Ginkgo supplements are usually taken in the range of 40–200 mg per day. Recently, a meta-analysis of clinical trials have shown Ginkgo to be moderately effective in improving cognition in dementia patients but not preventing the onset of Alzheimer's Disease in normal people.
I have been taking these and they make life so much better I get them from the pound shop. With in a week life was better, not with the pain, but with the foggy brain. Has been years since I've been able to think this clearly. I would tell any if you to take these, there great.