title: Effect of green tea on reward learning in healthy individuals: a randomized, double-blind, placebo-controlled pilot study.
abstract: BACKGROUND
  Both clinical and preclinical studies revealed that regular intake of green tea reduced the prevalence of depressive symptoms, as well as produced antidepressant-like effects in rodents. Evidence proposed that disturbed reward learning has been associated with the development of anhedonia, a core symptom of depression. However, the relationship between green tea and reward learning is poorly investigated. Our goal was to test whether chronic treatment with green tea in healthy subjects affects the process of reward learning and subsequently regulates the depressive symptoms.
  
  
  METHODS
  Seventy-four healthy subjects participated in a double-blind, randomized placebo-controlled study with oral administration of green tea or placebo for 5weeks. We used the monetary incentive delay task to evaluate the reward learning by measurement of the response to reward trial or no-reward trial. We compared the reaction time of reward responsiveness between green tea and placebo treatment. Furthermore, we selected Montgomery-Asberg depression rating scale (MADRS) and 17-item Hamilton Rating Scale for Depression (HRSD-17) to estimate the depressive symptoms in these two groups.
  
  
  RESULTS
  The results showed chronic treatment of green tea increased reward learning compared with placebo by decreasing the reaction time in monetary incentive delay task. Moreover, participants treated with green tea showed reduced scores measured in MADRS and HRSD-17 compared with participants treated with placebo.
  
  
  CONCLUSIONS
  Our findings reveal that chronic green tea increased the reward learning and prevented the depressive symptoms. These results also raised the possibility that supplementary administration of green tea might reverse the development of depression through normalization of the reward function.
authors.affiliation: Department of Pediatric Surgery, Qilu Hospital, Shandong University, 107 Wenhuaxi Road, Jinan, Shandong 250012, China.
authors.forename: Qiangye
authors.initials: Q
authors.lastname: Zhang
authors.forename: Hongchao
authors.initials: H
authors.lastname: Yang
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Aiwu
authors.initials: A
authors.lastname: Li
authors.forename: Wentong
authors.initials: W
authors.lastname: Zhang
authors.forename: Xinhai
authors.initials: X
authors.lastname: Cui
authors.forename: Kelai
authors.initials: K
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000928:Antidepressive Agents / Q000008:administration & dosage*; D003863:Depression / Q000453:epidemiology / Q000517:prevention & control; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007858:Learning; D008297:Male; D010865:Pilot Projects; D010936:Plant Extracts / Q000008:administration & dosage*; D015995:Prevalence; D012201:Reward; D013662:Tea / Q000737:chemistry*; D055815:Young Adult
chemical_list: D000928:Antidepressive Agents; D010936:Plant Extracts; D013662:Tea