(HealthDay News) – For older adults, the lipidation state of β-amyloid (Aβ) peptides is associated with cognitive impairment and APOE genotype, and can be modulated by diet, according to a study published online June 17 in JAMA Neurology.

Angela J. Hanson, MD, from the University of Washington School of Medicine in Seattle, and colleagues characterized the lipidation states of Aβ peptides and apolipoprotein E in the cerebrospinal fluid in 20 older adults with normal cognition (mean age, 69 years) and 27 with amnestic mild cognitive impairment (mean age, 67 years), after a dietary intervention. Participants were randomized to a diet high in saturated fat content with a high glycemic index (High) or a diet low in saturated fat content and with a low glycemic index (Low).

The researchers found that adults with mild cognitive impairment had significantly greater baseline levels of lipid-depleted (LD) Aβ. In adults with mild cognitive impairment and the ε4 allele, these findings were magnified, with higher LD apolipoprotein E levels, regardless of cognitive diagnosis. There was a decrease in LD Aβ levels with the Low diet, and an increase with the High diet. There was a negative correlation between changes in LD Aβ levels with the Low diet and changes in the cerebrospinal fluid levels of insulin.

“The lipidation states of apolipoproteins and Aβ peptides in the brain differ depending on APOE genotype and cognitive diagnosis. Concentrations can be modulated by diet,” the authors write. “These findings may provide insight into the mechanisms through which apolipoprotein E4 and unhealthy diets impart risk for developing Alzheimer’s disease.”

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