Effect of extra virgin olive oil on mild cognitive impairment and dementia in older adults: a systematic review and meta-analysis of clinical trials

Abstract

Background: Extra virgin olive oil (EVOO) has been investigated as a potential dietary strategy for

cognitive health due to its neuroprotective properties. This systematic review and meta-analysis eval- uated the potential impact of EVOO as an adjunct intervention for older adults within the spectrum of

mild cognitive impairment (MCI) and dementia. Methods: A comprehensive search was conducted across nine databases for randomized controlled

trials (RCTs) that compared EVOO to a control group in older adults with MCI and/or dementia. Sta- tistical analysis used random-effects models to determine mean differences (MD) and standardized

mean differences (SMD), with the risk of bias assessed using Cochrane Risk of Bias (RoB2) and quality of evidence assessed using the GRADE tool.

Results: Five studies met the inclusion criteria (n = 747 participants). Meta-analysis showed a signifi- cant, albeit preliminary, improvement in global cognitive function scores with EVOO consumption,

including the Mini-Mental State Examination (MD = 0.42, 95 % CI = 0.15–0.68; p = 0.002), Clock Drawing Test (MD = 0.47, 95 % CI = 0.15–0.78; p = 0.004), and the Alzheimer’s Disease Assessment Scale-Cognitive Subscale (MD = 1.45, 95 % CI = 0.39–2.51; p = 0.007). The overall pooled effect was SMD = 0.29 (95 % CI = 0.18–0.41; p < 0.0001). However, the certainty of evidence was rated as low according to GRADE, and the small number of trials limits the robustness of these findings. Conclusion: The findings suggest a potential association between EVOO consumption and improvement in global cognitive function among older adults within MCI and dementia. Due to the low certainty of evidence, small sample sizes, and the lack of established clinical significance, these results should be interpreted with caution, and further larger-scale RCTs are required.