Rosemary (Rosmarinus officinalis) extract, including proprietary preparations like "Rosemary antioxidant S-32," has been the subject of several preclinical and a few human studies exploring its neuroprotective and cognitive-enhancing effects. The primary rationale for its use in dementia support relates to the presence of antioxidant compounds such as carnosic acid and rosmarinic acid, which have demonstrated the ability to reduce oxidative stress and inhibit acetylcholinesterase activity in laboratory models. Since oxidative stress and cholinergic dysfunction are implicated in the pathogenesis of Alzheimer's disease and other dementias, these effects are considered potentially beneficial.

Animal studies have reported that rosemary extract can improve memory and protect against neurotoxicity. Some small clinical studies and pilot trials have suggested mild cognitive benefits or improvements in memory performance with rosemary supplementation or aromatherapy, but these studies are generally limited by small sample sizes, short durations, and methodological weaknesses. There is no high-quality, large-scale clinical evidence demonstrating that rosemary extract—including S-32—can prevent, slow, or treat dementia in humans.

In summary, while there is a scientific rationale and preliminary supportive evidence from in vitro and animal research, the clinical evidence for rosemary antioxidant S-32 in dementia is weak and not yet conclusive. Its use is not established in clinical guidelines, and further well-designed human studies are needed.