasive in the brain and plays a role in synaptic transmission and the related health of the myelin sheath coating nerve fibers. In this way, an extremely high-fat diet has been found to improve cognitive ability in Alzheimer’s patients. Now, a study from researchers at SUNY Downstate and the University of Gothenburg has shown that women with the APOEe4 gene variant experience a steeper decline in body mass index (BMI) after age 70 whether they go on to develop dementia or not. The team state that their findings add to a sturdy body of evidence suggesting that body weight change may aid in the diagnosis and management of Alzheimer’s disease. The study is published in the Journal of Alzheimer’s Disease.
Previous studies show that from middle age to approximately 70 years of age, adults gain weight on average. After age 70, weight tends to decrease on average. This weight change over the life course may be due to aging, changes in body composition, energy metabolism, sensory changes, and changes in the brain related to regulation of basic body processes. However, among adults who develop dementia the life course of BMI differs. Research has shown that being more overweight or obese in mid-life may increase risk for dementia. Past findings also show that after age 70 years adults who develop dementia may lose weight more rapidly compared to those who do not develop dementia and that if one is a bit more overweight in later life, it is protective for both dementia and death.
Earlier studies from the lab showed that development of dementia is associated with specific pattern of BMI change over the life course. Women who developed dementia after age 65 tended to gain BMI at a slower rate during middle age. The current shows that those with the APOEe4 allele experience greater or steeper decline in BMI after age 70 years, whether they develop dementia or not
The current study followed 1462 Swedish women for almost 40 years from 38-60 years of age. The group tracked the participant’s BMI in relation to dementia onset, and considered the potential role of the APOEe4 allele, a known risk factor for late-onset dementia.
Results show that on average, patients with Alzheimer’s disease with the APOEe4 allele lost between 2.1 and 5.9 kg whereas noncarriers gained between 2.6 and 5 kg, after controlling for diabetes and exercise. Data findings show that when men and women were analyzed separately, weight loss was observed only in those women with Alzheimer’s disease and the APOEe4 allele. The group note that clinically significant weight loss, defined as loss of more than 5% of body weight, occurred more frequently in both patients with Alzheimer’s disease and healthy individuals carrying the APOEe4 allele.
The team surmise that body weight change and BMI are easily measured, noninvasive potential prognostic indicators for dementia. For the future, the researchers state that better understanding of a relatively common risk allele such as APOEe4 and how it modifies risk may aid in the understanding of how to better intervene among those at highest risk for dementia.
Source: SUNY Downstate Medical Center
