Just found this- seems to have good info -
Cognitive Function and Brain Health - Scientific Review on Usage, Dosage, Side Effects | Examine.com

Ginseng 75 mg seems very low to me.. it that per day?
Not sure what type you are using but there are differences between types -
[Recommended dosage, active amounts, other details
Panax Ginseng tends to be taken in doses of 200 to 400mg daily for general 'preventative' medicine, although some studies on the inclusion of Panax Ginseng in a multivitamin suggest doses as low as 40mg might be bioactive. The 400mg dose appears to confer most cognitive benefit.

These doses refer to standard 'Ginseng Extract' which is around 2-3% total Ginsenosides, and is a once daily dosage.]
Panax ginseng - Scientific Review on Usage, Dosage, Side Effects | Examine.com