Improvement of memory recall by quercetin in rodent contextual fear conditioning and human early-stage Alzheimer’s disease patients

Patients with Alzheimer’s disease (AD) experience a wide array of cognitive deficits, which typically include the impairment of explicit memory. In previous studies, the authors reported that a flavonoid, quercetin, reduces the expression of ATF4 and delays memory deterioration in an early-stage AD mouse model. In the present study, the effects of long-term quercetin intake on memory recall were assessed using contextual fear conditioning in aged wild-type mice. In addition, the present study examined whether memory recall was affected by the intake of quercetin-rich onion (a new cultivar of hybrid onion ‘Quergold’) powder in early-stage AD patients. In-vivo analysis indicated that memory recall was enhanced in aged mice fed a quercetin-containing diet. Memory recall in early-stage AD patients, determined using the Revised Hasegawa Dementia Scale, was significantly improved by the intake of quercetin-rich onion (Quergold) powder for 4 weeks compared with the intake of control onion (‘Mashiro’ white onion) powder. These results indicate that quercetin might influence memory recall.