(HealthDay News) – Elevated cerebral β-amyloid (Aβ) load is associated with greater decline in episodic and working memory for healthy and cognitively normal older adults over an 18-month period, with a larger effect than that seen for the APOE ε4 allele, according to research published in the Oct. 16 issue of Neurology.

Yen Ying Lim, M.Psych., of the University of Melbourne in Parkville, Australia, and colleagues conducted an 18-month prospective study involving 141 healthy and cognitively normal older adults to assess the significance of Aβ load, determined using positron emission tomography, on cognitive changes over time. Participants underwent APOE genotyping and cognitive assessments as part of their baseline evaluation and 18 months later.

The researchers found that, at 18 months, compared to those with low cerebral Aβ, individuals with high cerebral Aβ exhibited significantly greater decline in working memory and verbal and visual episodic memory, after adjustment for baseline cognitive function. At the 18-month assessment, APOE ε4 carriers had a significantly greater decline in visual memory compared with non-carriers. There was no interaction observed between APOE ε4 and cerebral Aβ load for any measure of cognitive function.

“In this prospective study of healthy older adults, high cerebral Aβ load was associated with greater decline in episodic and working memory over 18 months,” the authors write. “The APOE ε4 genotype was also associated with a decline in visual memory, although the effect was less than that observed for cerebral Aβ load.”

Several authors disclosed financial ties to the pharmaceutical industry and to CogState Ltd., which produced the tests used in the study.

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