Vit B 3 or Niacin has been know as a cognitive enhancer for a long time. It also has a profound effect on cardiovascular problems, in particular high cholesterol. It is not recommended for people who have high blood pressure, a frequent problem in the older population. To find Niacin in an amount that would be sufficient you could try the Niacitol from Pure Encapsulation. It comes in 1500 mg which is very close to the amount they suggested in the British study.
Information from Bertrand Babinet PhD., LAc.