IMPORTANCE:
Observational
data have suggested that high dietary intake of saturated fat and low
intake of vegetables may be associated with increased risk of Alzheimer
disease.
OBJECTIVE:
To test the effects of oral supplementation with nutrients on cognitive function.
DESIGN, SETTING, AND PARTICIPANTS:
In
a double-masked randomized clinical trial (the Age-Related Eye Disease
Study 2 [AREDS2]), retinal specialists in 82 US academic and community
medical centers enrolled and observed participants who were at risk for
developing late age-related macular degeneration (AMD) from October 2006
to December 2012. In addition to annual eye examinations, several
validated cognitive function tests were administered via telephone by
trained personnel at baseline and every 2 years during the 5-year study.
INTERVENTIONS:
Long-chain
polyunsaturated fatty acids (LCPUFAs) (1 g) and/or lutein (10
mg)/zeaxanthin (2 mg) vs placebo were tested in a factorial design. All
participants were also given varying combinations of vitamins C, E, beta
carotene, and zinc.
MAIN OUTCOMES AND MEASURES:
The
main outcome was the yearly change in composite scores determined from a
battery of cognitive function tests from baseline. The analyses, which
were adjusted for baseline age, sex, race, history of hypertension,
education, cognitive score, and depression score, evaluated the
differences in the composite score between the treated vs untreated
groups. The composite score provided an overall score for the battery,
ranging from -22 to 17, with higher scores representing better function.
RESULTS:
A
total of 89% (3741/4203) of AREDS2 participants consented to the
ancillary cognitive function study and 93.6% (3501/3741) underwent
cognitive function testing. The mean (SD) age of the participants was
72.7 (7.7) years and 57.5% were women.
There were no statistically
significant differences in change of scores for participants randomized
to receive supplements vs those who were not. The yearly change in the
composite cognitive function score was -0.19 (99% CI, -0.25 to -0.13)
for participants randomized to receive LCPUFAs vs -0.18 (99% CI, -0.24
to -0.12) for those randomized to no LCPUFAs (difference in yearly
change, -0.03 [99% CI, -0.20 to 0.13]; P = .63). Similarly, the yearly
change in the composite cognitive function score was -0.18 (99% CI,
-0.24 to -0.11) for participants randomized to receive lutein/zeaxanthin
vs -0.19 (99% CI, -0.25 to -0.13) for those randomized to not receive
lutein/zeaxanthin (difference in yearly change, 0.03 [99% CI, -0.14 to
0.19]; P = .66). Analyses were also conducted to assess for potential
interactions between LCPUFAs and lutein/zeaxanthin and none were found
to be significant.
CONCLUSIONS AND RELEVANCE:
Among
older persons with AMD, oral supplementation with LCPUFAs or
lutein/zeaxanthin
had no statistically significant effect on cognitive
function.
TRIAL REGISTRATION:
clinicaltrials.gov Identifier:
NCT00345176.
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