depends on what you mean by nerd really,
if you mean the social outcast that are interested in things that most people have not heard of, or really into a certain fandom ( starwars, startreck, doctor who, ect. ).
then a lot of things actually. ._.
most of which fall into the whole depression thing
being lonely and shit.
but I mean, people are people, nerd or not.
its not like all nerds are fkn, socially awkward or some shit. they're fucking human.
I'd consider myself quite a nerdy person irl, but I have plenty of friends and I get along with most people, so.