I'm not sure if this has been mentioned, but all the same I'll say this. I started taking Singulair several years ago and noticed myself becoming more and more detached from the people around me. I would feel paranoid towards those who were close to me and would have thoughts of shoving people into fences or walls... just a buncha violent ideas would come to me. Then once after I'd run out of a container of Singulair, I began feeling tons more social and friendly. It was like knots in my chest slowly loosened themselves and I could breathe again. My asthma was under control without the medication, but I eventually got another month's worth of Singulair, and suddenly the old thoughts returned except now I developed insomnia to the point where I could hardly fall asleep even with sleep aids. There were nights when I'd sit up in my bed and imagine the worst things in the world about friends in my life and how they'd all turn on me one day. I noticed I had begun having these thoughts after I'd restarted taking Singulair, and stopped immediately. Instead, I chewed on some Ginseng leaves, which I'd boughten on a trip in Thailand every so often (they're green and not pills, and I didn't even chew them everyday) and both my asthma and my allergies seemed to be a thing of the past.
I ran out of the leaves and went back to Singulair, and now I'm having the same paranoid dillusions. But trust me, I've noticed and I'm not going to take any more.
Take my advice though, try Ginseng leaves. Not the roots, the leaves.