Nigella seed (Nigella sativa), also known as black seed or black cumin, has been traditionally used in various cultures for its purported health benefits. In recent years, there has been growing interest in its potential for supporting cognitive function and treating neurodegenerative diseases, including Alzheimer's disease. The scientific basis for its use lies primarily in preclinical studies. Research has identified thymoquinone, a major active compound in Nigella sativa, as having neuroprotective, antioxidant, and anti-inflammatory properties. Animal models of Alzheimer's disease have shown that administration of Nigella sativa extract or thymoquinone can reduce oxidative stress, decrease neuroinflammation, and improve memory performance. Some studies suggest that these effects may be due to inhibition of acetylcholinesterase and the modulation of amyloid-beta plaque formation, both of which are key factors in Alzheimer's pathology.

However, human clinical trials are very limited. Only a few small, preliminary studies have investigated Nigella sativa supplementation in older adults or those with mild cognitive impairment, with some reporting modest improvements in memory and cognition. No large-scale, high-quality randomized controlled trials have been published to confirm its efficacy in Alzheimer's patients specifically. As such, while there is early scientific evidence indicating possible benefits, the strength of the evidence remains low and primarily preclinical. More rigorous human studies are necessary to determine its true therapeutic potential for Alzheimer's disease.