Home›Nutrition & Obesity Medicine› Antioxidants improve oxidative stress and neuropsychiatric symptoms but not cognition in Alzheimer's
Antioxidants improve oxidative stress and neuropsychiatric symptoms but not cognition in Alzheimer'sAntioxidants May Improve Neuropsychiatric Symptoms in Alzheimer's Patients
Frontiers in MedicinePublished June 24, 2026DOI ↗Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease
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Key Takeaway
Consider antioxidants for symptom relief in Alzheimer's but not as disease-modifying therapy.
This meta-analysis of 23 randomized controlled trials involving 10,537 patients with Alzheimer's disease (AD) evaluated the effects of antioxidants (including vitamins, polyphenols, and other antioxidant preparations) on cognitive function, oxidative stress biomarkers, neuropsychiatric symptoms, daily living abilities, neuroimaging measures, and fluid biomarkers.
Key findings: Antioxidant supplementation significantly improved the oxidative stress marker urinary 8-iso-prostaglandin F2α (SMD 0.75, 95% CI 0.12–1.38) and reduced neuropsychiatric symptoms as measured by the NPI (SMD -0.85, 95% CI -1.13 to -0.57). However, no significant benefit was observed for cognitive function on the ADAS-Cog (SMD 0.01, 95% CI -0.21 to 0.23) or MMSE (SMD 0.19, 95% CI -0.17 to 0.56). Fluid biomarkers (Aβ42, p-tau, t-tau) remained unchanged.
The authors note high heterogeneity across multiple outcomes due to variability in antioxidant types, dosages, and patient populations. Adverse events were not reported. The findings suggest antioxidants may improve certain biomarkers and symptoms but do not consistently enhance core cognitive function or alter AD-specific pathology. They are not supported as disease-modifying therapies.
How this fits prior evidence
This meta-analysis extends prior coverage of Alzheimer's disease interventions by showing that antioxidants, unlike single-target amyloid-beta and tau therapies, may improve oxidative stress markers and neuropsychiatric symptoms. However, consistent with prior findings that amyloid-beta and tau therapies lack clear clinical benefit, antioxidants also failed to improve cognitive function or alter fluid biomarkers. The results contrast with the strong association between periodontal disease and Alzheimer's (OR 2.67) by suggesting a more limited role for antioxidant supplementation.
This review looked at 10,537 people with Alzheimer's disease across 23 different clinical trials. Researchers analyzed how various antioxidants, including vitamins and polyphenols, affected the condition. The goal was to see if these supplements could improve cognitive function or change biological markers of the disease.
The results showed that antioxidant treatments did not significantly improve core memory scores or other standard measures of cognitive function. However, there were significant improvements in neuropsychiatric symptoms and certain markers of oxidative stress. Other biological markers related to Alzheimer's pathology remained unchanged during the study period.
Because different types of antioxidants and dosages were used across many studies, the results are varied. It is important to note that while some symptoms improved, these supplements are not currently considered a way to change the underlying progression of Alzheimer's disease. Patients should talk to their doctor before starting any new supplement routine.
What this means for you:
Antioxidants may help with certain behaviors in Alzheimer's but do not improve core memory or cognitive scores.
Common questions
Can antioxidants improve memory in people with Alzheimer's?
The study found that antioxidant treatments did not provide a significant benefit for standard cognitive function measures like ADAS-Cog or MMSE. While these supplements are being studied, they do not currently show consistent results in improving core memory skills for those living with Alzheimer's disease.
What specific symptoms might antioxidants help with?
The analysis showed that antioxidant treatments significantly improved neuropsychiatric symptoms. They also showed a significant improvement in oxidative stress markers, specifically urinary 8-iso-prostaglandin F2. These findings suggest some benefits for behavior and stress markers rather than core memory.
Are antioxidants a way to slow down Alzheimer's disease?
The evidence does not support using antioxidants as a disease-modifying therapy. While they may help with certain symptoms, the study showed that fluid biomarkers related to Alzheimer's pathology remained unchanged. You should consult a healthcare provider regarding specific treatment plans.
BackgroundOxidative stress plays a central role in the pathogenesis of Alzheimer's disease (AD), contributing to neuronal damage, amyloid-beta aggregation, tau hyperphosphorylation, and neuroinflammation. Although antioxidants have been proposed as potential therapeutic agents, clinical trials have yielded inconsistent results.ObjectiveTo systematically evaluate the efficacy of various antioxidants—including vitamins, polyphenols, and other antioxidant preparations—on cognitive function, oxidative stress biomarkers, neuropsychiatric symptoms, and disease progression in patients with AD.MethodsWe conducted a systematic search of PubMed, Embase, and Web of Science from inception to October 2, 2025, for randomized controlled trials (RCTs) evaluating antioxidant interventions in AD patients. Study selection, data extraction, and quality assessment were performed independently by multiple reviewers. Meta-analyses were conducted using random-effects models where significant heterogeneity was present (I2 > 50%). Outcomes included cognitive function scales (e.g., ADAS-Cog, MMSE), oxidative stress markers, neuropsychiatric symptoms, daily living abilities, neuroimaging measures, and fluid biomarkers.ResultsA total of 23 RCTs comprising 10,537 participants were included. Antioxidants showed mixed effects across outcomes. While certain oxidative stress markers (urinary 8-iso-prostaglandin F2α: SMD 0.75, 95% CI 0.12–1.38) and neuropsychiatric symptoms (NPI: SMD −0.85, 95% CI −1.13 to −0.57) improved significantly, core cognitive endpoints such as ADAS-Cog (SMD 0.01, 95% CI −0.21 to 0.23) and MMSE (SMD 0.19, 95% CI −0.17 to 0.56) showed no significant benefit. Fluid biomarkers including Aβ42, p-tau, and t-tau remained unchanged. High heterogeneity was observed across multiple outcomes, reflecting variability in antioxidant types, dosages, and patient populations.ConclusionAntioxidants may improve certain oxidative stress markers and neuropsychiatric symptoms in AD patients but do not consistently enhance core cognitive function or alter AD-specific pathology. Current evidence does not support antioxidants as disease-modifying therapies, though they may serve as adjunctive interventions to improve quality of life and behavioral symptoms. Well-designed RCTs with longer follow-up and standardized protocols are warranted.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD420261321660, identifier: CRD420261321660.
