Valerian –  favourable effects on cognitive function

Valerian (Valeriana officinalis) root is well known for its applications in anxiety or insomnia, for which it has been used for thousands of years. Its anti-anxiety (anxiolytic) and sedative effects are mainly attributed to modulation and enhancement of the neurotransmitter GABA (gamma amino butyric acid), which prevents overstimulation of neurons implicated in anxiety and seizure disorders such as epilepsy. Behavioural studies in mice and clinical trials in humans are now expanding our understanding of this notable herb, and revealing other potential applications of relevance to modern day health gaps and needs.

One of these was a behavioural study in aged mice using a water maze performance test, reflective of spatial memory and the ability to cope with stress(1). Administration of valerian or valerenic acid improved the preferential exploration of new objects in a test of object recognition, and enhanced escape latency, swimming speeds, platform crossings, and a spatial preference for the target quadrant. These changes were accompanied by reduced blood levels of the stress-induced adrenal hormone corticosterone, and increased growth of nerve cell precursors (neuroblasts). The results suggest Valerian may help performance in stressful situations and moderate some of the less desirable neurological and physiological changes associated with becoming elderly, such as reduced cognitive function and confidence. This suggests adaptogenic (improved stress-coping ability) and possible nootropic (cognitive enhancing) properties for Valerian.

Other studies reporting anticholinesterase (cholinergic enhancement) activity, thought to be a mechanism of anti-dementia effects, and nerve growth stimulation by various Valerian iridoid and sesquiterpenoid constituents, further support such actions(2, 3).

Potential benefits of Valerian on cognitive function in patients undergoing certain forms of surgery, have also been revealed in a recent clinical trial(4).  Surgery is a stressful event, particularly so for patients with cardiovascular disease undergoing coronary artery bypass surgery. The trial involved 61 patients aged 30-70 years who underwent elective coronary artery bypass graft surgery using cardiopulmonary bypass. Patients received either one valerian capsule containing 530 mg valerian root extract (1,060 mg/daily), or a placebo capsule twice daily for 8 weeks. Cognitive brain function was evaluated prior to surgery then at 10 days and 2 months post surgery, using a test known as “Mini Mental State Examination (MMSE)”.

Following Valerian treatment, the mean MMSE score dropped from 27.03 in the preoperative period to 26.52 at the 10th day, then increased to 27.45 at the 60th day. This return to a normal MMSE was greater than that measured in the placebo group, in which the mean MMSE score fell from 27.37 at  baseline to 24 at day 10, and increased only slightly to 24.83 on the 60th day. This clinical trial provides evidence that Valerian may prevent early postoperative cognitive dysfunction after coronary artery bypass surgery. Given the high burden on the healthcare system and patients of such surgical procedures, further investigations using adjunctive Valerian in this and other forms of surgery, are warranted.

While unlike most sedative drugs Valerian shows little signs of impeding performance or producing an unwanted hangover effect the next day, until recently no study has specifically investigated these potential adverse effects.  Outcomes from a placebo-controlled clinical trial by Californian researchers in which participants received a dose of either 1600mg valerian or placebo then underwent a driving simulator, field sobriety and other tests of visual reactions and performance, are therefore of interest(5). No significant differences were recorded between groups in the simple visual reaction test or sleepiness scales, standardised field sobriety test total and individual test failure rates. This suggests a single dose of 1600mg valerian is unlikely to impair driving performance, in the way that alcohol or sedative drugs are known to do.

Finally, it is noted that Valerian’s reputation as a useful medicine in humans has attracted the attention of U.S. biotechnology researchers recently, who in a quest for new anti-anxiety agents have genetically engineered a strain of the E coli bacteria, to produce substantial quantities of the valerenic acid precursor valerenadiene(6, 7).

 

Refs:

  1. Nam SM et al, Exp Gerontol. 2013;48(11):1369-77
  2. Chen HW et al, 2016;110:142-9.
  3. Dong FW et al, Phytochemistry 2015; 118: 51-60.2015
  4. Hassani S et al, Psychopharmacology (Berl). 2015;232:843-50
  5. Thomas K, Accid Anal Prev 2016; 92:240-244.
  6. Nybo SE et al, J Biotechnol. 2017 Nov 20;262:60-66. doi: 10.1016/j.jbiotec.2017.10.004. Epub 2017 Oct 5.
  7. Ricigliano V et al, Phytochemistry 2016; 125:43-53.
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