I spotted this book in a Waterstone in Amsterdam, but couldn't find it locally. Public libraries FTW!
I was expecting in this book a list of here are things you can do to increase your intelligence. In an ideal world, it would include variations based on gender, age, and weight - something like "do this, this, and that and you'll be smarter." Of course, one's expectations should be kept to a minimum, as life has a way of being, regardless of expectations.
The first part of the book is about defining intelligence (which isn't that easy to do, and we haven't done it well), and the history of defining intelligence, in all its ugly forms of repression and genocide that resulted. We humans really do like to create an us versus them about everything.
After defining intelligence, there were the ethics of what to do with intelligence, is it morally okay to increase one's intelligence? Atheletes are banned from performance enhancing drugs, is the mental realm any different when attempting to get an advantage?
The book did have three suggestions for increasing intelligence: modafanil, electric brain stimulation, and transcranial magnetic stimulation (which is a different way of getting the same as the electrical stimulation, just with a different electricity-producing mechanism, what with moving magnetic fields creating electric currents and all).
Experiments with increasing intelligence suffer the same fate as pretty much all cutting edge science: the bad results are ignored, the good results are emphasized, no one knows if things really work, there are no control studies, people are all different enough that we'll always have warnings, and it's all the wild west with the experimenting.