Honestly, besides the horrible potential physical effect it may cause, it DEFINITELY does cause (from my OWN experience and talking to many others who were in a similar situation as me) If extremely potent cannabinoids (which effects the density of the CB1 receptor at a rate exponential than that of THC, a much less potent cannabinoid) cause such severe downregulation of your endocannabinoid system (Endogenous THC-like molecules that effect the CB1 receptor) that it takes MONTHS AND MONTHS (if not years) of non-use to get the same feeling again from marijuana like you used to..
I smoked JWH-018 at the peak of my addiction to it - close to 4-5 times a day for months and months(4-5).. And I swear at the end, my tolerance grew so high that I actually have used an entire gram of 073 and 1/2-3/4g of 018 in ONE day. I ended up convincing myself I had fibromyalgia (severe pains everywhere after quitting, never stopped completely, acts up when I get anxiety, it got so severe they had to prescribe me a neuropathic pain treating medicine (Lyrica). The reason I know it's neuropathic is because opiates don't relieve ANY or much pain at all at reasonable doses (ive tried really high ones too, sometimes it would make the pain worse or maybe just more noticeable?).
It also has given me a edge of paranoia to myself that I never had and severe, severe anxiety issues that weren't nearly as bad beforehand.
If any of you guys are interested, I have talked to many people in similar situations as me and they have confirmed every symptom I have, they had gotten it also (not every single one, but a majority of them. And with the help of multiple people, they have all been confirmed multiple times.. These people describe to me things that they couldn't know concerning what JWH did to me mentally and neurologically unless they went through it too..
STAY AWAY from synthetic cannabinoids, the only good ones are banned anyway (the CP cannabinoids were so sick)