Yizhi capsule for vascular dementia

BACKGROUND: Vascular dementia (VD) is a syndrome or diagnosis that has different causes and clinical manifestations relating to several different vascular mechanisms and changes in the brain. Some traditional Chinese herbal medicines were developed for treating VD. Yizhi capsule is one such herbal concoction which is reported to improve clinical symptoms significantly. The efficacy and adverse effects of Yizhi capsule need to be reviewed systematically and assessed critically to inform clinical practice and guide the continued search for new treatment regimens. OBJECTIVES: To assess the effectiveness and possible adverse events of 'Yizhi capsule' in treating vascular dementia. SEARCH STRATEGY: The Cochrane Dementia and Cognitive Improvement Group's Specialised Register, The Cochrane Library, EMBASE, MEDLINE, PsycINFO, CONAHL, LILACS, clinical trial registries and grey literature sources were searched on 8 January 2009 using the terms yi-zhi, "yi zhi" and yizhi. In addition the review authors searched a variety of Chinese databases. SELECTION CRITERIA: Randomised, placebo controlled trials in which patients with vascular dementia were treated with 'Yizhi capsule' were included. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We telephoned study authors for missing information as to whether treatment allocation was randomised and other methodological details. MAIN RESULTS: No studies were found that met the inclusion criteria. We identified nine references to trials which included the term 'Yizhi capsule' in the description of the interventions. Two study authors were contacted by telephone and we discovered that the allocation methods they had used were not actually randomised. Four references were describing the same study. Three studies were excluded because 'positive drugs' were used as a control. AUTHORS' CONCLUSIONS: There is no evidence from randomised controlled trials to support or proscribe against the use of 'Yizhi capsule' as a treatment for vascular dementia.