Reviewed: Hassani S, Alipour A, Darvishi Khezri H, et al. Can Valeriana officinalis root extract prevent early postoperative cognitive dysfunction after CABG surgery? A randomized, double-blind, placebo-controlled trial. Psychopharmacology (Berl). March 2015;232(5):843-850.
One of the most commonly performed surgeries in the world is coronary artery bypass graft (CABG). A prevalent complication of the surgery is cognitive dysfunction, which occurs in 20-80% of patients. The authors of this article propose that such cognitive dysfunction is the result of brain damage caused by inflammation and other processes such as embolism (i.e., artery obstruction) and cellular debris picked up and reinfused by the cell salvage processing system. Sleep disruption is another risk factor for post-CABG cognitive dysfunction. Traditionally used as a sedative and anxiolytic, valerian (Valeriana officinalis, Caprifoliaceae) root has been shown to inhibit the inflammatory nuclear factor-kappa B (NF-κB) protein complex, stimulate serotonergic and cholinergic receptors, and improve sleep quality. Therefore, the authors hypothesized that valerian may prevent postoperative cognitive dysfunction in patients undergoing CABG surgery. This randomized, double-blind, placebo-controlled study evaluated the prophylactic effect of valerian root on the occurrence of cognitive dysfunction after CABG surgery.
Men and women aged 30-70 years who were undergoing elective CABG with cardiopulmonary bypass surgery participated in this study conducted at the Mazandaran University of Medical Sciences Mazandaran Heart Center in Sari, Iran. Patients were excluded if they required additional concurrent cardiac surgeries such as valve replacement; were undergoing reoperation; had a history of cerebrovascular disease, alcoholism, or known mental illness; used psychotherapeutic drugs in the previous three months, had hepatic failure, severe pulmonary insufficiency, acute renal failure, previous heart surgeries, or heart failure; were deaf, blind, or unable to speak; had sensitivity to valerian; or had a pH < 7.25 or serum base excess of < −6 mmol/L and coagulopathy (i.e., bleeding disorders).
Patients took capsules containing either placebo or 530 mg dried valerian root extract (Goldaru Company; Isfahan, Iran) every 12 hours, starting one day before surgery and continuing for 60 days post-surgery. The concentration and chemical characteristics of the valerian extract were not reported. The placebo capsules were prepared by emptying valerian capsules and refilling them with wheat (Triticum spp., Poaceae) flour to create a placebo with the same color, texture, taste, and odor as the valerian capsules. All patients had routine anesthesia and CABG with cardiopulmonary bypass surgery. The Mini-Mental State Examination (MMSE) was used to assess cognitive function before surgery, 10 days post-surgery, and two months post-surgery. Scores ≥ 25 were classified as normal, while scores of 21-24 were categorized as mild cognitive dysfunction. Of the 76 patients randomly assigned to receive valerian or placebo, seven in the valerian group and eight in the placebo group were lost to follow-up. No other measures (e.g., degree of inflammation) were obtained that could have provided evidence for alternate mechanisms of cognitive dysfunction.
Mean preoperative MMSE scores were within the normal range (~27) for both groups. In the valerian group (n=31), the mean MMSE score decreased slightly when assessed 10 days post-surgery (26.52) but remained within the normal range and returned to normal (27.45) after two months. In comparison, the mean MMSE score in the placebo group (n=30) decreased significantly when evaluated 10 days after surgery (24.0) and increased slightly to 24.83 after two months, indicating continuing mild cognitive dysfunction. There was a significant downward trend (P<0.05) in all MMSE scores in the placebo group, except for the attention and calculation domains. After adjusting for other variables, analysis using the generalized estimating equation indicated that valerian prophylaxis reduced the odds of cognitive dysfunction compared to the placebo group (odds ratio=0.108; 95% confidence interval [CI], 0.022-0.545). It should be noted that the MMSE is greatly affected by education level and is not very sensitive to mild cognitive impairment.
In summary, the valerian group had a significantly lower incidence of cognitive dysfunction and a greater improvement in cognitive function during the eight weeks after CABG surgery compared to the placebo group (as measured by the MMSE). The authors suggest that patients undergoing CABG surgery may also benefit from the reported anticoronaryspastic, antihypertensive, and antibronchospastic properties of valerian.
Acknowledged limitations of the study were the use of a single subjective instrument to assess cognitive function (completed only once per day), and the relatively small sample size. The authors conclude that “the use of V. officinalis root extract may prevent early postoperative cognitive dysfunction after on-pump CABG surgery.… However, further robust randomized, blinded studies with large sample sizes are required.…” More specific cognitive tests and additional measures (e.g., of inflammation) should have been used as well.
—Heather S. Oliff, PhD