A Promising Compound Herbal Treatment for Vascular Dementia
Large human clinical trials are ongoing.
Posted Aug 09, 2019
Vascular dementia: a debilitating neurodegenerative disorder that has no effective treatment
Currently there are no effective treatments of vascular dementia, a condition in which a compromise of blood supply to the brain caused by stroke (i.e. cerebrovascular accidents) results in step-wise cognitive decline frequently associated with behavioral changes and neurologic impairment.
Vascular dementia is the most common form of dementia following Alzheimer's disease. As many as one quarter of individuals develop dementia within one year following stroke, and roughly 2% of individuals over age 70 are afflicted by this condition globally.
In this blog post I review promising emerging findings of placebo-controlled trials on a Chinese herbal formula that is being investigated as a potential treatment of vascular dementia.
Research focus on Chinese compound herbal formulas
Numerous placebo-controlled studies have investigated Chinese herbal formulas as potential treatments of vascular dementia. Many early studies were small and methodologically flawed, hence their findings are largely inconclusive. However several large high quality studies are yielding promising results.
A systematic review of studies on compound herbal formulas in vascular dementia found that the majority of formulas investigated resulted in significantly greater improvements in cognitive functioning compared to conventionally used medicines or placebo (Man et al 2012).
Four studies in which herbal medicines were combined with conventional medicines such as cholinesterase inhibitors reported better cognitive functioning compared to conventional medicines alone, however the significance of findings was limited by serious methodological flaws in study design.
A separate meta-analysis (Gong 2015) (see full reference below) included 24 randomized clinical trials (all conducted in China) on individuals diagnosed with vascular dementia. In a subgroup analyses, complex herbal interventions significantly enhanced cognitive function when compared to individuals receiving piracetam (in 10 studies) or placebo (in 3 studies). Individuals receiving herbal medicine experienced greater improvements in activities of daily living compared to those treated with piracetam. However, the significance of findings of studies included in the review was also limited by methodological flaws.
SLT: a promising compound herbal formula for vascular dementia
In response to research challenges posed by studies on compound herbal formulas, for over a decade a collaborative effort has been ongoing between the Academy of Chinese Medical Sciences and Western Sydney University to develop a standardized compound herbal formula for the treating vascular dementia.
The formula, called SLT, contains standardized preparations of Ginkgo biloba (ginkgo), Panax ginseng (ginseng), and Crocus sativus (saffron). Preclinical trials demonstrated significant improvement in learning and memory, markers of neuropathology and antioxidant activity in animal models of dementia. Cumulative findings from preclinical trials have also demonstrated cerebrovascular benefits of SLT, including decreased areas of focal cerebral ischemia, decreased platelet aggregation, and increased free radical scavenging activity (Cong et al 2012; Seto et al 2016).
In a small 1-week randomized placebo-controlled trial, 16 healthy adults randomized to SLT experienced improvements in working memory. In another small study individuals diagnosed with probable vascular dementia randomized to SLT showed significantly greater improvement in cognitive functioning, and a sub-set showed increased blood flow in brain regions associated with memory, auditory and speech processing.
A 12-month human clinical trial on 325 individuals with probable vascular dementia found similar cognitive improvements (Jia et al., 2018). The placebo-controlled randomized study lasted 59 weeks and involved 16 academic centers in China. Findings of this multi-center study support that SLT significantly improves cognition and daily functioning in patients with mild to moderate symptoms of vascular dementia following 6 months of treatment. Neither study reported serious adverse effects related to SLT.
At the time of writing two multi-center phase III trials are ongoing. If findings of these studies confirm the effectiveness of SLT in vascular dementia, this Chinese herbal formula will emerge as an evidence-based herbal treatment of vascular dementia, a neurodegenerative disorder for which there is presently no effective treatment.
Gong, D., J. Xu, and Y. Fan, (2015) “Meta-analysis of clinical trials of oral Chinese herbal prescriptions for treatment of vascular dementia based on mini mental state examination scores,” European Journal of Integrative Medicine, vol. 7, no. 2, pp. 108–117