I remember looking into tDCS quite recently with the thought of boosting intelligence as there are actually consumer devices available right now that claim to be efficacious at increasing attention, memory, etc. Part of that process involved looking at the studies on Google, checking out meta-analysis etc - and what I found was there didn't seem to be enough evidence to conclude anything substantial.

Anyway, picture me staring at a bunch of electrodes on a fancy, high tech startups website and seriously considering whether strapping them to my head was a good idea. I felt kind of ridiculous even entertaining the thought after the scant scientific evidence - especially if the end goal was to increase IQ. Needless to say the device did increase IQ but only through the direct act of not purchasing it.

(I don't mean to be so negative but intelligence doesn't seem that easy to hack.)