Effects of saffron (Crocus sativus L.) on cognitive function. A systematic review of RCTs.

Improvement of cognitive function may be desirable for healthy individuals and clinically beneficial for those with cognitive impairment such as from Alzheimer's disease (AD) or mild cognitive impairment (MCI). The aim of this systematic review is to investigate the cognitive effects of oral saffron intake, in patients with MCI/AD and/or in non-demented individuals, by following the PRISMA guidelines. We performed a literature search on MedLine, Cochrane library, and ClinicalTrials.gov to identify randomized controlled trials (RCTs) investigating the effects of oral saffron administration in patients with MCI/AD and/or in non-demented individuals. Five studies (enrolling 325 individuals) met our inclusion criteria. Four studies included patients with MCI/AD, and one study included cognitively normal individuals. Saffron was well-tolerated in all groups. Regarding cognitively impaired patients, scores on Alzheimer's Disease Assessment Scale-cognitive subscale or Mini mental state examination were significantly better when saffron was compared with placebo and did not differ significantly when saffron was compared with donepezil or memantine. Saffron effects on functional status were similar with its effects on cognition. Saffron was shown to be equally effective to common symptomatic drugs for MCI/AD and resulted in no difference in the incidence of side effects, when compared with placebo or drugs. The promising results should be seen cautiously, since the evidence was derived from studies with potentially high risk of bias (ROB). RCTs with larger sample sizes and low ROB are required to definitively assess the potential role of saffron as an MCI/AD treatment.