Some evidence of its neuroprotective effects:
http://ginsengres.org/Upload/files/GINSENG/342-353(0015).pdf
Here you can find a thread in neurotalk that shows people's personal experiments with panax ginseng:
http://neurotalk.psychcentral.com/thread183181.html
Of course this is not real science but many of the people report serious improvement after taking panax ginseng.