Botanicals Offer Options to Support Brain Function and Cognitive Health

Many botanical medicines are used to enhance cognitive function, concentration, and memory. The author reviews several substantial scientific and traditional support.

Curcumin from turmeric (Curcuma longa, Zingiberaceae) has been tried in healthy adults to prevent cognitive decline and in those with dementia and cognitive impairment (CI). In a randomized, double-blind, placebo-controlled clinical trial (RCT), 57 community-dwelling elders who took curcumin for six months had less cognitive decline than those who took a placebo. In another RCT, taking daily 400 mg oral curcumin acutely improved sustained attention and working memory vs. placebo and, with four weeks of use, significantly bettered working memory and mood vs. placebo. In an RCT involving individuals with mild-to-moderate Alzheimer’s disease (AD), 2 or 4 g/d curcumin produced no biochemical or clinical effects vs. placebo, nor differences in cognition. This supplement was not shown to be bioavailable at either dose, an issue in some curcumin studies. In a small RCT involving 34 participants with probable/possible AD, all patients took 120 mg/d of a standardized ginkgo (Ginkgo biloba, Ginkgoaceae) extract. They were randomized to three groups to further receive 4 or 1 g/d curcumin or placebo. At six months, there were no significant differences in the Mini-Mental Status Exam (MMSE) scores between groups. Data suggest that bioavailable curcumin may help prevent cognitive decline, but had no benefit in AD. Other cognitive conditions should be studied.

Ginkgo is well known for cognitive support but other botanical extracts have been investigated as well. Boswellia spp. resins’ triterpenic acids may mediate anti-inflammatory effects. Boswellia spp. naturally, act as acetylcholinesterase inhibitors and reduce τ protein levels in astrocytes. In an RCT with 70 healthy elders, an extract standardized for boswellic acids was combined with lemon balm (Melissa officinalis, Lamiaceae) standardized for rosmarinic acid. After one month, memory improved in those who took the herbal tablet vs. placebo. In 80 patients with relapsing-remitting multiple sclerosis, those who took 300 mg/b.i.d. Sudanese frankincense (B. papyrifera) for two months had better visuospatial, but not verbal, memory, or information processing speed vs. placebo.

Over 100 clinical trials have assessed ginkgo in cognitive conditions. A systematic review (SR) and meta-analysis (MA) of RCTs using EGb 761 (Dr. Willmar Schwabe Company; Karlsruhe, Germany), in 2684 people with dementia found significant, dose-dependent benefits for the standardized extract vs. placebo in cognition and activities of daily living (ADLs). In an SR/MA of EGb 761 in CI and dementia, with eight of nine trials in AD, significant benefits of EGb 761 were seen in cognition and ADLs. Patients with neuropsychiatric symptoms had better results at 240 mg/d than all participants, suggesting that EGb 761 may be of special benefit in such patients. In another SR/MA, 2608 people with mild CI or AD received standard drugs or standard plus ginkgo. After 24 weeks of treatment, standard plus ginkgo produced better MMSE scores in CI and AD groups, and, in AD, better ADLs. Concerns about bleeding and drug interactions raised preclinically may limit ginkgo’s use. Limited clinical data suggest that use by healthy adults and elders who concomitantly take aspirin causes no clinically relevant changes in platelet function or aggregation. Further studies of co-use with warfarin are needed. Mixed published results have assessed single combined doses. Ginkgo seems to have little impact on cytochrome P450 enzymes, relieving some concern about other interactions.

Resveratrol, a polyphenol in grapes (Vitis vinifera, Vitaceae), red wine, apples (Malus pumila syn. M. domestica, Rosaceae), and some berries, is an antioxidant/free radical scavenger. It boosts vascular function, lowers circulating insulin-like growth factor-1, and activates sirtuin-1, a neuroprotector. Sirtuin-1 falls in AD, possibly linked to the accumulation of β amyloid and τ proteins. In an RCT, 119 people with mild-to-moderate AD took resveratrol or placebo for a year. The resveratrol group had less disease progression than the placebo. Drug interactions may be a concern as inhibition/induction occurs at CYP450 enzymes.

Culinary and medicinal mushrooms such as lion’s mane (Hericium erinaceus, Hericiaceae), turkey tail (Trametes versicolor, Polyporaceae), and reishi (Ganoderma lucidum, Ganodermataceae) all have some in vivo support for cognitive benefit. Lion’s mane stimulates nerve growth factor, potentially affecting AD pathology. In an RCT in mild CI, it boosted cognition vs. placebo after just eight weeks. Effects decreased four weeks after stopping treatment. Turkey tail’s anti-inflammatory β-glucan polysaccharides and polysaccharopeptides may affect AD pathology. No turkey tail clinical trials have been reported. In a small, brief RCT in confirmed AD, reishi had no cognitive benefits vs. placebo. Turkey tail plus ginkgo had beneficial effects in a mouse model of AD, a finding which deserves follow-up human studies. An SR is pending so new information may be published soon about the rationale, data, and efficacy of using Ganoderma lucidium in cases of AD.

Bacopa (Bacopa monnieri, Plantaginaceae) reduced depression and anxiety and improved word recall in healthy elders. It affects many aspects of cognition and memory. Gotu kola (Centella asiatica, Apiaceae), rich in flavonoids, triterpenoids, and glycosides, improved working memory and mood in healthy elders. In patients with vascular CI after a stroke, 750 or 1000 mg/d for six weeks improved cognition more than 3 mg/d folic acid. Toothed club-moss (Huperzia serrata, Lycopodiceae) produces Huperzine-A (HA), an acetylcholinesterase-inhibiting sesquiterpene alkaloid. In an MA, HA improved cognition vs. placebo. A Cochrane review reached the same conclusion, but both reports noted the poor quality of RCTs to date. Finally, Asian ginseng (Panax ginseng, Araliaceae), with adaptogenic and brain health effects, is mentioned. Reported to have many benefits on cognition in different groups under different conditions, it is often used with other herbs, e.g., ginkgo, for synergistic effects. These and other botanicals offer options to support cognitive health to the world’s aging populations.

Resource:

Lucius K. Nutritional and botanical approaches for cognitive health — Part 2. Altern Complement Ther. October 2019;25(5):257-265. doi: 10.1089/act.2019.29242.klu.