Antioxidant supplements ineffective against Alzheimer’s disease
MedWire News: Alzheimer's disease (AD) biomarkers appear uninfluenced by a dietary intake of antioxidant supplements, according to research published in the Archives of Neurology.
Adding an antioxidant supplement containing vitamin E, vitamin C, and α-lipoic acid (E/C/ALA), or coenzyme Q (CoQ) to the diet was shown to have no effect on cerebrospinal fluid (CSF) biomarkers linked to AD.
Douglas Galasko (University of California, San Diego, USA) and colleagues explain that observational studies had suggested that an antioxidant-rich diet may reduce the risk for AD, but that randomized clinical trials had produced mixed results. They therefore aimed to resolve the uncertainty surrounding antioxidants and AD by investigating their effect on known AD-related CSF biomarkers.
"We hypothesized that if antioxidant treatment affects key pathogenic mechanisms in patients with AD, this would be reflected by [CSF] biomarker changes," write Galasko and team.
The study participants were randomly assigned to receive one of three treatments for 16 weeks: vitamin E 800 IU/day plus vitamin C 500 mg/day plus ALA 900 mg/day, or CoQ 400 mg three times per day, or placebo. The changes in CSF biomarkers related to AD and oxidative stress, cognition, and function were then recorded over the 16-week period.
The final analysis included data from 66 patients with mild to moderate AD: 26 who received E/C/ALA treatment, 20 who received CoQ, and 18 who received placebo.
The researchers report that the treatments were well-tolerated but that there was an accelerated decline in cognition, as assessed using the Mini-Mental State Examination (MMSE) in the E/C/ALA group, which they highlight as a potential safety concern.
No significant difference was found in the changes in the levels of the CSF AD biomarkers Aβ42, tau, and P-tau181 between the three groups.
The researchers report a 19% decrease in the oxidative stress biomarker CSF F2-isoprostane levels in the E/C/ALA group, which remained unchanged in the other groups, but they stress safety concerns with the treatment.
"It is unclear whether the relatively small reduction in CSF F2-isoprostane level seen in this study may lead to clinical benefits in AD. The more rapid MMSE score decline raises a caution and indicates that cognitive performance would need to be assessed if a longer-term clinical trial of this antioxidant combination is considered," Galasko and co-workers conclude.
They also state that while CoQ was well-tolerated, their results "do not support further clinical trial development of CoQ in AD," as it was found to have no effect on oxidative stress or neurodegeneration.
By Chloe McIvor