Ginseng may improve working memory in young adults

American ginseng significantly improved working-memory performance in a double-blind, placebo-controlled crossover study of healthy young adults presented at the congress.

The effects are distinct from those of Asian ginseng, and suggest that psychopharmacological properties depend on the plant’s ginsenoside profiles, according to a professor of behavior and brain sciences at the Brain Science Institute at Swinburne University, Melbourne.

The previous studies show that Asian ginseng (Panax ginseng) lowers blood glucose, improves cognitive performance, and alleviates the mental fatigue that is associated with intense cognitive processing.

American ginseng (Panax quinquefolious) shares Panax’s glycemic properties, but no previous studies have been conducted to evaluate the capacity of American ginseng to modulate cognitive function. The availability of a highly standardized extract of P. quinquefolious (Cereboost) led us to evaluate its neurocognitive properties.

The randomized crossover trial involved 32 healthy young adults. Subjects were assessed for acute mood, neurocognitive, and glycemic effects of three doses (100, 200 and 400 mg) of American ginseng (standardized to 10.65% ginsenoside). On study days, separated by at least a 7-day wash-out period, participants’ mood, cognitive function and blood glucose were measured at 1, 3, and 6 hours after administration of the ginseng.

To measure cognitive effects, investigation used the COMPASS (Computerized Mental Performance Assessment System) battery, which was developed to include tests that have proved sensitive to nutritional manipulation. COMPASS gauge performance on tasks of attention, working memory, secondary memory and executive function.

The cognitive tests included word presentation, immediate word recall, picture presentation, face presentations, simple reaction times, choice reaction times, four-choice reaction times, Stroop color-word task, N-back task, delayed picture recognition, delayed face recognition, serial sevens subtraction task, and rapid visual information processing or Bakan task.

The study found, for the first time, cognitive and mood enhancement after the administration of American ginseng. Cognition-enhancing effects of the extract were observed across a range of cognitive parameters at a range doses.

The most striking finding was a significant improvement of working-memory performance.

Compared with placebo, all doses of the extract were found to improve some aspect of cognition.

For all doses combined, a significant effects of treatment was observed for choice reaction time accuracy (P=.030), numeric working memory (P=.007), speed of alphabetic working memory (P=.04), and Corsi block score (P=.041).

No significant baseline differences were found between conditions, showing post treatment effects were not attributable to differences in baseline performance.

No differences were observed on blood glucose levels, which rules out the effects of glucose on insulin-mediated mechanisms.