Effects of a Saffron Alcoholic Extract on Visual Short-Term Memory in Humans: a Psychophysical Study

Abstract

The effects of an extract from saffron (Crocus sativus L.) on visual short-term memory (STM) were examined in 20 volunteers. The extract was obtained from saffron petals using 100% ethylic alcohol, concentrated by vacuum evaporation, dried, and encapsulated (30 mg per capsula). Ten participants received the extract each day for three weeks, while other 10 subjects received encapsulated placebo. Then, the contrast sensitivity of a subject was estimated; sinusoidal grating patches with different contrast levels (0 – 100%) were used (experiment 1). In experiment 2, the retention of STM was assessed in two-force choice tests, using a delayed match to sample paradigm. In experiment 3, the n-back memory test with different interstimulus intervals (up to 14 sec) was used. It was found that subjects after medication with the saffron extract demonstrated better correct memorizing of the preceding visual stimuli (from two to five). At the same time, extract medication somewhat improved retention of visual STM, but only for several intermediate interstimulus intervals, and the effect was not very remarkable. Our findings emphasize the expedience to research the effects of physiologically active dietary constituents in humans.