Mix Joseph A, Crews W David
Department of Health Sciences, Liberty University, Lynchburg, Virginia 24502, USA.
Hum Psychopharmacol. 2002 Aug;17(6):267-77. doi: 10.1002/hup.412.
There appears to be an absence of large-scaled clinical trials that have examined the efficacy of Ginkgo biloba extract on the neuropsychological functioning of cognitively intact older adults. The importance of such clinical research appears paramount in light of the plethora of products containing Ginkgo biloba that are currently being widely marketed to predominantly cognitively intact adults with claims of enhanced cognitive performances. The purpose of this research was to conduct the first known, large-scaled clinical trial of the efficacy of Ginkgo biloba extract (EGb 761) on the neuropsychological functioning of cognitively intact older adults. Two hundred and sixty-two community-dwelling volunteers (both male and female) 60 years of age and older, who reported no history of dementia or significant neurocognitive impairments and obtained Mini-Mental State Examination total scores of at least 26, were examined via a 6-week, randomized, double-blind, fixed-dose, placebo-controlled, parallel-group, clinical trial. Participants were randomly assigned to receive either Ginkgo biloba extract EGb 761(n = 131; 180 mg/day) or placebo (n = 131) for 6 weeks. Efficacy measures consisted of participants' raw change in performance scores from pretreatment baseline to those obtained just prior to termination of treatment on the following standardized neuropsychological measures: Selective Reminding Test (SRT), Wechsler Adult Intelligence Scale-III Block Design (WAIS-III BD) and Digit Symbol-Coding (WAIS-III DS) subtests, and the Wechsler Memory Scale-III Faces I (WMS-III FI) and Faces II (WMS-III FII) subtests. A subjective Follow-up Self-report Questionnaire was also administered to participants just prior to termination of the treatment phase. Analyses of covariance indicated that cognitively intact participants who received 180 mg of EGb 761 daily for 6 weeks exhibited significantly more improvement on SRT tasks involving delayed (30 min) free recall (p < 0.04) and recognition (p < 0.01) of noncontextual, auditory-verbal material, compared with the placebo controls. The EGb 761 group also demonstrated significantly greater improvement on the WMS-III FII subtest assessing delayed (30 min) recognition (p < 0.025) of visual material (i.e. human faces), compared with the placebo group. However, based on the significant difference (p < 0.03) found between the two groups' pretreatment baseline scores on the WMS-III FII, this result should be interpreted with caution. An examination of the participants' subjective ratings of their overall abilities to remember by treatment end on the Follow-up Self-report Questionnaire also revealed that significantly more (p = 0.05) older adults in the EGb 761 group rated their overall abilities to remember by treatment end as 'improved' compared with the placebo controls. Overall, the results from both objective, standardized, neuropsychological tests and a subjective, follow-up self-report questionnaire provided complementary evidence of the potential efficacy of Ginkgo biloba EGb 761 in enhancing certain neuropsychological/memory processes of cognitively intact older adults, 60 years of age and over.
目前似乎缺乏大规模临床试验来检验银杏叶提取物对认知功能完好的老年人神经心理功能的疗效。鉴于目前大量含有银杏叶的产品正广泛销售给认知功能完好的成年人,并宣称具有增强认知表现的功效,此类临床研究的重要性显得至关重要。本研究的目的是针对银杏叶提取物(EGb 761)对认知功能完好的老年人神经心理功能的疗效开展首次已知的大规模临床试验。通过一项为期6周的随机、双盲、固定剂量、安慰剂对照、平行组临床试验,对262名年龄在60岁及以上的社区居住志愿者(男女皆有)进行了检查,这些志愿者报告无痴呆病史或显著神经认知障碍,且简易精神状态检查表总分至少为26分。参与者被随机分配接受银杏叶提取物EGb 761(n = 131;180毫克/天)或安慰剂(n = 131),为期6周。疗效测量包括参与者在以下标准化神经心理测量中从治疗前基线到治疗即将结束前获得的表现分数的原始变化:选择性提醒测试(SRT)、韦氏成人智力量表第三版积木设计(WAIS - III BD)和数字符号编码(WAIS - III DS)子测试,以及韦氏记忆量表第三版面孔I(WMS - III FI)和面孔II(WMS - III FII)子测试。在治疗阶段即将结束前,还向参与者发放了一份主观的随访自我报告问卷。协方差分析表明,与安慰剂对照组相比,每天接受180毫克EGb 761、为期6周的认知功能完好的参与者在涉及延迟(30分钟)自由回忆(p < 0.04)和对非情境性听觉语言材料的识别(p < 0.01)的SRT任务上表现出显著更大的改善。与安慰剂组相比,EGb 761组在评估视觉材料(即人脸)延迟(30分钟)识别(p < 0.025)的WMS - III FII子测试中也表现出显著更大的改善。然而,基于两组在WMS - III FII上治疗前基线分数之间发现的显著差异(p < 0.03),这一结果应谨慎解释。对参与者在随访自我报告问卷中对治疗结束时总体记忆能力的主观评分进行检查还发现,与安慰剂对照组相比,EGb 761组中显著更多(p = 0.05)的老年人将他们治疗结束时的总体记忆能力评为“有所改善”。总体而言,客观、标准化的神经心理测试和主观的随访自我报告问卷的结果都为银杏叶EGb 761在增强60岁及以上认知功能完好的老年人某些神经心理/记忆过程方面的潜在疗效提供了补充证据。