Sage oil, particularly from Salvia officinalis and Salvia lavandulaefolia, has been investigated for its effects on cognitive function, with a focus on the cholinergic system that involves acetylcholine. Several clinical and preclinical studies suggest that sage extracts and essential oils can inhibit acetylcholinesterase, the enzyme responsible for breaking down acetylcholine in the brain. By inhibiting this enzyme, sage oil may help maintain higher levels of acetylcholine, a neurotransmitter important for memory and learning and often deficient in neurodegenerative conditions such as Alzheimer's disease.

Human trials, though small in size, have shown that acute administration of sage essential oil can improve memory and attention in healthy adults and individuals with mild to moderate Alzheimer's disease. For example, a 2003 double-blind, placebo-controlled study published in "Pharmacological Biochemical Behavior" found significant cognitive improvements in Alzheimer’s patients treated with Salvia officinalis extract compared to placebo. Additional in vitro and animal studies support sage’s acetylcholinesterase-inhibitory effects.

However, most of the research uses extracts or oral preparations, and the evidence base is limited by small sample sizes and short study durations. There is scientific plausibility and preliminary evidence, but more robust clinical trials are needed to confirm efficacy.