Mh, I managed my first quasi-psychotic panic attack with just one hit of strong sativa. It was really darn freaky. It also included pseudo-hallucinations on the curtains; Imagining a microwave, people inside it, etc. Whatever I thought, would show very real on that curtain - Shaky, twitchy, couldn't breath, freaking out enough to want to go to hospital - Or not just wanting, demanding rather.
Well, got through it without hospital. But, the panic attacks continued without cannabis. Still do and now it's been almost 5 months. Have only smoked two times since then.. Once in a park a careful indica hit - It was relaxed and OK, later I took few hits of hybrid and kaboom, same quasi-psychotic state of utter terror. Best part: We were outside in Rotterdam. And I'm definitely not Dutch. Anyhow, I asked my friends to take me back to the youth hostel (since I couldn't fucking tell which way was left and which was right), going under a bridge was most terrifying experience I've ever had. All those sounds of cars going over was like thunder inside my brain, so real hallucinations and such a complete fear that not even the worst of my psychedelic experiences (and I've had quite irresponsible ones at that) was even near. Because, unlike with psychedelics, I could simply not tell what was real and what was a hallucination. No chance. I was SO sure I get stuck to this eternal horror with no escape.. ..Luckily my body at least was tired as hell (having just staid up whole night in trains) so I managed to quickly get sleep in the hostel. Day after - Good as ever and ready to party (with mere alcohol though. Learned my lesson).
Stopped smoking there, not planning to touch weed again in at least a few year. I'm pretty assured that what I experienced was a real warning sign of underlying mental problems that have to be addressed before I get back on that ride.
I'd otherwise dismiss the experiences as mere extreme panic attacks with sensitiveness to psychedelic affects due to.. well, usage of psychedelics, but the fact how strongly I'd doubt myself - and how I couldn't talk with myself in my head anymore - was simply not right. I'm still very doubtful of my mental health and I've got brain scans coming up and all sort of other funny stuff.
Could say, my subjective experience is, that while I hold a very strong imagination sided with equally capable rational thinking, cannabis really takes away my capability to logic; Allowing my imagination roam too free and feed myself into all sort of semi-psychotic states. Psychedelics don't do that.